Effects of inclusion types on the high-cycle fatigue properties of high-strength steel

The high-cycle fatigue fracture behavior induced by different types of inclusions for high-strength steels was investigated. It is found that fatigue cracking of high carbon chromium bearing steel mainly originated from the interface between the matrix and the oxide inclusions while from the inside for nitride inclusions in the fatigue failure origin, respectively. The two fatigue cracking modes induced by different types of inclusions often result in a great difference in the fatigue lives even though considering the stress amplitude as well as the inclusion size. Therefore, an inclusion type factor was established for the first time to unify the effects of the inclusion types on the fatigue properties and the modified stress intensity factor could well predict the fatigue lives. These results distinguish the differences of the inclusion types in the fatigue performance and the role in trace elements control in metallurgy for the high-strength steels.