Experimental Studies and Models for Ductile Fracture in ASTM A992 Steels at High Triaxiality

Abstract

This study presents the results of experimental investigation and models for ductile fracture in the ASTM A992 structural steels subjected to high stress triaxiality. To this end, uniaxial tension tests on the notched tensile specimens are conducted, and subsequent scanning electron microscopy (SEM) studies are performed on the fractured surfaces. From this SEM analysis, the fracture initiation mechanism in ASTM A992 steels is found to be the ductile fracture; however, the fracture propagation mode can be either ductile or cleavage fracture. Nonlinear finite-element analysis of the notched specimens is carried out to obtain the stress triaxiality distributions, and the location of the peak stress triaxiality is found to be strongly correlated to the location of the ductile fracture initiation zones. Finally, two uncoupled ductile fracture prediction models, the void growth model (VGM) and the stress modified critical strain model (SMCS), are calibrated, and the model parameters are provided for A992 steels.