Overview
ISO 25239-2:2020 - Friction stir welding (FSW) - Aluminium - Part 2: Design of weld joints defines the design requirements and documentation needed when specifying friction stir welds in aluminium and aluminium alloys. It sets out what designers and fabricators must record to ensure welds meet intended performance, and clarifies that friction stir spot welding is excluded (see ISO 18785 series).
Keywords: ISO 25239-2:2020, friction stir welding, aluminium, design of weld joints, FSW joint design, DMOS.
Key topics and requirements
- Documentation and traceability
- The welded assembly must be designed in accordance with documented requirements tied to the product’s intended use.
- Essential process controls shall be defined to demonstrate compliance with the welding procedure (DMOS).
- Design data for weld joints
- Covers typical joint types (butt, lap/overlap, T‑joints, corner joints, circumferential butt joints, semi‑overlap).
- Specifies that design must consider material properties of aluminium and its alloys.
- Butt and lap joint specifics
- Essential welding variables are to be defined in the DMOS (see ISO 25239-4 for procedural qualification).
- For overlap (lap) joints, the distance from the tool axis to the plate edge must be specified.
- Highlights FSW asymmetry (advance side vs. retreat side) and its effect on strength; joint orientation and loading must account for this.
- Essential information to specify for each weld
- Base material (alloy, temper, product form), surface condition and coatings, weld position and tool path, finish state, and any post‑weld heat treatment.
- Dimensional and inspection rules
- Drawn dimensions for welded assemblies must represent final dimensions (exclude shrinkage allowances).
- Inspection methods and acceptance criteria must be defined; welds inspected and tested per ISO 25239-5.
- Standardized symbols
Applications and users
- Who uses ISO 25239-2:2020:
- Design engineers and structural designers specifying aluminium FSW joints
- Welding engineers and procedure writers preparing DMOS/WPS for FSW
- Fabricators, quality/control engineers and certifiers verifying weld acceptance
- OEMs in rail, aerospace, marine, automotive, food processing and consumer products using aluminium FSW
- Practical value:
- Ensures consistent weld joint design, reduces risk from asymmetric FSW behavior, and aligns documentation, inspection and procedure qualification.
Related standards
For designers and welding teams working with aluminium FSW, ISO 25239-2:2020 provides the required framework to document, specify and control joint design for reliable, repeatable welds.