一、球化衰退与孕育衰退稀土镁球墨铸铁一经球化处理完毕就应立即浇注,若停留时间过长(一般以不超过15分钟为宜),则将出现球化衰退。而且,即使是同一包铁水,也存在着先期浇注的铸件球化良好,后期浇注的铸件球化率降低的现象。产生球化衰退的主要原因不外乎两个方面:一是由于氧化烧损,铁水中的镁和稀土的残留量随着铁水停留时间的延长而逐步减少,到一定时间后,球化剂的残留量已不足以保证铁水中石墨的球化,从而造成球化不良。对此,若能加强脱硫措施,扒净熔渣,尽可能削弱“回硫作用”,厚厚地复盖草灰和木炭,加强保温并防止 First, the decline of the ball and the recession Rare earth magnesium ductile iron castings should be immediately after the pouring, if the residence time is too long (usually not more than 15 minutes is appropriate), there will be a ball decline. In addition, even in the same ladle, there is a phenomenon that the cast of the precast ingot is well spheroidized and the nodularity of the cast cast of the later stage is reduced. The main reason for the spheroidization recession is nothing more than two aspects: First, due to oxidative burning, the residual amount of magnesium and rare earth in molten iron gradually decreases with the extension of the hot metal residence time. After a certain period of time, Residues have not enough to ensure the ball of molten iron in the ball, resulting in bad ball. In this regard, if we can strengthen the desulfurization measures, clean the slag, try to weaken the “back to the role of sulfur”, thick grass and charcoal to cover grass, and to enhance insulation and prevent