间隙填充电弧增材制造成形质量及组织性能研究

Forming Quality,Microstructure and Mechanical Properties of Gap-filling Wire and Arc Additive Manufacturing

目的传统多道焊缝搭接模型存在沉积环境不对称、热量累积严重及最终成形质量差的问题,针对以上情况,提出了间隙填充模型,并研究了该模型对成形质量及组织性能的影响。方法以4043铝合金为填充材料,探究了沉积顺序、沉积方向、道间冷却时间及CMT电弧模式对搭接质量的影响。确定了多层多道沉积策略,分别基于间隙填充模型和传统搭接模型进行了长方体式试样的沉积,对比分析了所成形试样的成形质量、微观组织及力学性能。结果当送丝速度为5 m/min、焊接速度为0.6 m/min时,在CMT+P的电弧模式下,采用由内而外的沉积顺序、道间反向的沉积方向及无道间冷却时间的工艺组合所成形试样的搭接质量最佳,所沉积试样的表面不平度低于0.004 mm2。结论由间隙填充模型和传统搭接模型所成形试样的微观组织和力学性能并无明显差异,但基于间隙填充模型的沉积策略所成形的试样的成形质量更好。其顶部微观组织主要由柱状晶组成,底部微观组织以细小的等轴晶为主,中部的热影响区主要为粗大的柱状晶,且晶粒尺寸分布不均匀,而焊缝区主要由细小的等轴晶和柱状晶组成。

The work aims to propose a gap-filling model and study the effects of this model on forming quality,microstruc-ture and mechanical properties to solve the asymmetric deposition environment,severe heat accumulation,and poor forming quality of the traditional multi-bead overlapping model.Here,the effects of deposition sequence,deposition direction,inter-bead cooling time and CMT arc mode on overlapping quality were investigated with 4043 aluminum alloy as filler material.After the multi-layer multi-bead deposition strategy was determined,the rectangular samples were deposited based on the gap-filling model and the traditional overlapping model respectively.The forming quality,microstructure and mechanical properties of the formed samples were compared and analyzed.It was found that when the wire feed speed was 5 m/min and the welding speed was 0.6 m/min,in the arc mode of CMT+P,the samples formed by adopting the process combination of deposition sequence from inside to outside,reverse deposition direction and no inter-bead cooling time achieved the best overlapping quality.The surface unevenness of the deposited sample was less than 0.004 mm2.The results show that there is no obvious difference in the microstructure and mechanical properties of the samples formed by the gap-filling model and the traditional overlapping model, but the formed sample based on the gap-filling model achieves better forming quality. Its top microstructure is mainly composed of columnar grains, and its bottom is dominated by fine equiaxed grains. The heat affected zone in the middle is mainly com-posed of coarse columnar grains with uneven grain size distribution. The weld zone is mainly composed of small equiaxed grains and columnar grains.