厚大断面球墨铸铁件生产中若干问题的探讨(3)

A Discussion on Some Problems in Heavy Section Nodular Iron Production(Ⅲ)

介绍了厚大断面球墨铸铁的凝固时间长、共晶结晶平台长、石墨球数少、易畸变、基体组织异常等凝固特性,通过理论与生产实例相结合的方法,阐述了碎块状石墨问题,石墨球数少与石墨畸变的关系,球化剂、w(Mg残)量、RE与石墨畸变的关系,CE及化学成分的选择问题,厚大断面球墨铸铁件若干问题的措施,球化剂中RE问题以及如何增加石墨球数问题。最后指出:要保证厚大断面球墨铸铁正常生产,除上述问题外,还有浇注系统优化和浇注时间控制的问题,生产过程质量控制以及生产组织等问题,这些都需要注意和严格控制。

An introduction was given to the solidification characteristics of heavy section nodular iron including long solidification time,long eutectic crystallization platform,small graphite nodule number,easy to deform,and abnormal matrix structure.Through the combination of theory and production examples,explanation was given to the chunky graphite problem,the relation between small graphite nodule number and graphite deformation,the relation between nodularizing alloy,residual Mg content,RE content and graphite deformation,CE and chemical composition choice problem,measures to solve some problems of heavy section nodular iron,problem of RE in nodularizing alloy,as well as,the problem about how to increase graphite number.Finally,it was pointed out that to ensure the normal production of heavy section nodular iron,in addition to above problems,there were also the problems of gating system optimization and pouring time control,production process quality control and production organization,all these require attention and strict control.