Enhancing Surface Textures and Tribological Properties of GCr15 Bearing Materials through Laser Peen Texturing

Enhancing Surface Textures and Tribological Properties of GCr15 Bearing Materials through Laser Peen Texturing | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Enhancing Surface Textures and Tribological Properties of GCr15 Bearing Materials through Laser Peen Texturing Julius Caesar Puoza, Tainyao Zhang, Abdulai Musah, Awudu Ibrahim, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8354982/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract This study explores the feasibility of employing laser peen texturing to fabricate surface textures on GCr15 bearing steel and evaluates its influence on the material’s mechanical and tribological properties. GCr15 samples were treated using various laser parameters, and the resulting mechanical and tribological properties were analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness testing, X-ray residual strain analysis (LXRD). The results demonstrated that the depth of micro-dimples increased with rising laser energy, pulse width, and impact times. At 12 J single impact, dimple depth reached 38.39 µm, while double impacts at the same energy produced deeper dimples of up to 49.05 µm. A gradient energy strategy (6 J followed by 12 J) further increased dimple depth to 58.61 µm. Microhardness tests indicated that dimple hardness increased with both laser energy and impact times, though it showed a nonlinear relationship with pulse width. Tribological testing revealed a notable improvement in wear resistance, low friction coefficient, with tiny wear scar widths. The wear rate was reduced by 17–21%, as abrasive wear was the dominant wear mechanism with minor oxidative wear present. Overall, laser peen texturing significantly enhanced surface integrity by generating precise micro-dimples, increasing surface hardness, and improving tribological behavior. These results offer valuable theoretical and practical guidance for applying laser peen texturing to improve the performance of bearing steel in advanced engineering and manufacturing applications. GCr15 bearing steel laser peen texturing laser parameters surface textures surface morphology mechanical properties tribological properties Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 1.0 Introduction GCr15 bearing steel represents the primary material used in the first generation of bearing steels, accounting for over 90% of total bearing steel production in China. It is widely employed in the fabrication of spherical bearings 1 , 2 . Bearings play a critical role in various modern industrial sectors, including machinery, agriculture, aerospace, and others 3 – 6 . GCr15 bearing steel exhibits desirable properties such as low friction, excellent wear resistance, and high hardness; however, it suffers from limited plasticity and toughness 7 , 8 . As operating conditions evolve, encompassing extreme temperatures, corrosive environments, vacuum, high speeds, and fluctuating loads, the performance demands on bearing steel continue to rise. It is of great practical significance to improve the fatigue life, wear resistance and other properties of this type of bearing steel material. Recent studies have demonstrated that surface micro-texturing and surface modification effectively enhance the mechanical and tribological properties of metals 9 , 10 . Laser Peen Texturing (LPT), an emerging surface texturing technique, integrates the principles of laser shock peening with laser surface texturing. Laser Peen Texturing forms micro-dimple arrays on metal surfaces by utilizing the mechanical impact of laser-induced shock waves in combination with the surface hardening effect of repeated shock loading. This approach minimizes the introduction of thermally induced residual tensile stresses 11 , extends the fatigue life of materials 12 , maintains the surface integrity of the treated substrate, and significantly improves the tribological performance of the friction interface 13 . At present, there are various surface texture technologies, and the most commonly used is laser thermal etching micro-modeling technology. Wu et al. 14 compared the advantages and disadvantages of laser ablation and laser shock processing to prepare surface micro-textures. The preparation of surface texture by laser shock can effectively avoid the adverse effects of laser thermal effect on the accumulation of molten material at high temperature, which causes the texture edge to bulge. Li et al. 15 . developed a numerical simulation model for Laser Peen Texturing and validated it by comparing the simulated surface deformation with experimental results. They systematically investigated the effects of laser power density and laser spot radius on residual stress, with particular attention to residual stress loss. Their findings indicate that increasing either the laser power density or the laser spot radius leads to a greater thickness of the residual compressive layer in the depth direction. However, this increase also results in a higher magnitude and a larger affected zone of residual stress loss, suggesting a more pronounced residual stress loss phenomenon. Li and others 16 again used laser shock induced surface texture technology to prepare micro-dimple arrays on 7075 aluminum alloy and pure copper samples. By comparing with the micro-dimple array prepared by laser thermal etching, it was found that the surface texture prepared by laser shock had no heat-affected zone, which could better ensure the regularity and uniformity of the surface texture. At the same time, it was found that the geometric physical properties of micro-dimples were closely related to the selection of laser shock process parameters. Cao et al. 13 explores the effects of laser peen texturing (LPT) parameters on surface morphology and tribological performance of E690 high-strength steel. The LPT process, incorporating multiple shocks, was simulated using ABAQUS and validated experimentally. The results indicated that plastic deformation depths increased with shock number, ranging from − 8.82 µm (one shock) to -36.34 µm (four shocks). The simulation closely matched experimental results, with deviations within 3.3%. Tribological results showed that the average friction coefficient decreased with increasing laser peen texture density, reaching a minimum at 20%. The untextured samples exhibited severe abrasive and adhesive wear and the optimal laser peen texture parameters for enhanced wear resistance are a 20% texturing density and three laser shocks. Kumar and his research team 17 explores the effect of laser peening (LP) as a surface modification technique to enhance the tribological properties of Ti–6Al–4V alloy. The result showed that laser peening significantly enhanced surface hardness and residual compressive stress, especially when applied in a water-confining medium. At an optimal fluence of 100 J/cm², hardness increased by 28% in air and 35% in water. Residual stresses rose from 540 MPa to 604 MPa, while wear volume decreased significantly against AISI E52100 steel. The improved tribological behavior, especially in water, highlights laser peening's potential in extending the wear life of biomedical implants. Guo et al. 18 systematically analyzed the influence of varying laser power densities during Laser Shock Peening (LSP) on the tribological behavior of ZK60 magnesium alloy. Their findings revealed that laser shock peening treatment significantly increased surface roughness from 0.32 µm to 9.3 µm, improved microhardness by 39%, and elevated grain count from 1,045 to 1,461. Additionally, laser shock peening reduced the wear rate by a maximum of 17.6%. While adhesive and oxidative wear dominated the untreated specimens, abrasive wear became the primary mechanism in LSP-treated samples. These results confirm that laser shock peening effectively enhances wear resistance, especially under higher normal loads. Li et al. 19 investigated the tribological performance of dimple-textured GCr15 steel surfaces with square arrays of varying geometric parameters, namely dimple diameter, depth, and area density. They conducted friction and wear tests under starved lubrication using a graphene-based suspension in the liquid crystal 4-n-pentyl-4'-cyanobiphenyl (5CB) as the lubricant. Their results demonstrated optimal performance when dimples had a depth of 10 µm, an area density of 8%, and a diameter of 100 µm. Under these conditions, the friction coefficient decreased to 0.031, representing a 32.6% reduction compared to the untextured surface (0.046). This improvement primarily stemmed from enhanced load-bearing capacity, increased lubricant retention, reduced real contact area, and the facilitation of secondary lubrication. In contrast, Yan et al. 20 explored the effect of laser shock peening on the tribological behavior of WC-Ni under seawater lubrication and reported an unexpected deterioration in performance. Unlike previous studies, their results showed that laser shock peening negatively impacted tribological properties. Further analysis attributed this outcome to insufficient improvements in material properties, which failed to compensate for the increased surface roughness induced by laser shock peening treatment. Currently, research on the mechanical properties and tribological performance of GCr15 bearing steel material after laser peen texturing (LPT) remains limited. In this research article, we systematically investigate the effects of key laser peen texturing parameters, namely laser energy, impact time, and pulse width on micro-dimple depth, diameter, and surface hardness. Furthermore, we examine the changes in microstructure, mechanical properties, and tribological behavior of GCr15 bearing steel following the application of laser peen texturing. 2.0: Materials and Methods 2.1: Materials The material selected for the experiment is annealed GCr15 bearing steel. The heat treatment process of GCr15 bearing steel is quenching and tempering. The quenching temperature (845 ± 5) ℃, quenching time 65 min, tempering temperature (165 ± 5) ℃, tempering time 190 min. After quenching and tempering, the hardness of the sample is 61HRC. The chemical composition of GCr15 bearing steel is shown in Table 1 . The quenched specimens were wire cut into rectangular blocks of 20 mm × 20 mm × 7 mm, and the surface of the specimens was ground step by step with SiC sandpaper (400#, 800#, 1200#), and then the surface was polished. The specimens were then immersed in anhydrous ethanol for ultrasonic cleaning for 5 min, and then blown dry. Table 1 Chemical composition of GCr15 bearing steel used in the research. Element C Mn Si P S Cr Ni Mo Cu Fe Wt.% 0.95–1.05 0.15–0.35 0.25–0.45 ≤ 0.025 ≤ 0.025 ≤ 0.10 ≤ 0.30 ≤ 0.30 ≤ 0.25 Bal. 2.2 Laser peen texturing Laser Peen Texturing (LPT) involves irradiating a material surface with a short-pulse, high peak power density laser. This laser pulse causes the surface to absorb energy and generate plasma. A confinement layer restricts the expansion of the plasma, resulting in the formation of a high-pressure shock wave that propagates into the material. The mechanical action of this shock wave induces plastic deformation on the material surface and alters its microstructure. When the peak pressure of the shock wave surpasses the dynamic yield strength of the material, the surface undergoes strain hardening and develops residual compressive stresses, thereby enhancing the material’s mechanical and tribological performance 21 . Laser peen texturing relies on laser-induced localized plastic deformation to fabricate surface textures. Figure 1 (a) illustrates the schematic diagram of the laser peen texturing process, while Fig. 1 (b) presents the dimensions of the treated specimen. The laser peen texturing process employed a Nd:YAG high-energy pulsed laser operating at a wavelength of 1064 nm, with a laser shock energy range of 1–12 J, a pulse width of 10–26 ns, and a repetition frequency of 1–5 Hz. The laser beam featured a circular spot shape with a diameter of 3 mm and was applied with a defocus of -1 mm. The detailed laser peen texturing parameters are listed in Table 2 . To protect the specimen surface from direct thermal damage caused by the high-energy laser, a 0.1 mm thick black tape was applied as both an absorptive and protective layer. Additionally, a 1 mm thick layer of flowing deionized water served as the confinement medium to facilitate effective shock wave generation. Following the laser peen texturing treatment, the specimen underwent ultrasonic cleaning with anhydrous ethanol to remove any residual black tape from the surface. Table 2 Laser peen texturing parameters Parameter Value Laser wavelength (nm) 1064 Spot diameter (mm) 3 Laser energy (J) 6, 8, 10, 12 Pulse width (ns) 10, 14, 18, 22, 26 The surface morphology of the micro-texture and the material’s microstructure were characterized using a 3D non-contact surface profiler (Wyko-NT1100, Veeco, Tucson, AZ) and a field emission scanning electron microscope (SEM) (JSM-7001F, Japan). The three-dimensional topography of the micro-dimples was analyzed to extract contour data, including the diameter and depth of each dimple. Surface hardness in the laser-affected zones was evaluated using a FALCAN-511 Vickers microhardness tester, applying a load of 0.98 N. Measurements were taken at intervals of 0.3 mm, with each point measured three times to obtain an average value. Residual stress distribution along the cross-section of the samples was determined using an X-ray residual stress analyzer (LXRD, PROTO, Canada), operating with nine β angles in the range of -30° to 30°, and a scanning area of 3 mm × 3 mm. 2.3 Tribological Test Tribological performance was assessed using a multifunctional tribometer (MRT-5000, Rtec, USA). Tests were conducted under reciprocating motion with applied normal loads of 200, 300, and 400 N. The stroke length was set to 6 mm, with a test duration of 10 minutes at a frequency of 2 Hz. A GCr15 steel ball with a diameter of 6.5 mm served as the counterface material in a pin-on-block configuration. All tests were performed under starved lubrication conditions using 30# mechanical oil. The density of the laser-induced surface texture was calculated using Eq. ( 1 ). Post-test analysis of the wear scars was performed using SEM (JSM-7001F), including energy-dispersive spectroscopy (EDS) for compositional analysis. The width and depth of the wear scars were quantified using Origin software, and the wear volume (Wv) was computed using Eq. ( 2 ). $${\rho _t}=\frac{{\pi {d^2}}}{{4{L^2}}} \times 100\%$$ 1 where ρt is the areal density, d is the diameter of the micro-dimple, and L is the micro-dimple spacing. $${W_v}=\frac{{1000\Delta V}}{{vt}}$$ 2 Where: ΔV is the wear volume (mm 3 ); v is the reciprocating speed (mm/s); t is the wear time (min); Wv is the volume wear rate (mm 3 /m). 