Friction Stir Welding (FSW)
Friction Stir Welding (FSW) generates heat by friction between the high-speed rotating weld head and the workpiece, which softens the weld interface material into a plastic state, and then forms a dense solid phase weld through the stirring and squeezing of the weld head. This process avoids porosity, hot cracks and other defects associated with molten metal, and is particularly suitable for high-quality welding of aluminum alloys, copper alloys and titanium alloys.
In FSW technology, the weld head is the core component that determines the quality of the weld. Not only does it need to remain stable under high temperatures (up to 1000°C), high pressures and intense friction, but it also has to control the material flow to form a defect-free weld precisely. Therefore, the choice of welding head material directly impacts welding efficiency, tool life and production costs. In the face of new energy vehicles, semiconductors, and other high-end manufacturing areas, the welding process has stringent requirements, and cobalt alloy, with its unique performance advantages, is becoming the industry’s first choice.
FSW Welding Tip Material Comparison
Tool steel (e.g. H13, M2):
Tool steel was a commonly used material for FSW weld heads in the early days. It offers some hardness and cost advantages, but its hardness decreases significantly at high temperatures (performance drops above about 600°C), making it suitable only for simple welding scenarios with low loads and short cycle times.
Tungsten Carbide (WC):
Although it has exceptionally high hardness and melting point, it is brittle, difficult to process, prone to fracturing the weld head of complex structures due to stress concentration, and expensive, which limits its large-scale application.
Cobalt Alloys
Cobalt alloys take cobalt as the matrix, and through the addition of chromium, tungsten, carbon and other elements to form a solid solution strengthened and carbide strengthened composite structure, which is a perfect balance of hardness, wear resistance and thermal stability. Cobalt alloy can still maintain high hardness at 1000°C, to meet the heat input requirements of aluminum alloy welding (the melting point of aluminum alloy is about 660°C), to avoid softening and deformation of the tip, and also effectively resist the adhesive wear and corrosion of aluminum chips in the process of welding. The tool’s life span can be increased by 3 to 5 times compared with the tool steel’s, and there is no risk of melting loss in the process of solid state welding. Combined with precision-machined threaded stirring needles or eccentric shoulder structures, it can significantly improve material flow and reduce weld porosity.
Core application scenarios of the cobalt alloy welding head
New Energy Vehicle Manufacturing: Core technology for lightweight welding
In the new energy vehicles (NEV) field, aluminum alloy has become the mainstream material for battery shells and body frames due to its lightweight advantage. The FSW process can realize the connection of thin plate (0.5-5mm) and thick plate (10-20mm) without melting loss, and the cobalt alloy welding head can accurately control the heat input of the welding by the high-temperature-resistant property, avoiding the coarsening of aluminum alloy grain. With its high temperature resistance, the cobalt alloy welding head can precisely control the welding heat input and avoid the loss of strength caused by the coarsening of aluminum alloy grain.
Application example: A head automobile enterprise uses a cobalt alloy welding head to weld the lower shell of the battery pack; the welding efficiency is improved, the life of the individual welding head is improved, and the replacement cost is lower than that of a tool steel welding head.
Semiconductor and precision electronics: micro-scale welding precision revolution
Semiconductor equipment in the ultra-thin aluminum substrate (thickness ≤ 1mm), heat dissipation module welding needs to strictly control the thermal deformation of traditional welding can easily lead to thermal damage to the components. The low coefficient of thermal expansion and stable thermal conductivity of the cobalt alloy welding head can control the welding temperature fluctuation within ±10°C to meet the welding needs of precision electronic devices.
Aluminum Formwork and Aerospace: Efficient Forming of Large Structural Components
The FSW produces weld seams several meters long in a single pass, avoiding the distortion associated with conventional fusion welding in welding aluminum architectural formwork and aerospace thin-walled structural components. The cobalt alloy welding head supports a complex helical stirring needle design, forming a “forged” weld through the three-dimensional flow of the material, with a strength of more than 90% of the base material, significantly improving structural reliability.
How do I customize an efficient FSW weld head?
Depending on the type of material to be welded and the load of the working conditions, the appropriate cobalt alloy composition is selected, with cobalt alloy #3 being the most common.
Three main criteria for selecting a professional manufacturer
R&D capability: Prefer manufacturers with in-house R&D capability for alloy compositions
Customization experience: Provide full-process services from material selection to structural design, support non-standard dimensions
Industry certifications: The Automotive industry needs to be IATF 16949 certified, aerospace needs to comply with AMS 5779 and other standards.
Cobalt Alloy Welding Heads – The Efficiency Revolution in High-End Manufacturing
As the global manufacturing industry is transforming to lightweight and precision, friction stir welding technology has risen from a marginal process to a core manufacturing technology, and cobalt alloy welding heads have been the key driver of this change. Its comprehensive advantages in high temperature stability, wear resistance and process adaptability not only solve the technical bottleneck of traditional welding, but also provide reliable technical support for new energy vehicles, semiconductors and other strategic industries through efficiency improvement and cost optimization.
Contact SYTOP today for a customized FSW welding head solution for your application. Let the excellent performance of cobalt alloys become the core competitiveness of your production line upgrade!
