Study on the high cycle fatigue behavior of titanium microalloyed high strength beam steel by magnesium treatment

Non-metallic inclusions, which was mainly modified by magnesium treatment process in this work, played a decisive role in controlling the high cycle fatigue behavior of titanium microalloyed high strength beam steel. Magnesium treatment process profoundly reduces the large-sized inclusions in experimental steels, leading to a high fatigue strength and crack growth resistance simultaneously. The magnesium treatment process improved fatigue strength by 5.1% despite a 7.3% decrease in tensile strength of 6-Mg steel. In addition, Generalized Pareto Distribution (GPD) statistical method is used to evaluate the maximum inclusion size, which decreases by 25.3% through magnesium treatment process. These findings provide a new strategy to develop a titanium microalloyed beam steel with outstanding fatigue resistance.