316H钢锻后固溶处理混晶缺陷产生原因与控制策略

Investigation and control strategy of mixed-grain defects in 316H steel during solution treatment after forging

针对316H奥氏体不锈钢锻后固溶处理混晶缺陷产生的原因进行了研究,结果发现当固溶温度过高或材料内部存在非均匀变形储能时,在固溶处理中极易出现混晶缺陷。对退火态316H钢在高温条件下的晶粒长大行为进行了系统性研究,结果发现,316H钢在1020~1040℃范围内保温时晶粒长大速率增长较为平缓,而在高于1040℃保温时则出现了晶粒急剧长大的现象,故确定固溶处理温度应在1020~1040℃之间。提出了通过消除非均匀变形储能方法主动控制混晶的策略,采用在固溶处理前对材料进行940℃左右预退火处理的方法,有效地消除了316H钢内部的非均匀变形储能,最终使316H钢的晶粒度达到了3.5级以上的工程要求。

The causes of mixed-grain defects of 316H austenitic stainless steel during solution treatment after forging were studied.The results show that mixed-grain defects are easy to occur in the solid solution treatment when the solution temperature is too high or the nonuniform deformation energy storage exists in the material.The grain growth behavior of annealed 316H steel at high temperature was systematically investigated.The results show that grain growth rate of 316H steel increases gently at 1020-1040℃,while the grain growth rate increases sharply at higher temperature than 1040℃.Therefore,the solution temperature should be between 1020-1040℃.The strategy of actively controlling mixed-grain defects by eliminating non-uniform deformation stored energy was proposed.Through a pre-annealing at about 940℃for 316H steel before solution treatment,the non-uniform deformation stored energy of 316H steel is effectively eliminated.Finally,the grain size and grain uniformity meet the engineering requirements of grade more than 3.5.