Size Effect on the Load-displacement Curves of Compact Specimen of SUS 316 Steel

Abstract

The size effect on the crack growth in SUS 316 steel was studied by observations of load-displacement curves of many proportional compact specimens with various nominal widths. When the thickness was less than 0.2 times the width, the critical crack-tip opening-displacement (CTOD) for the start of steady crack growth was proportional to the thickness. The proportional constant was expressed by the experimental constants (yield stress, work-hardening parameters and fracture true stress) obtained by the unidirectional tensile tests. It was concluded that a ductile crack grows when the normal stress ahead of the crack-tip exceeds the fracture true stress of the materials.