3 Results and discussion 3.1 Influence of laser peen texturing parameters on dimple morphology 3.1.1 Dimple morphology under single shocks at varying energy levels When the laser spot diameter is set to 3 mm and the pulse width to 20 ns, the two-dimensional morphology and contour profiles of single-point dimples vary with different laser energies, as illustrated in Fig. 2 (a and b). Figure 2 (b) demonstrates that increasing the laser energy consistently deepens the dimples, while also altering the uniformity of the dimple bottoms. At a laser energy of 12 J, the dimple reaches its maximum depth of 38.39 µm; however, the bottom surface becomes markedly uneven. This unevenness arises because high shock energy intensifies the rarefaction wave effect produced by the laser-induced plasma shock wave. Consequently, the shock wave exhibits a non-uniform distribution within the impact zone, leading to irregular surface deformation 22 . As laser energy increases, the peak pressure of the laser-induced shock wave also rises. This results in greater plastic deformation of the material and subsequently deeper dimples formed by single-point shock. Figure 2 (c) shows that the dimple diameter remains approximately 3.5 mm across different energy levels, indicating that the dimple diameter primarily depends on the laser spot diameter, with laser energy exerting minimal influence. 3.1.2 Dimple morphology after secondary impact at different energies Under laser impact loading at constant energy, the dimple depth increases with the number of impacts 23 . Using a laser spot diameter of 3 mm and a pulse width of 20 ns, secondary impacts were applied to the samples at varying laser energy levels. Figure 3 (a) presents the resulting dimple morphologies and contour profiles. As shown in Fig. 3 (b), similar to the single-impact case, the dimple diameter primarily depends on the laser spot diameter, while the dimple depth increases significantly under secondary impact due to the accumulation of plastic deformation. Figure 3 (c) indicates that as the laser energy increases, the rate of increase in dimple depth gradually diminishes. At 12 J, the dimple reaches a depth of 49.05 µm after the secondary impact; however, the depth increase becomes less pronounced. This trend suggests that once the laser energy approaches the plastic strain limit threshold of GCr15 steel, the laser peen texturing effect reaches its optimal state. Beyond this energy level, the sample surface no longer undergoes further plastic deformation 24 . The dimple depth resulting from the secondary impact depends not only on the material’s ultimate plastic strain threshold but also on its strain hardening behavior. During the first impact, plastic deformation occurs through slip mechanisms, and dislocation pile-ups readily form under stress. As the applied stress increases, dislocation density rises sharply, leading to significant work hardening. Consequently, after the initial impact, the material surface becomes increasingly resistant to further plastic deformation. During the secondary impact at higher energy, the hardened surface resists the propagation of the laser-induced shock wave, thereby limiting additional impact-induced deformation. 3.1.3 Influence of energy gradient on the dimples Figure 4 presents the dimple morphologies and contour curves resulting from impacts with varying energy gradients. The data clearly show that when the first impact energy is 6 J, increasing the second impact energy to 8, 10, or 12 J leads to a substantial increase in dimple depth. In contrast, when the first impact energy is 8 or 10 J and the second impact energy is 10 or 12 J, the depth still increases but at a reduced rate. Figure 5 (a) further illustrates that when the initial impact energy is 6 J and the second impact energy increases incrementally, the dimple depth increases correspondingly. At a second impact energy of 12 J, the dimple reaches its maximum depth of 58.61 µm. However, when the initial energy is 10 J and the second impact energy is also 12 J, the increase in dimple depth is minimal. This trend suggests that a lower first impact energy results in limited surface hardening, allowing the second, higher-energy impact to induce greater plastic deformation. Conversely, a higher first impact energy brings the material close to its plastic strain limit, causing significant initial plastic deformation and partial grain refinement. As a result, the surface exhibits increased resistance to further plastic deformation, which limits the effectiveness of the second impact in deepening the dimple. As shown in Fig. 5 (b), variations in the energy gradient do not significantly affect the dimple diameter. The dimple diameter remains largely determined by the laser spot diameter, rather than the energy levels used during impact. 3.1.4 Effect of pulse width on dimple morphology Figure 6 displays the surface profile curves following laser shock at constant energy but varying pulse widths. The data indicate that increasing the pulse width at constant energy leads to a gradual deepening of the dimples, with the maximum depth occurring at a pulse width of 26 ns. Figure 7 (a) further demonstrates that at lower energy levels, dimple depth increases markedly as pulse width increases. Specifically, when the impact energy remains below 8 J, the relationship between pulse width and dimple depth becomes more pronounced. This behavior can be attributed to the extended duration of shock wave pressure associated with increased pulse width. At constant energy, a longer pulse duration enhances the time over which pressure acts on the material, promoting more significant plastic deformation and resulting in increased dimple depth. When the impact energy exceeds 10 J, however, increasing the pulse width produces only a marginal increase in depth. This limited response occurs because the material approaches its plastic strain limit, beyond which additional pulse duration has minimal effect on further deformation. These findings suggest that when the laser energy is fixed, extending the pulse width effectively increases dimple depth during secondary impacts, thereby facilitating the formation of micro-textures. Figure 7 (b) shows the corresponding changes in dimple diameter under different pulse widths, indicating that pulse width has little to no effect on dimple diameter, which remains primarily governed by the laser spot diameter. 3.2 Effect of laser peen texturing on mechanical properties of GCr15 bearing steel 3.2.1 Microstructural Analysis Under the pressure of the laser-induced shock wave, the material surface undergoes plastic deformation, leading to the formation of a high dislocation density and refined grains. This process increases the surface hardness and results in the development of a hardened layer. Figure 8 illustrates the microstructural changes in GCr15 steel before and after laser shock. Following laser treatment, the grains near the surface become significantly refined, while the grain size exhibits a gradient distribution along the depth direction, increasing with distance from the surface. This gradient arises because the laser-induced shock wave delivers the highest energy at the surface, where attenuation is minimal. The intense shock energy at the surface causes severe plastic deformation, generating high-density dislocations within the crystal structure. These dislocations evolve into subgrain boundaries, ultimately leading to grain refinement. As the shock wave propagates deeper into the material, its energy diminishes, reducing the degree of plastic deformation. Consequently, the extent of grain refinement decreases with increasing depth. 3.2.2 Hardness under different laser energy combinations Figure 9 illustrates the variation in surface hardness of the samples subjected to different laser energies. As laser energy increases, the surface hardness of the dimples also increases. Figure 9 (a) shows that, compared to the untreated sample, both single and secondary impacts at the same energy result in a significant rise in microhardness. The secondary impact further enhances hardness, although the rate of increase gradually diminishes. At 12 J, the secondary impact produces no notable hardness improvement over the single impact, indicating that the surface of GCr15 steel has reached its hardening saturation point. Figure 9 (b) presents the hardness results for sequential impacts using different energy combinations. When the first impact energy is 6 J and the second impact energy progressively increases, the surface hardness rises significantly. However, when the initial energy is 10 J and the second impact energy increases, the additional gain in hardness is minimal. This behavior occurs because the first laser shock induces plastic deformation and strain hardening on the sample surface, increasing its dynamic yield strength. As a result, subsequent laser shocks require more energy to generate further plastic deformation. When the total shock wave energy remains constant, the proportion of energy effectively contributing to plastic deformation decreases, thereby limiting further increases in surface hardness. 3.2.2 Hardness under different laser pulse width Figure 10 presents the hardness variations of samples subjected to laser peen texturing at different energy levels and pulse widths. Across all energy levels, the microhardness follows a consistent trend with increasing pulse width. Compared to the untreated samples, laser shock significantly enhances the surface microhardness. When the energy remains constant, the microhardness initially decreases with increasing pulse width, then increases again. This trend can be explained by the relationship between pulse width and shock wave peak pressure. According to the shock wave pressure equation, increasing the pulse width at constant energy results in a reduction in peak pressure. At shorter pulse widths of 10 ns, the high peak pressure dominates the deformation process, leading to increased hardness. However, as the pulse width increases, the peak pressure decreases and the shock duration becomes the dominant factor. Extended shock duration promotes more extensive plastic deformation, increases dislocation density, and ultimately leads to a renewed increase in surface hardness. Thus, the microhardness exhibits a characteristic trend of initial decline followed by a rise as the pulse width increases under constant energy conditions. 3.3 Mechanism of laser peen texturing Laser peen texturing (LPT) employs a short-pulse, high peak power density laser to irradiate the material surface, generating a high-pressure shock wave that modifies surface properties and enhances material strength. Figure 11 illustrates the mechanism of micro-dimple fabrication through LPT. The process initiates with full-coverage, overlapping laser shocks applied to the untreated specimen, resulting in a hardened surface layer with refined grains and significantly increased hardness. Subsequently, a second laser shock, applied using adjusted process parameters, targets the pre-strengthened surface. This controlled energy input facilitates the formation of a regular array of micro-dimples. During the second stage, the shock wave pressure exceeds the material’s dynamic yield strength, causing localized plastic deformation. As the shock load dissipates, residual plastic strain leads to the formation of surface depressions (micro-dimples) with well-defined depths. This two-step approach produces a surface that integrates enhanced mechanical properties with functional micro-texturing. Following dimple formation, surface grinding removes the ripples induced by laser processing, thereby reducing surface roughness. The final surface exhibits a refined micro-dimple array with low roughness and improved mechanical integrity, effectively combining structural reinforcement with functional surface patterning. 