热处理对高铬铸铁组织和硬度的影响
Effects of Heat Treatment on Microstructure and Properties of High Chromium Cast Iron
刘 嘉1， 张锁梅1， 赵爱民2， 张宇光2
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作者单位：（1.北京科技大学 机械工程学院，北京 100083；2.北京科技大学 冶金工程研究院，北京 100083）
中文关键字：高铬铸铁；硬度；马氏体；奥氏体；淬火温度
英文关键字： high chromium cast iron; hardness; martensite; austenite; quenching temperature
中文摘要：利用X-射线衍射、金像显微镜和洛氏硬度计，对不同淬火温度、保温时间以及回火后组织进行了分析，研究了不同的热处理工艺对高铬铸铁组织和性能的影响。结果表明：在970 ℃淬火，保温4 h，200℃回火，使硬度值达到 62.8 HRC。随着淬火温度升高和保温时间的延长，能使奥氏体中的碳含量增加，转变成的马氏体中的含碳量也增加，提高基体硬度；当淬火温度过高或保温时间过长，奥氏体中的碳含量过高，降低MS点，增加残余奥氏体，降低基体硬度。随着回火温度的升高，加速了马氏体的分解和碳化物的析出，马氏体硬度下降，使高铬铸铁的硬度下降。
英文摘要：By means of X-ray diffraction method, optical microscopy, scanning electron microscopy and rockwell hardness test, the microstructure of high chromium cast iron under different quenching temperatures, holding times and temper temperatures were analysed, the effects of heat treatment on the microstructure and properties of the iron were studied. The results show that after quenching at 970 ℃, holding for 4 h and tempering at 200 ℃, the cast iron exhibits impact hardness 62.8 HRC. With the increase of quenching temperature and holding time, the amount of carbon in austenite also increase, and this also happens in obtained martensite. When quenching temperature is too high and holding time is too long, there are too much carbon in austenite, the MS point falls down, which increases the amont of residual austenite. Therefore, the hardness of the matrix decreases. With the increase of temper temperature, more martensite disassemble and more carbides separate out, so the hardness of high chromium cast iron decreases.