混合元素法激光立体成形Ti-6Al-4V的组织及性能研究

Microstructure and Mechanical Properties of Laser Solid Formed Ti-6Al-4V from Blended Elemental Powders

摘要:

以Ti、Al、V混合元素粉末为原料激光沉积Ti-6Al-4V，并对沉积态试样的组织演化及力学性能进行研究。结果表明，与采用预合金Ti-6Al-4V粉末为原料所获得的沉积试样的凝固组织特征有所不同，采用混合元素粉末为原料获得的沉积试样的凝固组织随激光功率的提高逐渐由等轴晶转化为柱状晶，熔池内合金化过程所产生的混合热的扰动作用是导致低功率条件下等轴晶形成的原因。原始β晶粒内的微观组织由大量的魏氏α板条和一定体积分数的板条间β相组成。这与采用预合金粉末基本相同。混合元素法激光立体成形Ti-6Al-4V的氧含量仅约0.1wt.%，沉积态Ti-6Al-4V的室温拉伸性能超过锻件标准要求。

Abstract:

The microstructure and mechanical properties of laser solid formed Ti-6Al-4V from the blend of Ti, Al, and V powders were investigated. It is found that the macrostructure changes from equiaxed to columnar grains with the increase of the laser power, which is very different from that of the samples using pre-alloyed powders as cladding materials. The disturbance effect of the mixing enthalpy during laser deposition is considered responsible for the formation of equiaxed grains at low laser powers. The microstructure within prior-β grains mainly consists of Widmanst?tten α laths separated by β-Ti, which is basically identical to those from pre-alloyed powders. Oxygen content of as-deposited samples was measured and the tensile testing was carried out. The results show that the oxygen content of as-deposited Ti-6Al-4V from blended elemental powders is only about 0.1wt.% and the mechanical properties are comparable to or even better than that of conventionally wrought material.