QT900-2高强韧厚大断面球墨铸铁的研究

摘要

研究了Sb和热处理工艺对厚大断面球墨铸铁组织和性能的影响,试验结果表明:(1)合理的RE加入量可以中和Sb的反球化作用,改善石墨形态,增加石墨球数量;(2)Sb强烈细化珠光体,但是含量太高会影响球化和导致碳化物的生成;(3)采用940℃(3 h)正火+460℃(4 h)回火的热处理工艺,合金元素含量为w(Cu) 1.0％、w(Sn) 0.15％、w(Sb)0.025％时,厚度为70 mm的附铸试块性能达到了QT900-2的要求,尺寸为500 mm×500 mm×700 mm的方形试块布氏硬度达到了311 HB以上,并且硬度偏差只有17 HB.%The effects of Sb and heat treatment on microstructure and properties of heavy section nodular cast iron were studied.The experimental results showed that:(1)Reasonable addition amount of RE could neutralize the anti-spheroidization effect of Sb,improve graphite morphology and increase the number of graphite balls.(2)Sb strongly refined pearlite,but when the content was too high,it will affect the spheroidization and lead to carbide formation.(3)When the content of alloying elements was 1.0％ of w(Cu),0.15％ of w(Sn) and 0.025％ of w(Sb),the heat treatment process was normalizing at 940 ℃ for 3 h and tempering at 460 ℃ for 4 h,the cast test block with a thickness of 70 mm meets the QT900-2 requirements.The square test block with a size of 500 mm×500 mm×700 mm had a brinell hardness above 311 HB and the hardness deviation was only 17 HB.