尺寸对TC4板材β退火工艺影响的模拟分析

Simulation Analysis of Effect of Size on Beta Annealing Processing of TC4 Titanium Alloy Plate

通过对小尺寸试样和成品板冷料入炉、直接加热的β退火工艺进行有限元模拟,对比分析了尺寸对TC4板材加热过程温度场的影响。结果表明,随尺寸的增加,板材表面、心部进入β相区的时间差异越大。而这种差异将导致β晶粒沿断面的大小不均匀,进而引起性能的不均匀。因而,对于尺寸较大的成品板,采用两阶段退火:(850℃保温60 min+995℃保温50 min),热处理后板材的断面组织基本均匀一致,均为魏氏组织。

The temperature field of small samples and big finished plates during beta annealing by the one-step heating was simulated by EFM. The effects of size on temperature field were analyzed. The results show that the time difference between the surface and the center which reach the beta phase field is bigger with the increase of the size. Moreover the difference will lead to the in_homogeneous microstructures and properties of the plate. The two-step heating is carried out for the final annealing processing of big finished TC4 plates, which is soaking at 850℃ for 60 n＇fin, followed holding for 50 min at 995 ℃. Thus the homogeneous widmanstatten structure is achieved.