电子束熔丝沉积快速制造成型技术与组织特征

The Forming Character of Electron Beam Freeform Fabrication

利用电子束熔丝沉积快速制造技术制备了TC4钛合金薄壁结构和实体结构试样,分析了成型技术特点,探讨了组织形貌特征及形成机制。研究表明:对于薄壁结构,采用合理的工艺参数,获得的熔积层的宽度为7.4mm,层高为1.5mm;结构纵截面的组织形貌特征是原始β柱状晶与沉积高度方向大约成15°角,较为粗大,宽3～5mm,单个柱状晶贯穿几层到十几层熔积层不等。对于实体结构,熔积间距为4.7mm时得到的试样表面较为平整,熔积高度基本一致;试样纵截面可观察到明显的层带,而原始β柱状晶垂直向上生长。

Electron Beam Free Form Fabrication （EBF3） is an advanced rapid manufacturing technology based on electron beam welding with filler wire. In this paper, two kinds of TC4 titanium components were prepared by EBF3, one is thin-wall parts and the other is cubic samples with large dimension. The depositing characteristics during the process, microstructure appearances and formation mechanism were discussed in detail. The results show that a single-clad track with the width of 7.4 mm and the height of 1.5 nun were proper for depositing thin-wall parts. The cross-sectional structures were composed of primary solidified β columnar grains which deriving about 15° from the depositing direction. The diameters of the grains were in the range of 3 to 5 mm which present an epitaxial growth mode and crossing several layers. While depositing the large scale cubic components, the interval width between two tracks of 4.7 nun is preferable for acquiring smooth surfaces and uniform heights. Distinguished with the thin-wall parts＇ structures, the primary solidified β columnar grains in the cubic grew vertically.