Failure strain formulation via average stress triaxiality of an EH36 high strength steel

The paper deals with formulation of failure strain according to average stress triaxiality of a low temperature high-tensile steel, EH36, used for mainly arctic marine structures. Stress triaxiality is recognized as one of the important factors for prediction of failure strain of ductile metals. A number of tensile tests are carried out for flat specimens with different notches from relatively smooth to very sharp levels. Numerical simulations of each specimen are performed via nonlinear finite element analysis (FEA). By means of comparing engineering stress versus strain curves obtained from the tests with simulated ones, failure initiation in numerical simulations are identified. Equivalent plastic strains to fracture are plotted in average stress triaxiality domain, then a new failure strain formula is proposed in relatively low average stress triaxiality region.