离子渗碳温度对316L不锈钢渗层组织和性能的影响

利用低温离子渗碳技术.在不同温度下对AISI 316L奥氏体不锈钢进行渗碳处理.利用光学显微镜、显微硬度计、XRD以及电化学测试技术研究了渗碳温度对不锈钢表面显微组织和性能的影响.结果表明,渗碳温度显著影响AISI 316L奥氏体不锈钢渗碳层的组织结构与性能.渗碳温度在400～550℃之间时,可以获得无碳化物析出的、具有单一γ_c相结构的渗碳层;渗碳温度在550℃时,渗碳层为γ相+Cr_(23)C_6+Cr_7C_3+Fe_3C+Fe_2C的混合组织.渗碳层的厚度与硬度均随渗碳温度的升高而增加.550℃是AISI 316L奥氏体不锈钢中铬的碳化物析出的临界温度.为了避免铬的碳化物析出而降低不锈钢的耐蚀性能.奥氏体不锈钢渗碳必须在低于550℃的渗碳温度下进行.

Influence of plasma carburizing temperature on microstructure and properties of carburized layer for AISI 316L stainless steel

Plasma carburizing of AISI 316L austenitic stainless steel was carried out at different carburizing temperatures. The effect of carburizing temperatures on microstructure and properties of the carburized layer were investigated using optical microscope, vickers hardness tester, X-ray diffraction and polarization testing. The results show that the microstructure and properties of carburized layers are significantly affected by carburizing temperature. Thickness and hardness of the carburized layer increase with increasing carburizing temperature. The carburized layer with single γ_c, phase is obtained when the carburizing temperatures are within the range of 400～550℃. When the carburizing temperature is 550℃., some carbides, such as Cr_(23)C_6+Cr_7C_3,Fe_3C,Fe_2C, begin to precipitate. The precipitation of chromium carbides significantly deteriorates the corrosion resistance of the carburized layer. Therefore, the carburizing temperature of 550℃ is a critical temperature to precipitate chromium carbides for AISI 316L austenitic stainless steel and it is suggested that the carburizing temperature of 316L stainless steel must be lower than 550℃ .