Additive manufacturing has advantages of cutting the time from design to making new parts but it suffers from metallurgical defects such as porosity. For example, wired arc additive manufacturing(WAAM) of new alloys such as Al–Li alloys is very challenging due to the fact that the porosity level is so high as to degrade not only fatigue life but also the static mechanical properties. In this study, we found that large chains of porosity could form at the interdendritic liquid during WAAM of an AA2196 Al–Li alloy. After T6 heat treatment, those chains of porosity actually grow bigger than the as-deposit state, with the microporosity size over 50 µm increasing from 2.8% to 5.8% and the maximum size grow up to 107 µm. Using X-ray Computed Tomography (XCT), we have quantified the spatial distribution of microporosity as a function of hot deformation after WAAM. It was found that the chain of microporosity along the direction of deposition could be effectively eliminated by controlling the strain. Combining the 42% hot deformation and T6 heat treatment, the closure of microporosity together with nano-sized T₁ precipitates can be achieved and yield tensile strength (YTS) can be improved by 199%, the ultimate tensile strength (UTS) can be increased by 168%, and the elongation can be extended by 460%, reaching up to 372 MPa, 439 MPa, and 6.9%, respectively. Therefore, the solidification defects during WAAM can be remediated by applying proper hot deformation which is extremely useful for the Al–Li alloys with a long solidification range and high susceptibility to solidification cracking.

增材制造的优势是可以缩短从设计到制造新零件的时间，但它会遭受诸如孔隙率之类的冶金缺陷的困扰。例如，由于孔隙率很高，不仅降低了疲劳寿命，而且降低了静态机械性能，因此诸如Al–Li合金之类的新型合金的电弧增材制造（WAAM）极具挑战性。在这项研究中，我们发现，AA2196铝锂合金的WAAM过程中，在树枝状晶间的液体中可能会形成大孔隙链。经过T6热处理后，这些孔隙链实际上比沉积时的状态长大，超过50 µm的微孔尺寸从2.8％增加到5.8％，最大尺寸增长到107 µm。使用X射线计算机断层扫描（XCT），我们已经量化了微孔的空间分布与WAAM热变形的关系。发现通过控制应变可以有效地消除沿沉积方向的微孔链。结合42％的热变形和T6热处理，封闭了微孔以及纳米级可以实现T ₁沉淀，屈服拉伸强度（YTS）可以提高199％，极限拉伸强度（UTS）可以提高168％，延伸率可以提高460％，达到372 MPa，分别为439 MPa和6.9％。因此，可以通过施加适当的热变形来消除WAAM过程中的凝固缺陷，这对于具有长凝固范围和高凝固裂纹敏感性的Al-Li合金非常有用。