多段引抜き加工時のシェブロンクラック発生予測

抄録

The aim of this study was to examine the effect of accumulated equivalent plastic strain on the ductile fracture criterion. Spheroidized medium-carbon steel JIS-S55C was adopted as the test material. An investigation into the ductile crack initiation behavior of round-bar tensile specimens with/without circumferential notches was carried out. Tensile prestrain was applied by cold drawing. The stress triaxiality and accumulated equivalent plastic strain were calculated by the finite element method (FEM). The ductile fracture limit of tensile prestrained steel was expressed as a function of the stress triaxiality and accumulated equivalent plastic strain. The validity of the ductile fracture limit was confirmed by the prediction of chevron crack generation in multipass drawing.