Strain-Induced Martensitic Transformation and the Mechanism of Wear and Rolling Contact Fatigue of AISI 301LN Metastable Austenitic Stainless Steel

AISI 301LN metastable austenitic stainless steels (MASSs) are known to exhibit high work-hardening rates attributed to martensite evolution during straining which results in the second-phase strengthening mechanism. This enhances surface hardness and potentially reduces wear and rolling contact fatigue (RCF). The aim of this study is therefore to evaluate the work hardening, wear, and RCF performance of AISI 301LN metastable austenitic stainless steel as a possible alternative material for rolling and sliding applications by varying the contact conditions such as slip ratio against the standard R350HT rail steel using a twin-disc simulator. The results show that 301LN MASS has high surface work hardening and increased hardness because of martensitic transformation, while R350HT rail steel has only slightly changed. The formation of a hard martensitic phase is also confirmed by X-ray diffraction analysis as well as by two other techniques, indicating a secondary hardening effect. Although it shows potential for work hardening, its susceptibility to wear-related problems may make it less suitable for rolling and sliding applications due to a cracking and spalling mechanism induced by martensite formation. The surface strains required for the observed martensite formation are calculated and found to be very high, approaching 0.4. The effect of slip ratio on the formation of strain-induced martensite under rolling and sliding contact is investigated. Lower slip ratios result in more strain-induced martensite due to lower contact temperatures, which favor martensitic transformation. Higher slip ratios increase contact temperatures, causing deformation mainly through the twinning of austenite rather than martensitic transformation.image (c) 2024 WILEY-VCH GmbH