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以3M78缸体为研究对象,使用自制蠕化剂,通过金相观察和力学性能测试,系统研究了不同蠕化剂加入量对蠕墨铸铁的石墨形态、力学性能和壁厚敏感性的影响。实验结果表明,随着蠕化剂加入量的增加,石墨发生由片状向蠕虫状再向球状形态的转变,力学性能逐渐提高。铸件蠕化效果受壁厚敏感性影响显著,壁厚较薄处蠕化率相对较低。对于3M78缸体,蠕化剂最佳加入范围为0.325%~0.335%,加入量为0.33%时,壁厚为5 mm、12 mm、27 mm部位处的蠕化率分别高达65%、80%、85%。研究结果为蠕墨铸铁发动机缸体的稳定生产提供技术参考。
Taking 3M78 cylinder as the research object and using homemade vermicomponent, the effect of different amount of vermiculite on graphite morphology, mechanical properties and wall thickness sensitivity of vermicular graphite cast iron was systematically studied through metallographic observation and mechanical properties test. The experimental results show that with the increase of the amount of vermiculite, graphite changes from flake to worm and then to spherical morphology, and the mechanical properties gradually increase. The effects of wall thickness sensitivity on the effect of casting vermiculite are significant, and the relatively low wall-to-wall creep rate is relatively low. For 3M78 cylinder, the optimal addition range of vermiculite is 0.325% ~ 0.335%. When the addition amount is 0.33%, the creep rates at the wall thickness of 5 mm, 12 mm and 27 mm are as high as 65% and 80% , 85%. The research results provide a technical reference for the stable production of vermicular graphite cast iron engine block.