薄壁蠕墨铸铁的组织与性能研究

Microstructure and Mechanical Properties of Thin-Section Compacted Graphite Cast Iron

蠕墨铸铁(CGI)是制造高功率密度发动机机体及气缸盖等部件的理想材料。本试验通过金相显微分析和力学性能测试,研究了CE和Cu、Mo合金化对薄壁蠕墨铸铁组织和力学性能的影响。结果表明:CE为4.5%时,壁厚6 mm铸件的蠕化率可达到80%～85%,同时可使壁厚3 mm铸件消除游离渗碳体,获得无白口组织;Cu-Mo复合强化效果要优于Cu、Mo单因素强化作用,复合加入量为0.6%时,综合力学性能可稳定达到Rm≥450 MPa、A≥3%。

The effects of carbon equivalent （CE） and elements Cu and Mo on the microstructure and mechanical properties of thin-section compacted graphite cast iron were investigated. The results showed that the percentage of 80%-85% compacted graphite （CG） can be obtained in the casting with thickness 6 mm and the free cementite can be eliminated in the casting with thickness 3 mm when CE is 4.5%. The mechanical properties of compacted graphite cast iron are improved effectively by combining addition of Cu and Mo and when the combining addition is 0.6%, the ultimate tensile strength Rm and elongation A of the test alloy are equal to or greater than 450 MPa and 3%, respectively.