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在610℃下对SAF2906双相不锈钢分别进行了60、90、120、150和180min的QPQ处理,采用OM、SEM、XRD、显微硬度计以及摩擦磨损试验机研究了各试样的组织与耐磨性。研究发现,QPQ处理后的试样渗层组织由表及里依次为氧化层、化合物层和扩散层。其中,氧化层主要由Fe3O4组成,渗N层(化合物层和扩散层)主要物相为CrN、α-N、Fe2-3N和S相。随着渗N时间延长,化合物层生长速度逐渐减缓,缩松程度逐渐加重;同时,渗层孔隙率随着渗N时间的延长而增加,渗层致密性下降。另外,QPQ处理试样的表面硬度高出基材3倍以上,且随着渗N时间的延长呈先增加后下降的变化规律,经120min处理时,硬度(HV0.2)达到峰值,为1 164。干摩擦磨损试验结果表明,QPQ处理试样的耐磨性能比基材提高了20倍以上,最佳渗N时间为120min。磨损表面形貌观察发现,基材的磨损形式为磨粒犁削,而QPQ处理试样的磨损形式为磨粒的显微切削。
SAF2906 duplex stainless steel was treated with QPQ at 60, 90, 120, 150 and 180 minutes at 610 ℃. The microstructure and resistance of each sample were studied by OM, SEM, XRD, microhardness tester and friction and wear tester Grindability. The study found that, QPQ sample after treatment of the specimen from the surface layer and the oxide layer, compound layer and diffusion layer. Among them, the oxide layer mainly composed of Fe3O4, infiltration N layer (compound layer and diffusion layer) the main phase is CrN, α-N, Fe2-3N and S phase. With the extension of infiltration time, the growth rate of compound layer gradually slowed down and the degree of shrinkage gradually increased. At the same time, the porosity of infiltration layer increased with the infiltration of N and the densification of infiltration layer decreased. In addition, the surface hardness of QPQ treated samples was more than 3 times higher than that of the substrate, and then increased with the increase of infiltration time and then decreased. The hardness (HV0.2) peaked at 120 min 164. Dry friction and wear test results show that the wear resistance of QPQ treated specimens increased more than 20 times the substrate, the best infiltration time of 120min. Abrasion surface morphology observation found that the wear form of substrate abrasive grain plow, and QPQ treatment sample wear form of abrasive micro-cutting.