大型发动机缸套的组织与性能改善措施

Improvement Measures of Micorstructure and Properties of Large Engine Cylinder Liner

对缸套进行了逐层解剖和组织金相分析,得出了导致缸套本体抗拉强度偏低的原因,即缸套本体存在宏观偏析缺陷,组织中有B型、D型石墨和粗大磷共晶及白斑。探讨了白斑及异常组织形成机理,并通过调整化学成分,适当提高碳当量,采用硅锰锆型高效瞬时孕育剂及新型涂料,浇注前预热模套、浇注主槽并适当提高浇注温度,充型完后强化水冷等措施,消除了白斑及异常组织,使缸套材质力学性能合格率从60%提高至98%。

By dissecting the cylinder liner layer by layer and analyzing its microstructure, it was concluded that the reason for the cylinder liner having low tensile strength is that the cylinder liner has the macro segregation defect and there exist B-type, D-type graphite, coarse phosphorus eutectic and white spot in the microstructure. The formation mechanism of white spot and abnormal structure was analyzed. By adjusting chemical composition, increasing carbon equivalent properly, adopting silicon-manganese-zirconium type high-efficiency instantaneous inoculant and new coating, preheating mold sleeve and gating system before pouring, properly increasing pouring temperature, strengthening water cooling after filling, etc., white spots and abnormal structure were eliminated, and the qualified rate of mechanical properties of cylinder liner was increased from 60% to 98%.