铸态厚大断面QT700-3铸件的生产实践

为解决铸态QT700-3球铁滑枕出现异常石墨和球化衰退与孕育衰退等问题,将铁液化学成分调整为:w(C)3.4%～3.6%,w(Si)1.9%～2.0%,w(Mn)0.2%～0.4%,w(S)0.015%～0.025%,w(Cu)0.5%～0.8%,低量的P,以及微量的Ba、Bi、Sb等。采用重REMg球化剂进行倒包冲入法球化处理,球化剂的加入量为1.4%～1.6%;选用含Ba、Sb、Bi的多元复合孕育剂进行多次孕育处理。生产结果表明:铸态QT700-3滑枕的金相组织、力学性能完全达到国家规定的要求。

Production Practice of An As-cast Heavy Section Nodular Iron Castings

In order to solve the problems that there was abnormal graphite morphology, nodularization and inoculation degeneration occurring with an as-cast QT700-3 grade nodular iron machine tool ram casting, the chemical composition of the iron melt was modified as follows： ω（C） 3.4%-3.6%,ω（Si） 1.9%-2.0%,ω（Mn） 0.2%-0.4%,ω（S） 0.015%-0.025%, ω （Cn） 0.S%-0.8%, low P, and trace amount of Ba,Bi,Sb etc.; Reladling pour-over process and heavy RE-containing REMg nodularizing alloy was adopted to conduct nodularizing treatment and Ba,Sb,Bi-containing composite inoculant was adopted to conducted multiple times of inoculating treatment. The production result showed that the as-cast microstructure and mechanical properties of the ram casting completely met the QT 700-3 grade requirements of the China national standard.