3.4: Tribological characteristic 3.4.1 Effect of laser peen texturing on friction coefficient Figure 12 presents the friction coefficients of both untreated and laser peen textured (LPT) specimens under varying loads. As shown in Figs. 12 (a) and 12(b), after a brief running-in period, the friction coefficient of each sample stabilizes and fluctuates within a limited range. At a load of 200 N, the untreated specimen exhibits an average friction coefficient of 0.428, while the LPT-treated specimen shows a significantly lower value of 0.335. As the load increases to 300 N, the average friction coefficient decreases to 0.309 for the untreated sample and 0.297 for the LPT-treated one. At the maximum load of 400 N, the coefficients further decline to 0.274 and 0.268, respectively. This decreasing trend in friction coefficient with increasing load arises from the elastic-plastic nature of the contact between the mating surfaces. While the friction force is proportional to the real contact area, the actual contact area of metallic surfaces increases at a slower rate than the applied load. Consequently, under dry friction conditions, the friction coefficient tends to decrease as the load increases 25 , 26 . Under all tested loads, the LPT-treated specimens consistently exhibit lower friction coefficients than the untreated ones. This reduction is attributed to the significant grain refinement induced by laser peen texturing, which increases surface hardness by impeding dislocation motion. Since LPT minimally affects surface roughness, the enhanced mechanical properties, rather than changes in surface texture, primarily contribute to the observed decrease in friction. 3.4.2 Effect of laser peen texturing on wear properties of GCr15 bearing steel Figure 13 illustrates the three-dimensional morphology of the wear scars on specimens before and after laser peen texturing under varying loads. Under a 200 N load (Figs. 13 a and 13 d), the untreated specimen exhibits a wear scar width of 1,056.57 µm and a depth of 3.18 µm, while the LPT-treated specimen shows a narrower wear scar of 724.23 µm and a shallower depth of 2.43 µm. At 300 N (Figs. 13 b and 13 e), the untreated specimen's wear scar widens to 1,131.52 µm with a depth of 3.35 µm, whereas the LPT-treated specimen maintains a smaller width and depth of 809.73 µm and 2.47 µm, respectively. Under the highest load of 400 N (Figs. 13 c and 13 f), the untreated specimen exhibits a wear scar width of 1,332.61 µm and a depth of 4.17 µm, while the LPT-treated specimen shows a reduced width of 875.47 µm and a depth of 2.80 µm. In all cases, the LPT-treated specimens demonstrate smaller wear scar widths and depths compared to the untreated counterparts under the same load conditions. Additionally, both untreated and LPT-treated specimens experience an increase in wear scar width and depth as the applied load increases. These results indicate that laser peen texturing effectively enhances wear resistance by reducing material loss under tribological stress. Figure 14 presents the wear rates of specimens subjected to varying loads before and after laser peen texturing (LPT). The data reveal that as the applied load increases, the wear rates of both untreated and LPT-treated specimens increase correspondingly. However, under identical loading conditions, the LPT-treated specimens consistently exhibit lower wear rates than their untreated counterparts. Specifically, for untreated specimens, the average wear rate increases from 620.15 mm³/m at 200 N to 694.16 mm³/m at 300 N, and reaches 809.80 mm³/m at 400 N. In contrast, LPT-treated specimens demonstrate wear rates of 486.65 mm³/m at 200 N, 570.48 mm³/m at 300 N, and 651.07 mm³/m at 400 N. These results indicate that laser peen texturing reduces the wear rate by 21.53%, 17.82%, and 19.60% at loads of 200 N, 300 N, and 400 N, respectively, compared to the untreated specimens. The increase in wear rate with load is attributed to the proportional relationship between frictional force and the actual contact area, which expands as the load increases. The improved wear resistance of LPT-treated specimens primarily arises from grain refinement induced by high-strain-rate plastic deformation during laser peen texturing. Finer grains enhance resistance to plastic deformation. Furthermore, laser peen texturing introduces deep compressive residual stresses in the subsurface region, which are gradually released during sliding contact, thereby impeding further plastic deformation and material removal. Collectively, these mechanisms contribute to the reduction in wear rate and the enhancement of wear resistance after laser peen texturing. Table 3 presents the elemental spectra of the wear morphology of GCr15 bearing steel under different loads, both before and after laser peen texturing (LPT). The data show that the degree of oxidation on both sides of the wear scar increases with rising load, while oxidation in the central region remains minimal. The oxygen content in regions 2 and 4 of the untreated sample exceeds that in regions 7 and 9 of the LPT-treated sample, indicating a more pronounced oxidation in the untreated specimen. Figure 15 illustrates the wear morphologies of the samples under varying loads before and after laser peen texturing. At a load of 200 N, the untreated sample exhibits prominent surface spalling, along with minor plowing and oxidation. The dominant wear mechanism in this condition is adhesive wear, accompanied by limited abrasive and oxidative wear (Fig. 15 a). When the load increases to 300 N, the severity of both adhesion and oxidation rises, indicating a combined adhesive and oxidative wear mechanism (Fig. 15 b). At 400 N, the surface is extensively covered with oxidized debris and wear spots, further intensifying adhesive and oxidative wear (Fig. 10 c). In contrast, the LPT-treated sample under a 200 N load shows only small spalling dimples and shallow plowing grooves, suggesting milder wear (Fig. 15 d). As the load increases, the size of the spalling dimples and the prominence of plowing grooves also increase. An oxide film begins to form on the wear scar surface at higher loads (Fig. 15 e). At 400 N, the LPT-treated surface displays slightly more adhesion, deeper plowing grooves, and intensified oxidation (Fig. 10 f). The untreated samples exhibit a wear mechanism dominated by adhesive and oxidative wear, which becomes more severe as the load increases. Conversely, the LPT-treated samples primarily experience abrasive wear, with only minor contributions from adhesive and oxidative mechanisms. As the load increases, abrasive wear becomes more pronounced. Compared to the untreated specimens, the LPT-treated surfaces exhibit significantly reduced adhesion and oxidation, indicating a shift in the wear mechanism toward abrasion. This improved wear resistance in LPT-treated samples results from the refinement of surface grains and the introduction of high residual compressive stress, which enhance the yield strength and inhibit crack initiation. Under increasing load and friction, the tangential force rises, promoting surface fragmentation and debris adhesion, thereby exacerbating adhesive wear. Simultaneously, the increase in frictional heat elevates the surface temperature, intensifying oxidation. However, the refined microstructure and induced residual stress from laser peen texturing significantly mitigate spalling and oxidation, resulting in superior wear performance compared to untreated samples. Table 3 Wear morphology energy spectrum of GCr15 bearing steel before and after LPT under different loads Area Fe C O Cr 1 87.0 7.7 3.7 1.6 2 69.0 11.2 18.3 1.5 3 87.5 10.1 1.0 1.4 4 59.0 7.0 32.8 1.1 5 89.0 6.7 2.4 1.8 6 89.2 7.1 2.2 1.4 7 78.0 8.2 12.5 1.3 8 87.0 6.9 4.6 1.5 9 73.0 7.5 18.0 1.5 10 88.3 7.0 3.2 1.4 Figure 16 presents the residual stress distributions obtained via LXRD measurements for both untreated and laser peen textured (LPT) samples under varying loads. The untreated sample, which did not undergo laser peen texturing prior to testing, exhibits significant compressive residual stress within the central region of the wear scar following friction and wear. As the applied load increases, the average residual stress in the wear scar area also increases. Specifically, as shown in Figs. 16 (a) and 16(c), the residual stress rises from − 653 MPa under a 200 N load to -739 MPa at 300 N. Under a 400 N load (Fig. 16 (e)), the compressive stress further increases to -802 MPa. In contrast, the regions on either side of the wear scar, which did not experience frictional contact, retain much lower residual stress levels ranging from − 8 MPa to -40 MPa values attributed to residual stress from machining processes. This development of compressive residual stress under dry sliding conditions stems from severe plastic deformation in the surface layer caused by frictional loading. The GCr15 steel ball, acting as the counterface, induces a Hertzian stress field near the contact area, thereby generating residual compressive stress in the surface layer of the sample 27 , 28 . In the case of LPT-treated samples, Figs. 16 (b), 16(d), and 16(f) reveal a markedly different residual stress distribution. Under a 200 N load, the average residual stress in the wear scar center is approximately − 632 MPa, while the unaffected side regions retain significantly higher compressive stresses of about − 1,100 MP, a difference of 468 MPa. At 300 N, the stress in the wear scar area increases slightly to -635 MPa, while the surrounding areas maintain an average stress of -1,050 MPa, resulting in a difference of 415 MPa (Fig. 16 (d)). Under a 400 N load, the wear scar region reaches − 738 MPa, and the adjacent regions remain around − 1,100 MPa, reducing the difference to 362 MPa (Fig. 16 (f)). These findings indicate that the compressive residual stress layer introduced by laser peen texturing is initially unstable and gradually relaxes when subjected to external stress or elevated temperature during friction and wear processes 29 . The residual compressive stress counteracts the tensile stresses generated on the surface during wear, thereby delaying or suppressing the initiation and propagation of fatigue cracks. Moreover, this residual stress layer also resists plastic deformation induced by the Hertzian contact stress, thereby limiting structural damage to the surface. As shown in Figs. 16 (b), 16(d), and 16(f), the residual stress distribution after the combined effects of LPT and friction reveals a convex-shaped stress profile across the wear scar, indicating a decrease in compressive stress specifically within the worn region. In summary, laser peen texturing (LPT) enhances the wear resistance of GCr15 bearing steel through both microstructural refinement and the introduction of beneficial residual stresses. From a microstructural perspective, the high-energy, high-density plasma shock waves generated during laser peen texturing induce intense plastic deformation in the surface and subsurface layers of the material. This deformation significantly increases the dislocation density, resulting in dislocation entanglement and the refinement of martensitic grains into a nanocrystalline structure. These microstructural changes contribute to a notable increase in surface hardness, thereby improving the material's resistance to wear. From the perspective of residual stress, the compressive stresses introduced by LPT play a crucial role during the friction and wear process. As these residual stresses are gradually released, they impede plastic deformation in the surface layer, thereby mitigating structural degradation. Moreover, the compressive residual stress promotes crack closure, elevates the critical stress intensity factor required for crack propagation, and reduces the amplitude of alternating tensile stresses acting on the material. When the depth of the LPT-induced affected layer exceeds the depth of microcrack formation, the reduction in average tensile stress effectively slows crack growth 30 . Consequently, the wear scar area exhibits a lower residual compressive stress compared to the untreated regions, indicating that the material absorbed part of the stress during wear. This stress redistribution ultimately enhances the wear resistance of the material by reducing surface damage and delaying crack propagation. 