New automotive welding technique promises stronger bonds

Engineers at The Ohio State University announced they have developed a new welding technique — called vaporized foil actuator (VFA) welding – that the team says requires 80 percent less energy than spot welding, yet creates bonds that are 50 percent stronger. In addition, the process produces strong bonds between metals that were unacceptably weakened by the melting and re-solidification involved in conventional welding.

“Materials have gotten stronger, but welds haven’t,” said Glenn Daehn, professor of materials science and engineering at Ohio State, who helped create the technique. “We can design metals with intricate microstructures, but we destroy the microstructure when we weld. With our method, materials are shaped and bonded together at the same time, and they actually get stronger.”

Unlike in resistance spot welding, Ohio State’s VFA process doesn’t melt the metal parts. Instead, a high-voltage capacitor bank creates a very short and low-energy electrical pulse inside a piece of aluminum foil. As the foil vaporizes, the resulting plasma mashes the metal pieces together, bonding the atoms of one metal to atoms of the other. Seen under a high-powered microscope, the bond often features wave patterns where veins of both materials wrap around each other.

So far, the engineers have successfully bonded different combinations of copper, aluminum, magnesium, iron, nickel and titanium, as well as commercial steel and aluminum alloys with weld regions that are stronger than the base metals.

Daehn and his team now want to join with manufacturers to further develop the technology, which will be licensed through Ohio State’s Technology Commercialization Office.
www.osu.edu