Characterization of uncoupled ductile fracture criteria for 0Cr17Ni4Cu4Nb stainless steel under different stress states

Ductile fracture behavior of 0Cr17Ni4Cu4Nb stainless steel was evaluated under six distinct stress states (Flat shear, Flat with a circular hole, Smooth round bar, Flat notched tension, Notched round bar R3.0, Notched round bar R1.5) using eight widely applied fracture criteria: Freudenthal, Cockcroft and Latham, Oh, Brozzo, Rice and Tracey, Ayada, LeRoy, and Lou and Yoon criteria in this study. A combination of experimental and numerical methods was used to analyze plastic deformation characteristics and predict damage distribution under diverse stress states. The findings highlight the strengths and limitations of each ductile fracture criteria in predicting fracture behavior under diverse loading conditions for 0Cr17Ni4Cu4Nb stainless steel. The comparative analysis revealed that although the Lou-Yoon criterion performed best overall, it significantly over-predicted the fracture strain in the highest stress triaxiality case (Notched Round Bar R1.5), exposing a critical limitation. To address this, a modified Lou-Yoon criterion was proposed by introducing a stress triaxiality weighting function. The improved Lou-Yoon model was validated against all six stress states, and it achieved high accuracy across the entire range of stress states.