304奥氏体不锈钢低温盐浴氮化处理及其耐蚀性

Salt bath nitriding of 304 austenitic stainless steel at low temperature and corrosion resistance of nitriding layer

采用低温(430°C)盐浴对304奥氏体不锈钢进行氮化处理,研究了氮化时间对渗氮层组织、显微硬度及耐蚀性的影响。分别用X射线衍射仪(XRD)、表面显微硬度计、光学显微镜分析了渗氮层的相组成、显微硬度、截面形貌和厚度。结果表明,304不锈钢表面的渗氮层厚度和显微硬度都随处理时间的延长而增大。氮化处理1h得到的渗氮层由单一的S相组成。经盐浴渗氮处理的304不锈钢,其耐Cl-点蚀性能得到改善,430°C下氮化4h得到的渗氮层耐蚀性能最好。

304 austenitic stainless steel was nitrided in a salt bath at low temperature （430 ℃）. The effects of nitriding time on microstructure, microhardness, and corrosion resistance of nitriding layer were studied. The phase composition, microhardness, cross-sectional morphology, and thickness of nitriding layer were examined by X-ray diffraction （XRD）, microhardness tester, and optical microscopy. The results showed that the thickness and microhardness of nitriding layer on 304 stainless steel substrate are increased with the increasing of nitriding time. The layer obtained by nitriding for 1 h is composed of a single S phase. The 304 stainless steel shows improved corrosion resistance by nitriding and exhibits optimal corrosion resistance after nitriding for 4 h.