Effect of tempering temperature on carbide evolution and hardness of high nitrogen wear-resistant plate
High-nitrogen martensitic wear-resistant plates are widely used in engineering because of their good strength, hardness and wear resistance, excellent corrosion resistance and fatigue properties, and certain toughness. Earlier, it was discovered that adding nitrogen to wear-resistant plates can improve the strength of wear-resistant plates without reducing plasticity and toughness. It can have high strength and high fracture toughness at the same time. Later, it was gradually discovered that nitrogen contributes to the resistance of steel. Corrosion performance.
Scientific researchers directly quenched the high-nitrogen martensitic wear-resistant plate and repeated two deep cooling and tempering treatments at different temperatures. They used optical microscopes, SEM electron microscopes, TEM electron microscopes and Rockwell hardness testers to study different tempering treatments. The correlation between the evolution law of carbides under temperature and the change of hardness. Under different tempering temperatures, according to the trend of hardness first decreasing, then increasing and then decreasing, the size interval distribution frequency, number per unit area, and The average size and unit area ratio of carbides were characterized and analyzed.
The results show that as the tempering temperature increases from 150 to 500°C, the size of the carbide grows from 0.39 to 0.62 μm, and the carbide is nearly spherical M23C6 type. The decrease in hardness during tempering at 150-300°C is related to the desolvation of the matrix; the number and area fraction of carbides per unit area increase during tempering at 300-450°C; when tempered to 500°C, fine carbides aggregate and grow larger per unit area. The quantity decreases and the area fraction occupied by carbides decreases. It can be concluded that the change in hardness during tempering is related to the unit number of precipitated carbides and their area fraction.
