Crack tip transformation zones in austenitic stainless steel

Crack tip conditions in SUS 304 austenitic stainless steel are studied using a constitutive model in which the martensitic phase transformation is an integral part. The phase transformation occurring in the crack tip region gives rise to fracture toughening of the material whereby the resistance against crack initiation, as well as the macroscopic material response are strongly altered by the presence of a martensitic phase. The constitutive model employed herein permits studying the transformation zones under different isothermal conditions. Local crack tip conditions and related plastic deformation is confirmed to depend strongly on the varying extent of the martensitic phase transformation at different temperatures. The shape and size of the plastic and transformation zones in the neighborhood of the crack tip are obtained from numerical simulations, as well as derived analytically.