基于激光选区熔化成形的TC4钛合金各向异性研究

Research on Anisotropy of TC4 Titanium Alloy Formed by Laser Selective Melting

利用激光选区熔化技术(SLM)成形TC4钛合金,分析了合金微观组织和力学性能。结果发现:SLM成形TC4钛合金组织存在各向异性,纵向试样组织呈现明显的β柱状晶形貌,柱状晶内部为针状的过饱和α′马氏体相,横向试样组织呈现深浅不一的类棋盘形貌,棋盘内部主要包括长针状α′相以及一定含量的β相,棋盘格之间过渡区域为短针状马氏体α′及网篮状马氏体,且横向组织中的针状马氏体α′比纵向的要细;SLM成形TC4钛合金试样室温拉伸性能也存在各向异性,总体上表现为横向室温抗拉强度优于纵向,但在不同扫描速率下,各向异性程度存在差异。总体上,本研究激光功率280W、扫描速率1100mm/s工艺参数下成形的TC4钛合金试样综合力学性能最优,且各向异性程度最小。

The microstructure and mechanical characteristics of the TC4 titanium alloy created by laser selective melting(SLM)were examined.The results demonstrate that anisotropic in the TC4 titanium alloy generated via SLM.The longitudinal sample's structure isβmorphology of columnar crystal clearly defined,but transverse sample structure has a checkerboard shape with varying depths.The interior of the checkerboard is primarily made up of long needle-likeα′phase and some content ofβphase.The transition area between the checkerboards is made up of short needleα′martensite and net basket martensite.The needleα′martensite in the transverse structure is thinner than the longitudinal one.The tensile properties of TC4 titanium alloy samples produced by SLM at ambient temperature are also anisotropic;however,the degree of anisotropy changes with the scanning rate.The tensile properties in the transverse direction are better than those in the longitudinal direction.The TC4 titanium alloy samples produced using a 280W laser power and a 1100mm/s scanning speed often exhibit the best overall mechanical properties and the least amount of anisotropy.