Analysis of carbides in 95Cr18 bearing steel die casting billet

This paper calculated the phase transition and carbide precipitation of 95Cr18 bearing steel based on Thermo-Calc 2020b. The microstructure and carbide of the steel die casting were analyzed using metallographic corrosion, metallographic microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction (XRD) detection technology integrated into the scanning electron microscope. The three-dimensional morphology of carbides was studied through three-dimensional corrosion technology. The results showed that the carbides in 95Cr18 bearing steel were mainly Cr-rich M₇C₃ and M₂₃C₆ carbides, which were divided into three morphologies: blocky, fibrous, and spherical. During the solidification process, M₇C₃ gradually transformed into M₂₃C₆ carbides in situ. From the edge to the center, the carbide morphology changed as follows: Block → Chain → Triangular Pyramid → Network, with network carbides being predominant from 1/4 of the ingot to the center. The proportion of carbide area increased from 2.7% at the edge to 5.5% at the center, and the carbide area was mainly distributed between 4~10 μm².