Influence mechanism of grinding surface quality of 20CrMnTi steel on contact failure

Abstract To reveal the influence mechanism of the grinding surface quality of 20CrMnTi steel components on the tribological characteristics and contact fatigue performance, accelerated tests for sliding friction wear and fatigue damage were carried out, and the damage morphology characteristics were analyzed. Tribological characteristics and contact fatigue performance get worse with increasing surface roughness while getting better with increasing surface microhardness. The surface roughness affects the contact conditions of micromorphology and hydrodynamic lubrication, while the microhardness enhances the plastic deformation resistance. Residual compressive stress is conducive to inhibiting the initiation and propagation of cracks and promoting contact fatigue performance. Additionally, a competing failure mechanism is formed under the synergistic effect of frictional wear and contact fatigue failure, in which various phenomena (mechanical friction, abrasive wear, adhesive wear, and fatigue damage) co-exist. Mechanical friction leads to deformation folding and local stress concentrations, resulting in the generation of microcracks, which propagate along the direction parallel to the contact surface to form pitting. The stress concentration at the edge of micro-pitting pits would further induce the number and propagation length of micro-cracks to increase rapidly, prompting the occurrence of a large area of spalling in the shallow layer. This study is more beneficial to promote the 20CrMnTi steel transmission parts manufacturing products for high precision, low damage, and long life.