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采用光学显微镜、扫描电子显微镜以及硬度和冲击试验等方法,研究了不同热处理工艺对过共晶高铬铸铁显微组织和性能的影响。结果表明:试验的过共晶高铬铸铁铸态显微组织由共晶莱氏体和粗大杆状或六方形状的一次Cr_7C_3型碳化物组成;由于淬透性较低,当保温时间为2 h,淬火温度较低时,在共晶碳化物周围存在铁素体;只有加热到1 050℃时,共晶中的奥氏体在随后的空冷过程中才能转变为全部马氏体组织,硬度达到最高值64.5 HRC;淬火加热温度为1 050℃时,随保温时间的延长,硬度降低;随着淬火加热温度的升高,过共晶高铬铸铁的冲击吸收功呈下降趋势,但数值总的来说不高且差别不大,范围在1~2 J之间。
The effects of different heat treatment processes on microstructure and properties of hypereutectic high chromium cast iron were studied by optical microscopy, scanning electron microscopy and hardness and impact tests. The results show that the as-cast microstructure of hypereutectic high chromium cast iron consists of eutectic ledeburite and primary rod-shaped or hexagonal Cr_7C_3 carbides. Due to the low hardenability, when the holding time is 2 h , When the quenching temperature is low, the ferrite exists around the eutectic carbide; only when heated to 1050 ℃, the austenite in the eutectic can be transformed into all martensite structure in the subsequent air-cooling process, and the hardness reaches The highest value of 64.5 HRC; quenching heating temperature of 1 050 ℃, with the extension of the holding time, the hardness decreases; with the quenching heating temperature, the impact absorption power of hypereutectic high chromium cast iron shows a downward trend, but the value of the total Not high and the difference is not large, ranging from 1 ~ 2J.