高强韧珠光体球墨铸铁的研究

Research of pearlite ductile cast iron with high strength and toughness

在球墨铸铁成分优化基础上,用万能材料试验机、布氏硬度计和金相分析显微镜研究了球墨铸铁经多元合金化、型内孕育处理和等温正火后的组织和和性能。结果表明:经Cu、Mo、Sb多元合金化和型内孕育处理的球墨铸铁,其铸态和等温正火处理后的组织明显改善,共晶团数目增加,基体组织细化,石墨球形态圆整、细小,珠光体数量增多,比例均大于90%,力学性能显著提高。与未合金化的球墨铸铁比,Cu,Mo,Sb多元合金化的球墨铸铁,其铸态和等温正火处理后的屈服强度R_(0.2)、抗拉强度R_(m)和硬度HB分别提高了25%、20%,47%、17%,41%、11%,达到502、620 MPa,811、975 MPa,256HB、298HB,伸长率A均大于6%。

On the basis of composition optimization,the microstructure and properties of the ductile cast iron after multiple element alloying,inoculation in casting mold and isothermal normalizing were investigated by means of universal material testing machine,hardness tester and optical microscope. The results show that Cu,Mo,Sb multiple element alloying and inoculation in casting mold help to refine matrix microstructures,increase the numbers of eutectic clusters,improve roundness of the graphite sphere,decrease size of graphite sphere,increase pearlite ratio(more than 90%)in the as-cast and heat-treated ductile cast iron, and which improve mechanical properties significantly. Compared with the ductile cast iron without alloying,the yield strength R_(0.2),tensile strength R_(m) and hardness HB of the as-cast and as-heat-treated ductile cast iron alloyed by Cu,Mo,Sb increase by 25% and 20%,47% and 17%,41% and 11% respectively,and which reach to 502 MPa,620 MPa,811MPa,975 MPa and 256HB,298HB,the percentage elongations are more than 6%.