In this paper, the precipitation of carbide and wear loss of high-carbon 8 mass% Cr tool steel at two tempering conditions (i.e., 773⁻803 K and 823⁻853 K) were studied by INCA Steel, EPMA-1720H, XRD, and ML-10 tester. The results show that the particles of test steels include the carbides (Cr₇C₃ and Cr23C₆) and carbides nucleated on Al₂O₃. When carbides are of the same size, the number of carbides in test steel at a tempering temperature of 773⁻803 K is greater than that at a tempering temperature of 823⁻853 K, especially when the size of carbides is less than 5 μm. Compared with the test steel tempered at 823⁻853 K, the distance between adjacent actual particles reduced by 80.6 μm and the maximum amount of reduction was 9.4% for single wear loss at the tempering temperature of 773⁻803 K. It can be concluded from thermodynamics results that Al₂O₃ inclusions began to precipitate in liquid, and the precipitation of carbides was at the solid⁻liquid region. Al₂O₃ can be used as the nucleation interface of carbide, thus promoting the formation of carbides. During the cooling of molten steel, a lower temperature can increase the difference of actual solubility product bigger than equilibrium solubility product, thus promoting the carbide formation.
Keywords: carbide precipitation; different tempering temperatures; high-carbon 8 mass% Cr tool steel; wear resistance.