Revisiting fundamental welding concepts to improve additive manufacturing: From theory to practice

Additive manufacturing has revolutionized the manufacturing paradigm in recent years due to the possibility of creating complex shaped three-dimensional parts which can be difficult or impossible to obtain by conventional manufacturing processes. Among the different additive manufacturing techniques, wire and arc additive manufacturing (WAAM) is suitable to produce large metallic parts owing to the high deposition rates achieved, which are significantly larger than powder-bed techniques, for example. The interest in WAAM is steadily increasing, and consequently, significant research efforts are underway. This review paper aims to provide an overview of the most significant achievements in WAAM, highlighting process developments and variants to control the microstructure, mechanical properties, and defect generation in the as-built parts; the most relevant engineering materials used; the main deposition strategies adopted to minimize residual stresses and the effect of post-processing heat treatments to improve the mechanical properties of the parts. An important aspect that still hinders this technology is certification and nondestructive testing of the parts, and this is discussed. Finally, a general perspective of future advancements is presented.

Current Status and Perspectives on Wire and Arc Additive Manufacturing (WAAM)

Wire and arc additive manufacturing : Opportunities and challenges to control the quality and accuracy of manufactured parts

A study on V-groove GMAW for various welding positions

Effect of TIG current on microstructural and mechanical properties of 6061-T6 aluminium alloy joints by TIG–CMT hybrid welding

Influence of the external magnetic field on fluid flow, temperature profile and humping bead in high speed gas metal arc welding

Backward flowing molten metal in weld pool and its influence on humping bead in high-speed GMAW

A comparison of TIG-MIG hybrid welding with conventional MIG welding in the behaviors of arc, droplet and weld pool

A 3D model is developed to perform numerical investigation on the coupled interaction mechanism of the plasma arc, weld pool and keyhole in plasma arc welding. By considering the traveling of the plasma arc along the welding direction, unified governing equations are solved in the whole domain including the torch, plasma arc, keyhole, weld pool and workpiece, which involves different physical mechanisms in different zones. The local thermodynamic equilibrium-diffusion approximation is used to treat the interface between the plasma arc and weld pool, and the volume-of-fluid method is used to track the evolution of the keyhole wall. The interaction effects between the plasma arc, keyhole and weld pool as well as the heat, mass and pressure transport phenomena in the whole welding domain are quantitatively simulated. It is found that when the torch is moving along the joint line, the axis of the keyhole channel tilts backward, and the envelope of molten metal surrounding the keyhole wall inside the weld pool is unsymmetrical relative to the keyhole channel. The plasma arc welding tests are conducted, and the predicted keyhole dimensions and the fusion zone shape are in agreement with the experimentally measured results.

https://iopscience.iop.org/article/10.1088/0022-3727/48/46/465504/pdf

Ji Chen

Papers

Influence of the external magnetic field on fluid flow, temperature profile and humping bead in high speed gas metal arc welding

Backward flowing molten metal in weld pool and its influence on humping bead in high-speed GMAW

A comparison of TIG-MIG hybrid welding with conventional MIG welding in the behaviors of arc, droplet and weld pool

A unified 3D model for an interaction mechanism of the plasma arc, weld pool and keyhole in plasma arc welding

Influence of low current auxiliary TIG arc on high speed TIG-MIG hybrid welding