采用不同的碳当量, 对某发动机用灰铸铁材料的化学成分进行了优化改进, 改进前硅碳含量比cSi/cC=0.63, 改进后硅碳含量比cSi/cC=0.7左右, 对改进前后附铸试棒的静力学性能和疲劳性能进行了检测。结果表明: 当碳当量cCE=3.80%(质量分数)、硅碳含量比cSi/cC=0.7左右时, 灰铸铁材料的各项性能均处于较好状态; 硅碳含量比cSi/cC高的材料, 其弹性模量也高, 而抗拉强度和规定总延伸强度又均随弹性模量的提高而提高; 相同疲劳环境下, 弹性模量高的材料, 其疲劳循环周次也高; 经改进后, 试验灰铸铁材料的抗拉强度在330~350 MPa、弹性模量在185 000~195 000 MPa, 拉拉疲劳极限在47.5~51 MPa。

Using different carbon equivalent contents, the chemical compositions of gray cast iron material used for an engine were improved and optimized with the ratio of silicon content to carbon content (cSi/cC) changing from 0.63 (before improvement) to 0.7 (after improvement), and the static mechanical properties and fatigue properties of the attached cast test blocks were tested before and after improvement. The results show that when the carbon equivalent content cCE=3.80% (mass) and cSi/cC=0.7, the performances of the gray cast iron material were in good condition. The material with higher cSi/cC had higher elastic modulus, and the tensile strength and total extension proof strength also increased with the increase of elastic modulus. Under the same fatigue condition, the material with higher elastic modulus had higher fatigue cycles. After improvement, the tensile strength of the gray cast iron material was 330~350 MPa, the elastic modulus was 185 000~195 000 MPa, and the tensile fatigue limit was 47.5~51 MPa.