**1. Introduction**

High-velocity impact welding (HVIW) methods are rapidly gaining popularity in joining of similar and dissimilar metals. Compared to conventional fusion-based welding techniques, impact welding is very rapid and could be applied to a wide variety of metals. The primary advantage of impact welding is that metals are joined due to the high impact, thus achieving melting temperatures is not required. Therefore, metals with widely di ffering melting temperatures and mechanical properties can be welded by impact alone, hence, avoiding the formation of brittle intermetallic compounds. During the short impact welding process, and depending on materials, their surface morphologies, and impact angle and velocity, material flow 'waves' that lead to interlocking and bonding may be observed at the impact interface. Depending on the end-use application and dimensions of the impacting metals, various means have been used for impact generation. From larger to smaller scale, the four main impact-driven joining methods are Explosive Welding (EXW), Magnetic Pulse Welding (MPW), Vaporizing Foil Actuator Welding (VFAW), and LIW, named according to their source of impact upon launching a flyer plate towards a target (base) plate. The high-impact pressure loads are generated in EXW, MPW, VFAW, and LIW, respectively, due to explosive detonation, large magnetic

field, high voltage rapid vaporization of a metal foil, and surface ablation of a metal by a focused laser beam.

In the past few decades, both experimental and numerical investigations have been conducted into the aforementioned processes. In previous numerical studies on HVIW of both similar and dissimilar metals, an initial flyer velocity, impact angle, deformed flyer shape (at impact), and corresponding simplified boundary conditions have been assumed. These numerical studies have focused on mimicking the material jetting and morphology of the weld interface. In addition, only two-dimensional simulations of small sections of the entire model have been considered even though the actual dimensions of the flyer and target plates, as well as their boundary conditions, are important to accurately capture the deformed shapes prior to and during impact.

In consideration of the above, we briefly introduce the various HVIW methods and a discussion of related experimental and numerical studies reported in the literature.
