高铬铸铁的正火组织与性能研究

研究正火温度对新型高铬铸铁组织、硬度(HRC)及冲击韧性的影响。实验结果表明高铬铸铁在800~950℃正火时,其组织由珠光体+少量铁素体+网状共晶碳化物组成;在1 000~1 050℃正火时,碳化物溶解析出,珠光体球化,得到铁素体基体上分布的粒状碳化物+共晶碳化物+少量珠光体,硬度略有降低;在1 100~1 150℃正火时,共晶碳化物溶解得更多,冷却过程中奥氏体中析出弥散碳化物,冷却后得到马氏体(过饱和铁素体)基体上弥散碳化物+共晶碳化物,硬度明显升高,并在1 150℃时硬度达到最大值,在800~1 150℃正火加热温度范围内,冲击韧性在4.2~4.7 Jcm2之间波动,总体变化不大。

Study on the Normalized Microstructure and Mechanical Properties of High Chromium Cast Iron

In this paper, the effect of normalizing temperature on the microstructure, Rockwell hardness （HRC） and impact toughness of a new type of high chromium cast iron was studied. The results showed that the microstructure of high chromium cast iron consists of large quantities of pearlites, a small amount of ferrites and some reticular eutectic carbides after normalizing at 800℃ to 950℃. After the normalizing treatment at 1 000℃ to 1 050 ℃, the dissolution and precipitation of the carbides and the spheroidization of the pearlites occurred, and then ferrite substrate was obtained. Some granular carbides, eutectie carbides and a small amount of pearlites dispersed in the obtained substrate, which caused the slight decrease of hardness. When the normalizing temperature was between 1 100℃ and 1 150℃, more eutectic carbides began to dissolve. During the following cooling after the normalizing, some dispersed carbides precipitated from austenite. In the end of the cooling, martensite substrate （ supersaturated ferrite） formed with the dispersion of some dispersed carbides and eutectic carbides, and the hardness of the substrate significantly increased and reached it maximum around 1 150℃. When the normalizing temperature was between 800 ℃ and 1 150℃, the impact toughness fluctuated between 4.2 J/cm2 and 4.7 J/cm2.