模型处理对SEBM法制备TC4合金成型性能影响

Influence of Model Treatment on Forming Properties of TC4 Alloy Prepared by SEBM

摘要:

模型处理是影响电子束选区熔化（SEBM）成型件性能和精度的关键因素之一。以TC4钛合金为研究对象，利用电子束选区熔化快速成型技术制备横、竖两种不同摆放方式打印的R7拉伸试件，并对拉伸试件进行室温拉伸试验。结果表明：横向摆放的打印试件的力学性能，比竖向摆放的打印试件的更优；对拉伸断口进行宏观断口分析发现，横向摆放的打印试件断口处没有明显的塑性变形且断裂位置几乎在中间，而竖向打印的试件断口有明显的被拉长且断裂位置在试件上方；对试件沿长度方向剖开，分别选取试件上下两段进行金相组织观察分析发现，横向打印试件上下端金相组织差异不大，但竖向打印上端呈现出α相及转变相，并且存在分层和气孔缺陷。由于横向摆放位置的打印试件与加工电子枪扫描方向一致，且受热均匀，因此具有较好的组织特性。

Abstract:

The model processing is one of the key factors affecting the performance and precision of the selective electron beam melting parts. This paper takes TC4 titanium alloy as the research object， and uses an electron beam selective melting rapid prototyping technique to prepare R7 tensile specimens with two different placement modes of horizontal and vertical printing. The tensile test of the tensile specimen at room temperature shows that the mechanical properties of the printed specimen placed laterally are better than those placed vertically. The macroscopic fracture analysis of the tensile fracture reveals that the horizontally printed specimen has no obvious plastic deformation and the fracture position is almost in the middle， while the vertically printed specimen has an obvious elongated fracture position and the fracture position is above the specimen. After the specimen is split along the length direction， the upper and lower sections of the specimen are selected for metallographic structure analysis. It can be seen that there is little difference in the metallographic structure between the upper and lower ends of the horizontally printed specimen， but the upper end of the vertically printed specimen presents α phase and transformation phase and exists stratification and porosity defects. In summary， the horizontally printed specimen has better microstructure characteristics because it has the same direction as the scanning electron gun and can be heated evenly.