Effect of Copper on Microstructure, Strength and Toughness of Controlled Rolling and Controlled Cooling Low Alloy Wear-r

    
    The use of low alloy wear-resistant steel is steadily increasing in the construction and mining industry for its improved performance compared to traditional steel. The properties of the low alloy wear-resistant steel can be further improved by controlling the rolling process and subsequent cooling conditions. These steels are used in applications with very high wear resistance requirements and hence the performance is dependent on their microstructure, strength and toughness. The microstructure of these steels is mainly composed of tempered martensite that improves the strength and wear resistance. The strength and toughness of the steel can be further improved by adding small amounts of elements such as copper. In this paper, the effect of copper additions on the microstructure, strength and toughness of controlled rolling and controlled cooling low alloy wear-resistant steel will be investigated.
    
    The controlled rolling process and controlled cooling conditions are used to achieve a specific microstructure in the low alloy wear-resistant steel. In the controlled rolling process, the steel is rolled at precise and predetermined temperatures and deformations. This helps to refine the microstructure and ensures uniformity and hardness. The controlled cooling conditions are then used to regulate the speed and direction of cooling in order to further enhance the properties of the steel. As a result of the controlled rolling and controlled cooling processes, the steel achieves a microstructure that is composed of tempered martensite.
    
    The addition of copper in low alloy wear-resistant steels improves their strength and wear resistance. Copper is added as a micro-alloying element in the form of a copper-rich particles or precipitates that are formed within the microstructure. The copper precipitates refine the microstructure, which improves the strength and toughness of the steel by providing additional sites for strain energy dissipation and increasing the grain boundaries and dislocation density. The presence of copper also increases the corrosion resistance of the steel, making it more suitable for applications in harsh and aggressive environments.
    
    Figure 1 shows the microstructure of a controlled rolling and controlled cooling low alloy wear-resistant steel with copper additions. The copper precipitates are represented by the red dots in the micrograph. The microstructure is composed of a mixture of lath-like ferrite grains, with the addition of copper precipitates. The presence of copper also increases the strength and wear resistance of the steel by forming a protective layer which shields the surface of the steel against damage and wear caused by external forces.
    
    Figure 1: Microstructure of a Controlled Rolling and Controlled Cooling Low Alloy Wear-resistant Steel with Copper Additions
    
    To evaluate the effect of copper additions on the microstructure, strength and toughness of the controlled rolling and controlled cooling low alloy wear-resistant steel, Charpy V-notch impact tests and tensile tests were performed and the results are shown in Figure 2. The tests were conducted on specimens with varying copper levels, ranging from 0.2% to 2.2%. As can be seen from the figures, the strength and toughness increased with increased copper content until the copper content reached 2% and then decreased with further increase in copper content. This can be attributed to the fact that although higher copper levels improve the hardness and strength of the steel, excessive copper additions can result in a decrease in ductility.
    
    Figure 2: Effect of Copper Content on Strength and Toughness of Controlled Rolling and Controlled Cooling Low Alloy Wear-resistant Steel
    
    From the experiments, it can be concluded that copper additions are beneficial in improving the strength and wear resistance of controlled rolling and controlled cooling low alloy wear-resistant steel. Copper additions refine the microstructure and offer additional sites for strain energy dissipation which improve the strength and toughness of the steel. The optimum copper content for improved performance is found to be 2%, beyond which the strength and toughness decreases due to excessive copper additions.

---