稀土变质在汽缸盖铸件上的应用研究

Rare Earth Alloy as A Modifier in Cylinder Head Castings

稀土变质与三元变质剂相比,ZL104合金显微组织及机械性能稍有逊色,但符合国标和企标要求。铸件经T_6处理后的硬度较高,因而加工性能较好,并利于铸件刚性的提高;稀土变质有效时间长,晶粒粗大和渣孔等废品减少,故铸件合格率提高;稀土变质解决了因三元钠盐变质剂浸蚀坩埚而使其难以用涂料保护,造成铝液严重渗铁的质量问题;稀土有良好的除气作用,减少了铸件的针孔度。这种工艺适合于金属型低压铸造。

The microstructure and mechanical properties of alloy ZL104 modified by rare earth are a little inferior to three-component modifier, but the alloy can come up to the State Standard (GB) and the Factory Standard. The hardness of the castings after T6 treatment is high which is advantageous to rigidity, thereby the castings possess good machinability. Because the Rare earth modification gives lone effective time, reduces the rejects due to coarse grain and dross hole, hence the casting's qualified rate is raised. Rare earth modification solves the problem that the crucible is difficultly protected by coating from the etching by three-component natrium salt which leading the aluminium-liquid to pick up iron. Rare earth metals have good degasification effect, reducing the degree of dross hole. This technology is suitable to low pressure die casting.