TC4钛合金激光金属沉积力学性能各向异性机理研究

Study on the Mechanisms of Mechanical Property Anisotropy of TC4 Titanium Alloy by Laser Metal Deposition

采用激光金属沉积方式制备横向与纵向上的TC4钛合金试样,包括室温拉伸试样、室温冲击试样、金相试样,研究其组织结构与力学性能各向异性之间的关系。结果表明:对于退火态激光金属沉积TC4钛合金而言,不同面组织均由典型的网篮组织α+β组成,但相比XOZ面、YOZ面,XOY面组织更为细小,α相呈织网状交错,整体尺寸为XOZ面、YOZ面的1/3~1/2,β粗大柱状晶的α晶界(α_(GB))数量更多;横向试样的强度高,塑性低,纵向试样的强度低,塑性高;横向(Y向)与纵向(Z向)上的力学性能存在各向异性的原因在于:晶界强化发挥了至关重要的作用,晶界越多,强度越高,塑性越低。

Transverse and longitudinal TC4 titanium alloy samples were prepared by laser metal deposition, including room temperature tensile samples, room temperature impact samples, metallographic samples. The relationship between microstructure and anisotropy of mechanical properties was studied. The results show that the different plane structures are composed of typical net basket structure α+β for annealed laser metal deposition of TC4 titanium alloy, but compared with XOZ plane and YOZ plane, the XOY plane has the finer microstructure, the α phase is interlaced with a woven network, the overall size is 2~3 times smaller, there are more α grain boundaries(α;) in coarse columnar β;the transverse specimen has high strength and low plasticity, and the longitudinal specimen has low strength and high plasticity;the reasons for the anisotropy of mechanical properties in transverse(Y direction) and longitudinal(Z direction) directions are as follows: grain boundary strengthening plays a crucial role, the more grain boundaries, the higher strength and the lower plasticity.