ISO 4289:2023 PDF

Overview

ISO 4289:2023 - "High velocity oxygen fuel (HVOF) cermet coatings for metallurgical roll components - Guidance with requirements" provides practical recommendations and mandatory requirements for selecting, applying and evaluating HVOF cermet coatings on key metallurgical rollers. The standard covers material selection, surface pre-treatment, HVOF spraying, post‑processing (sealing, heat treatment, balancing) and quality/performance evaluation for four roller types: pot inner (sink/stabilizing) rollers in continuous galvanizing lines (CGL), cold‑rolling process rollers, hot‑rolled straightening rollers and furnace rollers.

Key topics and technical requirements

• Coating selection: Typical HVOF cermet systems include tungsten‑carbide based (WC‑xCo, WC‑xM (NiCr, Co)), chromium‑carbide (CrC‑xNiCr) and high‑temperature MCrAlY + oxides/carbides for furnace applications. The metallic phase fraction (x) is recommended between 10% and 50% by mass.
• Surface pre‑treatment:
  • Remove production residues (e.g., residual zinc on CGL pot rollers) using dilute sulfuric acid (3–7 % mass), immersion 6–72 h, followed by rinsing and drying.
  • Repair/limit defects: shrinkage cavities/pores <0.5 mm; no pits >3 mm after processing.
  • Target substrate roughness: initially <3.2 µm; grind/polish to <0.8 µm prior to blasting. Sandblasting is then used to achieve the roughened profile for adhesion.
• HVOF application: Spraying shall follow ISO 14921 procedures for thermal spraying.
• Post‑process: Seal pores (especially for CGL and furnace rollers) promptly; perform heat treatments and dynamic/static balancing as required. Inspect thickness, roughness, microhardness and bond strength after spraying.
• Performance targets (typical ranges reported):
  • Coating thickness: generally 100–200 µm (application‑dependent)
  • Bond strength: commonly >65–70 MPa
  • Porosity: