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观察分析了不同稀土添加量高铬铸铁的铸态微观组织;通过对不同氧化温度和保温时间下不同稀土添加量的高铬铸铁高温氧化过程的对比,探讨了含稀土高铬铸铁抗高温氧化机制。研究结果表明:随着稀土元素的加入,高铬铸铁组织中晶粒得到了明显细化,碳化物形状发生了变化;高铬铸铁单位面积上氧化增重随时间变化遵循抛物线规律;稀土质量分数为0%～0.3%时,高铬铸铁的抗高温氧化性随着稀土含量的增加而提高,但当稀土质量分数超过0.3%,其抗高温氧化性降低。含稀土高铬铸铁抗高温氧化机制:在高温阶段,扩散主体从阳离子逐渐转变为阴离子,减缓了氧化膜的生长速度,抑制应力的产生,从而阻止了氧化膜起皱,有效地防止裂纹。
The microstructure of as-cast high chromium chrome cast iron with different rare earth additions was observed and analyzed. By comparing the high temperature oxidation of high chromium cast iron with different rare earth additions at different oxidation temperatures and holding times, the mechanism of high temperature oxidation resistance of high chromium cast iron with rare earths . The results show that with the addition of rare earth elements, the grain size of high chromium cast iron has been obviously refined and the shape of carbide has been changed. The oxidation weight gain per unit area of high chromium cast iron obeys the parabolic law over time. The content of rare earth mass fraction When 0% ~ 0.3%, the high temperature oxidation resistance of high chromium cast iron increases with the increase of rare earth content, but when the mass fraction of rare earth exceeds 0.3%, its high temperature oxidation resistance decreases. Anti-high-temperature oxidation mechanism of rare-earth high-chromium cast iron: During the high temperature stage, the diffusion body gradually changes from cations to anions, slowing the growth rate of the oxide film and restraining the generation of stress, thereby preventing the oxide film from wrinkling and effectively preventing cracks.