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一、可锻铸铁石墨化过程概述铁索体可锻铸铁是将白口铸铁坯件,通过石墨化处理而获得的。所谓石墨化处理,就是指在热处理过程中,使白口铸坯中的渗碳体(包括共晶渗碳体、二次渗碳体和共析渗碳体)分解,析出团絮状石墨,其最终的金相组织是铁素体+团絮状石墨。渗碳体石墨化过程是极其复杂的,铸坯的化学成分、微量元素;铸坯的初生组织、截面尺寸;退火炉内气氛、炉型结构和退火工艺等,都影响到石墨化时间。采取什么样措施,促使渗碳体分解,以期达到缩短退火周期,这是可锻铸铁工作者长期以来探讨的中心课题。 1964年以来,我国范文瑞等同志认为:空气中的氢、氧、氮等均具有反石墨化的倾向,是促使可锻铸铁退火周期冗长的原因之一,如果
First, an overview of malleable iron graphitization Ferroalloy malleable iron is white cast iron billet obtained by graphitization. The so-called graphitization, refers to the heat treatment process, the white cast slab cementite (including eutectic cementite, secondary cementite and eutectoid cementite) decomposition, precipitation of flocculent graphite, Its final microstructure is ferrite + flocculent graphite. Graphite cementite process is extremely complex, the chemical composition of slab, trace elements; billet primary tissue, cross-sectional size; annealing furnace atmosphere, furnace structure and annealing process, all affect the graphitization time. What measures to take to promote the decomposition of cementite, in order to achieve shorten the annealing cycle, which is the central topic for malleable cast iron workers to explore for a long time. Since 1964, our country such as Fan Wenrui and other comrades believe that: the air of hydrogen, oxygen, nitrogen, etc. have anti-graphitization tendency is to promote the malleable iron annealing cycle lengthy one of the reasons, if