灰铸铁铸件N_2气孔的产生原因和防止

Formation Reason and Prevention of Nitrogen Fissure in Gray Iron Castings

介绍了N2气孔的特征,分析了采用中频感应电炉熔炼灰铸铁时N2气孔产生的原因,并且通过实际生产证明了N2气孔的产生与废钢的加入量并无直接的线性关系.最后指出在熔炼合成灰铁时,预防N2气孔的产生的有效措施是：使用低N的结晶石墨型增C剂,将铸件w（N）量控制在80～120 ppm;制芯和造型使用中、低N的有机树脂粘结剂,铁液熔炼温度高于1520℃,高温镇静时间≥10 min,以及使用经过高温石墨化处理的石墨型孕育剂或SiC对铁液进行预处理.

The characteristics of nitrogen fissure were introduced. The formation reason of nitrogen fissure when using intermediate frequency induction fnrnace to melt gray iron was analyzed. It has been proved by praclical prndnetion that there was no linear relation existing between the nitrogen fissure formation and the addition amount of steel scraps. It was pointed out by the end that when using intermediate frequency furnace to melt gray irnn,the effective measures to prCwent nitrogen fissure were as follows： using low nitrogen content crystal graphite type carburizer;contrnlling the nitrogen enntent of castings in the range of 80~120 ppm;using low nitrogen organic resin binder for cnre and mold manufacturing;iron melting temperature to be higher than 1 520 ℃ ,and the high temperature holding duration time/〉 10 rain;as well as using the graphite-type inoculant which had been graphitizing-pretreated at high temperature or using SiC to pretreat the iron meh.