Multi-index comprehensive evaluation for optimal overlap rate in weaving wire arc additive manufacturing process

Overlap rate significantly influences residual stress distribution, warping deformation and microstructural characteristics in wire arc additive manufacturing (WAAM) process. A thermo-mechanical coupled finite element (FE) model based on the oscillatory deposition method was developed to simulate the additive manufacturing process of single-layer multi-track deposition with different overlap rates. Subsequently, FE simulations and microstructural characterization experiments were combined to investigate the effects of overlap rate on residual stress distribution, warpage deformation, and microstructural evolution. The results showed that increasing overlap rate reduces residual stress, while high sensitivity of material to heat input intensified thermal stress and uneven cooling, resulting in greater warpage deformation of workpiece. Greater heat accumulation in deposition layers resulted in coarser grain structures and thicker deposition layers. However, at a low overlap rate, the columnar grain structure in deposition area was more evenly distributed, while surface flatness was poorer. Finally, the multi-index comprehensive evaluation method was used to assess the optimal overlap rate in the weaving WAAM process. The optimal overlap rate for the material was 30%. This work provides theoretical guidance for the design and optimization of weaving WAAM processes.