Effect of QPQ nitriding time on microstructure and wear resistance of SAF2906 duplex stainless steel

1st International Conference on New Material and Chemical Industry

材料科学;化学工业

Liu, D.^1 ; Wu, G.X.^1 ; Shen, L.X.^1

School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou

350108, China^1

关键词: Heating temperatures;    Intermediate layers;    Maximum hardness;    Microhardness tests;    Microstructure observation;    Saf2906 duplex stainless steels;    Surface hardness;    Worn surface morphology;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/167/1/012046/pdf
DOI  :  10.1088/1757-899X/167/1/012046

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

QPQ salt bath treatment of SAF2906 duplex stainless steel was conducted at 570 °C for 60 min, 90 min,120 min,150 min and 180 min, followed by post-oxidation process with heating temperature of 400°C and holding duration of 30 min. The effect of QPQ nitriding time on microstructure and wear resistance of SAF2906 duplex stainless steel was investigated by means of OM, SEM, XRD, microhardness test, adhesion strength test and wear resistance test. Microstructure observation showed outer layer was composed of Fe3O4. The main phase of the intermediate layer was CrN, αN and Fe2-3N. The main phase of the inner layer was CrN and S. The adhesion strength test of the surface layer-substrate showed the QPQ treated samples have favorable adhesion strength of HF-1 level. With the increase of nitriding time, the growth rate of the compound layer gradually slowed down and the surface hardness first increased and then decreased, and the maximum hardness was 1283 HV0.2at 150 min. The dry siliding results showed that the wear resistance of the QPQ treated samples was at least 20 times than that of the substrate, and the optimum nitriding time to obtain the best wear resistance is 150 min. The worn surface morphology observation showed the main wear mechanism of the substrate was plough wear, while micro-cutting is the main wear mechanism that causes the damage of the QPQ treated samples.