By Frank Rovella Maximizing
strength and minimizing weight is a critical design factor that has vexed
engineers throughout the automotive and aerospace industries. Even with the
advancements in material science and the increasing sophistication of FEA and
modeling software, in the end, it always a trade-off between strength and
weight, however, that may all be about to change. In a small shop in the
industrial heart of Austria, a team from Voestalpine AG, one of Europe’s
largest steel manufacturers may have developed a solution. Until now there were not many options for joining dissimilar metals, mechanical fastening, brazing, and friction stir welding were the only available alternatives. The use of fasteners and adhesives has their place but are quite limited when it comes to a high strength joint. The remaining options are friction stir welding and brazing. Brazing isn't technically welding and doesn't offer the same strength characteristics to make it a viable option. Friction stir welding has been in use for some time, but it requires the use of high-pressure clamping and the exertion of heavy forces making it very expensive. It does have advantages in certain scenarios, but it lacks the flexibility to allow widespread deployment. There is also the development of an increasing number of special alloys and heat-treating processes that impart various characteristics. But, in the end, specialized materials and processes equal higher expenditures through limited material production and increased manufacturing costs.
The process that Voestalpine is developing may change all that, although it is still in the early stages of development it shows great promise. Unfortunately, there are very few technical details available, but it is basically MIG welding with special wire, an argon shield, and a zinc coating. There also a number of very critical, precise, and undisclosed parameters that have to be met for the process to be successful. Representatives of Voestalpine state that the weld is so robust that it can even be die-stamped with no effect on weld integrity.
If this new process delivers on its promise, then the economy of scale will take this quickly into the mainstream. The design flexibility it would give engineers would be unprecedented. Imagine the effects on a large structure such as airframe or an automotive chassis. For the automotive and aerospace industries, weight is horsepower, and a tool that would allow for practical welding of dissimilar metals will no doubt have a huge impact. This technology will also affect many other industries as well and could eventually make a significant impact on the cost of many high strength alloys. You'll probably never see one of these for sale at Home Depot, but if you're in the metal fabrication business, then this is certainly a development worth following.
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