4.0: Conclusions This research explores the feasibility and processes for producing micro-dimples on GCr15 bearing steel through laser peen texturing. The study examines the impact of various laser peen texturing parameters on the morphology of the micro-dimples. Additionally, it explores the effects of laser peen texturing on the mechanical and tribological properties of GCr15 bearing steel. Based on the results and discussion, the following key conclusions were drawn: Laser energy, pulse width, and the number of impacts significantly influence the depth of surface micro-dimples induced by laser peen texturing (LPT). As these parameters increase, the depth of the micro-dimples correspondingly increases. In contrast, the diameter of the micro-dimples depends solely on the diameter of the laser spot. Laser peen texturing effectively strengthens the surface of GCr15 steel. Following the enhancement of surface hardness, it becomes possible to generate surface textures with defined depth by applying Laser peen texturing parameters involving higher energy or extended interaction time. Under the combined influence of optimized Laser peen texturing conditions, the process simultaneously strengthens the material and forms micro-dimples with controlled depth. The selection of composite process parameters depends on the desired degree of surface strengthening and the required depth of micro-dimple formation. By adjusting key parameters such as laser energy and pulse width, researchers can tailor the formation of micro-dimples with varying depths on the surface of the laser-shock-treated specimens. Laser peen texturing significantly enhances the tribological performance of GCr15 steel. After treatment, the average coefficient of friction decreases, and the width and depth of the wear scars reduce notably. The wear rate declines by approximately 17% to 21%. The primary wear mechanism remains abrasive, accompanied by a degree of adhesive and oxidative wear, indicating a marked improvement in wear resistance. The evolution of the surface stress field during the friction and wear process results from the gradual release of residual compressive stress introduced by LPT. This compressive stress restricts the plastic deformation of the surface layer. Furthermore, a deep and extensive residual compressive stress layer effectively suppresses the initiation and propagation of cracks, thereby enhancing the overall wear resistance of the material. Declarations Acknowledgment I acknowledge the support of Sunyani Technical University in the use of library resources in conducting this research. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Declaration of Competing Interest The authors declare that they have no competing financial interests or personal relationships that could have influenced the work reported in this paper. Data availability statement Data sharing not applicable to this article as no datasets were generated or analysed during the current study Credit contribution statement Author 1: Julius Caesar Puoza Conceptualized the study, designed the experimental methodology, supervised laboratory activities, and contributed to data interpretation and manuscript writing. Author 2: Tainyao Zhang Conducted the experiments, performed advanced characterization (e.g., SEM, XRD, microhardness), collected and curated the data, performed formal analysis, and prepared the initial draft of the manuscript Author 3: Abdulai Musah Supported experimental setup and optimization, contributed to materials preparation and characterization, validated the results and assisted in data analysis. Author 4: Awudu Ibrahim Contributed to statistical analysis, data visualization, and refinement of the discussion section, and reviewed the manuscript for technical accuracy. Author 5: Yakubu Kuusana Provided project supervision, secured resources, guided the overall research direction, and critically revised the manuscript for intellectual content. All authors: Reviewed the final manuscript and approved it for publication. References Bhadeshia, H.K.D.H.: Steels for bearings. Prog. Mater. 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Int. 151 , 106537 (2020). https://doi.org/10.1016/j.triboint.2020.106537 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 25 Jan, 2026 Reviews received at journal 14 Jan, 2026 Reviewers agreed at journal 20 Dec, 2025 Reviews received at journal 18 Dec, 2025 Reviewers agreed at journal 18 Dec, 2025 Reviewers agreed at journal 18 Dec, 2025 Reviewers invited by journal 18 Dec, 2025 Editor assigned by journal 18 Dec, 2025 Submission checks completed at journal 18 Dec, 2025 First submitted to journal 13 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8354982","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":563480489,"identity":"5bc56909-8277-437a-b937-f0662915dbe0","order_by":0,"name":"Julius Caesar 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09:10:14","extension":"xml","order_by":35,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":114272,"visible":true,"origin":"","legend":"","description":"","filename":"e7c9c2ffb3ea47109cdaed8bd9ae98811structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/568eb0d0601c5e6d97f1d388.xml"},{"id":98777759,"identity":"f5d2c591-c236-4632-93fc-7af43173ed47","added_by":"auto","created_at":"2025-12-22 12:28:25","extension":"html","order_by":36,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":125722,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/d72d221c83701992a0c157bc.html"},{"id":98751460,"identity":"8c8b9bdb-f6b6-4129-8e23-334b74dcec98","added_by":"auto","created_at":"2025-12-22 09:10:13","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":411472,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of laser peen texturing of (a) micro-texture and (b) specimen dimension\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/f4ee1f3e25ebb081fa8cfbd5.png"},{"id":98751486,"identity":"268aab2e-5427-4571-bf37-2f605afe796c","added_by":"auto","created_at":"2025-12-22 09:10:15","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":188011,"visible":true,"origin":"","legend":"\u003cp\u003eEvolution of micro-dimples under single laser impact at varying energy levels: (a) surface morphology of the micro-dimples, (b) contour profiles of the micro-dimples, and (c) variation in dimple depth and diameter.\u003c/p\u003e","description":"","filename":"2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/643d5b1ae223fa0024e2273d.jpeg"},{"id":98751482,"identity":"f62dae02-03a7-4050-98eb-10d16d03a634","added_by":"auto","created_at":"2025-12-22 09:10:14","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":187116,"visible":true,"origin":"","legend":"\u003cp\u003eEvolution of micro-dimples under double laser impact at varying energy levels: (a) surface morphology of the micro-dimples, (b) contour profiles of the micro-dimples, and (c) variation in dimple depth and diameter.\u003c/p\u003e","description":"","filename":"3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/e7ff80e9d1f01e70f5172e0f.jpeg"},{"id":98751452,"identity":"bf926a58-5de0-4205-b653-9da336677e92","added_by":"auto","created_at":"2025-12-22 09:10:12","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":277522,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in micro-dimples subjected to different energy gradients: (a) surface morphology of the micro-dimples; (b) profile curves of the micro-dimples.\u003c/p\u003e","description":"","filename":"4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/63abdcbcdc5adca42fdd2605.jpeg"},{"id":98751492,"identity":"d3fc13d3-5776-4576-abdf-14d4cabcd254","added_by":"auto","created_at":"2025-12-22 09:10:15","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":2490514,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in depth and diameter of micro-dimples formed under different energy gradients: (a) depth of the micro-dimples; (b) diameter of the micro-dimples.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/e944ecb9dfe7cbed59d1dd3a.png"},{"id":98777744,"identity":"01e2861f-6b9a-42ef-8145-acbcf1e7c0da","added_by":"auto","created_at":"2025-12-22 12:28:24","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":243802,"visible":true,"origin":"","legend":"\u003cp\u003eprofile curves of micro-dimples under different pulse widths for (a) 6J, (b) 8 J, (c) 10J and (d) 12J\u003c/p\u003e","description":"","filename":"6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/2944f5ff97591001579fa9be.jpeg"},{"id":98777735,"identity":"dd8963fd-7808-4dbc-8514-038ca7f3c166","added_by":"auto","created_at":"2025-12-22 12:28:24","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":2723902,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in depth and diameter of micro-dimples under different impact parameters: (a) depth of the micro-dimples; (b) diameter of the micro-dimples.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/2515ed7861e20dc74d9cc5bd.png"},{"id":98751481,"identity":"143633e8-c487-43ba-bbf3-12b077c92f57","added_by":"auto","created_at":"2025-12-22 09:10:14","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":4367644,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructural changes of GCr15 steel (a) before and (b) after laser peen texturing\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/b36374067a0756268fb52c0d.png"},{"id":98751399,"identity":"1d5223d5-10d6-41b1-8782-7a638d709cc3","added_by":"auto","created_at":"2025-12-22 09:10:09","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":831947,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in surface hardness under different energy conditions: (a) comparison between single and double impacts; (b) effects of energy gradient impacts\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/d0f2b13ddb53deb3cffec3c1.png"},{"id":98779604,"identity":"0a03e382-c5b9-4976-9798-a037878f587a","added_by":"auto","created_at":"2025-12-22 12:30:31","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1279739,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in microhardness with different impact pulse widths: (a) 6J, (b) 8J, (c) 10J and (d) 6J\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/1c39f433ca47a588ef8038fb.png"},{"id":98751329,"identity":"16f17583-0f3c-4aea-9a97-17f5f176fb82","added_by":"auto","created_at":"2025-12-22 09:10:07","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":603202,"visible":true,"origin":"","legend":"\u003cp\u003eMechanism of laser peen texturing of micro-dimples\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/997283de79d239f3289d9b9f.png"},{"id":98779528,"identity":"2a84ab80-9a32-4e4b-9baa-ec9337c8621a","added_by":"auto","created_at":"2025-12-22 12:30:26","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":628885,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical presentation of the coefficient of friction for GCr15 bearing steel under varying loads for (a) untreated sample, (b) LPT-treated sample.\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/fa0b19cb2b6a5888e308da3c.png"},{"id":98751332,"identity":"f8a5294a-053a-4158-8ffe-3849dbbbf0ef","added_by":"auto","created_at":"2025-12-22 09:10:07","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":2088995,"visible":true,"origin":"","legend":"\u003cp\u003eIllustration of three-dimensional morphology of the wear scars on GCr15 bearing steel under varying loads for: (a) untreated sample-200 N; (b) untreated sample-300 N; (c) untreated sample-400 N; (d) LPT sample-200 N; e) LPT sample-300 N; (f) LPT sample-400 N.\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/7702823d3f4aefae6110e3ad.png"},{"id":98751502,"identity":"476c9611-5ab2-453c-ad04-53ffeb12b01f","added_by":"auto","created_at":"2025-12-22 09:10:15","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":2846881,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical presentation of the wear rate under different loads of GCr15 bearing steel before and after laser peen texturing\u003c/p\u003e","description":"","filename":"14.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/3674d75db456b3026dd8f5e5.png"},{"id":98777445,"identity":"27a1b6e3-3ed3-402d-a45d-0e74f6adb41e","added_by":"auto","created_at":"2025-12-22 12:27:07","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":5327562,"visible":true,"origin":"","legend":"\u003cp\u003eWear morphology of GCr15 bearing steel under different loads for: (a) untreated sample-200 N; (b) untreated sample-300 N; (c) untreated sample-400 N; (d) LPT sample-200 N; (e) LPT sample-300 N; (f) LPT sample-400 N\u003c/p\u003e","description":"","filename":"15.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/3e2b866625672d098df1a463.png"},{"id":98751462,"identity":"e4b9347b-bc22-49f8-89e9-66fa2d8f1386","added_by":"auto","created_at":"2025-12-22 09:10:14","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":2039297,"visible":true,"origin":"","legend":"\u003cp\u003eResidual stress diagrams of GCr15 bearing steel before and after LPT under different loads: (a) untreated sample-200 N; (b) LPT sample-200 N; (c) untreated sample-300 N; (d) LPT sample-300 N; (e) untreated sample-400 N; (f) LPT sample-400 N\u003c/p\u003e","description":"","filename":"16.png","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/17ab9e993e238a7bf38beafc.png"},{"id":98784026,"identity":"d311c7ae-c459-46a2-81e6-a8f228beb009","added_by":"auto","created_at":"2025-12-22 12:42:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":26396511,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8354982/v1/45fe7bd0-aa7d-4053-9ddc-6ef7fd18d850.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Enhancing Surface Textures and Tribological Properties of GCr15 Bearing Materials through Laser Peen Texturing","fulltext":[{"header":"1.0 Introduction","content":"\u003cp\u003eGCr15 bearing steel represents the primary material used in the first generation of bearing steels, accounting for over 90% of total bearing steel production in China. It is widely employed in the fabrication of spherical bearings \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Bearings play a critical role in various modern industrial sectors, including machinery, agriculture, aerospace, and others \u003csup\u003e\u003cspan additionalcitationids=\"CR4 CR5\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. GCr15 bearing steel exhibits desirable properties such as low friction, excellent wear resistance, and high hardness; however, it suffers from limited plasticity and toughness \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. As operating conditions evolve, encompassing extreme temperatures, corrosive environments, vacuum, high speeds, and fluctuating loads, the performance demands on bearing steel continue to rise. It is of great practical significance to improve the fatigue life, wear resistance and other properties of this type of bearing steel material.