冷却强度对连续定向凝固电渣重熔GCr15轴承钢中碳化物的影响

观察并研究了连续定向凝固电渣重熔前后及电渣过程不同冷却强度下,GCr15轴承钢中碳化物的行为和组织变化.结果表明,GCr15轴承钢中主要以M3C型的液析碳化物为主,铸态轴承钢中心偏析严重;经过电渣重熔,钢锭表面光洁,致密度高,碳化物细小且分布均匀.随着电渣重熔冷却强度的增大,GCr15轴承钢中粗大的碳化物数量明显减少,破碎成粒径小、形状规则、分布弥散均匀的圆粒状,能够有效改善碳化物偏析.增大电渣重熔冷却强度,能够缩短凝固时间,缩小树枝晶间距,可以大大减轻树枝偏析.

Effect of cooling intensity on carbides in continuous unidirectional solidification ESR GCr15 bearing steel

Behavior and texture change of carbides in GCr15 bearing steel were observed and studied during,before and after the continuous unidirectional solidification ESR processes under a condition of different cooling intensities.The results showed that, the main carbides in the GCr15 bearing steel are M3C type carbides precipitated from the liquid, and the as-cast bearing steel has a central macrosegregation.After ESR treatment, the carbides are tiny and well distributed.With increase of the ESR cooling intensity, amount of large carbides in the GCr15 bearing steel decreases strongly, become round grain well-distributing with regular form or small particle, which effectively improves the carbide segregation.Increasing the cooling intensity could shorten the solidification time and greatly reduce the branch segregation.