Overview - ISO 14920:2023 (Thermal spraying of self-fluxing alloys)
ISO 14920:2023 specifies the procedures for thermal spraying of self-fluxing alloys that are either fused simultaneously during spraying or fused subsequently to produce a homogeneous, diffusion-bonded fused coating. The third edition (2023) updates materials allowed for fusing, defines grit blasting media, and clarifies spray methods affecting coating quality. This standard guides process control, surface preparation, spraying/fusing sequences and inspection criteria for durable metallurgical coatings.
Key topics and technical requirements
- Scope and process types: Defines both simultaneous fusion and subsequent fusion spray-fuse processes and their procedural differences (preheating, spraying, fusing, cooling).
- Substrate influence and design: Highlights heat transfer effects (scaling, stress relief, irreversible metallurgical changes). Notes that austenitic steels can be fused without structural transformation; other base metals must have melting points well over 1 200 °C. Empirical alloying limits for ferritic steels are given (C ≤ 0.5%, Cr ≤ 5%, Ni ≤ 4%, W ≤ 3%, Mo ≤ 3%).
- Spray material selection & composition: Coating performance-hardness, wear/corrosion resistance, machinability-depends on powder chemistry and particle size ranges referenced in the standard.
- Surface preparation: Requires cleanliness, removal of prior treatments, and grit blasting per EN 13507 and ISO 11124‑1 / ISO 11126‑1. Preferred abrasives: sharp-edged steel grit or chilled iron. Ceramic grit can become embedded and produce porosity during fusing.
- Masking and plugs: Guidance on masking to protect adjacent surfaces and on plug materials (steel/rubber/carbon) for holes and orifices.
- Process control and inspection: Preheating, spray technique, fusing, cooling, final machining and hardness testing (reference values in Annex A) are specified to ensure metallurgical bonding and expected coating properties.
Practical applications
ISO 14920 is applicable for repair and protective coatings where diffusion-bonded, fused layers are required, including:
- Wear- and corrosion-resistant overlays on shafts, valves, dies and tooling
- Remanufacturing and restoration of worn components
- Industrial components in power generation, oil & gas, mining, automotive and aerospace where long-life surface protection is required
- Thermal spray operators and process engineers
- Coating and metallurgical engineers
- Maintenance, refurbishment and remanufacturing specialists
- OEMs, quality and inspection personnel setting acceptance criteria
Related standards
- EN 13507 (Pre‑treatment of surfaces for thermal spraying)
- ISO 11124‑1 / ISO 11126‑1 (Grit blasting / abrasive materials)
Keywords: ISO 14920, thermal spraying, self‑fluxing alloys, spray and fuse, fused coating, surface preparation, grit blasting, coating hardness.