\u003c/p\u003e \u003cp\u003eRecent studies have demonstrated that surface micro-texturing and surface modification effectively enhance the mechanical and tribological properties of metals \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Laser Peen Texturing (LPT), an emerging surface texturing technique, integrates the principles of laser shock peening with laser surface texturing. Laser Peen Texturing forms micro-dimple arrays on metal surfaces by utilizing the mechanical impact of laser-induced shock waves in combination with the surface hardening effect of repeated shock loading. This approach minimizes the introduction of thermally induced residual tensile stresses \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, extends the fatigue life of materials \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e, maintains the surface integrity of the treated substrate, and significantly improves the tribological performance of the friction interface \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. At present, there are various surface texture technologies, and the most commonly used is laser thermal etching micro-modeling technology. Wu et al. \u003csup\u003e14\u003c/sup\u003e compared the advantages and disadvantages of laser ablation and laser shock processing to prepare surface micro-textures. The preparation of surface texture by laser shock can effectively avoid the adverse effects of laser thermal effect on the accumulation of molten material at high temperature, which causes the texture edge to bulge. Li et al. \u003csup\u003e15\u003c/sup\u003e. developed a numerical simulation model for Laser Peen Texturing and validated it by comparing the simulated surface deformation with experimental results. They systematically investigated the effects of laser power density and laser spot radius on residual stress, with particular attention to residual stress loss. Their findings indicate that increasing either the laser power density or the laser spot radius leads to a greater thickness of the residual compressive layer in the depth direction. However, this increase also results in a higher magnitude and a larger affected zone of residual stress loss, suggesting a more pronounced residual stress loss phenomenon. Li and others \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e again used laser shock induced surface texture technology to prepare micro-dimple arrays on 7075 aluminum alloy and pure copper samples. By comparing with the micro-dimple array prepared by laser thermal etching, it was found that the surface texture prepared by laser shock had no heat-affected zone, which could better ensure the regularity and uniformity of the surface texture. At the same time, it was found that the geometric physical properties of micro-dimples were closely related to the selection of laser shock process parameters. Cao et al. \u003csup\u003e13\u003c/sup\u003e explores the effects of laser peen texturing (LPT) parameters on surface morphology and tribological performance of E690 high-strength steel. The LPT process, incorporating multiple shocks, was simulated using ABAQUS and validated experimentally. The results indicated that plastic deformation depths increased with shock number, ranging from \u0026minus;\u0026thinsp;8.82 \u0026micro;m (one shock) to -36.34 \u0026micro;m (four shocks). The simulation closely matched experimental results, with deviations within 3.3%. Tribological results showed that the average friction coefficient decreased with increasing laser peen texture density, reaching a minimum at 20%. The untextured samples exhibited severe abrasive and adhesive wear and the optimal laser peen texture parameters for enhanced wear resistance are a 20% texturing density and three laser shocks. Kumar and his research team \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e explores the effect of laser peening (LP) as a surface modification technique to enhance the tribological properties of Ti\u0026ndash;6Al\u0026ndash;4V alloy. The result showed that laser peening significantly enhanced surface hardness and residual compressive stress, especially when applied in a water-confining medium. At an optimal fluence of 100 J/cm\u0026sup2;, hardness increased by 28% in air and 35% in water. Residual stresses rose from 540 MPa to 604 MPa, while wear volume decreased significantly against AISI E52100 steel. The improved tribological behavior, especially in water, highlights laser peening's potential in extending the wear life of biomedical implants.\u003c/p\u003e \u003cp\u003eGuo et al. \u003csup\u003e18\u003c/sup\u003e systematically analyzed the influence of varying laser power densities during Laser Shock Peening (LSP) on the tribological behavior of ZK60 magnesium alloy. Their findings revealed that laser shock peening treatment significantly increased surface roughness from 0.32 \u0026micro;m to 9.3 \u0026micro;m, improved microhardness by 39%, and elevated grain count from 1,045 to 1,461. Additionally, laser shock peening reduced the wear rate by a maximum of 17.6%. While adhesive and oxidative wear dominated the untreated specimens, abrasive wear became the primary mechanism in LSP-treated samples. These results confirm that laser shock peening effectively enhances wear resistance, especially under higher normal loads. Li et al. \u003csup\u003e19\u003c/sup\u003e investigated the tribological performance of dimple-textured GCr15 steel surfaces with square arrays of varying geometric parameters, namely dimple diameter, depth, and area density. They conducted friction and wear tests under starved lubrication using a graphene-based suspension in the liquid crystal 4-n-pentyl-4'-cyanobiphenyl (5CB) as the lubricant. Their results demonstrated optimal performance when dimples had a depth of 10 \u0026micro;m, an area density of 8%, and a diameter of 100 \u0026micro;m. Under these conditions, the friction coefficient decreased to 0.031, representing a 32.6% reduction compared to the untextured surface (0.046). This improvement primarily stemmed from enhanced load-bearing capacity, increased lubricant retention, reduced real contact area, and the facilitation of secondary lubrication. In contrast, Yan et al. \u003csup\u003e20\u003c/sup\u003e explored the effect of laser shock peening on the tribological behavior of WC-Ni under seawater lubrication and reported an unexpected deterioration in performance. Unlike previous studies, their results showed that laser shock peening negatively impacted tribological properties. Further analysis attributed this outcome to insufficient improvements in material properties, which failed to compensate for the increased surface roughness induced by laser shock peening treatment.\u003c/p\u003e \u003cp\u003eCurrently, research on the mechanical properties and tribological performance of GCr15 bearing steel material after laser peen texturing (LPT) remains limited. In this research article, we systematically investigate the effects of key laser peen texturing parameters, namely laser energy, impact time, and pulse width on micro-dimple depth, diameter, and surface hardness. Furthermore, we examine the changes in microstructure, mechanical properties, and tribological behavior of GCr15 bearing steel following the application of laser peen texturing.\u003c/p\u003e"},{"header":"2.0: Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1: Materials\u003c/h2\u003e \u003cp\u003eThe material selected for the experiment is annealed GCr15 bearing steel. The heat treatment process of GCr15 bearing steel is quenching and tempering. The quenching temperature (845\u0026thinsp;\u0026plusmn;\u0026thinsp;5) ℃, quenching time 65 min, tempering temperature (165\u0026thinsp;\u0026plusmn;\u0026thinsp;5) ℃, tempering time 190 min. After quenching and tempering, the hardness of the sample is 61HRC. The chemical composition of GCr15 bearing steel is shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The quenched specimens were wire cut into rectangular blocks of 20 mm \u0026times; 20 mm \u0026times; 7 mm, and the surface of the specimens was ground step by step with SiC sandpaper (400#, 800#, 1200#), and then the surface was polished. The specimens were then immersed in anhydrous ethanol for ultrasonic cleaning for 5 min, and then blown dry.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eChemical composition of GCr15 bearing steel used in the research.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElement\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSi\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCr\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eNi\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eMo\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eFe\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWt.%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.95\u0026ndash;1.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.15\u0026ndash;0.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.25\u0026ndash;0.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eBal.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Laser peen texturing\u003c/h2\u003e \u003cp\u003eLaser Peen Texturing (LPT) involves irradiating a material surface with a short-pulse, high peak power density laser. This laser pulse causes the surface to absorb energy and generate plasma. A confinement layer restricts the expansion of the plasma, resulting in the formation of a high-pressure shock wave that propagates into the material. The mechanical action of this shock wave induces plastic deformation on the material surface and alters its microstructure. When the peak pressure of the shock wave surpasses the dynamic yield strength of the material, the surface undergoes strain hardening and develops residual compressive stresses, thereby enhancing the material\u0026rsquo;s mechanical and tribological performance \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. Laser peen texturing relies on laser-induced localized plastic deformation to fabricate surface textures. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(a) illustrates the schematic diagram of the laser peen texturing process, while Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(b) presents the dimensions of the treated specimen.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe laser peen texturing process employed a Nd:YAG high-energy pulsed laser operating at a wavelength of 1064 nm, with a laser shock energy range of 1\u0026ndash;12 J, a pulse width of 10\u0026ndash;26 ns, and a repetition frequency of 1\u0026ndash;5 Hz. The laser beam featured a circular spot shape with a diameter of 3 mm and was applied with a defocus of -1 mm. The detailed laser peen texturing parameters are listed in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. To protect the specimen surface from direct thermal damage caused by the high-energy laser, a 0.1 mm thick black tape was applied as both an absorptive and protective layer. Additionally, a 1 mm thick layer of flowing deionized water served as the confinement medium to facilitate effective shock wave generation. Following the laser peen texturing treatment, the specimen underwent ultrasonic cleaning with anhydrous ethanol to remove any residual black tape from the surface.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLaser peen texturing parameters\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaser wavelength (nm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1064\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpot diameter (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaser energy (J)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6, 8, 10, 12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePulse width (ns)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10, 14, 18, 22, 26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe surface morphology of the micro-texture and the material\u0026rsquo;s microstructure were characterized using a 3D non-contact surface profiler (Wyko-NT1100, Veeco, Tucson, AZ) and a field emission scanning electron microscope (SEM) (JSM-7001F, Japan). The three-dimensional topography of the micro-dimples was analyzed to extract contour data, including the diameter and depth of each dimple. Surface hardness in the laser-affected zones was evaluated using a FALCAN-511 Vickers microhardness tester, applying a load of 0.98 N. Measurements were taken at intervals of 0.3 mm, with each point measured three times to obtain an average value. Residual stress distribution along the cross-section of the samples was determined using an X-ray residual stress analyzer (LXRD, PROTO, Canada), operating with nine β angles in the range of -30\u0026deg; to 30\u0026deg;, and a scanning area of 3 mm \u0026times; 3 mm.