一、优选前:以前,我们对稀土镁中间合金加入量,一般控制在1%左右,经过一年多的生产,质量都不稳定。在浇铸135机油泵齿轮和泵盖过程中,经常因球化不良,有时甚至不球化而报废,废品率高达40%以上,严重影响了抓革命促生产的工作。二、优选试验: First, the preferred front: Before, we added rare earth magnesium master alloy, the general control at about 1%, after more than a year of production, the quality is not stable. In the process of casting 135 oil pump gear and pump cover, often due to bad ball, and sometimes even non-ball and scrapped, the rejection rate as high as 40% or more, seriously affecting the work of grasping the revolution to promote production. Second, the preferred test: