The Effect of QPQ Salt-Bath Nitriding on Microstructure and Wear Resistance of 3Cr2W8V Steel

The wear resistance, corrosion resistance and hardness can be greatly increased by using low temperature QPQ salt-bath nitriding treatment. And it is a new strengthening method without distortion in the treating process. In this paper, 3Cr2W8V steel is dealt with QPQ salt-bath nitriding at 520°C, 540°C, 560°C and 2h, 4h, 6h, respectively. The treated surface microstructure was analyzed by using SEM. The depth of nitriding layer, scratch hardness and wear-resistance were tested for both QPQ salt-bath treated and untreated specimen. The corrosion resistance was tested in the 5%NaCl water by using spraying method. The experimental results indicate that a certain depth of white layer and diffusion layer of the steel can be obtained by using low temperature QPQ salt-bath nitriding treatment. The nitriding compound layer with high hardness, superior wear-resistance and stable microstructure can also be obtained on the surface of the parts. With increasing the temperature and the nitriding time, the depth of nitriding layer, scratch hardness and wear-resistance of 3Cr2W8V steel were greatly increased. Comparing with the untreated specimen, its hardness enhances 95.0%, wear resistance enhances 212.3%, anti-corrosion enhances 1288.9%. The experimental results show that the low temperature QPQ salt-bath nitriding treatment has many advantages, such as fast nitriding speed, uniform heating, short process time, low treating temperature, small distortion, high production rate, low cost, stable nitriding quality without pollution and so on.