Comparison of Fracture Model Parameters for Indian Stainless Steel

This paper focuses on predicting ductile fracture initiation of IRS 450 CR and IRS 350CR stainless steel subjected to monotonic loading. Notched specimens, especially those developing high-stress triaxiality, are extracted from 25 mm stainless steel plates for both grades. The extracted specimens are subjected to uniaxial testing to obtain the load-displacement history until the specimen fractures. Isotropic hardening models built into the ABAQUS/CAE platform are employed in this study to replicate the plastic response obtained from experiments accurately. The hardening parameters of the validated numerical model are reported in this paper. Further, the validated numerical model is used to extract the principal stresses, von Mises stress, and equivalent plastic strain (PEEQ) at the point of ductile fracture initiation. The extracted histories of principal and von Mises stresses are used to calculate the evolution of stress triaxiality (T) and Lode angle parameter (L). This study compares the two widely used uncoupled ductile fracture prediction models based on the fracture parameters and function used to combine these fracture parameters in their formulation. The noted critical values of T, PEEQ, and L are used to calibrate the free parameters of all these models. The two-dimensional fracture locus is compared for India’s currently used carbon and stainless-steel grades.