Examination on Fatigue Limit and Crack Growth Characteristic of SBHS700 Base Metal

The object of this study is to clarify fatigue limit and fatigue crack growth characteristic of SBHS700 base metal which is 780 MPa class steel. This study carried out the fatigue tests of SBHS700 base metal containing different defect size, and the fatigue limit was compared with that of the conventional steel. Test results indicate that the fatigue limit increased with decrease initial defect size, and can be precisely evaluated by using area−−−−√ parameter model. This paper also presents that crack growth characteristic was almost the same as that of the conventional steel from the observation of striations by using Scanning electron microscope and length of beach marks.