Gigacycle Fatigue Fracture of Low Strength Carbon Steel, Tested using a Simulated Heat Affected Zone Microstructure

Abstract

In this study, gigacycle fatigue properties were investigated for several microstructures prepared by heat treatment designed to simulate the heat-affected zone (HAZ) that results from welding. The results showed that internal matrix crack origin gigacycle fatigue becomes dominant in coarse-grained microstructures in spite of low tensile strength of only about 600 MPa. It was found that, high material strength is not always necessary and that microstructure plays an important role in the development of internal-origin gigacycle fatigue fractures.