The deformation-induced phase transformation hardening phenomenon is normally observed in austenitic stainless steels of the AISI 300 series. The amount of hardening is limited by the structural stability of the material. In fact, during the cold forming process, low nickel austenitic stainless steels can undergo deformation-induced phase transformation of fcc gamma-austenite to bcc alpha'-martensite. On the other hand, by heat treatments, the austenitic structure can be recovered. The reversion of martensite to austenite is studied on a set of austenitic stainless steel specimens existent at our laboratory. These had been submitted to 63% deformation at a temperature of (-70°C), followed by isochronic, isothermal heat treatments at temperatures between 250 and 800°C. Thus, series of specimens with different phase content were available. The reversion of martensite in the specimens is studied by optical and electron microscopy, X-ray diffraction, and electromagnetic non destructive (ND) methods (Feritscope, permeability evaluation by eddy currents, conductivity measurement). The quantification results obtained with different techniques a compared, in order to assess the scope of the ND techniques in the characterization of rolled stainless steel products.
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