中文摘要：

本研究对15-5PH和17-4PH沉淀硬化不锈钢进行了460℃等离子体渗碳处理。利用金相观察、X射线衍射分析对渗碳层组织和相结构进行表征,采用显微硬度计测量,渗碳层的硬度,通过极化曲线研究渗碳层在3.5wt%NaCl溶液中的耐蚀性能。结果表明,经等离子渗碳后,15 SPH和174PH不锈钢表面均形成了＂双层＂组织,渗层主要由含碳＂膨胀＂马氏体α’c和少量Fe3C相组成,渗碳后不锈钢硬度均显著提高。在本试验条件下,渗碳后不锈钢的耐蚀性均略有下降,其中随着渗碳时间增加,15-5PH和17-4PH不锈钢的耐蚀性均没有明显变化,而随着渗层深度的增加,15-5PH不锈钢表面渗碳层的耐蚀性逐渐变差;而17-4PH不锈钢表面渗碳层的耐蚀性先增加后降低。

英文摘要：

15-5PH and 17-4PH precipitation hardening stainless steels were plasma carburized at 460℃.Metallographic observation,X-ray diffraction analysis were used to characterize the microstructure and phase composition of the carburized layer.Hardness change of the carburized layer was tested by microhardness tester.The corrosion behavior of carburized layer was tested by electrochemical polarization method in 3.5wt%NaCl solution.The results show that after plasma carburizing,a ＂double＂ structure forms on the surface of stainless steels.The phases formed on stainless steel surfaces are mainly of carbon ＂expanded＂ martensite with a small amount of Fe3C phase.The hardnesses of low temperature plasma carburized steels are all remarkablely improved.The corrosion test results show that,under the present test conditions,the corrosion resistance of stainless steel samples shows a little decrease after carburizing.For 15-5PH and 17-4PH stainless steels,as the carburized time increase,the corrosion resistances of the layer almost does not change;with increase of the carburized layer depth,for 15-5PH stainless steel,the corrosion resistance of the carburized layer decreases,while for 17-4PH stainless steel,the corrosion resistance of the carburized layer first increase and then decreases.