Effect of cooling rate on microstructure, hardness, and residual stress of 0.28C–0.22Ti wear-resistant steel

    
    0.28C–0.22Ti wear-resistant steel is a popular material for a variety of industrial applications, such as medical implants and cutting tools. In the manufacturing of 0.28C–0.22Ti wear-resistant steel parts, the cooling rate during the quenching process has a significant effect on the resulting microstructure, hardness, and residual stresses. In this article, the effect of cooling rate on the microstructure, hardness, and residual stress of 0.28C–0.22Ti wear-resistant steel is discussed.
    
    Overview of 0.28C–0.22Ti Wear-Resistant Steel
    
    0.28C–0.22Ti wear-resistant steel is a type of ferritic matrix steel. It is a low-alloy steel with a carbon content of about 0.28 wt.% and high chromium and molybdenum content for added wear resistance. The microstructure of this type of steel consists of a fine Martensite-austenite microstructure. It can be heat treated to obtain different mechanical properties by varying the cooling rate during quenching.
    
    Effect of Cooling Rate on Microstructure
    
    The microstructure of 0.28C–0.22Ti wear-resistant steel can be manipulated by controlling the quenching rate. A faster cooling rate results in smaller grain sizes and an increased volume fraction of fine Martensite, while slower cooling rates result in larger grain sizes and an increased volume fraction of coarse pearlite. For this type of steel, optimal hardness and wear resistance are generally obtained when the cooling rate is between 500–800°C/min (930–1460°F/min).
    
    Effect of Cooling Rate on Hardness
    
    The hardness of 0.28C–0.22Ti wear-resistant steel is highly dependent on the cooling rate during quenching. Fast cooling rates result in higher hardness values as the Martensite structure forms quickly and fine grains are rapidly present. When the cooling rate is too fast, however, the hardness of the steel can be too high and can cause deformation. Slow cooling rates result in softened steel due to the formation of coarser pearlite structures. The optimal hardness for this steel is achieved when the cooling rate is between 500–800°C/min (930–1460°F/min).
    
    Effect of Cooling Rate on Residual Stress
    
    The residual stress of 0.28C–0.22Ti wear-resistant steel is also affected by the cooling rate. Fast cooling rates result in higher residual stresses due to the rapid formation of the Martensite structure. Slow cooling rates result in lower residual stresses as the coarser pearlite structure is allowed to form. To achieve a balance between minimal residual stress and optimal hardness, the cooling rate should be kept at 500–800°C/min (930–1460°F/min).
    
    Conclusion
    
    0.28C–0.22Ti wear-resistant steel is a popular material for a variety of industrial applications due to its good wear-resistance and hardness. By controlling the cooling rate during the quenching process, the microstructure, hardness, and residual stress of the steel can be manipulated. Optimal hardness and minimal residual stress are achieved when the cooling rate is between 500–800°C/min (930–1460°F/min).

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