倾斜角度对激光选区熔化成形Ti6Al4V合金的影响

Effect of inclination angle on the selective laser melting of Ti6Al4V alloy

利用自主研发的Di Metal-100型激光选区熔化设备制备与基板平面成不同倾斜角的Ti6Al4V非标准拉伸试样,研究熔化成形后合金的显微组织、物理和力学性能。结果表明,Ti6Al4V合金粉末熔化成形后的组织为针状α′马氏体和(α+β)相,随倾斜角度变化,试样中α/α′相与β相的相对含量也发生变化,倾斜角为45°试样中β相含量最高;α′马氏体呈柱状分布于(α+β)相中,并且方向始终平行于成形方向(Z轴方向)。随SLM成形试样的倾斜角从0°增加到90°,其相对密度先减小后增大,并在90°时达到最大值96.1%;试样的硬度和抗拉强度均先升高后降低,在45°时达到最大值,硬度为393 HV,抗拉强度为1 288 MPa;试样表面粗糙度Ra也呈先增大后减小的趋势,在0°时达到最小值8.77μm,在30°时达到最大值19.55μm。

Nonstandard tensile specimens of Ti6Al4V alloy were fabricated by selective laser melting （SLM） process with different inclination angles on a self-developed DiMetal-100 machine. Microstructures, physical and mechanical properties of the samples were studied. The results indicate that microstructures of SLM samples are composed of acicular α＇ martensite and （α＋β）, and their contents varies with different inclination angles, the maximum content of β occurs in samples with an angle of 45°. The α＇ grains distribute in （α＋β） phase as cylindrical shape, and the direction of columnar α＇ grains is parallel to the forming direction. With increasing the inclination angle from 0° to 90°, the relative density of SLM samples decreases firstly, and then increases to the maximum value of 96.1% at 90°. On the contrary, the hardness and the ultimate tensile strength increase firstly and then decrease, and both of them reach the maximum values of 393 HV and l 288 MPa, respectively, when the inclination angle is 45°. Meanwhile, the surface roughness of the specimens also increases initially, and then decreases. A minimum roughness of 8.77 μm and a maximum roughness of 19.55 μm are obtained at 0° and 30°, respectively.