Identification of cyclic softening and σ-ε hysteresis in austenitic steel with plasticity-induced martensitic transformation

The essential aim of this paper is the description of cyclic properties of metastable austenic steel with martensitic transformation induced by cyclic plastic deformation. The main problem is the model of σ-ε hysteresis loop as well as the phenomenon of cyclic softening. The original model of elasto-plastic body was applied to make a description. The model includes the appearance of cyclic plasticity limit and strain ε1 corresponding to the inflexion point at CSS curve. This point separates the one phase range (austenite) from the two phase range (austenite + martensite). The plastic deformation ε1 was accepted as the material constant and named the cyclic limit of martensitic transformation. The experimental fatigue investigations of high nickel alloy steel of the type AISI 304 were carried to identify the model. The experiments were performed for the controlled plastic deformation ampliture value εp = constant. The results confirmed adequacy of the accepted model.