High-Velocity Impact Welding Process: A Review

Abstract

High-velocity impact welding is a kind of solid-state welding process that is one of the solutions for the joining of dissimilar materials that avoids intermetallics. Five main methods have been developed to date. These are gas gun welding (GGW), explosive welding (EXW), magnetic pulse welding (MPW), vaporizing foil actuator welding (VFAW), and laser impact welding (LIW). They all share a similar welding mechanism, but they also have different energy sources and different applications. This review mainly focuses on research related to the experimental setups of various welding methods, jet phenomenon, welding interface characteristics, and welding parameters. The introduction states the importance of high-velocity impact welding in the joining of dissimilar materials. The review of experimental setups provides the current situation and limitations of various welding processes. Jet phenomenon, welding interface characteristics, and welding parameters are all related to the welding mechanism. The conclusion and future work are summarized.Various solid-state welding methods have been developed recently, for example, friction stir welding, explosive welding (EXW), friction welding, magnetic pulse welding (MPW), cold welding, ultrasonic welding, roll welding, pressure gas welding, resistance welding, vaporizing foil actuator welding (VFAW), gas gun welding (GGW), and laser impact welding (LIW). Among those solid-state welding methods-GGW, EXW, MPW, VFAW, and LIW-are five kinds of high-velocity impact-welding methods. They shared the same welding mechanism, but have different welding energy sources indicated by their names: high-speed gas [13], explosive [14,15], capacitor bank energy (MPW and VFAW) [16], and laser [17], respectively.High-velocity impact welding is characterized by a low welding temperature and fast welding speed. The process is conducted at room temperature. Furthermore, there is no external heat input during the welding process. Figure 1 is a schematic transient state in the welding process. After the transient force is applied on the external surface of the flyer, the flyer moves toward the target at the velocity of several hundred meters per second [18]. When the flyer collides on the target, a jet is generated at the collision point, which contains contaminants, oxide layers, and a thin layer of metals. As a result, the "clean" metals (no contaminants, oxide layers) are exposed to each other. With the transient force, they are brought within atomic distance, where the atomic bond is formed. This process is usually takes several to dozens of microseconds based on different welding processes. For example, in LIW, it usually takes less than one microsecond. In other high-velocity impact-welding processes, it takes longer than that. Metals 2019, 9, x FOR PEER REVIEW 2 of 19However, Al 7075 alloy is susceptible to hot cracking [8,9], and titanium is chemically active at high temperature [10][11][12]. Zinc-coated steel is an important structural material in automobiles. However, during the fusion-weldin...

A dynamic study of effect of multiple parameters on interface characteristic in double-vertical explosive welding

“…The island region was essentially another form of melting layer. It can be contributed that the higher collision velocity caused more heat, complying with the previous researches [33,34]. In the explosive welding process, due to the violent impact of the flyer plate in a very short time, the whole process can be regarded as an adiabatic process, and a large amount of heat was generated, resulting in the generation of melting layer.…”

Microstructure of the interface zone after explosive welding and further annealing of A1050/Ni201 clads using various joining conditions

“…The most striking difference is related to the amount of melted regions and shape of the waves, which will be discussed later. During the EXW, high velocity impact generates high stress and high energy in the neighborhood of the collision point and causes local melting and plastic deformation of welded alloys [21,22]. Crosland et al [13] indicated that the kinetic energy from explosion is transformed to heat energy, which leads to the local melting at the collision point and crystallization of the intermetallic phases in this region [13].…”

Influence of Surface Preparation on the Interface of Al-Cu Joints Produced by Magnetic Pulse Welding

“…Plastic deformation joining can be categorized as metallurgical and mechanical processes, the former type involves a temperature increase caused by a severe plastic deformation effect, e.g., during the friction welding process, the mechanical type can be achieved without a thermal effect such as riveting. However, there are other techniques such as explosive welding and magnetic pulse welding (MPW), and these processes also involve a high velocity plastic deformation and collision effects [4]. The pressure is provided by an explosive material for the former technique.…”

“…This jet is controlled by the collision angle and must fly away otherwise it is trapped at the collision interfaces. Thus, a clean surface is provided, and virgin metals are contacted under extreme pressure resulting in the formation of atomic bonds of flyer and target [4].…”