HFMI effectiveness at high stress ratios (R = 0.55–0.70) in four-point bending of high-strength steel butt welds

HFMI effectiveness at high stress ratios (R = 0.55–0.70) in four-point bending of high-strength steel butt welds | 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 HFMI effectiveness at high stress ratios (R = 0.55–0.70) in four-point bending of high-strength steel butt welds Miloslav Kepka Jr., Radovan Minich, Jakub Štěpán, Pavel Ryjáček This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7613878/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract High-frequency mechanical impact (HFMI) is among the most effective post-weld treatments for improving fatigue performance. However, the current IIW Recommendation provides design guidance only up to a stress ratio of R = 0.52, leaving high-R applications without codified rules. This paper addresses that gap by quantifying HFMI effectiveness at R = 0.55 and R = 0.70 under constant-amplitude four-point bending. We tested 93 transverse V- and X-butt welds in S355J2 + N, S460NL, S690QL, and S960QL at 5 Hz to failure or 1×10⁷ cycles (51 specimens at R = 0.55; 42 at R = 0.70) in both as-welded and HFMI-treated conditions. HFMI shifts the S–N curves upward by up to six FAT classes and increases fatigue life typically by ≈ 3–10× (ranging from ≈ 1× to > 30× at R = 0.70 and up to > 200× at R = 0.55), with the largest gains observed for high-strength grades. The benefit persists to R = 0.70 provided the nominal maximum stress remains at or below yield (elastic regime); cases with local plastification show reduced gains. Elastic HFMI data scatter by only ≈ ± 0.19 decades around draft IIW design lines, supporting a cautious extension of HFMI design rules toward R ≤ 0.70 and supplying bending-mode evidence for components operating at elevated mean stress. high-frequency mechanical impact (HFMI) stress ratio (R) four-point bending fatigue strength butt welds S–N curve Full Text Supplementary Files Kepkaetal2025WITWHFMIhighR4PBAnnexAv1.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 30 Sep, 2025 Reviewers invited by journal 30 Sep, 2025 Editor invited by journal 29 Sep, 2025 Editor assigned by journal 25 Sep, 2025 First submitted to journal 23 Sep, 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-7613878","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":522783474,"identity":"c5c849ca-5bb9-44f2-82f7-3e0ca37522b0","order_by":0,"name":"Miloslav Kepka Jr.","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2klEQVRIie3QPQrCMBiA4U8K7fJJ15T6c4VKQBxEr5IScCoeQTLVpcXVkzhHhDrpFayTi0JXQcFkE5HUbg55ISRDHvIDYLP9YQTA0RP6jmxIOkHKWqIJgXFU/EqCZb6L7skIaeFdSnhMYuHtSyMJ8cjjfENwWOBAAPJYIGNG0iMJlW1NTpm6GJGxICDNpH+l26ciNPXOAiJNat4Uqs1cnxK5oC7GNHGMAoJszmlXEaLesmaS0xRnZkL2h11w2yymfuqVVfWYdFd1PwaAb2umhluz/4PYbDab7VsvvBk+IcmjpOUAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0003-3070-4773","institution":"University of West Bohemia in Pilsen Faculty of Mechanical Engineering: Zapadoceska univerzita v Plzni Fakulta strojni","correspondingAuthor":true,"prefix":"","firstName":"Miloslav","middleName":"","lastName":"Kepka","suffix":"Jr."},{"id":522783475,"identity":"4165f90b-518c-4cac-bd2d-cbbd0310eba9","order_by":1,"name":"Radovan Minich","email":"","orcid":"","institution":"University of West Bohemia in Pilsen Faculty of Mechanical Engineering: Zapadoceska univerzita v Plzni 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welds","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"welding-in-the-world","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"witw","sideBox":"Learn more about [Welding in the World](https://www.springer.com/journal/40194)","snPcode":"40194","submissionUrl":"https://www.editorialmanager.com/witw/","title":"Welding in the World","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"high-frequency mechanical impact (HFMI), stress ratio (R), four-point bending, fatigue strength, butt welds, S–N curve","lastPublishedDoi":"10.21203/rs.3.rs-7613878/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7613878/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHigh-frequency mechanical impact (HFMI) is among the most effective post-weld treatments for improving fatigue performance. However, the current IIW Recommendation provides design guidance only up to a stress ratio of R\u0026thinsp;=\u0026thinsp;0.52, leaving high-R applications without codified rules. This paper addresses that gap by quantifying HFMI effectiveness at R\u0026thinsp;=\u0026thinsp;0.55 and R\u0026thinsp;=\u0026thinsp;0.70 under constant-amplitude four-point bending. We tested 93 transverse V- and X-butt welds in S355J2\u0026thinsp;+\u0026thinsp;N, S460NL, S690QL, and S960QL at 5 Hz to failure or 1\u0026times;10⁷ cycles (51 specimens at R\u0026thinsp;=\u0026thinsp;0.55; 42 at R\u0026thinsp;=\u0026thinsp;0.70) in both as-welded and HFMI-treated conditions. HFMI shifts the S\u0026ndash;N curves upward by up to six FAT classes and increases fatigue life typically by \u0026asymp;\u0026thinsp;3\u0026ndash;10\u0026times; (ranging from \u0026asymp;\u0026thinsp;1\u0026times; to \u0026gt;\u0026thinsp;30\u0026times; at R\u0026thinsp;=\u0026thinsp;0.70 and up to \u0026gt;\u0026thinsp;200\u0026times; at R\u0026thinsp;=\u0026thinsp;0.55), with the largest gains observed for high-strength grades. The benefit persists to R\u0026thinsp;=\u0026thinsp;0.70 provided the nominal maximum stress remains at or below yield (elastic regime); cases with local plastification show reduced gains. Elastic HFMI data scatter by only\u0026thinsp;\u0026asymp;\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19 decades around draft IIW design lines, supporting a cautious extension of HFMI design rules toward R\u0026thinsp;\u0026le;\u0026thinsp;0.70 and supplying bending-mode evidence for components operating at elevated mean stress.\u003c/p\u003e","manuscriptTitle":"HFMI effectiveness at high stress ratios (R = 0.55–0.70) in four-point bending of high-strength steel butt welds","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-13 16:23:32","doi":"10.21203/rs.3.rs-7613878/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-09-30T09:59:45+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-30T09:55:48+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Welding in the World","date":"2025-09-29T14:07:47+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-25T07:27:35+00:00","index":"","fulltext":""},{"type":"submitted","content":"Welding in the World","date":"2025-09-23T08:51:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"welding-in-the-world","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"witw","sideBox":"Learn more about [Welding in the World](https://www.springer.com/journal/40194)","snPcode":"40194","submissionUrl":"https://www.editorialmanager.com/witw/","title":"Welding in the World","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"afbb3efb-8ce7-4003-a87b-571639eadf5d","owner":[],"postedDate":"October 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-01-05T08:06:13+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-13 16:23:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7613878","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7613878","identity":"rs-7613878","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}