On the mechanisms of ductility decreasing of compressively prestrained steel

It is well known that the critical equivalent plastic strain for ductile fracture initiation is strongly influenced by the stress triaxiality and decreased exponentially as the stress triaxiality increases. Authors have found that the critical equivalent plastic strain of compressively prestrained steel for ductile fracture initiation decreases from that of no-prestrained steel as the compressive prestrain increases. In this investigation, the ductile fracture surfaces of compressively prestrained steel were examined by SEM observation. It is found that the micro-cleavage cracks appear in the ductile fracture surface and enhance the ductile fracture initiation of compressively prestrained steel.