一种节镍经济型双相耐热铸钢的高温氧化

High Temperature Oxidation of a Low Nickel Austenitic Heat Resistant Steel

对ZG40Cr25Ni20耐热铸钢和节镍经济型双相耐热铸钢进行恒温氧化实验,得到了两种材料的氧化动力学行为曲线,结合扫描电镜、能谱分析仪及X射线衍射等手段研究了高温抗氧化的差异,并探究了高温氧化的微观机理。结果表明,节镍经济型耐热铸钢虽然降低了Ni的含量,但是增加Cr和Mn能在氧化层的外层形成稳定的保护型氧化膜Cr_2O_3,一定程度上阻挡了金属阳离子的向外扩散和O离子的向内扩散,使其氧化激活能由148.4 k J·mol^(-1)提高至245.7 k J·mol^(-1),从而降低了氧化速率,改善了材料的高温抗氧化性能。

High temperature oxidation performance of ZG40Cr25Ni20 steel and a kind of low nickel austenitic heat resistant cast steel were comparatively investigated by means of isothermal oxidation test,scanning electron microscope（SEM） with energy dispersive spectrometry（EDS） and X-ray diffraction analysis. The results show that a protective oxide scale Cr_2O_3 forms at the interface of substrate and the outer oxide scale, which can certainly block the inward diffusion of oxygen ions and the outwards diffusion of metal action, thereby reducing the oxidation rate, therefore, the heat-resistant cast steel exhibits better high temperature oxidation resistance in comparison with the ZG40Cr25Ni20 steel, whilst the nickel saving steel contains lower Ni but a little higher Cr and Mn than the ZG40Cr25Ni20 steel.