Evaluation of the martensitic transformations in austenitic stainless steels

Austenitic stainless steels present unique characteristics, being that part of its behavior is due to the stability of the austenite, obtained primarily through variations of its chemical composition. When metastable austenite is present, this can be transformed in martensite by deformation and the amount induced is directly related to the level of deformation. These microstructural transformations result, in some cases, at a significant increase of the ductility. Thus, the objective of this work was to evaluate the effect of martensitic transformations during the deformation of AISI304 and AISI304N stainless steel plates, under different deformation paths. The evaluation was performed by Nakazima tests, by metallographic analyses, as well tensile and hardness tests. It was observed that the deformation-induced martensitic transformation tend to form a larger amount of α′-martensite when submitted to a tensile load conditions and to form a greater amount of ɛ-martensite when applied primarily compressive component load.