γ-TiAl金属间化合物细晶棒材挤压变形工艺

Extrusion Process of Fine Grained γ-TiAl Alloy Bar

结合数值模拟与工艺试验的方法研究了γ-TiAl合金细晶棒材挤压工艺,获得了挤压过程中各场变量的分布规律及不同挤压比组合下挤压棒材中温度场、应变速率场、等效应变场和断裂因子分布的信息。结果表明,采用3.5+4.3两步挤压比组合时可以获得较为均匀的温度场、应变速率场和等效应变场,且断裂因子数值较小。采用该挤压比组合进行了挤压工艺试验,通过这种两步挤压组合可以获得质量良好,晶粒尺寸细小、均匀的γ-TiAl合金挤压棒材。

The numerical simulation and experiment is ernployed to study the extrusion process of fine grained TiAl alloy bar. It gets the distribution of each field variable in the extrusion process, and obtains the field variable about temperature field, strain rate field, equivalent strain field, and breaking factor distribution under different extrusion ratios. The results show that 3.5＋4.3 two-step extrusion ratio is beneficial to homogeneity of above-men- tioned distribution of fields. Extrusion experiment is em- ployed based on the prediction to verify those conclusions of the simulation work. Assuredly, crack-free extrusion bar is obtained, and homogeneous and refined microstructure are observed.