Damage evaluation for AISI 304 steel under cyclic loading based on coercive force measurements

Abstract

The authors present the results of experimental investigations on the damage evaluation of AISI 304 steel under tension and cyclic loading based on coercive force measurements. It was established that kinetics of the coercive force demonstrates descending and ascending sections on the kinetic curve independently on the loading type. The increase of coercive force is caused by the deformation-induced transformation of the paramagnetic austenite into ferromagnetic martensite. The increasing coercive force is observed during the deformation process up to the loss of metal continuity (initiation and propagation of cracks and voids). While the coercive force shows a decreasing tendency due to the loss of metal continuity (stage of crack propagation). In the coercive force monitoring, it is required to pay attention to the variation in the direction of the kinetic curve and not to the absolute values of coercive force. Thus, the coercive force monitoring in the most critical zones of the structural elements allows one to control for the damage accumulation at each stage of crack initiation or propagation.