Hot deformation and dynamic recrystallization behavior of austenite in low alloy wear-resistant steel

    
    Wear-resistant steels, having superior wear and abrasion resistance, are widely used in high demanding workpieces, such as mining and building construction applications. To enhance the wear resistance of low alloy steels, fine grain microstructural features are obtained by heat treatment process to obtain wear-resistant steel. The thermo-mechanical response of austenite obtained from the heat treatment process has a significant effect on the material properties.
    
    Hot deformation, which is triggered by plastic strain, is a major thermo-mechanical process employed to achieve microstructural refinement. The dynamic recrystallization (DRX) behavior of austenite during hot deformation has been extensively studied in various steel alloys, including low alloy wear-resistant steel. The DRX mechanism helps in reducing the average grain size of austenite and provides favorable conditions for improved material properties.
    
    The hot deformation of low alloy wear-resistant steel goes through several distinct stages. Initially the material experiences a period of dynamic strain aging, which results in increased flow stress, followed by yield plateau and necking. During the yield plateau, DRX activity starts to take place, leading to the formation of new grains, which ultimately results in an increase in the average grain size. During the later stage of deformation, the average grain size decreases rapidly due to dynamic recrystallization. The phase transformation of austenite into other intermetallic compounds can also occur during hot deformation.
    
    Numerous parameters affect the DRX behavior of austenite during hot deformation such as deformation temperature, strain rate, and mechanical loading. The temperature must be kept within the range at which austenite is thermodynamically stable to obtain the DRX effect. Similarly, the strain rate needs to be kept above certain level to avoid the secondary recovery effects. The higher the deformation temperature, the longer the time needed for DRX to occur.On the other hand, the mechanical loading needs to be high enough to achieve the desired levels of plastic strain, and at the same time, it should be low enough to prevent excessive grain refinement.
    
    The DRX behavior of austenite in low alloy wear-resistant steel can be observed through an optical microscopy. It is possible to observe the newly formed grains, which are usually larger than the original austenite grains, by applying different etching techniques. The evolution of grain size distribution curves during hot deformation can be obtained through scanning electron microscopy.
    
    In conclusion, DRX of austenite during hot deformation of low alloy wear-resistant steel is a complex process. It is important to understand the DRX behavior in order to obtain optimal mechanical properties. The interplay between different parameters such as temperature, strain rate and mechanical loading need to be carefully examined to achieve the desired levels of microstructural refinement.

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