引張変形を与えたフェライト・パーライト鋼中のひずみ分配と延性破壊ボイドの発生

抄録

A study has been made of the deformation behavior of pearlite nodule and void formation process in the course of tensile deformation of ferrite-pearlite steels containing 0.05 to 0.91 wt%C.
Since pearlite nodule deforms to less extent than matrix, strain partitioning occurs between pearlite nodule and matrix ferrite. The degree of partitioning increases as pearlite volume fraction decreases, which means that the strain of pearlite nodule differs with the volume fraction of pearlite at a given strain of the specimen.
As the deformation of specimen proceeds, void formation occurs at pearlite nodule and the strain at void formation increases with decreasing volume fraction of pearlite. The strain of pearlite nodule at this point, however, is approximately equal (ε_p=0.3) regardless of the volume fraction of pearlite. Furthermore, the estimated stress to pearlite nodule at void formation is about 110-120kg/mm² in each steel and this stress corresponds the fracture stress of pearlite nodule.
The results reveal that void formation in ferrite-earlite steel occurs when the strain and/or stress of pearlite nodule reaches to the critical levels relating to the fracture of pearlite nodule per se.