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对化学成份、球化率与铸态基体组织基本相同的球墨铸铁试棒进行高温正火、部分奥氏体化正火、快速不平衡正火和二阶段正火,然后测定拉伸性能,以比较不同正火工艺对拉伸性能的影响;分析了经不同正火工艺处理后得到的金相组织和拉伸性能的关系;结合曲轴服役条件,讨论了选用合适的正火工艺问题;结合第二类破碎状铁素体的成因及其对球墨铸铁机械性能的影响,提出了对二阶段正火的一些观点,并肯定了二阶段正火对于中小型发动机曲轴是切实可行的热处理工艺。
The chemical composition, spheroidization rate and as-cast matrix microstructure of ductile iron test specimens were high-temperature normalizing, partial austenitizing normalizing, rapid unbalanced normalizing and two-stage normalizing, and then determine the tensile properties to The effects of different normalizing processes on the tensile properties were compared. The relationship between the microstructure and the tensile properties obtained through different normalizing processes was analyzed. Combining with the service conditions of the crankshaft, the suitable normalizing process was discussed. The causes of the second type of crushed ferrite and its influence on the mechanical properties of ductile iron are put forward some opinions on the second-stage normalizing and confirmed that the second-stage normalizing is a feasible heat treatment process for the crankshaft of small and medium-sized engine.