锻造变形对扩散连接TC4钛合金的影响

Influence of forging deformation on diffusion bonded TC4 titanium alloy

本文开展了TC4钛合金棒材扩散连接及锻造工艺实验,研究了锻造变形量对扩散连接界面显微组织和力学性能的影响规律。结果表明,采用950℃、140 MPa、4 h的扩散连接工艺,TC4钛合金连接界面实现了冶金结合,合金强度达到母材强度的95%以上,延伸率为7%,合金在扩散区发生脆性断裂。扩散连接的TC4钛合金经过高温锻造后,扩散连接界面完全消失,显微组织由等轴α相、次生α相与少量的β相组成;随着锻造变形量的增加,等轴α相的尺寸逐渐降低、次生α相体积分数增大,合金强度呈现升高趋势;当变形量为40%时,等轴α相和次生α相含量达到较优匹配度,抗拉强度达到950 MPa,延伸率达到17.5%,锻造后合金的断裂方式转变为韧性断裂。

In this paper,TC4 titanium alloy bars were employed to study the effect of forging deformation on the microstructure and mechanical properties of the diffusion bonding interface.The results showed that the TC4 titanium alloy interface was metallurgically bonded by diffusion bonding process at 950℃ and 140 MPa for 4 h.The strength of the diffusion bonded sample was 95% higher than that of the base metal,and the elongation was 7%.The brittle fracture occurred in the diffusion zone.After high-temperature forging,the diffusion bonding interface of the TC4 titanium alloy completely disappeared.The microstructure consisted of an equiaxed α phase,a secondaryαphase,and a small amount of β phase.With increasing forging deformation,the size of the equiaxedαphase decreased,the volume fraction of the secondaryαphase and the alloy strength increased.When the deformation was 40%,the content of the equiaxedαphase and secondaryαphase reached the best matching degree.The tensile strength reached 950 MPa,the elongation reached 17.5%,and the fracture mode of the alloy transformed into ductile fracture.