Friction Stir Welding vs. TIG-Assisted FSW: Which Method Creates Stronger Copper Joints?

Friction Stir Welding (FSW) is a solid-state joining process that uses frictional heat and plastic deformation. A non-consumable rotating tool is plunged into the material and moved along the joint line, generating heat. This softens the material, allowing it to be mixed and forged together behind the tool, creating a solid-state weld. It's important because, unlike fusion welding, it joins metals at a molecular level without melting, making it suitable for materials like copper with high thermal conductivity. The implications are stronger, more durable joints, and the ability to weld materials that are difficult to join using traditional methods.

Tungsten Inert Gas (TIG)-assisted Friction Stir Welding (FSW) is a variation of FSW that incorporates a TIG torch. This hybrid approach introduces additional heat, aiming to increase welding speed and reduce tool wear. The significance lies in its potential to improve production efficiency. The implications involve a trade-off; while TIG-assisted FSW can increase welding speed and reduce tool wear, it may compromise the microhardness of the copper joint, a key indicator of its overall mechanical performance.

The microhardness of a welded joint is a measure of its resistance to localized plastic deformation. It reflects changes in the material's microstructure, grain size, and precipitation state, all of which are affected by the welding process. In this context, it's a key indicator of the overall mechanical performance of the weld. Higher microhardness generally indicates a stronger joint. The implications of microhardness values inform the choice of welding method and the suitability of the joint for specific applications. The study found that FSW resulted in higher microhardness values in the experiment.

Copper's high thermal conductivity, at least ten times greater than most steel alloys, presents challenges to welding. It rapidly dissipates heat, making conventional fusion welding difficult. Lower-temperature processes are preferred as a solution. FSW is a viable method as it joins metals at a molecular level without melting. The implications of this property impact the choice of welding methods, favoring techniques like FSW that mitigate heat-related issues to produce strong joints in copper.

The choice between FSW and TIG-assisted FSW depends on the application and the desired balance between production speed and joint strength. The study indicates that while TIG-assisted FSW can increase welding speed, it may compromise the microhardness of the copper joint. Classic FSW resulted in higher microhardness values. Further research into cooling methods during TIG-assisted FSW may help mitigate the reduction in microhardness. This choice has implications for production efficiency, weld strength, and the suitability of the joint for specific applications. For instance, if strength is the priority, standard FSW might be favored, but for faster production, TIG-assisted FSW could be considered, with awareness of potential strength trade-offs.