AISI431不锈钢表面“膨胀”α相层的制备和性能

Preparation and properties of “expanded” α phase layer on AISI431 stainless steel

对AISI431马氏体不锈钢进行低温等离子体改性处理,通过金相观察、X射线分析等对渗层组织结构进行表征,利用显微硬度仪以及腐蚀极化曲线等对渗层硬度和耐蚀性能进行测试。结果表明,通过低温改性处理,均可在不锈钢表面获得含有"膨胀"α相的渗层,其中渗氮处理后表面主要含Fe4N和含氮"膨胀"α相,渗碳处理后表面主要为含碳"膨胀"α相,且渗氮层厚度明显大于渗碳层厚度。经低温改性处理后,不锈钢表面硬度显著提升,且渗氮层硬度高于渗碳层硬度。然而,在本试验条件下渗氮渗碳的不锈钢耐蚀性能均略有下降,和渗氮相比,渗碳处理后的试样耐蚀性能更差,且在腐蚀过程中,两类渗层表面所产生钝化膜均为具有n型半导体特性。

AISI431 martensitic stainless steel was treated by low-temperature plasma modification. Microstructure of the layers was characterized by optical metallography and X-ray analysis, the hardness and corrosion resistance of the layer were tested by microhardness test and corrosion polarization curves. The results show that the ＂expanded＂α phase can be formed on the surface of the stainless steel by both nitriding and carburizing, the nitrided layer mainly consists of Fe4N and ＂expanded＂α phase with nitrogen, carburized layer mainly consists of ＂expanded＂α phase with carbon, and the thickness of nitrided layer is higher than that of the carburized layer. After low- temperature modification, the hardness of the stainless steel increases significantly, and the hardness of the nitrided layer is higher than that of the carburized layer. However, under the present nitriding or carburizing conditions, the corrosion resistance of the stainless steels all decreases slightly, comparing to the nitrided specimen, the corrosion resistance of the eaburized specimen is weaker, and the passivation films formed on these two kinds of the layer during the process of corrosion all possess the character of n type of semiconductor.