Friction stir welding (FSW) is a welding method devised by The Welding Institute Ltd. in the year 1991. Despite the fact that it was developed more than 25 years ago, it has seen a quick increase in demand in the past few years, specifically due to the increase in the demand for higher strength and durability requirements in modern engineering applications.
It is a unique method of combining metals with each other, which is largely different from conventional methods such as gas welding or arc welding. The fact that it is a solid-state welding technique makes it unique, suggesting that neither of the materials being combined are melted.
Rather, they are simply softened to an extent that they can penetrate each other’s surface with a little help. This method produced exceptional mechanical properties such as fatigue strength and stiffness, as well as negligible defects in the weld region. Furthermore, this welding technique also reduces the wastage of materials and ensures an enhanced appearance, indicating lower surface finishing requirements. Lastly, one of the most lauded benefits is that it does not have any harmful effects on the environment since toxic fumes are not produced in the complete process.
Recently, SpaceX—the aerospace manufacturing company led by Elon Musk—has launched its Falcon Heavy rocket into space with a Tesla Roadster as the payload, which is the fourth-highest of all rockets developed to date with respect to the load-carrying capacity, featuring the use of friction stir welding. This aspect underscores FSW’s significance in the aerospace industry and its probable application in future engineering applications.
SpaceX design engineers employed FSW to connect the break-off fuel tanks in their rocket, which have a vital role in the propelling of the spacecraft after it enters space and settles in its orbit. The reason for this application was evidently the requirement of remarkable strength in break-off fuel tanks of such a powerful rocket, which cannot be fulfilled by traditional methods such as liquid-state welding or non-permanent joints like rivets.