ISO 15609-4:2009

Overview - ISO 15609-4:2009 (Laser Beam Welding WPS)

ISO 15609-4:2009 defines the required content of a welding procedure specification (WPS) for laser beam welding, including overlay welding. It is part of the ISO 15609 series on specification and qualification of welding procedures for metallic materials. The standard identifies the variables that influence weld quality and properties and sets out the information that must be recorded to make, reproduce and qualify laser welds. It does not apply to other cladding processes (for example, thermal spraying).

Key topics and technical requirements

ISO 15609-4 lists the technical content a WPS must contain. Important topics include:

• Welding process identification (laser beam welding - ISO 4063 process number)
• Manufacturer and WPS traceability (references to WPQR or qualification records)
• Equipment and laser source details, such as:
  • source type (e.g., Nd:YAG, CO2), nominal power, continuous or pulsed mode
  • beam quality parameters (TEM, beam divergence, wavelength, polarization, beam parameter product/BPP)
• Beam delivery and focusing system: transmission method (fiber, mirrors), beam shaping, focal length, focal spot and beam diameter on the workpiece
• Beam and pulse parameters: laser power at the workpiece, peak power, pulse energy, repetition rate, pulse duration and pulse shape, slope up/down (power ramping), oscillation patterns
• Mechanical and process parameters: travel speed, feed rates for filler/wire, working distance, beam orientation and angles, weld position (per ISO 6947)
• Gas and powder handling for overlay welding: plasma suppression, shielding/backing gas flow, carrier gas composition and flow (for powder feeding)
• Parent materials and filler details: material designations, thickness/diameter ranges, cleaning/handling instructions
• Joint design, preparation and fixturing: sketches, tolerances, jigs, backing, tack/cosmetic passes
• Thermal treatments and post‑weld operations: preheat/post‑weld heat treatment temperatures and times, mechanical or chemical finishing
• Examples and annex: model WPS formats and guidance are provided (informative Annex A)

Applications and users

ISO 15609-4 is used to:

• Prepare reproducible, auditable WPS documents for laser beam welding
• Assist welding engineers, procedure writers, quality managers and welding inspectors in ensuring consistency and traceability of laser welding operations
• Support manufacturers in aerospace, automotive, energy, medical devices and high-precision fabrication where laser welding or overlay welding is applied
• Provide a basis for welding procedure qualification and conformity to contractual or regulatory requirements

Related standards

• ISO 15607 (general rules for welding procedure specification series)
• ISO 4063 (welding process nomenclature)
• ISO 6947 (weld working positions)
• ISO 14175 (gases for welding)
• ISO/TR 25901 (welding vocabulary)
• Other parts of ISO 15609 (Parts 1–5 cover arc, gas, electron beam, laser beam, resistance welding)

Keywords: ISO 15609-4:2009, laser beam welding, WPS, welding procedure specification, overlay welding, beam parameters, focal spot, welding qualification.