电弧增材制造TB6钛合金的组织和力学性能研究

Microstructure and Mechanical Properties of TB6 Titanium Alloy Fabricated by Arc Additive Manufacturing

  • 摘要: 利用电弧增材制造技术制备TB6钛合金沉积件,分析了沉积件在不同沉积高度的宏微观组织特征和力学性能各向异性,并研究了沉积电流参数对宏微观组织和力学性能的影响规律。结果表明:沉积件的宏观组织主要由柱状和等轴β晶粒组成,并且随着沉积电流升高,等轴β晶粒的体积分数降低。而微观组织主要为均匀分布在β基体上的α网篮组织,其中α片层的尺寸随沉积高度的升高呈现先增大后减小的趋势,这主要归因于不同沉积高度下,沉积层间的热累积和散热能力差异所致。此外,柱状β晶粒和α片层的尺寸均随着沉积电流的升高而增大。而对于沉积件的力学性能,其横向和纵向力学性能均表现为随着电流降低,沉积件的抗拉强度、屈服强度增大,而塑性降低,这是由于小电流条件下,沉积件热输入小,α尺寸相对细小,相应的晶界数量较多,晶界在阻碍位错运动的同时,又容易导致界面处的位错塞积,进而导致沉积件的强度增加,塑性降低。进一步地对沉积件横纵向力学性能的各向异性进行计算发现,伸长率的各向异性最为显著。

     

    Abstract: The TB6 titanium alloy deposition parts are prepared by arc additive manufacturing technology. The macro and micro structure characteristics and mechanical properties anisotropy of the deposition parts at different deposition heights are analyzed, and the influence of deposition current parameters on macro and micro structure and mechanical properties is studied. The results show that the macrostructure of the deposited parts is mainly composed of columnar and equiaxed β grains, and the volume fraction of equiaxed β grains decreases with the increase of deposition current. The microstructure is mainly composed of α basketweave structure uniformly distributed on the β matrix. The size of α lamellae increases first and then decreases with the increase of deposition height, which is mainly due to the difference of heat accumulation and heat dissipation capacity between the sedimentary layers at different deposition heights. In addition, the size of columnar β grains and α lamellae increases with the increase of deposition current. For the mechanical properties of the deposited parts, the transverse and longitudinal mechanical properties show that with the decrease of current, the tensile strength and yield strength of the deposited parts increase, while the plasticity decreases. This is because under the condition of low current, the heat input of the deposited parts is small, the size of α is relatively small, and the corresponding number of grain boundaries is large. While the grain boundaries hinder the movement of dislocations, they easily lead to the dislocation accumulation at the interface, which leads to the increase of the strength of the deposited parts and the decrease of plasticity. Further calculation of the anisotropy of the transverse and longitudinal mechanical properties of the deposited parts shows that the anisotropy of elongation is the most significant.

     

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