Overview
ISO 18274:2023 - "Welding consumables - Solid wire electrodes, solid strip electrodes, solid wires and solid rods for fusion welding of nickel and nickel alloys - Classification" - defines a chemical-composition based classification system for nickel-base welding consumables. The standard covers solid wire electrodes, solid strip electrodes, solid wires and solid rods whose nickel content exceeds that of any other element. Its principles can also be applied to metal powders used for cladding, hardfacing and additive manufacturing.
Key topics and technical requirements
- Classification scheme: A two-part symbol:
- product form symbol - S for solid wire/rod/electrode, B for solid strip electrode; and
- chemical symbol - Ni####, a four‑digit numeric code that identifies alloy group and composition (see Table 1).
- Alloy groups (first digit): Numeric indicators identify major alloy families (examples from the standard):
- 1 = nickel‑molybdenum alloys, 2 = no significant alloy addition, 4 = nickel‑copper, 5 = copper + Al/Ti precipitation hardening, 6 = Ni‑Cr with Fe < 25 %, 7 = 6 with Al/Ti hardening, 8 = Ni‑Fe‑Cr with Fe > 25 %, 9 = precipitation‑hardenable alloys.
- Chemical composition rules: Table 1 lists alloy symbols and permitted element ranges (C, Mn, Fe, Si, Cu, Co, Al, Ti, Cr, Nb, Mo, W, others). Notable global limits given in the standard:
- unspecified elements ≤ 0.50 % (mass fraction),
- phosphorus normally ≤ 0.020 % and sulfur ≤ 0.015 % unless stated otherwise,
- up to 1 % of the nickel content may be cobalt (unless otherwise agreed),
- up to 20 % of niobium content can be substituted by tantalum.
- Product variants: Symbols suffixed with “B” indicate more restricted composition ranges (B = narrower tolerances).
- Supporting requirements and clauses: Chemical analysis (Clause 6), mechanical properties of weld metal (Clause 7), rounding, retests, technical delivery conditions and designation (Clauses 8–11) - plus informative annexes on designation, uses and national equivalents (Annexes A–C).
Practical applications and users
ISO 18274:2023 is intended for:
- Welding consumable manufacturers - for product classification, marking and specifications.
- Welding engineers and fabricators - to select appropriate solid electrodes/rods/wires for fusion welding of nickel and nickel alloys.
- Procurement and quality assurance teams - to specify and verify chemical composition and delivery conditions.
- Additive manufacturing, cladding and hardfacing specialists - to adapt the classification principles for metal powders.
- Standards bodies and certifiers - for harmonizing national classifications and testing.
Using ISO 18274 helps ensure consistent material selection, easier supplier communication and traceable classification of nickel welding consumables.
Related standards
Normative references include ISO 544, ISO 14344 and ISO 80000‑1, plus informative Annex C which maps corresponding national classifications and typical weld metal tensile strengths.
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