The Evaluation of Varying Ductile Fracture Criteria for 3Cr20Ni10W2 Austenitic Heat-Resistant Alloy

Abstract

Most bulk metal forming processes may be limited by ductile fracture, such as an internal or surface fracture developing in the workpiece. Finding a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and strain-softening behavior of 3Cr20Ni10W2 heat-resistant alloy is very important, which, however, is a nontrivial issue that still needs to be addressed in greater depth. Based on cumulative damage theory, an innovative approach involving heat physical compression experiments, numerical simulations, and mathematical computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions. It is concluded that, as for strain-softening material, ductile damage starts at work hardening phase, and the damage cumulation is more sensitive in work hardening phase than in work softening phase. In addition, DFC of 3Cr20Ni10W2 heat-resistant alloy in a wide temperature range of 1203∼1403 K and the strain rate of 0.01∼10 s −1 are not constant but change in a range of 0.099∼0.197; thus they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of strain rate and temperature. According to VDFC diagram, the exact fracture moment and position during various forming processes will be predicted conveniently.