Analysis on forming mechanism of defects as white spot and cloud on centrifugal casting cylinder sleeve of ship diesel engine resulted in that white spot had been produced with austenite branch crystal separated out due to chilled iron melt around bean-shaped iron grains falling down from those collected on bottom of pouring spout and coarse austenite deflection gather from overcooled iron melt while cloud had formed from abnormal structure caused by deflection gather and asymmetry distribution of graphite separated out. Appearance of white spot and cloud could be obviously decreased with reducing content of elements as Mn, P, S apt to deflection while increasing elements as Cu,Ni etc without solid solubility limit as well as measures such as centrifugal casting changine from bottom pouring into side pouring and addition of 0.2％75FeSi with pouring hence 20～30MPa or so increased with tensile strength of cylinder sleeve while obvious decrease of both coarse graphite and coarse P eutectic in microstructure.%分析离心铸造某型船用柴油机缸套白斑云斑缺陷的形成机理后认为:白斑是由浇注过程中浇注槽底聚集的铁豆掉入型腔对周围铁液激冷析出奥氏体枝晶以及铁液过冷所析出的粗大奥氏体偏聚形成的;云斑是由析出石墨偏聚及不均匀分布导致出现异常组织而形成.采取降低易偏析的Mn、P、S等元素、提高Cu、Ni等无限固溶元素,并改底漏式离心浇注为侧浇式,以及浇注时加入0.2%75FeSi等措施,可明显减少白斑云斑的出现,同时缸套本体抗拉强度提高约20～30MPa,金相组织中粗大石墨和粗大磷共晶明显减少.
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