Vaporizing Metal Foil Explosion Welding
T2012-121 A novel method that uses electrically vaporizing conductors to achieve explosion welding safely, efficiently, and in a factory environment.
Explosion welding (EXW) is a solid-phase process where welding is accomplished by accelerating one of the components at extremely high velocity through towards the other. Explosion welding can produce a bond between two dissimilar metals that typically cannot be welded together by other conventional means. The process does not melt either metal, but instead plasticizes the surfaces causing them contact sufficiently to create a weld. This is a similar principle to other non-fusion welding techniques, such as friction welding. Large areas can be bonded extremely quickly and the weld itself is very clean, however, the process has disadvantages related to knowledge of the explosives used and regulations. Although a key advantage is that explosion welding can join a wide array of compatible and non-compatible metals.
Researchers at The Ohio State University, led by Dr. Glenn Daehn, have developed a novel variation of explosion welding by electrically vaporizing thin metallic foils that causes a rapid phase change creating high pressure around the vaporizing conductor. This process drives one metallic plate towards another at high speed and welds the materials together to form a joined part. This results in an uncontaminated metal surface weld that forms an atomic bond on contact; wavy interfaces, typically observed in traditional explosion welds (EXW), are attained.
More descriptive, this method for forming a piece of a sheet metal is performed by positioning a consumable body (foil), made of metal, proximate to a piece of the sheet metal. The consumable body is rapidly vaporized, accomplished by passing by a high electrical current through the foil, and the gas pressure generated thereby is directed into the piece of the sheet metal. This results in acceleration of the piece of sheet metal, and it collides into a stationary body at a velocity, generally in excess of 200 m/s. Depending upon the type of stationary body, the piece of sheet metal is deformed into a predetermined shape or is welded onto the stationary body. The effect of the vaporized metal may be augmented by additional components in the consumable body.
- Unlike EXW, couples, such as Al-Cu, Al-Mg, Cu-Ti, Cu-Fe, Ti-Fe, have been welded in limited laboratory/industrial spaces.
- Flyer material does not have to be to be electrically conductive, which is a requirement for magnetic pulse welding.
- Use of aluminum foils as actuators and other robust parts of the device reduces costs.
- Weld regions can be made stronger than parent materials.
- Fewer safety standard concerns and significantly reduces energy consumption.