HT300高强度缸体缸盖材料熔炼技术研究

A Study on Melting Technique of HT300-Grade Hi-Strength Gray Iron for Cylinder Blocks and Heads

分析了熔炼工艺、碳硅成分、锰硫成分、合金化及孕育处理对高强度灰铸铁铁液质量的影响,认为大量使用生铁使铁液收缩倾向增大且使铸件性能降低;增碳剂的选用是全废钢熔炼的关键;在较高碳硅含量条件下生产高强度灰铸铁件,必须设法在熔炼过程中增加石墨晶核,并增硫防止石墨长成粗大片状;适当的合金化和孕育处理,可以使铁液的收缩倾向得到明显改善。指出可以通过延迟开箱时间使铸件在砂箱中缓慢冷却以消除铸造应力,为生产优质铸件提供最后保证。

The influences of melting process, carbon and silicon, manganese and sulphur, alloying and inoculation on mohen iron quality of hi- strength gray irons were analyzed. It is considered that using pig iron in large fraction would increase shrinkage tendency of the molten iron and decrease properties of castings; selection of carburizing agent is the key of melting with full steel scrap charge; it is necessary, in order to produce hi- strength gray iron castings with relatively high carbon and silicon content, to take measures to increase graphite nuclei in the melting process and, at the same time, increase sulphur content to prevent the graphite from growing into coarse flakes; proper alloying and inoculation can obviously decrease the shrinkage tendency of the mohen iron. It was pointed out that, by delaying knock out to let castings slowly cool in moulds, it is possible to eliminate casting stress and to offer the last guarantee for producing hi-quality castings.