TC4钛合金低压电子束熔丝沉积层组织与性能

对TC4钛合金进行了低压电子束熔丝沉积试验，探究了该方法的可行性，并分析了沉积层数对微观组织和性能的影响. 结果表明，在加速电压为10 kV的低压时也可完成TC4钛合金的多层熔丝沉积. 多层沉积之后得到的沉积件的平均显微硬度在260 HV左右，只有沉积件底部条带状纹理聚集处的显微硬度接近退火态TC4基材的288 HV. 条带状纹理产生于多层沉积的过程之中，β相晶粒受热循环影响而发生了β → α + α′ + β的转变，其中硬度较高的网篮状α′相与片状的α相组成了条带状纹理，该显微组织的特点是随着与基板距离的增加，网篮状组织逐渐融入片状组织. 沉积件的拉伸断裂形式为韧性断裂，最高抗拉强度为862 MPa，略低于国家标准，这是因为在多层沉积的沉积件中β柱状晶会变得巨大，同时还会出现等轴晶，晶粒的巨大化使得沉积件的抗拉性能出现了下降.

Microstructure and properties of low voltage electron beam wire deposition layer of TC4 titanium alloy

The low voltage electron beam wire deposition tests on TC4 titanium alloy were carried out to explore the feasibility of the method, and the influence of the number of deposited layers on the microstructure and properties was analyzed. The results show that the multi-layer wire deposition of TC4 titanium alloy can also be completed on the accelerated voltage of 10 kV. The average microhardness of the deposited parts after multi-layer deposition is about 260 HV, and only the microhardness of the banded texture at the bottom of the deposited parts is close to 288 HV of the annealed TC4 substrate. Banded texture produced in multi-layer deposition process, β phase grain transformed to α + α′ + β by the influence of thermal cycle, the banded texture which composited with basket-like α′ phase and lamellar α phase have high microhardness, the other feature of banded texture is that more basket-like phase gradually integrated into the lamellar structure as the increase of the distance with substrate. The tensile fracture of the deposited part is also ductile fracture with the maximum tensile strength of 862 MPa, which is slightly lower than the national standard. It because the columnar crystals will become huge in the deposited parts with multiple layers, and equiaxed crystals will also appear. The huge size of the grains will decrease the tensile properties of the deposited parts.