Experimental Research on the Performance of High-Temperature Bearing Steel Cr4Mo4 V

Background: Cr4Mo4 V steel is widely used in high-temperature bearings because of its excellent high-temperature performance. Based on the research status of Cr4Mo4 V nationally and internationally, this paper explores its mechanical properties and friction properties at high temperatures. Objective: To characterize the composition, microstructure, and properties of Cr4Mo4 V steel and explore its tensile properties, hardness, and friction properties at high temperatures. Methods: Many methods are adopted, including chemical element analysis, metallographic analysis, hardness test, tensile test, damping test, and friction test. Results: Cr4Mo4 V has a tempered martensite microstructure. The hardness and maximum tensile strength of Cr4Mo4 V decrease with increasing temperature. The grain of the Cr4Mo4 V steel after heating becomes refined, and the grain boundary increases. At room temperature, the surface friction coefficient and wear rate of Cr4Mo4 V steel decrease. Moreover, a Cr4Mo4 V steel-ceramic ball shows the best friction resistance. At high temperatures, the friction coefficient and wear of Cr4Mo4 V steel first decrease with increasing temperature and then increase sharply at 200°C. Conclusion: With an increase in temperature, the hardness, breaking force, and tensile strength of Cr4Mo4 V bearing steel decrease, whereas the friction property increases. By analyzing the threedimensional morphology of different wear samples, the optimal working temperature of Cr4Mo4 V steel bearing is determined as 200°C.