Effect of Nb on Microstructure and Properties of Medium Carbon Low Alloy Wear-resistant Steel
Nb is an important element used to form microstructure of alloy steel. Its addition can reduce the formation of carbides, promote grain refining, increase the hardness and toughness of the steel, and improve its fatigue strength, corrosion resistance and wear resistance. Nb also modifies other carbide-forming elements, improves the wear resistance of martensite, and improves the corrosion properties of martensite.
In medium carbon low alloy wear-resistant steel, Nb can decrease the microstructure’s retained austenite content to improve the microstructure’s stability. It also increases the hardness of retained austenite and prevents the formation of low-hardness regions, thus improving the wear resistance. At the same time, Nb also replaces some of the alloying elements in the steel to form intermetallic compounds and improves the precipitation strengthening effect of the steel.
The microstructure of medium carbon low alloy wear-resistant steel with and without Nb is shown in Figure 1. It can be seen that the addition of Nb results in the formation of fine grains and secondary carbide precipitates. The fine grains result in a more uniform distribution of carbides and improved wear resistance of the steel, while the increased number of secondary carbides increases the strength and hardness of the steel.
In summary, the addition of niobium in medium carbon low alloy wear-resistant steel helps improve the microstructure by promoting grain refining, increasing carbide formation and precipitate strengthening. This leads to improved wear resistance and higher mechanical performance.
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