Influence of carbon content on the martensitic transformation of titanium stabilized austenitic stainless steels

Abstract

Austenitic stainless steels (ASS) are corrosion resistant alloys in which the desirable mechanical properties may be attained by cold working in the final stages of the fabrication process. This manufacturing process may induce martensitic transformation from the austenitic phase, where the chemical composition plays an important role as it influences the stacking fault energy (SFE). Therefore, this work evaluated the influence of carbon content on martensitic transformation of Ti stabilized ASS. Thus, the austenite transformed into martensite by cold rolling was observed by Light Optical Microscopy (LOM) and quantified by Vibrating Sample Magnetometer (VSM), and X-Ray Diffraction (XRD) for Ti stabilized ASS with different carbon contents. The experimental results about the martensitic transformation behavior for each alloy were compared with previous results on other ASS and Duplex Stainless Steel (DSS), tested in similar conditions, verifying a high correlation with a sigmoidal model previously applied in these alloys. Additionally, it was carried out a SFE analysis, estimated by thermodynamic model, corroborating that the alloy’s carbon content has a strong influence on the material’s stability. Finally, it was observed a sudden increase in microhardness value as a consequence of the high amount of austenite transformed into martensite at very low strains that might affect the steels performance in several applications.