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Tribological Test\u003c/h2\u003e \u003cp\u003eTribological performance was assessed using a multifunctional tribometer (MRT-5000, Rtec, USA). Tests were conducted under reciprocating motion with applied normal loads of 200, 300, and 400 N. The stroke length was set to 6 mm, with a test duration of 10 minutes at a frequency of 2 Hz. A GCr15 steel ball with a diameter of 6.5 mm served as the counterface material in a pin-on-block configuration. All tests were performed under starved lubrication conditions using 30# mechanical oil. The density of the laser-induced surface texture was calculated using Eq.\u0026nbsp;(\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Post-test analysis of the wear scars was performed using SEM (JSM-7001F), including energy-dispersive spectroscopy (EDS) for compositional analysis. The width and depth of the wear scars were quantified using Origin software, and the wear volume (Wv) was computed using Eq.\u0026nbsp;(\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${\\rho _t}=\\frac{{\\pi {d^2}}}{{4{L^2}}} \\times 100\\%$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere ρt is the areal density, d is the diameter of the micro-dimple, and L is the micro-dimple spacing.\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$${W_v}=\\frac{{1000\\Delta V}}{{vt}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere: ΔV is the wear volume (mm\u003csup\u003e3\u003c/sup\u003e); v is the reciprocating speed (mm/s); t is the wear time (min); Wv is the volume wear rate (mm\u003csup\u003e3\u003c/sup\u003e/m).\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results and discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Influence of laser peen texturing parameters on dimple morphology\u003c/h2\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e3.1.1 Dimple morphology under single shocks at varying energy levels\u003c/h2\u003e \u003cp\u003eWhen the laser spot diameter is set to 3 mm and the pulse width to 20 ns, the two-dimensional morphology and contour profiles of single-point dimples vary with different laser energies, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a and b). Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b) demonstrates that increasing the laser energy consistently deepens the dimples, while also altering the uniformity of the dimple bottoms. At a laser energy of 12 J, the dimple reaches its maximum depth of 38.39 \u0026micro;m; however, the bottom surface becomes markedly uneven. This unevenness arises because high shock energy intensifies the rarefaction wave effect produced by the laser-induced plasma shock wave. Consequently, the shock wave exhibits a non-uniform distribution within the impact zone, leading to irregular surface deformation \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. As laser energy increases, the peak pressure of the laser-induced shock wave also rises. This results in greater plastic deformation of the material and subsequently deeper dimples formed by single-point shock. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(c) shows that the dimple diameter remains approximately 3.5 mm across different energy levels, indicating that the dimple diameter primarily depends on the laser spot diameter, with laser energy exerting minimal influence.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e3.1.2 Dimple morphology after secondary impact at different energies\u003c/h2\u003e \u003cp\u003eUnder laser impact loading at constant energy, the dimple depth increases with the number of impacts \u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. Using a laser spot diameter of 3 mm and a pulse width of 20 ns, secondary impacts were applied to the samples at varying laser energy levels. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a) presents the resulting dimple morphologies and contour profiles. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(b), similar to the single-impact case, the dimple diameter primarily depends on the laser spot diameter, while the dimple depth increases significantly under secondary impact due to the accumulation of plastic deformation. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(c) indicates that as the laser energy increases, the rate of increase in dimple depth gradually diminishes. At 12 J, the dimple reaches a depth of 49.05 \u0026micro;m after the secondary impact; however, the depth increase becomes less pronounced. This trend suggests that once the laser energy approaches the plastic strain limit threshold of GCr15 steel, the laser peen texturing effect reaches its optimal state. Beyond this energy level, the sample surface no longer undergoes further plastic deformation \u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. The dimple depth resulting from the secondary impact depends not only on the material\u0026rsquo;s ultimate plastic strain threshold but also on its strain hardening behavior. During the first impact, plastic deformation occurs through slip mechanisms, and dislocation pile-ups readily form under stress. As the applied stress increases, dislocation density rises sharply, leading to significant work hardening. Consequently, after the initial impact, the material surface becomes increasingly resistant to further plastic deformation. During the secondary impact at higher energy, the hardened surface resists the propagation of the laser-induced shock wave, thereby limiting additional impact-induced deformation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e3.1.3 Influence of energy gradient on the dimples\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e presents the dimple morphologies and contour curves resulting from impacts with varying energy gradients. The data clearly show that when the first impact energy is 6 J, increasing the second impact energy to 8, 10, or 12 J leads to a substantial increase in dimple depth. In contrast, when the first impact energy is 8 or 10 J and the second impact energy is 10 or 12 J, the depth still increases but at a reduced rate. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(a) further illustrates that when the initial impact energy is 6 J and the second impact energy increases incrementally, the dimple depth increases correspondingly. At a second impact energy of 12 J, the dimple reaches its maximum depth of 58.61 \u0026micro;m. However, when the initial energy is 10 J and the second impact energy is also 12 J, the increase in dimple depth is minimal. This trend suggests that a lower first impact energy results in limited surface hardening, allowing the second, higher-energy impact to induce greater plastic deformation. Conversely, a higher first impact energy brings the material close to its plastic strain limit, causing significant initial plastic deformation and partial grain refinement. As a result, the surface exhibits increased resistance to further plastic deformation, which limits the effectiveness of the second impact in deepening the dimple. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(b), variations in the energy gradient do not significantly affect the dimple diameter. The dimple diameter remains largely determined by the laser spot diameter, rather than the energy levels used during impact.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e3.1.4 Effect of pulse width on dimple morphology\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e displays the surface profile curves following laser shock at constant energy but varying pulse widths. The data indicate that increasing the pulse width at constant energy leads to a gradual deepening of the dimples, with the maximum depth occurring at a pulse width of 26 ns. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(a) further demonstrates that at lower energy levels, dimple depth increases markedly as pulse width increases. Specifically, when the impact energy remains below 8 J, the relationship between pulse width and dimple depth becomes more pronounced. This behavior can be attributed to the extended duration of shock wave pressure associated with increased pulse width. At constant energy, a longer pulse duration enhances the time over which pressure acts on the material, promoting more significant plastic deformation and resulting in increased dimple depth. When the impact energy exceeds 10 J, however, increasing the pulse width produces only a marginal increase in depth. This limited response occurs because the material approaches its plastic strain limit, beyond which additional pulse duration has minimal effect on further deformation. These findings suggest that when the laser energy is fixed, extending the pulse width effectively increases dimple depth during secondary impacts, thereby facilitating the formation of micro-textures. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(b) shows the corresponding changes in dimple diameter under different pulse widths, indicating that pulse width has little to no effect on dimple diameter, which remains primarily governed by the laser spot diameter.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Effect of laser peen texturing on mechanical properties of GCr15 bearing steel\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e3.2.1 Microstructural Analysis\u003c/h2\u003e \u003cp\u003eUnder the pressure of the laser-induced shock wave, the material surface undergoes plastic deformation, leading to the formation of a high dislocation density and refined grains. This process increases the surface hardness and results in the development of a hardened layer. Figure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e illustrates the microstructural changes in GCr15 steel before and after laser shock. Following laser treatment, the grains near the surface become significantly refined, while the grain size exhibits a gradient distribution along the depth direction, increasing with distance from the surface. This gradient arises because the laser-induced shock wave delivers the highest energy at the surface, where attenuation is minimal. The intense shock energy at the surface causes severe plastic deformation, generating high-density dislocations within the crystal structure. These dislocations evolve into subgrain boundaries, ultimately leading to grain refinement. As the shock wave propagates deeper into the material, its energy diminishes, reducing the degree of plastic deformation. Consequently, the extent of grain refinement decreases with increasing depth.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e3.2.2 Hardness under different laser energy combinations\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e illustrates the variation in surface hardness of the samples subjected to different laser energies. As laser energy increases, the surface hardness of the dimples also increases. Figure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e(a) shows that, compared to the untreated sample, both single and secondary impacts at the same energy result in a significant rise in microhardness. The secondary impact further enhances hardness, although the rate of increase gradually diminishes. At 12 J, the secondary impact produces no notable hardness improvement over the single impact, indicating that the surface of GCr15 steel has reached its hardening saturation point. Figure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e(b) presents the hardness results for sequential impacts using different energy combinations. When the first impact energy is 6 J and the second impact energy progressively increases, the surface hardness rises significantly. However, when the initial energy is 10 J and the second impact energy increases, the additional gain in hardness is minimal. This behavior occurs because the first laser shock induces plastic deformation and strain hardening on the sample surface, increasing its dynamic yield strength. As a result, subsequent laser shocks require more energy to generate further plastic deformation. When the total shock wave energy remains constant, the proportion of energy effectively contributing to plastic deformation decreases, thereby limiting further increases in surface hardness.