选区激光熔化Ti6Al4V合金的各向异性

采用金相分析和拉伸测试等方法，分析了激光熔化成形Ti6Al4V试样在不同沉积高度、不同方向截面的组织和性能。结果表明，平行于沉积方向的截面其组织类似柱状晶，具有较弱的织构特征；垂直于沉积方向的截面其组织为块状结构，具有较强的织构特征。选区激光熔化成形Ti6Al4V合金在沉积高度方向上的力学性能受柱状晶尺寸的影响，随着沉积高度的增大其抗拉强度和屈服强度先降低后升高而延伸率先提高后降低。织构和熔合不良等缺陷，使试样垂直于沉积方向上的强度和塑性都比平行于沉积方向的试样高。

Anisotropy of Ti6Al4V Alloy Fabricated by Selective Laser Melting

The microstructure, texture and properties of samples intercepted at different deposition heights and directions of the Ti6Al4V alloy fabricated by selective laser melting were investigated by metallographic analysis, XRD and tensile test. The results show that the vertical section parallel to the building direction presents microstructure of columnar-like prior-β grains filled with acicular martensite, while the cross section perpendicular to the building direction presents a block-like microstructure. The texture for the later cross section is stronger than that for the former one. The size of the columnar prior-β grains influences the mechanical properties along the building direction of the Ti6Al4V alloy fabricated by selective laser melting. The tensile strength and yield strength decrease first and then increase with the increase of deposition height, while the elongation variation has an opposite trend. The strength and plasticity of samples perpendicular to the building direction is higher than those parallel to the building direction due to the formed defects related with the weaker-texture and poor-fusion.