前言目前国内生产的大断面球铁件,例如,大功率柴油机曲轴、冶金轧辊、钢锭模及其它厚大铸件等,都含有一定量的稀土。因此,大断面球铁件的心部或热节处经常出现的碎块形石墨缺陷是否与稀土有关,已成为许多生产厂和铸造工作者十分关切的问题。对这一问题,由于迄今尚缺乏系统的研究,因此,还存在着各种不同的观点。国内外文献认为,轻稀土 Preface At present, the domestic production of large section nodular iron pieces, for example, high-power diesel engine crankshaft, metallurgical rolls, ingot mold and other large castings, etc., contain a certain amount of rare earth. Therefore, it is a matter of great concern to many production plants and foundry workers whether the fragmentary graphite defects frequently appearing in the heart or hot section of large-section nodular iron parts are related to rare earths. To this question, due to the lack of systematic research so far, there are still different opinions. Literature at home and abroad that light rare earth