Factors influencing the GBF size of high strength steels in the very high cycle fatigue regime

The influences of major factors including applied stress amplitude, inclusion size and hydrogen content on granular-bright-facet (GBF) size of high strength steels in the very high cycle fatigue regime were studied in this article. It was found that the GBF size is determined by the applied stress amplitude and material hardness. If the applied stress amplitude is lower, the GBF size is larger. When a specimen containing bigger inclusions, the applied stress amplitude to form GBF can be reduced which results in the increase of GBF size. Hydrogen has different effects on the GBF size. The related reasons were discussed.