Effect of heat treatment process on microstructure and properties of 18Cr23MoVRE wear-resistant cast steel

Wear-resistant cast steel 18Cr23MoVRE is a type of martensitic cast steel characterized by superior hardness and wear resistance due to its high chromium and molybdenum content. Heat treatment is one of the major steps used in the production of this kind of steel, as it affects its microstructure and properties.
    
Heat treatment of 18Cr23MoVRE cast steel includes several stages such as austenitizing, tempering, nitriding and quenching. The purpose of the process is to modify the microstructure by changing the size and distribution of the ferrite and austenite grains, and improving the mechanical properties of the steel.
    
Through austenitizing, the steel is heated to a predetermined temperature. This temperature is selected to allow grains of ferrite and austenite to retain sufficient energy to increase in size. As the grains increase in size, they become more evenly distributed, which improves the properties of the steel. The steel is then tempered to reduce its hardness and increase its toughness.
    
During nitriding, the steel is exposed to nitrogen-enriched atmosphere at high temperature. This process produces a layer of nitride on the surface of the steel, which increases the wear resistance and surface hardness. Finally, quenching is performed to rapidly cool the steel in order to obtain a martensitic microstructure.
    
The effect of heat treatment on the microstructure and characteristics of 18Cr23MoVRE cast steel can be seen in Table 1. Heat treatment helps to improve its mechanical properties such as ductility, hardness, strength and fatigue resistance.
    
    Table 1: Effect of Heat Treatment on 18Cr23MoVRE Cast Steel
    
    Property/Process No Heat Treatment Heat Treatment
    
    Microstructure/Ferrite Content Ferrite is retained in a non-uniform distribution throughout the steel Unifrom distribution of ferrite and austenite
    
    Hardness Average Knoop Hardness decreased Increased
    
    Density Decreased Slightly decreased
    
    Ductility Increased Increased
    
    Strength Increased Increased
    
    Fatigue Resistance No significant change Improved
    

    
Conclusion
Heat Treatment is essential for improving the mechanical properties of 18Cr23MoVRE cast steel. Austenitizing, tempering, nitriding, and quenching are some of the major processes used to modify the steel’s microstructure and enhance its properties. The heat treatment process causes an increase in hardness and strength and a decrease in density. It also improves fatigue resistance and ductility, making the steel more suitable for wear-resistant applications.

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