Abstract
Comprehensive numerical and experimental studies were performed to investigate the plasticity and ductile fracture behaviors of the AISI 4340 steel alloy under multiaxial stress loading conditions and at different heat-treatments. The plasticity model with pressure and Lode angle effects (PPL plasticity model (Algarni et al. in Eng Fract Mech 147:140-157, 2015; Bai and Wierzbicki in Int J Plast 24(6):1071-1096, 2008) with modifications) and the modified Mohr-Coulomb (MMC) fracture model (Bai and Wierzbicki in Int J Fract 161(1):1-20, 2009) were used to predict plastic and fracture initiation behaviors under different loading conditions using finite element simulations. In addition, Drucker-Prager (DP) plasticity model was also used for comparison. The effects of heat-treatment on material strength and ductility of AISI 4340 steel were assessed and discussed.