Multifunktionell skrov-demonstrator

The research team that tested friction stir welding for Saab’s applications.

Friction Stir Welding (FSW) is a sustainable joining process that uses frictional heat and mechanical pressure to weld materials without melting them, reducing energy consumption compared to conventional fusion welding. As it doesn't require filler materials or produce harmful emissions, it minimizes waste and environmental impact. FSW also improves material strength and durability, enhancing product lifespan and reducing the need for repairs or replacements. Its low energy use and minimal environmental footprint make it an eco-friendly choice for industries like aerospace, automotive, and shipbuilding.

In aerospace, where materials like series 2xxx and 7xxx Al alloys are preferred for their high strength-to-weight ratios but present challenges with traditional fusion welding due to alloy element volatility and resulting defects, FSW provides a viable solution by enabling the welding of dissimilar alloys. It makes ideal for replacing rivets in lap joints to construct lightweight structures in aerospace.

This study, conducted in collaboration with Saab under IntDemo-Flygplan project, focused on evaluating the feasibility and performance of FSW Al alloy joints.

Three key experiments were conducted:

• Firstly, FSW of both similar (7475-T761 to 7475-T761) and dissimilar (2024-T3 to 7475-T761) Al alloy lap joints, which were subjected to tensile and fatigue testing.
• Secondly, the FSW of anodized dissimilar Al alloy T joints was examined.
• Thirdly, the FSW of non-anodized dissimilar Al alloy T joints with a sealant applied between sheets. The welds were analysed for microstructures, hardness and strength analysis.

IntDemo stands for Internationellt flygtekniskt demonstratorprogram för ökad konkurrenskraft, miljöanpassning och flygsäkerhet.

Learn more about the Vinnova-funded project led by Saab's business area Aeronautics between 2020 and 2024: https://www.vinnova.se/p/intdemo-flygplan/