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一、前言多年来球墨铸铁被用来制造一系列承受交变载荷的零件。随着我国国防、机械、冶金、矿山、石油等工业,特别是农业机械的迅速发展,从而对球墨铸铁这一新型结构材料的质量和数量提出了更高更多的要求。目前结合我国资源特点的稀土——镁球墨铸铁的生产已在全国范围内得到了很大的发展。在稀土——镁球墨铸铁的生产过程中,由于采用了稀土——镁中间合金作为球化剂,使石墨形态发生了变化,圆整度下降,在金相试片中经常观察到球状、团状及团片状石墨,即石墨较难以单一的球状存在,往往是几种石墨形态同时出现。已经实验测定稀土——镁球墨铸铁中团状石墨对静载下机械性能的影响并不象镁球墨铸铁那样大。石墨球化类型是评定稀土——镁球墨铸铁质量标准中的关键部分之一,如何正确地划分石墨球化类型,特别是球状、团状石墨显得极为重要。
I. INTRODUCTION Ductile iron has been used for many years to produce a series of parts that withstand alternating loads. With the rapid development of China’s national defense, machinery, metallurgy, mining, petroleum and other industries, especially agricultural machinery, higher and more requirements are placed on the quality and quantity of ductile iron, a new type of structural material. At present, the production of rare earth-magnesium nodular cast iron, which combines the characteristics of our country’s resources, has been greatly developed nationwide. In the production of rare earth-magnesium nodular cast iron, due to the use of rare earth - magnesium master alloy as a nodulizer, graphite morphology has changed, roundness decreased in the microstructure of the sample is often observed in the ball, Shape and group Flake graphite, graphite is more difficult to exist a single ball, often several forms of graphite simultaneously. It has been experimentally determined that the effect of agglomerated graphite in rare earth-magnesium nodular cast iron on the mechanical properties under static loading is not as large as that of magnesium nodular cast iron. Graphite ball type is one of the key parts in the quality standard of rare earth-magnesium ductile iron. It is extremely important to classify the graphite ball type correctly, especially the spherical and lump graphite.