利用废钢废机铁生产厚断面球墨铸铁研究

Investigation of Heavy Section on Ductile Cast Iron Production Using Machine Scrap Iron and Steel Scrap

以废钢、回炉料及少量的废机铁为主要原材料,配以增碳剂和球化剂,优化了中频炉熔炼工艺,生产出了铁素体球墨铸铁。通过对比分析Y-型试块和厚断面试块的组织与性能,结果表明:Y-型试块满足国标QT450-10的各项性能指标,基体组织为多边形铁素体,没有观察到珠光体;而在同一工艺条件下浇注的100mm厚断面试块,表面组织良好,性能同Y型试块相当。在断面的1/4处和1/2处(中心),力学性能呈下降趋势,球化效果减弱。在断面的中心处,明显发现有不完整的球状石墨、点状石墨和少量的破碎石墨存在。本文可对该工艺下生产厚断面球墨铸铁提供技术参考。

The ferrite ductile cast iron was developed by way of using steel scrap,foundry returns and a few of machine scrap iron as major materials,along with recarburizer and nodularizer additions to optimize medium frequency furnace smelting.Through comparative analysis of microstructures and mechanical properties between Y-type and heavy section block,the experimental results show that:the mechanical properties of Y-type block specimen meet the needs of QT450-10 as a standard.The microstructures composed of polygonal ferrite and no pearlite was observed.Under the same process condition to the 100mm in thickness block,the microstructures and mechanical properties on the surface are similar to the Y-type block specimen.However,the mechanical properties on the 1/4 and 1/2locations to the surface are decreased and the spheroidization effect are weakened.In particular,on the 1/2 locations to the surface,incomplete spheroidal graphite,punctate and very few of crushed graphite can easily observed.The experiment results can provide technological references to the production of heavy section ductile cast iron.