Chemical composition and processing effects on the pseudoelastic response of alpha' ferromagnetic martensite

Processing effects caused by homogenization heat treatment, hot rolling and solution treatment in three Fe-Cr-Ni-C alloys, with different Ni amounts, were analysed by optical and scanning electron microscopy. X-Ray diffraction (XRD), magnetic hysteresis data, Vickers micro-hardness and micro-indentation measurements were used in order to reveal chemical composition and processing effects. Dendrite fragmentation, caused by hot rolling and thermoelastic softening induced by solution treatment, in parallel with the substitution of a part of Cr with Ni, were reported and discussed. Structural changes were corroborated with the variations of magnetic (hysteresis) and mechanical (micro-hardness and micro-indentation) properties. The pseudoelastic character of Fe-Cr-Ni-C alloys was revealed in association with anelastic effect, determined by the variation rate in time of the average dimension of Vickers micro-hardness-induced notch. The confirmation of the pseudoelastic character of the alloys under study was found in the load-depth variations recorded within micro-indentation tests.