高铬铸铁不同工艺软化热处理后的组织与性能

Microstructure and Property of High Chromium Cast Iron After Different Softening Heat Treatment

采用组织观察、XRD物相分析和硬度测试等实验方法,研究了不同的软化热处理工艺对抗磨高铬铸铁组织和硬度的影响。结果表明:在硬化态三种高铬铸铁均具有较高硬度,具体硬度值≥58 HRC,组织均为初析M7C3型碳化物、共晶碳化物、马氏体、奥氏体组成。KmTBCr22NiMo具有较好的软化效果,分别采用950℃×2 h炉冷至820℃×4 h炉冷至250℃出炉空冷和1 050℃×4 h炉冷至720℃×10 h炉冷到室温的两种热处理工艺软化后,KmTBCr22NiMo的硬度分别由57 HRC降低为39.9 HRC和40 HRC。KmTBCr25NiMo和KmTBCr28NiMo在采用不同热处理工艺软化后,软化效果均不理想,其最佳实验结果分别为硬度由硬化态的60 HRC下降到53.7 HRC和由硬化态的61 HRC下降到54.5 HRC。实验结果表明,随高铬铸铁中铬含量的增加,其软化难度增大。

The microstructure and hardness of high chromium cast iron after different softening heat treatment have been studied by microstructure observation, XRD Phase analysis and Hardness test. The results showed that the three kinds of high chromium cast iron with high hardness at the hardening state, and the hardness of three kinds of high chromium cast iron was all greater than 58 HRC. The microstructure of the three kinds of high chromium cast iron all consisted of MTC3 primary carbide, eutectic carbide, martensite and residual austenite. The KmTBCr22NiMo had good softening effect after heat treatment at 950℃×2 h furnace cooling to 820 ℃×4 h furnace cooling to 250 ℃ air cooling and heat treatment at 1 050 ℃×4 h furnace cooling to 720℃× 10 h furnace cooling to room temperature, the hardness lowered from HRC57 to HRC39.9 and HRC40 respectively. The KmTBCr25NiMo and KmTBCr28NiMo all had Poor softening effect after different softening heat treatment, the best test results was that the hardness of KmTBCr25NiMo lowered from HRC60 to HRC53.7 and the hardness of KmTBCr28NiMo lowered from HRC61 to HRC54.52. The results showed that with the increase of the content of chromium, to soften the high chromium cast iron became more difficult.