New Welding Process Joins High-Strength Metals

by John Kosowatz, Senior Editor, ASME.org

A new VFA welding method may help cars become stronger and lighter.

Connecting the pieces, whether it be for a bridge, boiler or small-scale medical device, is perhaps the most basic part of the manufacturing and construction 

process, and welding is one of the primary methods to do so. But the advent of lighter, high-strength metals used, for example, in automotive manufacturing has made the welder’s job more difficult because high heat and re-solidification can weaken the material along the bond. Now, Ohio State University materials science professor Glenn Daehn and his team believe they’ve devised a solution that joinsthe new materials without melting.

Their system is called vaporized foil actuator welding (VFA), and works using a high-voltage capacitor bank to produce a very short electrical pulse within a thin piece of aluminum foil. The foil vaporizes within microseconds and the resulting hot gas pushes pieces of metal together at very high speed, joining them without melting. The bond is produced by impact so there is not a seam of weakened metal that is the result of melting.

Daehn says his lab works on “mostly developing new processes based on ‘what does the world need?’ Now there is a problem with joining new materials,” and he says VFA can help solve the problem, especially in automotive manufacturing.

“One of the biggest potential applications is in auto body construction,” he says.“Manufacturers use hot stamped steels with remarkable high strength. There are aluminum alloys is door panels. Joining aluminum to steel and aluminum to aluminum are outstanding problems.”

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