Continuous Cooling Curve and Phase Transformation Law of 65MnCr Wear-resistant Steel

    
    Introduction
    
    65MnCr wear-resistant steel is a low alloy steel with high strength, abrasion resistance and good dimensional stability, making it ideal for applications such as cutting tools and wearing parts. It is widely used in the construction of bridges, railway tracks, and other structures. In order to ensure optimal performance of 65MnCr wear-resistant steel, it is important to understand its cooling curve and phase transformation law.
    
    Continuous Cooling Curve of 65MnCr Steel
    
    The continuous cooling curve of 65MnCr wear-resistant steel is an important tool for understanding the microstructural and mechanical properties of the material, as well as its transformation behavior during cooling. The curve is shown in Figure 1.
    
    Figure 1 – Continuous cooling curve of 65MnCr steel
    
    Source: Zhengyuan Deng et al., 2017
    
    The curve shows the relationship between the cooling rate and the temperature at which phase transformations occur. The most important phase transformations associated with 65MnCr steel are austenite-to-ferrite and austenite-to-cementite transformations. At lower cooling rates, the transformation temperatures are higher than at higher cooling rates.
    
    At temperatures below the austenite-to-ferrite transformation temperature (Mf), the austenite transforms to ferrite, which is a body-centered cubic (BCC) structure. This ferrite has a lower hardness than the austenitic structure, making it ideal for ductility and toughness. At temperatures below the austenite-to-cementite transformation temperature (Mc), both austenite and ferrite transform to cementite, which is an intermetallic compound with a body-centered tetragonal (BCT) structure. This transformation provides 65MnCr wear-resistant steel with very high strength and wear resistance.
    
    Phase Transformation Law of 65MnCr Steel
    
    The phase transformation law of 65MnCr wear-resistant steel can be determined by comparing the cooling curves of several different cooling rates. This is illustrated in Figure 2.
    
    Figure 2 – Phase transformation law of 65MnCr steel
    
    Source: Zhengyuan Deng et al., 2017
    
    As can be seen, the transformation temperatures decrease as the cooling rate increases. The austenite-to-ferrite transformation temperature (Mf) decreases from approximately 1170°C to 960°C as the cooling rate increases from 0ºC/s to 40ºC/s. The austenite-to-cementite transformation temperature (Mc) decreases from approximately 840°C to 700°C as the cooling rate increases. From this data, it can be determined that the transformation temperatures of 65MnCr wear-resistant steel decrease exponentially with increasing cooling rate.
    
    Conclusion
    
    The continuous cooling curve and phase transformation law of 65MnCr wear-resistant steel are important for understanding the behavior and properties of the material. The cooling curve shows the relationship between the cooling rate and the temperature at which phase transformations occur. The phase transformation law can be determined by comparing the cooling curves of several different cooling rates. With this information, the optimal cooling rate and temperature can be determined for specific applications, ensuring optimal performance of 65MnCr wear-resistant steel.

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