灰铸铁的石墨分布形状及其控制

Graphite Distributing Forms of Gray Iron and Its Control

介绍了灰铸铁中石墨分布形状的分类,强调2点:(1)C型和F型石墨都属初生石墨,石墨是在过共晶成分下从铁液中析出的;(2)A、B、D、E各型石墨存在于亚共晶铸铁中,它们是在共晶过程中产生的共晶石墨。指出:A型石墨分布均匀无方向性,具有A型石墨的铸铁,其性能均匀性和稳定性好,铸铁的强度利用率高。因此,A型石墨是高强度灰铸铁追求的目标。最后介绍了获得A型石墨的几个方法:(1)控制CE;(2)采用低合金化和适当提高Si/C比;(3)加强孕育处理;(4)合理选择炉料;(5)其它,如内浇道分散、铁流末端设溢流冒口、打箱不要过早,等。

The classification of graphite distributing forms of gray iron was introduced,and two points were stressed:( 1) Both type C and type F of graphite belong to the primary graphite,they separated from the iron liquid of hypereutectic composition.( 2) Type A,type B,type D and type E of graphite were existing in the hypoeutectic cast iron,they were graphite produced in the eutectic process. It was pointed out:the type A of graphite distributed uniformly and directionless,the properties uniformity and stability of the cast iron having type A graphite was good,and their strength usage rate was high. Therefore,type A of graphite was the target pursued when producing high strength cast iron. By the end,several methods to obtain type of graphite were introduced:( 1) Controlling CE.( 2) Using low alloying and properly increasing Si/C ratio.( 3) Intensifying inoculation treatment.( 4) Rational choosing melting charges.( 5) Others including using separated ingates,setting overflowing riser at the end of the iron melt flow,and not too early shakeout,et al.