A Systematic Study Of Sample Preparation-induced Martensitic Phase Formation In 304 L Austenitic Stainless Steel

Abstract

Routine sample preparation may unintentionally induce martensitic transformation on the surface of metastable 304 L stainless steel, potentially affecting accurate microstructural characterization. This study systematically investigates the effects of common sample preparation methods such as mechanical cutting, electrical discharge machining (EDM), grinding, and polishing on deformation-induced martensitic transformation on the surface of 304 L stainless steel. Using in-house X-ray diffraction (XRD) and synchrotron-based high-energy XRD, we demonstrate that martensitic transformation is confined primarily to the near-surface region and strongly influenced by the interplay between strain rate and temperature. Mechanical cutting promotes α′-martensite formation with increasing strain rates, whereas thermal effects arising from cutting can suppress transformation by elevating surface temperature above the upper temperature limit for deformation-induced martensite formation. Depending on the preparation route, the measured surface α′-martensite fraction varied from nearly undetectable levels to approximately 0.453. EDM introduced approximately 0.137 vol fraction α′-martensite, likely due to local thermal shock and residual stresses within the resolidified layer. Grinding generated substantial surface α′-martensite because of severe plastic deformation, resulting in α′-martensite volume fraction of 0.286 following mechanical cutting and grinding. In contrast, fine and prolonged polishing largely removed the transformed surface layer, reducing the α′-martensite volume fraction to approximately 0.020 and thereby minimizing its influence on microstructural characterization. These findings emphasize the critical role of sample preparation protocols in accurately characterizing metastable stainless steels. The study provides practical guidelines to minimize preparation-induced artifacts, thereby improving reliability in surface-involved characterizations/investigations.

Department(s)

Materials Science and Engineering

Comments

National Science Foundation, Grant DMR-2207965

Keywords and Phrases

304 Stainless steels; Austenitic steels; Deformation induced martensite; Phase transformation; Sample preparation

International Standard Serial Number (ISSN)

2589-1529

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2026 Elsevier, All rights reserved.

Publication Date

01 Dec 2026

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