Impact of sensitization on wear characteristics of thermo-mechanically processed SS316L: A comprehensive investigation

This study investigates the effect of thermo-mechanical processing (TMP) on sensitization and wear characteristics of austenitic stainless steel 316 L. Solution annealed (SA) material was rolled to induce deformation (4 R and 12 R) and subjected to heat-treatment at sensitization temperatures (400 °C, 600 °C, and 700 °C). Wear tests without lubrication were conducted on these TMP samples to analyze the interplay between sensitization and deformation in influencing wear behavior. Sensitization was observed in deformed samples after heat treatment at 600 °C and 700 °C, as evidenced by Tafel plots. The average coefficient of friction (COF) was found to be higher for SA and lower for 4 R and 12 R samples, but increased COF in the post heat-treatment regime up to 700 °C, indicating sensitization. Deformed sample shows ∼ 9.1 % and ∼ 5.8 % drop in average COF for 4 R and 12 R sample respectively till the onset of sensitization regime (400 °C). However, heat-treatment at the end of sensitization regime (400 °C) attribute to ∼ 7.8 % and ∼ 11.0 % increase in average COF for 4 R and 12 R sample w.r.t. SA sample at room temperature. Volumetric wear loss and wear rate decreased for SA during heat-treatment up to 700 °C, while deformed samples showed a significant increase at 700 °C. Our findings suggest a substantial impact of sensitization temperature above 600 °C on wear behavior in deformed samples, contrasting with the limited effect on SA and subsequently heat-treated samples. The extent of sensitization was observed to depend on the level of deformation. Further, worn surface characterization revealed abrasion and delamination followed by adhesion as dominant wear mechanisms in TMPed SS 316 L under fretting wear conditions.