含钼铁素体不锈钢的高温氧化行为

Oxidation Resistance of Ferritic Stainless Steel With Molybdenum Addition

采用增重法研究了排气系统用Type444铁素体不锈钢在1 000℃空气中的高温抗氧化性能,并结合X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)及辉光光谱(GDS)分析技术,对氧化膜的形貌和组成进行了分析。结果表明:Type444铁素体不锈钢在1 000℃下连续氧化100h,氧化动力学曲线按照抛物线线型氧化规律变化,氧化激活能为(277.5±10)kJ·mol-1,表面氧化膜由连续致密的Cr2O3组成,具有良好的高温抗氧化性能。铌和钼元素扩散至Fe2(Nb,Mo)Laves相,其氧化物颗粒会充当沉淀物从氧化膜表面逆扩散至基体和氧化膜界面处的孔洞里,从而降低了其在高温下的氧化速率,提高了抗高温氧化性能。

The high-temperature oxidation resistance of Type444 ferritic stainless steel for automotive exhaust systems in air at 1 000 ℃ was studied using the way of gain weight. The surface morphology, constituent and microstructure of the oxidation scale was analyzed using XRD, SEM, EDS and GDS technologies. The results indicate that a parabolic regime is observed all along the oxidation test at 1 000 ℃ during 100 h of tested Type444 ferritic stainless steel, the activation of oxidation is （277.5±10）kJ·mol-1. The surface oxide film is composed by Cr2O3 which is a continuous and dense oxide, and has good high temperature oxidation resistance. Niobium and molybdenum diffuse to the Fe2 （Nb,Mo） Laves phases and the mixed oxides particles may he capable of acting as sinks for the countercurrent diffusion of vacancies inwards through the surface film. The lower oxidation rate can get and improve the high temperature oxidation resistance.