为实现钛合金初生带状α相的球化,以具有这种组织的TA15钛合金为对象,研究其在热加工中的组织演变.结果表明:带状α相形态演变的机理与片层组织球化机理相同.由于带状α相尺寸较大,界面分离和末端物质迁移机制较粗化更为重要.带状α相在退火中较为稳定,主要原因是:内部晶界的几何取向不利于球化、带状组织的宽度较大和α粒子几何稳定性高.预变形和低速变形通过以下方式加速球化:直接改变α相的几何形状、通过增加大角度晶界以及相界的面积促进界面分离和末端物质迁移、通过形成位错结构促进粗化.采用大预变形结合高温退火是球化带状α相的有效途径.%Microstructural development inhot working of TA15 titanium alloy with primary stripα structure was investigated with the aim to globularizeα strips. Results show that the mechanisms of morphology transformation are the same to the spheroidization mechanisms of lamellar structure. Boundary splitting and termination migration are more important than coarsening due to the large size of stripα. Theα strips are stable in annealing due to the unfavorable geometrical orientation of intra-α boundaries, the large thickness of strip and the geometrical stability ofα particles. Predeformation and low speed deformation accelerate globularization ofα strips in the following ways: direct changing of particle shape, promotion of boundary splitting and termination migration by increasing high angle grain boundaries and interfacial area, promotion of coarsening by forming dislocation structures. Large predeformation combined with high temperature annealing is a feasible way to globularize stripα.
展开▼
