挤压比对TiAl合金铸锭挤压过程的影响

Influence of Extrusion Ratio on Extrusion Process of TiAl Alloy Cast Ingot

采用有限元模拟方法研究了挤压比对TiAl合金挤压变形的影响。结果表明:TiAl合金在热挤压过程中,挤压载荷和时间的关系与其它合金有所不同,即挤压载荷达到峰值后并未明显地降低,而是在某一数值附近波动。这与合金具有较高的加工硬化率有关。增大挤压比有利于变形向棒材心部深入,挤压比超过7时,锭坯内径向流速分布不均匀,进一步增大挤压比,金属流动的不均匀性也增大。

Effects of extrusion ratio on the extrusion deformation of TiA1 alloy were researched by using the finite element simulation method. The results show that the relationship between extrusion load and time is different from another alloy in hot extrusion process of TiAl alloy. That is extrusion load does not decrease obviously after the load is peak value, but it undulates in the vicinity of a certain value. This is, relative to the higher work hardening rate of the alloy. Increasing extrusion ratio helps to bar deformation to core entering. When the extrusion ratio exceeds 7, the radial velocity distribution of the cast ingot is inhomogeneous. Further increasing the extrusion ratio, non-uniformity of metal flow also increases.