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采用中频感应炉熔炼,制备了某型机用合成球墨铸铁和传统球墨铸铁,对比了两者的力学性能和断口特征,分析了两种铸铁的断裂机理。结果表明,用大量废钢加增碳剂制备的合成球墨铸铁球化率高,石墨球圆整,100%铁素体(F)基体。合成球墨铸铁冲击韧性显著提高,韧-脆转变温度为-40℃,相比传统球墨铸铁降低了60℃。合成球墨铸铁的基体塑性好,抵抗裂纹扩展能力强,拉伸试样断口上留下大量深韧窝和撕裂棱,属于韧性断裂。
A kind of machine ductile iron and traditional ductile iron were prepared by medium frequency induction furnace melting. The mechanical properties and fracture characteristics of the two machines were compared. The fracture mechanism of the two kinds of cast iron was analyzed. The results show that the synthetic ductile iron prepared by using a large amount of scrap plus carburizing agent has high nodularity, graphite ball roundness and 100% ferrite (F) matrix. The impact ductility of synthetic ductile cast iron is significantly improved, with a ductile-brittle transition temperature of -40 ° C, which is 60 ° C lower than conventional ductile iron. The matrix of ductile iron has good plasticity and strong resistance to crack propagation. A large number of deep dimples and tear edges are left on the fracture surface of tensile specimen, which belongs to ductile fracture.