控冷处理对锻造Inconel 617合金晶界组织的影响

Effect of controlled cooling treatment on grain boundary structure for forged Inconel 617 alloy

以锻造Inconel 617合金为研究对象,通过控冷处理在合金中引入锯齿晶界,在消除锻造残余内应力的同时,实现组织优化;分析了冷却速度对锯齿晶界的影响,揭示了晶界碳化物的类型及结构特征,阐明了锯齿晶界的形成原因。结果表明:控冷处理是获得锯齿晶界的必要环节,且冷却速度越慢,越有利于锯齿晶界的形成。通过将合金在1200℃保温1 h后以5℃·min^(-1)的冷却速度冷却至700℃再水冷,可在合金中引入锯齿晶界,其中锯齿晶界的平均振幅为0.8μm。此外,锯齿晶界的形成与晶界碳化物有着密切的联系,其主要表现为两种不同的形成机制:一种为晶界的一部分被碳化物钉扎,碳化物之间的晶界发生迁移形成锯齿晶界;另一种为板状碳化物沿晶界生长诱使晶界弯曲。

For forged Inconel 617 alloy,the serrated grain boundary was introduced into the alloy by controlled cooling treatment to elimi-nate residual internal stress and achieve structural optimization,and the influences of cooling speed on serrated grain boundaries were ana-lyzed.Then,the types and structural characteristics of carbides at grain boundary were revealed,and the formation reasons of serrated grain boundary were clarified.The results show that the controlled cooling treatment is a necessary step to obtain serrated grain bounda-ries,and the slower the cooling speed is,the more conducive to formation of serrated grain boundaries.By holding the alloy at 1200℃for 1 h,cooling it to 700℃at a cooling speed of 5℃·min^(-1),and then water cooling,the serrated grain boundaries can be introduced into the alloy,where the average amplitude of the serrated grain boundaries is 0.8μm.In addition,the formation of serrated grain bound-aries is closely related to the carbides at grain boundary,which are mainly manifested by two different formation mechanisms.One is that part of the grain boundary is pinned by carbides,and the grain boundaries between carbides migrate to form serrated grain boundaries.The other is the growth of plate-shaped carbides along the grain boundaries to induce bending of the grain boundaries.