TC4钛合金扩散连接区热变形特性行为研究

Thermal deformation behavior of diffusion-bonded region of TC4 titanium alloy

摘要:

以TC4钛合金扩散连接区为研究对象，在变形温度920，950，980，1010 ℃及应变速率0.01，0.1，1，10 s-1的条件下进行热变形试验，研究了变形温度和应变速率对TC4钛合金扩散连接区流变应力和微观组织的影响规律。研究结果表明：TC4钛合金扩散连接区在高温下具有明显的动态软化特征，流变应力随变形温度的升高而降低，随变形速率的提高而增大；高温变形后扩散连接界面消失，随变形温度的增加，等轴α相的体积分数减少，同时伴有短棒状和板条状的次生α相出现，且次生α相的体积分数随应变速率增加逐渐降低；当变形温度达到1010 ℃时，出现马氏体α′相；以双曲正弦形式修正的Arrhenius方程为基础，建立了TC4钛合金扩散连接区双曲正弦本构方程以及热加工图，确定TC4钛合金扩散连接区的最佳变形温度为920~950 ℃，变形速率为0.01~0.1 s-1。

Abstract:

The thermal deformation tests of diffusion-bonded region of TC4 titanium alloy was carried out at deformation temperatures of 920,950,980,1010 ℃ and strain rates of 0.01, 0.1, 1,10 s-1. The effects of deformation temperatures and strain rates on flow stress and microstructure of diffusion-bonded region of TC4 titanium alloy was investigated. The results show that the diffusion-bonded region of TC4 titanium alloy has obvious dynamic softening characteristics at high temperature,and the flow stress decreases with the increase of deformation temperature and increases with the increase of deformation rate; The diffusion-bonded interface disappears after high temperature deformation,and the volume fraction of isoaxial α phase decreases with the increase of deformation temperature,accompanied by the emergence of short rod-like and plate-like secondary α phase, and the volume fraction of secondary α phase decreases with the increase of strain rate; When the deformation temperature reaches 1010 ℃,martensite α ""phase appears; Based on the hyperbolic sinusoidal modified Arrhenius equation,the hyperbolic sinusoidal constitutive equation and the thermal processing diagram of diffusion-bonded region of TC4 titanium alloy were established.The optimal deformation parameters of diffusion-bonded region of TC4 titanium alloy were determined as T=920~950 ℃, ε=0.01~ 0.1 s-1.