Characteristics of Primary Carbide and Its Evolution During Hot Rolling in High-Carbon Chromium Bearing Steel

Clarifying the characteristics of primary carbidePrimary carbide and its evolution behavior during hot rollingHot rolling in high-carbon chromiumChromium bearing steelBearing steel is crucial to control the contact fatigue failure caused by it. The morphology, distribution, solute segregationSegregation, and the type of carbide were investigated via dendrite etching, scanning electron microscopy, and X-ray diffractionX-ray diffraction (XRD). Furthermore, the melting processProcess of primary carbidePrimary carbide and its evolution during rolling were studied by high-temperatureHigh temperature confocal laser scanning microscope and continuous casting-direct rolling simulator, respectively. The results show that primary carbidePrimary carbide exists almost only in the central equiaxed crystal zone of the continuously cast bloomBloom and appears as a Cr-rich white eutectic structureStructure between dendrites. The type of primary carbidePrimary carbide is M3CM3C cementite, and the decompositionDecomposition and melting temperaturesTemperature are 1066.5 ℃ and 1160.1 ℃, respectively. Rolling below the melting temperatureTemperature causes the primary carbidesPrimary carbide to fracture and flow as the metalMetals deforms, and are finally distributed in a chain-like manner in the banded structureBanded structure.