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铸铁的石墨化,即石墨的结晶过程,是铸铁金相学没有解决的根本问题之一,特别是球铁问世以来,对铸铁中的石墨为什么会球化,到现在还没有统一的理性认识。存在着表面张力;吸附薄膜;螺旋位错;晶核;气泡与空穴;精炼去气;过饱和等各种假说。这些假说对石墨化理论的完善都起到了不同的作用。但对铸铁生产实践中的各种现象还不能自圆其说,甚至自相矛盾。特别对纯Fe—C—Si合金只需要高速冷却就能获得球
The graphitization of cast iron, that is, the crystallization process of graphite, is one of the fundamental problems that cast iron metallography did not solve. Especially since the advent of ductile iron, why did graphite in cast iron become nodular? So far there is no unified rational understanding. There are surface tension; adsorption film; screw dislocation; nuclei; bubbles and holes; refining degassing; supersaturation and other hypotheses. These hypotheses play a different role in the improvement of graphitization theory. However, the various phenomena in the practice of cast iron production can not be justified and even self-contradictory. Especially for pure Fe-C-Si alloy can only get high-speed cooling ball