Friction Stir Welding (FSW) is a solid-state welding process that joins two metal pieces without melting them. This process was invented at The Welding Institute (TWI) in 1991 and has grown in popularity in the past two decades. FSW is being widely used in aerospace, automotive, railway, and shipbuilding industries due to its ability to produce high-quality welds with superior mechanical properties.
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Before delving into FSW, it is essential to differentiate friction stir welding from Friction Welding (FW). Friction Welding is a welding process that utilizes heat generated from rubbing two metal pieces together to produce a bond. FW is an older process than FSW and is mainly used for joining similar metals. In contrast, the stir welding process is designed for joining dissimilar metals.
Friction stir welding is a solid-state joining process that relies on the principle of using a non-consumable rotating tool to generate heat and plastic deformation between two metal plates which are butt-joined together. According to a review of literature by S.P. Songmene and colleagues, "the process involves material being subjected to severe plastic deformation by the rotating tool, leading to creation of a solid-state bond between the two workpieces". This results in a defect-free and uniform weld with excellent mechanical properties. As the friction stir welding tool moves through the joint line, it "stirs" the metal grains, resulting in grain refinement and a homogenous microstructure. The friction stir welding process is highly versatile and can be used to join a wide range of materials, including aluminum, copper, steel, and magnesium alloys. Given the above friction stir welding working principle, friction stir welding is an effective solid-state joining process that produces high-quality welds with excellent strength and durability.
The process of friction stir processing is outlined below:
1. First, two work plates are joined together in a butt joint, with their weldable surfaces touching.
2. A rotating tool pin is then inserted at the interface surfaces, causing the material to be deformed plastically through friction heating. This results in inter-molecular diffusion.
3. The tool moves forward along the joint line, creating a joint behind it.
4. The tool continues to move until the entire weld is complete. Once finished, the tool is removed, leaving a hole in the welding plates. This process is explained further in a friction stir welding video.
One of the significant advantages of FSW is its ability to join dissimilar metals. It can be used to join aluminum, magnesium, and copper alloys, but it is not limited to these metals. Some of the metals and alloys that can be joined using FSW include:
1. Aluminum Alloys – FSW is commonly used to join aluminum alloys like 2024, 6061, and 7075.
2. Magnesium Alloys – FSW is commonly used to join magnesium alloys like AZ31, AZ61, and AZ91.
3. Copper Alloys – FSW is commonly used to join copper alloys like brass and bronze.
FSW has a broad range of applications in various industries. Some of the significant applications include:
1. Friction Stir Welding In Aerospace Applications – Friction stir welding services are being used to manufacture aircraft components like fuel tanks, fuselages, and aerospace panels.
2. Friction Stir Welding In Automotive Industry – FSW is being used to manufacture car parts like engine blocks and suspension components.
3. Friction Stir Welding In Railway Industry – FSW services can manufacture train components like carriages, bogies, and frames.
4. Friction Stir Welding In Shipbuilding Industry – FSW is also being used to manufacture ship components like hulls, decks, and superstructures.
The FSW tool is a crucial component in the FSW process and the corresponding FSW products. Its design affects the quality of the final weld. The FSW tool consists of a cylindrical shoulder and a threaded pin. The shoulder provides heat and pressure to soften the metal, while the pin stirs the material and creates a welded joint.
The tool material is usually made of high-strength materials like tungsten carbide or polycrystalline diamond. The tool is also coated with a layer of wear-resistant material to ensure its longevity.
FSW is a solid-state welding process that produces high-quality welds with superior mechanical properties. It is being used in various industries, including aerospace, automotive, railway, and shipbuilding due to its ability to join dissimilar metals. The FSW process involves 4 stages, and the tool design affects the quality of the final weld. FSW is a cost-effective and efficient welding technique that is rapidly replacing traditional welding processes. As one of the professional friction stir welding suppliers in China, Cheeven provides you with quality friction stir welding solutions. Feel free to contact at any time.
Reference:
Songmene, V. S. P., Siew, W. H., & Tieu, A. K. (2012). Friction stir welding of structural materials: a review. Materials and Design, 34, 1-13. https://doi.org/10.1016/j.matdes.2011.06.051.
