气压对304奥氏体不锈钢低温离子渗氮组织与性能影响

Effect of gas pressure in low temperature plasma nitriding on the microstructure and properties for 304 austenitic stainless steel

在400℃、8 h、不同气压(80~400 Pa)条件下对304奥氏体不锈钢进行离子渗氮处理。采用扫描电镜(SEM)、X射线衍射仪、显微硬度计及万能摩擦试验机对表面改性后的304奥氏体不锈钢渗层组织、相结构、渗层硬度以及耐磨性进行了测试和分析。结果表明,400℃离子渗氮处理后304奥氏体不锈钢形成了明显的白亮层,即单相S相层;低压对304奥氏体不锈钢离子氮化具有良好的催渗效果,即渗层厚度随气压的减小而增加,在100 Pa条件下,渗层厚度达到最大值51.7μm;渗氮后试样表面硬度达到最大值1100 HV0.01;低温低压离子渗氮能够提高304奥氏体不锈钢耐磨性,80 Pa和100 Pa是提高304奥氏体不锈钢耐磨性的最佳气压。

Plasma nitriding of 304 austenitic stainless steel was conducted at different gas pressures of 80 Pa,100 Pa,120 Pa,160 Pa and400 Pa under the same temperature of 400 ℃ for 8 h. The nitrided specimens were characterized by scanning electron microscopy( SEM),X-ray diffractometer( XRD),microhardness test and pin-on-disc tribometer. The results show that a white layer,which is also called single S phase layer,is formed after plasma nitriding at 400 ℃ with different gas pressures,and lower gas pressure has significant catalysis effect on plasma nitriding of 304 austenitic stainless steel. The thickness of nitride layer increases with the decreasing of gas pressure and reaches the maximum of 51. 7 μm at 100 Pa,meanwhile the maximum surface hardness of 1100 HV0. 01 is obtained. The wear resistance of 304 austenitic stainless steel can be improved after plasma nitriding,and the optimal gas pressure for improving its wear resistance is 80 Pa and 100 Pa.