Friction Stir Welding in Marine and Rail

Marine and rail were FSW’s first production industries — aluminium panels have been stir welded for shipyards since 1997 — and both adopted it for the same reason. Long welds in thin aluminium distort badly under an arc, and straightening flame-cut, MIG-welded panels was a cost nobody could design out. FSW removed the distortion at source.

Where FSW is used today

Prefabricated marine panels

Scandinavian extruders (Sapa, Hydro/Marine Aluminium) pioneered stir-welded aluminium panels supplied flat, to length, ready to install — decks, bulkheads, superstructures and helidecks for fast ferries and offshore vessels. The weld is corrosion-resistant without filler-alloy galvanic mismatch, and the panels arrive needing no straightening.

Rail carbodies

Japanese and European builders moved carbody production from mechanised MIG to FSW from the late 1990s: Hitachi’s double-skin A-train construction, Shinkansen floor panels, Alstom roof and sidewall panels, and current-generation platforms such as Siemens’ Velaro Novo. Double-skin extrusions stir welded into full-length body sections give a straight, dimensionally stable carbody with the crash performance that welded HAZ failures in arc-welded aluminium had put in question.

Interior and equipment hardware

Cooling plates for traction power electronics, battery enclosures for hybrid vessels and trains — shared ground with thermal management and automotive & EV.

Where the research is heading

• Steel shipbuilding and repair. FSW of shipbuilding steels — including portable equipment concepts for afloat repair — to bring the distortion and fatigue benefits proven in aluminium to steel hulls. Tool life and cost per metre remain the gating questions.
• Fatigue design rules and standards. Generating the weld-detail fatigue classes and qualification routes (alongside ISO 25239 and rail welding standards) that let designers take credit for FSW’s superior fatigue performance instead of designing to arc-weld allowables.
• Bigger, thinner, faster. Wider double-skin extrusions, thinner gauges for lightweighting, and higher traverse speeds — pushing panel economics as aluminium price and energy cost pressure grows.
• On-site and robotic welding. Moving FSW from the panel line to the yard and depot: robotic systems for 3D seams, and portable machines for repair joints that today force component removal.