Friction Stir Welding of Dissimilar Alloys
Friction Stir Welding: The New Frontier in Welding
In 1991, an elegant new way to weld metals revolutionized the world. The process known as friction stir welding (FSW) moved welding out of the Stone Age and into the technology age, allowing precise, mess-free welding.
Friction stir welding is a solid-state joining process where a rotating and traversing FSW tool generates sufficient frictional heat along a joint between two metals to form a weld. It can be considered a “green” approach to joining since an external heating source is not needed and is more environmentally friendly than other methods since neither a flux nor a shielding gas are required.
There are several strength, speed, consumption, and cost benefits associated with friction stir welding. Many of these advantages are due to the fact that there is no microscopic melting during FSW, so the process is free of problems associated with traditional welding, such as porosity, lack of fusion, and change in material.
In this blog, we will discuss a remarkable benefit also associated with FSW: the ability to weld dissimilar aluminum alloys.
Welding of Dissimilar Alloys
Industries such as aerospace, military, transportation, manufacturing, and cargo ship production have a pressing need for welding dissimilar metals. Welding, instead of riveting, joints can produce significant cost savings while reducing the weight of their vessels or constructions.
However, the welding of dissimilar alloys poses quite a conundrum. The different chemical and physical properties of dissimilar alloys can cause havoc as metals flow into each other during a conventional welding process.
For example, the different melting temperature, thermal conductivity, coefficient of linear expansion, and heat capacity of steel and aluminum causes their joint to be brittle whenever they are fused.
Friction Stir Welding: Easier Welding of Aluminum Alloys
Fortunately, FSW has proven to be an effective way to join similar and dissimilar aluminum alloys. In contrast to traditional fusion welding, FSW is free of the problems associated with fusion welding of dissimilar alloys, like porosity, segregation, and liquation cracking. For these reasons and more, higher joint quality is a characteristic of this approach.
FSW’s ability for welding dissimilar aluminum alloys at an industrial level is aided by being a solid-state welding technique.
The Future of Friction Stir Welding and Dissimilar Alloys
Despite FSW’s success with aluminum, not every combination of metals can currently be welded by FSW, including some aluminum alloys. The formation of intermetallic compounds lowers weld quality.
Monumental efforts in research and development are being applied to the achievement of these FSW goals. This involves a lot of trial and error with spin speed, spin head and pin materials, and joint configurations.
Other options, such as submerged friction stir welding — submerging or having water run over the welding zone — might solve common problems associated with dissimilar welding alloys. The water helps extract heat from the joint, decreasing grain size and increasing tensile strength.
In other research areas, techniques such as friction stir knead welding have been used successfully to weld together very thin aluminum sheets with steel. The distinguishing feature of this variant of FSW is that it does not use the pin portion of the rotating tool.
A Grand Friction Stir Welding Facility
In America, Taber Extrusions added a 60,000 square foot expansion to their facility in Russellville, AR, giving them FSW capabilities. The machine allows for Taber to continue producing their extra wide profiles. Through this addition, Taber can continue to create stronger, environmentally friendly aluminum welds at a much faster speed for clients.
With the promising future of FSW, Taber has established itself as a key-player for futuristic welding.
About Taber Extrusions
Founded in 1973, Taber Extrusions originally pioneered a process for extruding rectangular billet which enables the company to extrude extra-large aluminum extrusion profiles up to 31 inches wide or hollows up to 29 inches. Taber expanded with the purchase of an extrusion facility in Gulfport, MS in 1995 which houses a state-of-the-art cast house and two additional presses, micro-extrusion capabilities, and the fabrication area has been expanded multiple times.
Taber continues to extrude billet in a wide range of alloys and sizes and has diversified its markets beyond military since its inception to include aerospace, automotive, marine, infrastructure, and sporting goods, among many others. With in-house casting solutions, ultra-precision extrusion manufacturing, friction stir welding capacities, and a full range of hard and soft aluminum alloys, Taber continues to align itself as an industry leader in having the broadest available capabilities.
Today, Taber Extrusions is proud of its recently added VF-12 CNC machining line and a full offering of extruded aluminum components, value-added machining services, and raw material supply to the North American market. Adding these capabilities to a growing portfolio propels Taber into the future in a quest to continuously improve the quality and service we provide to our customers.
Thank you for your continued support of Taber Extrusions, LLC. If you have any questions, please visit taberextrusions.com or contact one of Taber’s regional sales managers.
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