TB6钛合金β热处理晶粒生长及片层转变行为

β-grain growth and transition behavior of lamellar structure in TB6 titanium alloy

研究了TB6钛合金β热处理过程中的β晶粒生长及片层结构形成。结果表明,TB6钛合金经β固溶后随不同冷速形成全β组织和(α+β)片状组织。淬火形成的全β组织β晶界平直,晶粒呈等轴状。缓冷下形成的片状组织中原始β晶粒内包含多个α集束,集束间取向各异,集束内α片彼此平行。β晶粒尺寸随保温时间和加热温度增加而增加。β晶粒尺寸与保温时间满足幂函数关系。随冷却速度降低,片层厚度基本呈线性增加,而集束尺寸先快速增加,后增加缓慢。

The β-grain growth and formation of the lamellar structure of TB6 titanium alloy during β heat treatment process were studied.The results indicate that under various cooling rates after β solution treatment,the alloy presents two kinds of microstructures: fully βstructure and lamellar( α + β) structure. A detailed microstructure by optical microscopy of the fully β structure with straight grain boundary and equiaxed grain obtained by water quenching is also carried out. Prior β grain resulting from slow-cooling process contains lamellar microstructure consisting of several α-colonies. The α-laths within a α-colonies have the same habit plane,where the α-colonies within a prior β grain have different crystallographic orientations. The β grain size increases with the increasing of the holding time and heating temperature. The relationship between β grain size and holding time could be described by a power function with a power factor of0. 277. With decreasing of the cooling rate,the thickness of α-laths increase linely,whereas the colony size increase rapidly at first and then increase slowly.