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e3.2.2 Hardness under different laser pulse width\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e presents the hardness variations of samples subjected to laser peen texturing at different energy levels and pulse widths. Across all energy levels, the microhardness follows a consistent trend with increasing pulse width. Compared to the untreated samples, laser shock significantly enhances the surface microhardness. When the energy remains constant, the microhardness initially decreases with increasing pulse width, then increases again. This trend can be explained by the relationship between pulse width and shock wave peak pressure. According to the shock wave pressure equation, increasing the pulse width at constant energy results in a reduction in peak pressure. At shorter pulse widths of 10 ns, the high peak pressure dominates the deformation process, leading to increased hardness. However, as the pulse width increases, the peak pressure decreases and the shock duration becomes the dominant factor. Extended shock duration promotes more extensive plastic deformation, increases dislocation density, and ultimately leads to a renewed increase in surface hardness. Thus, the microhardness exhibits a characteristic trend of initial decline followed by a rise as the pulse width increases under constant energy conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Mechanism of laser peen texturing\u003c/h2\u003e \u003cp\u003eLaser peen texturing (LPT) employs a short-pulse, high peak power density laser to irradiate the material surface, generating a high-pressure shock wave that modifies surface properties and enhances material strength. Figure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e illustrates the mechanism of micro-dimple fabrication through LPT. The process initiates with full-coverage, overlapping laser shocks applied to the untreated specimen, resulting in a hardened surface layer with refined grains and significantly increased hardness. Subsequently, a second laser shock, applied using adjusted process parameters, targets the pre-strengthened surface. This controlled energy input facilitates the formation of a regular array of micro-dimples. During the second stage, the shock wave pressure exceeds the material\u0026rsquo;s dynamic yield strength, causing localized plastic deformation. As the shock load dissipates, residual plastic strain leads to the formation of surface depressions (micro-dimples) with well-defined depths. This two-step approach produces a surface that integrates enhanced mechanical properties with functional micro-texturing. Following dimple formation, surface grinding removes the ripples induced by laser processing, thereby reducing surface roughness. The final surface exhibits a refined micro-dimple array with low roughness and improved mechanical integrity, effectively combining structural reinforcement with functional surface patterning.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.4: Tribological characteristic\u003c/h2\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.4.1 Effect of laser peen texturing on friction coefficient\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e presents the friction coefficients of both untreated and laser peen textured (LPT) specimens under varying loads. As shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e(a) and 12(b), after a brief running-in period, the friction coefficient of each sample stabilizes and fluctuates within a limited range. At a load of 200 N, the untreated specimen exhibits an average friction coefficient of 0.428, while the LPT-treated specimen shows a significantly lower value of 0.335. As the load increases to 300 N, the average friction coefficient decreases to 0.309 for the untreated sample and 0.297 for the LPT-treated one. At the maximum load of 400 N, the coefficients further decline to 0.274 and 0.268, respectively. This decreasing trend in friction coefficient with increasing load arises from the elastic-plastic nature of the contact between the mating surfaces. While the friction force is proportional to the real contact area, the actual contact area of metallic surfaces increases at a slower rate than the applied load. Consequently, under dry friction conditions, the friction coefficient tends to decrease as the load increases \u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eUnder all tested loads, the LPT-treated specimens consistently exhibit lower friction coefficients than the untreated ones. This reduction is attributed to the significant grain refinement induced by laser peen texturing, which increases surface hardness by impeding dislocation motion. Since LPT minimally affects surface roughness, the enhanced mechanical properties, rather than changes in surface texture, primarily contribute to the observed decrease in friction.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003e3.4.2 Effect of laser peen texturing on wear properties of GCr15 bearing steel\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e illustrates the three-dimensional morphology of the wear scars on specimens before and after laser peen texturing under varying loads. Under a 200 N load (Figs.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ea and \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ed), the untreated specimen exhibits a wear scar width of 1,056.57 \u0026micro;m and a depth of 3.18 \u0026micro;m, while the LPT-treated specimen shows a narrower wear scar of 724.23 \u0026micro;m and a shallower depth of 2.43 \u0026micro;m. At 300 N (Figs.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003eb and \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ee), the untreated specimen's wear scar widens to 1,131.52 \u0026micro;m with a depth of 3.35 \u0026micro;m, whereas the LPT-treated specimen maintains a smaller width and depth of 809.73 \u0026micro;m and 2.47 \u0026micro;m, respectively. Under the highest load of 400 N (Figs.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ec and \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ef), the untreated specimen exhibits a wear scar width of 1,332.61 \u0026micro;m and a depth of 4.17 \u0026micro;m, while the LPT-treated specimen shows a reduced width of 875.47 \u0026micro;m and a depth of 2.80 \u0026micro;m. In all cases, the LPT-treated specimens demonstrate smaller wear scar widths and depths compared to the untreated counterparts under the same load conditions. Additionally, both untreated and LPT-treated specimens experience an increase in wear scar width and depth as the applied load increases. These results indicate that laser peen texturing effectively enhances wear resistance by reducing material loss under tribological stress.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e presents the wear rates of specimens subjected to varying loads before and after laser peen texturing (LPT). The data reveal that as the applied load increases, the wear rates of both untreated and LPT-treated specimens increase correspondingly. However, under identical loading conditions, the LPT-treated specimens consistently exhibit lower wear rates than their untreated counterparts. Specifically, for untreated specimens, the average wear rate increases from 620.15 mm\u0026sup3;/m at 200 N to 694.16 mm\u0026sup3;/m at 300 N, and reaches 809.80 mm\u0026sup3;/m at 400 N. In contrast, LPT-treated specimens demonstrate wear rates of 486.65 mm\u0026sup3;/m at 200 N, 570.48 mm\u0026sup3;/m at 300 N, and 651.07 mm\u0026sup3;/m at 400 N. These results indicate that laser peen texturing reduces the wear rate by 21.53%, 17.82%, and 19.60% at loads of 200 N, 300 N, and 400 N, respectively, compared to the untreated specimens. The increase in wear rate with load is attributed to the proportional relationship between frictional force and the actual contact area, which expands as the load increases. The improved wear resistance of LPT-treated specimens primarily arises from grain refinement induced by high-strain-rate plastic deformation during laser peen texturing. Finer grains enhance resistance to plastic deformation. Furthermore, laser peen texturing introduces deep compressive residual stresses in the subsurface region, which are gradually released during sliding contact, thereby impeding further plastic deformation and material removal. Collectively, these mechanisms contribute to the reduction in wear rate and the enhancement of wear resistance after laser peen texturing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e presents the elemental spectra of the wear morphology of GCr15 bearing steel under different loads, both before and after laser peen texturing (LPT). The data show that the degree of oxidation on both sides of the wear scar increases with rising load, while oxidation in the central region remains minimal. The oxygen content in regions 2 and 4 of the untreated sample exceeds that in regions 7 and 9 of the LPT-treated sample, indicating a more pronounced oxidation in the untreated specimen.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e illustrates the wear morphologies of the samples under varying loads before and after laser peen texturing. At a load of 200 N, the untreated sample exhibits prominent surface spalling, along with minor plowing and oxidation. The dominant wear mechanism in this condition is adhesive wear, accompanied by limited abrasive and oxidative wear (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003ea). When the load increases to 300 N, the severity of both adhesion and oxidation rises, indicating a combined adhesive and oxidative wear mechanism (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003eb). At 400 N, the surface is extensively covered with oxidized debris and wear spots, further intensifying adhesive and oxidative wear (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ec). In contrast, the LPT-treated sample under a 200 N load shows only small spalling dimples and shallow plowing grooves, suggesting milder wear (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003ed). As the load increases, the size of the spalling dimples and the prominence of plowing grooves also increase. An oxide film begins to form on the wear scar surface at higher loads (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003ee). At 400 N, the LPT-treated surface displays slightly more adhesion, deeper plowing grooves, and intensified oxidation (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ef). The untreated samples exhibit a wear mechanism dominated by adhesive and oxidative wear, which becomes more severe as the load increases. Conversely, the LPT-treated samples primarily experience abrasive wear, with only minor contributions from adhesive and oxidative mechanisms. As the load increases, abrasive wear becomes more pronounced. Compared to the untreated specimens, the LPT-treated surfaces exhibit significantly reduced adhesion and oxidation, indicating a shift in the wear mechanism toward abrasion. This improved wear resistance in LPT-treated samples results from the refinement of surface grains and the introduction of high residual compressive stress, which enhance the yield strength and inhibit crack initiation. Under increasing load and friction, the tangential force rises, promoting surface fragmentation and debris adhesion, thereby exacerbating adhesive wear. Simultaneously, the increase in frictional heat elevates the surface temperature, intensifying oxidation. However, the refined microstructure and induced residual stress from laser peen texturing significantly mitigate spalling and oxidation, resulting in superior wear performance compared to untreated samples.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eWear morphology energy spectrum of GCr15 bearing steel before and after LPT under different loads\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArea\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFe\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCr\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e87.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e69.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e18.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e87.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e59.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e32.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e89.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e89.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e78.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e87.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e73.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e18.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e88.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e presents the residual stress distributions obtained via LXRD measurements for both untreated and laser peen textured (LPT) samples under varying loads. The untreated sample, which did not undergo laser peen texturing prior to testing, exhibits significant compressive residual stress within the central region of the wear scar following friction and wear. As the applied load increases, the average residual stress in the wear scar area also increases. Specifically, as shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e(a) and 16(c), the residual stress rises from \u0026minus;\u0026thinsp;653 MPa under a 200 N load to -739 MPa at 300 N. Under a 400 N load (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e(e)), the compressive stress further increases to -802 MPa. In contrast, the regions on either side of the wear scar, which did not experience frictional contact, retain much lower residual stress levels ranging from \u0026minus;\u0026thinsp;8 MPa to -40 MPa values attributed to residual stress from machining processes. This development of compressive residual stress under dry sliding conditions stems from severe plastic deformation in the surface layer caused by frictional loading. The GCr15 steel ball, acting as the counterface, induces a Hertzian stress field near the contact area, thereby generating residual compressive stress in the surface layer of the sample \u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. In the case of LPT-treated samples, Figs.