抄録
Profiles of stretched zones were observed at various stages during crack tip blunting and stable crack growth in JIc tests on five steels with yield strength levels ranging from 765 to 333MPa. During the stable crack growth, the steel with a high yield strength of 765MPa indicated little deformation in both the stretched zone and the dimple region, while the medium and, particularly, low strength steels showed considerable deformation there. Based on the observations in this study, several proposals were made for improving the stretched zone width method in the JSME standard of test for JIc.
