摘要
针对GCr15SiMn钢锭易出现宏观偏析凝固缺陷的问题,研究了过热度对GCr15SiMn钢锭宏观偏析的影响规律,使用真空感应炉冶炼1 kg的GCr15SiMn钢锭,通过酸侵试验与OPA技术分别测定了钢锭的凝固组织与宏观偏析,并结合ProCAST软件分析了钢液流动的规律。结果表明,高过热度(70℃)时,中心下部出现一定程度的负偏析,中心上部形成了较严重的正偏析同时伴随疏松;中过热度(50℃)时,疏松范围较小,碳元素分布较均匀;低过热度(20℃)与极低过热度(-20℃)时,疏松范围扩大,凝固初期是严重负偏析,凝固末期是严重正偏析。过热度影响偏析的机理为,高过热度时,凝固过程热对流较强,溶质上浮,钢锭上部的正偏析严重;当过热度过低时,初期凝固大量形核并保留在钢锭底部,在底部形成严重的负偏析。
Some solidification defects such as macrosegregation will occur during the solidification of GCr15 SiMn steel ingots.The effect of superheat on the macrosegregation of GCr15 SiMn ingot was analyzed.GCr15 SiMn ingots of 1 kg were smelted by vacuum induction furnace.The solidification structure and macrosegregation of the steel ingot were obtained by acid erosion and OPA,respectively.The flow rule of molten steel was studied by ProCAST software.The results showed that at high superheat(70℃),a certain degree of negative segregation appeared in the lower part of the center,and serious positive segregation formed in the upper part of the center with porosity.The porosity range was smaller and the carbon distribution was more uniform at moderate superheat(50℃).In the case of low superheat(20℃)and extra-low superheat(-20℃),the porosity range was enlarged.Moreover,severe negative segregation was formed at the initial stage of solidification and severe positive segregation was formed at the end of solidification.The mechanism of superheat affecting segregation was that the heat convection was strong during solidification and solute floated upward at high superheat,causing serious positive segregation in the upper part of steel ingot.When the superheat was extra-low,a large number of crystals nucleated and remained at the bottom of the steel ingot in the early stage of solidification,and serious negative segregation formed at the bottom.
作者
张涛
成国光
侯雨阳
ZHANG Tao;CHENG Guo-guang;HOU Yu-yang(State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing,Beijing 100083,China)
出处
《中国冶金》
CAS
北大核心
2020年第9期60-66,共7页
China Metallurgy
基金
国家自然科学基金资助项目(51374020)。
