本文采用不同热处理温度(760℃、800℃、840℃和880℃)和不同保温时间(10 min、30 min、60 min和120 min)研究了热压缩后的Ti-5322钛合金片状组织的静态球化行为.结果表明:α相晶粒尺寸主要取决于热处理温度和保温时间,而与变形量、变形温度和应变速率关系不大.随着热处理温度升高和保温时间的延长,α相晶粒尺寸增大而α相的含量降低.静态球化分数随变形量、热处理温度和热处理时间的增加而增加,但对变形温度和应变速率的依赖性较小.另外,随着变形量、热处理温度和热处理时间的增加,静态球化分数的增速先增大后减小.Ti-5322钛合金组织粗化贯穿整个热处理过程,静态球化过程可以分为低温短时退火阶段和高温长时退火阶段;在前一个阶段,静态球化主要以边界分离的形式进行,而在后一个阶段,边界分离机理几乎消失,静态球化主要以末端迁移和奥斯瓦尔德熟化的形式进行.
In this paper,the static globularization behavior of lamellar structure of Ti-5322 titanium alloy after hot compression was studied at different heat treatment temperatures(760℃,800℃,840℃ and 880℃)and different holding times(10 min,30 min,60 min,and 120 min).The results show that the grain size of α phase mainly depends on the heat treatment temperature and holding time,but has little to do with the reduction,deformation temperature and strain rate.The grain size increases with the increasing heat treatment temperature and time.In addition,the volume fraction of α phase also decreased with the increases of treatment temperature and holding time.The static globularization fraction increases with the increases of reduction,heat treatment temperature,and holding time,but has little dependence on deformation temperature and strain rate.In addition,the growth rate of static globularization fraction increases first and then decreases with the increases of reduction,heat treatment temperature and holding time.The structure coarsening of Ti-5322 titanium alloy runs through the whole heat treatment process.The static globularization process can be divided into two stages,the stage with low temperature and short-time annealing,and he stage with high temperature and long-time annealing.In the previous stage,the static globularization occurs mainly in the form of boundary splitting,which leads to lamellar separation in the form of substructure.In the latter stage,the boundary splitting almost disappears,and the static globularization occurs mainly in the forms of termination migration and Oswald ripening.