为提升高铬铸铁的综合性能，以无Mo高铬铸铁和含1.0%(质量分数)Mo 高铬铸铁为研究对象，对比研究了添加Mo元素对铸态高铬铸铁组织结构以及550 ℃亚临界处理对其组织及硬度的影响。研究表明：2种铸态高铬铸铁的主要组成相均为奥氏体、马氏体及(Cr, Fe)7C3，但含Mo高铬铸铁中奥氏体含量明显增多。铸态高铬铸铁均以亚共晶方式结晶，其组织为初生树枝晶固溶体及其间的共晶组织组成，但含Mo高铬铸铁的树枝晶组织发生了明显细化。2种高铬铸铁经过550 ℃下不同保温时间的亚临界处理后均出现了硬化现象，但含Mo高铬铸铁的硬度峰值 (50 HRC) 比铸态硬度提高了31.6%，无Mo高铬铸铁的硬度峰值 (48 HRC) 比铸态硬度提高了14.2%；含Mo高铬铸铁的硬度峰值出现时间 (15 h) 长于无Mo高铬铸铁 (5 h)。Mo元素细化了高铬铸铁的枝晶组织，并提供了其亚临界处理后的硬化效果。
For improve the comprehension performance of high - chromium cast iron, the influences of Mo addition on the microstructure of as - cast high - chromium cast iron and the subcritical treatment effect at 550 ℃ on the microstructure and hardness of the as - cast high - chromium cast iron were studied with using the high - chromium cast irons with / without 1%(mass fraction) Mo as research objects. Results showed that the main constituent phases of the two kinds of as - cast high chromium cast iron are austenite, martensite and (Cr, Fe)7C3, but the content of austenite in the Mo - containing high chromium cast iron obviously increased. Meanwhile, the as - cast high - chromium cast iron crystallized in a hypoeutectic manner, and its microstructure was composed of primary dendritic solid solution and the eutectic microstructure between them. However, the dendritic microstructure of Mo - containing high - chromium cast iron was apparently refined. Both kinds of high - chromium cast iron hardened after subcritical treatment at 550 ℃ for different holding time. The peak hardness of Mo - containing high - chromium cast iron (50 HRC) was 31.6% higher than that of cast iron, while the peak hardness of high chromium cast iron without Mo (48 HRC) was 14.2% higher than that of cast iron. Moreover, the peak hardness time of high chromium cast iron containing Mo (15 h) was longer than that of high chromium cast iron without Mo (5 h). The addition of Mo element could refine the dendritic structure of high - chromium cast iron and improve the hardening effect after subcritical treatment.
