高强度合金灰铸铁件缩松形成原因与防止措施

介绍了高强度合金灰铸铁件的缩松缺陷情况,描述了铸件缩松的形貌特征,分析讨论了缩松的形成原因,并得出以下结论:(1)高强度合金灰铸铁件由于CE较低,含有较高的Cr、Mo、Ni元素,铁液在凝固过程中初生奥氏体枝晶发达,容易产生缩松;(2)高强度合金灰铸铁件缩松区域内部有发达的奥氏体枝晶末梢,内部无非金属夹杂物;(3)适当提高CE、降低浇注温度、增强孕育效果,可以减小缩松倾向,同时良好的孕育还可以促进A型石墨形成;(4)对浇注系统进行优化,增加横浇道截面积并采用横浇道压边工艺,加强顺序凝固,可以有效消除缩松缺陷。

Reasons Causing Shrinkage Porosities of High Strength Alloyed Gray Iron and Their Prevention Measures

The shrinkage porosities defects situation of high strength alloyed gray iron castings was introduced,the castings shrinkage porosities morphologies were described,the shrinkage reasons were analyzed and discussed,and following conclusions were obtained:(1)Since the high strength alloyed gray irons containing lower CE and containing higher Cr,Mo,Ni,the primary austenite dendrite during their solidification process was developed,therefore the shrinkage porosities were easy formed.(2)There were developed austenitic dendritic tips in the shrinkage porosities areas of the high strength alloyed gray irons,no non-metallic inclusions inside.(3)By properly increasing CE,decreasing pouring temperature,strengthening inoculation effect,it was possible to reduce shrinkage porosities tendency,at the same time,good inoculation also could promote A-type graphite formation.(4)By optimizing gating system,increasing section area of the runner and using runner kissing ingate,strengthening directional solidification,it was possible effectively eliminate shrinkage porosity defects.