QPQ处理对特级双相不锈钢SAF3207组织及性能的影响

Effect of QPQ treatment on microstructure and properties of SAF3207 super duplex stainless steel

采用QPQ工艺对N含量分别为0.51%和0.72%的固溶态SAF3207特级双相不锈钢进行表面处理。利用OM、SEM、XRD、显微硬度计和摩擦磨损试验机研究了不锈钢的渗层组织及耐磨性。渗层组织观察表明,SAF3207不锈钢经QPQ处理后,渗层由表及里为氧化层(Fe_3O_4)→化合物层(α_N+S+Cr N+ε)→扩散层(α_N+S+Cr N+γ');与QPQ处理的低N试样相比,高N试样化合物层厚度较低;渗层硬度变化趋势为先升高后平稳然后逐渐降低至基体硬度,其最高硬度达850 HV0.2。干摩擦试验结果表明,SAF3207双相不锈钢经QPQ处理后的磨损性能显著提高,低N试样比高N试样更耐磨。

Solid solution treated SAF3207 super duplex stainless steel with nitrogen content of 0. 51% and 0. 72% were treated by QPQ process respectively. The effects of QPQ treatment on microstructure and wear resistance were investigated by means of OM,SEM,XRD,microhardness tester,friction and wear tester. Microstructure observation results show that the nitrided layer structure of the SAF3207 stainless steel after QPQ treatment is composed of oxide layer（ Fe3O4）,compact compound layer（ αN＋ S ＋ Cr N ＋ ε） and diffusion layer（ αN＋ S ＋ Cr N ＋ γ＇） from the surface to the core. Compared with the low nitrogen steel after QPQ treatment,the thickness of the compound layer of the high nitrogen steel is smaller. The microhardness variation trend of the nitrided layer first increases and then smoothes and finally decreases gradually to the matrix hardness,and the maximum hardness is up to 850 HV0. 2. The dry-sliding friction test results indicate that the wear resistance of SAF3207 hype duplex stainless steel is significantly improved by the QPQ treatment,and the low nitrogen tested stainless steel shows better wear resistance than that of the high N steel.