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e(b), 16(d), and 16(f) reveal a markedly different residual stress distribution. Under a 200 N load, the average residual stress in the wear scar center is approximately \u0026minus;\u0026thinsp;632 MPa, while the unaffected side regions retain significantly higher compressive stresses of about \u0026minus;\u0026thinsp;1,100 MP, a difference of 468 MPa. At 300 N, the stress in the wear scar area increases slightly to -635 MPa, while the surrounding areas maintain an average stress of -1,050 MPa, resulting in a difference of 415 MPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e(d)). Under a 400 N load, the wear scar region reaches \u0026minus;\u0026thinsp;738 MPa, and the adjacent regions remain around \u0026minus;\u0026thinsp;1,100 MPa, reducing the difference to 362 MPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e(f)).\u003c/p\u003e \u003cp\u003eThese findings indicate that the compressive residual stress layer introduced by laser peen texturing is initially unstable and gradually relaxes when subjected to external stress or elevated temperature during friction and wear processes \u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. The residual compressive stress counteracts the tensile stresses generated on the surface during wear, thereby delaying or suppressing the initiation and propagation of fatigue cracks. Moreover, this residual stress layer also resists plastic deformation induced by the Hertzian contact stress, thereby limiting structural damage to the surface. As shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e(b), 16(d), and 16(f), the residual stress distribution after the combined effects of LPT and friction reveals a convex-shaped stress profile across the wear scar, indicating a decrease in compressive stress specifically within the worn region.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn summary, laser peen texturing (LPT) enhances the wear resistance of GCr15 bearing steel through both microstructural refinement and the introduction of beneficial residual stresses. From a microstructural perspective, the high-energy, high-density plasma shock waves generated during laser peen texturing induce intense plastic deformation in the surface and subsurface layers of the material. This deformation significantly increases the dislocation density, resulting in dislocation entanglement and the refinement of martensitic grains into a nanocrystalline structure. These microstructural changes contribute to a notable increase in surface hardness, thereby improving the material's resistance to wear. From the perspective of residual stress, the compressive stresses introduced by LPT play a crucial role during the friction and wear process. As these residual stresses are gradually released, they impede plastic deformation in the surface layer, thereby mitigating structural degradation. Moreover, the compressive residual stress promotes crack closure, elevates the critical stress intensity factor required for crack propagation, and reduces the amplitude of alternating tensile stresses acting on the material. When the depth of the LPT-induced affected layer exceeds the depth of microcrack formation, the reduction in average tensile stress effectively slows crack growth \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. Consequently, the wear scar area exhibits a lower residual compressive stress compared to the untreated regions, indicating that the material absorbed part of the stress during wear. This stress redistribution ultimately enhances the wear resistance of the material by reducing surface damage and delaying crack propagation.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4.0: Conclusions","content":"\u003cp\u003eThis research explores the feasibility and processes for producing micro-dimples on GCr15 bearing steel through laser peen texturing. The study examines the impact of various laser peen texturing parameters on the morphology of the micro-dimples. Additionally, it explores the effects of laser peen texturing on the mechanical and tribological properties of GCr15 bearing steel. Based on the results and discussion, the following key conclusions were drawn:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eLaser energy, pulse width, and the number of impacts significantly influence the depth of surface micro-dimples induced by laser peen texturing (LPT). As these parameters increase, the depth of the micro-dimples correspondingly increases. In contrast, the diameter of the micro-dimples depends solely on the diameter of the laser spot.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eLaser peen texturing effectively strengthens the surface of GCr15 steel. Following the enhancement of surface hardness, it becomes possible to generate surface textures with defined depth by applying Laser peen texturing parameters involving higher energy or extended interaction time. Under the combined influence of optimized Laser peen texturing conditions, the process simultaneously strengthens the material and forms micro-dimples with controlled depth.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe selection of composite process parameters depends on the desired degree of surface strengthening and the required depth of micro-dimple formation. By adjusting key parameters such as laser energy and pulse width, researchers can tailor the formation of micro-dimples with varying depths on the surface of the laser-shock-treated specimens.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eLaser peen texturing significantly enhances the tribological performance of GCr15 steel. After treatment, the average coefficient of friction decreases, and the width and depth of the wear scars reduce notably. The wear rate declines by approximately 17% to 21%. The primary wear mechanism remains abrasive, accompanied by a degree of adhesive and oxidative wear, indicating a marked improvement in wear resistance.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe evolution of the surface stress field during the friction and wear process results from the gradual release of residual compressive stress introduced by LPT. This compressive stress restricts the plastic deformation of the surface layer. Furthermore, a deep and extensive residual compressive stress layer effectively suppresses the initiation and propagation of cracks, thereby enhancing the overall wear resistance of the material.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgment\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eI acknowledge the support of Sunyani Technical University in the use of library resources in conducting this research.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing financial interests or personal relationships that could have influenced the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData sharing not applicable to this article as no datasets were generated or analysed during the current study\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCredit contribution statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthor 1: Julius Caesar Puoza\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eConceptualized the study, designed the experimental methodology, supervised laboratory activities, and contributed to data interpretation and manuscript writing.\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAuthor 2: Tainyao Zhang\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eConducted the experiments, performed advanced characterization (e.g., SEM, XRD, microhardness), collected and curated the data, performed formal analysis, and prepared the initial draft of the manuscript\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAuthor 3: Abdulai Musah\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eSupported experimental setup and optimization, contributed to materials preparation and characterization, validated the results and assisted in data analysis.\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAuthor 4: Awudu Ibrahim\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eContributed to statistical analysis, data visualization, and refinement of the discussion section, \u0026nbsp;and reviewed the manuscript for technical accuracy.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAuthor 5: Yakubu Kuusana\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eProvided project supervision, secured resources, guided the overall research direction, and critically revised the manuscript for intellectual content.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAll authors:\u003c/p\u003e\n\u003cp\u003eReviewed the final manuscript and approved it for publication.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBhadeshia, H.K.D.H.: Steels for bearings. 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Int. \u003cb\u003e151\u003c/b\u003e, 106537 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.triboint.2020.106537\u003c/span\u003e\u003cspan address=\"10.1016/j.triboint.2020.106537\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"lasers-in-manufacturing-and-materials-processing","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"lmmp","sideBox":"Learn more about [Lasers in Manufacturing and Materials Processing](http://link.springer.com/journal/volumesAndIssues/40516)","snPcode":"40516","submissionUrl":"https://submission.nature.com/new-submission/40516/3","title":"Lasers in Manufacturing and Materials Processing","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"GCr15 bearing steel, laser peen texturing, laser parameters, surface textures, surface morphology, mechanical properties, tribological properties","lastPublishedDoi":"10.21203/rs.3.rs-8354982/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8354982/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study explores the feasibility of employing laser peen texturing to fabricate surface textures on GCr15 bearing steel and evaluates its influence on the material\u0026rsquo;s mechanical and tribological properties. GCr15 samples were treated using various laser parameters, and the resulting mechanical and tribological properties were analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness testing, X-ray residual strain analysis (LXRD). The results demonstrated that the depth of micro-dimples increased with rising laser energy, pulse width, and impact times. At 12 J single impact, dimple depth reached 38.39 \u0026micro;m, while double impacts at the same energy produced deeper dimples of up to 49.05 \u0026micro;m. A gradient energy strategy (6 J followed by 12 J) further increased dimple depth to 58.61 \u0026micro;m. Microhardness tests indicated that dimple hardness increased with both laser energy and impact times, though it showed a nonlinear relationship with pulse width. Tribological testing revealed a notable improvement in wear resistance, low friction coefficient, with tiny wear scar widths. The wear rate was reduced by 17\u0026ndash;21%, as abrasive wear was the dominant wear mechanism with minor oxidative wear present. Overall, laser peen texturing significantly enhanced surface integrity by generating precise micro-dimples, increasing surface hardness, and improving tribological behavior. These results offer valuable theoretical and practical guidance for applying laser peen texturing to improve the performance of bearing steel in advanced engineering and manufacturing applications.\u003c/p\u003e","manuscriptTitle":"Enhancing Surface Textures and Tribological Properties of GCr15 Bearing Materials through Laser Peen Texturing","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-22 09:09:39","doi":"10.21203/rs.3.rs-8354982/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-25T23:39:10+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-14T07:34:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"180701388447144354368314110427127130429","date":"2025-12-20T18:46:52+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-19T03:44:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"336586471218400198868646093065268333561","date":"2025-12-19T01:31:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"211432306732669456423131196907211016558","date":"2025-12-18T16:45:30+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-18T15:07:46+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-18T15:00:38+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-18T07:28:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"Lasers in Manufacturing and Materials Processing","date":"2025-12-13T20:54:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"lasers-in-manufacturing-and-materials-processing","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"lmmp","sideBox":"Learn more about [Lasers in Manufacturing and Materials Processing](http://link.springer.com/journal/volumesAndIssues/40516)","snPcode":"40516","submissionUrl":"https://submission.nature.com/new-submission/40516/3","title":"Lasers in Manufacturing and Materials Processing","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"27aa09ce-c6a6-4581-a009-fdf4f50a2f69","owner":[],"postedDate":"December 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-05T18:53:09+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-22 09:09:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8354982","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8354982","identity":"rs-8354982","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}