开箱时间及热处理对Cr28铸铁组织和性能的影响

Influence of Shake-out Time and Heat Treatment on Microstructure and Properties of As-cast Cr28 High-chromium Cast Iron

研究了浇注后不同开箱时间及热处理对Cr28铸铁组织和性能的影响。结果表明,随着浇注后在砂型中冷却时间的延长,Cr28铸铁的硬度和冲击韧度降低,铸件在铸型中冷却3 h开箱空冷,硬度(HRC)可达58,冲击韧度ak可达4.5 J.cm-2。铸态Cr28铸铁的组织由马氏体、不同形状的M7C3型碳化物及残余奥氏体组成。1 040℃正火+100℃回火热处理可以提高铸件的硬度,HRC可达60。

Effects of shake-out time and heat treatment on microstructure and properties of Cr28 cast iron after poured have been investigated. The results indicate that although the hardness and impact toughness of the Cr28 cast iron can be decreased with increasing cooling time in the sand mold, the Cr28 cast iron exhibits higher hardness and impact toughness with air cooling after cooling for 3 h in sand mold. The hardness and impact toughness of the cast iron are more than 56 and 4.5 J, respectively. The microstructure of Cr28 cast iron with varied shake-out time at air cooling is composed of martensite, residual austenite and different shape M7C3 carbide. The Cr28 cast iron can be improved by more than 60 in hardness and more than 2.8J in impact toughness after normalizing at 1040℃ and tempering at 100 ℃ with different shake-out time at air cooling.