Observation of Fisheye Cracks around TiN and Al<sub>2</sub>O<sub>3</sub> Inclusions in Repeatedly Quenched High Carbon Bearing Steel

Martensitic high-carbon high-strength SAE 52100 bearing steel is one of the main alloys used for rolling contact applications where high wear resistance is required. Refining the prior austenite grain size through repeated heating is a process commonly used to enhance the material’s strength. In this work, the microstructure of repeatedly quenched Ti, N-rich ultra-clean SAE 52100 steel was investigated. The material was melted by an electric furnace and formed by continuous casting and forging, and the crack origin on the fracture surface was investigated. It was found repeated furnace quenching effectively refined the martenstic structure.