Overview
ISO 5832-9:2019 - Implants for surgery: Wrought high nitrogen stainless steel specifies the chemical, microstructural, corrosion and mechanical requirements, and associated test methods, for wrought stainless steel containing 0.25 % to 0.50 % nitrogen used in the manufacture of surgical implants that require high strength and corrosion resistance. This third edition updates previous versions and is part of the ISO 5832 series for metallic implant materials.
Key topics and requirements
- Chemical composition: Defined cast analysis limits for major elements (typical ranges):
- Nitrogen: 0.25 % – 0.50 %
- Chromium: 19.5 % – 22.0 %; Nickel: 9.0 % – 11.0 %
- Molybdenum: 2.0 % – 3.0 %; Niobium: 0.25 % – 0.80 %
- Carbon, silicon, manganese, sulfur, phosphorus and residuals constrained to maximum values.
- Microstructure: Austenitic grain size no coarser than No. 5; absence of delta ferrite, chi and sigma phases; controlled non‑metallic inclusion limits (cleanliness often achieved by electroslag remelting).
- Corrosion resistance: Must pass the Monypenny–Strauss intergranular corrosion test after heat treatment at 675 °C for 1 h, followed by air cooling (per ISO 3651‑2).
- Mechanical properties: Tensile strength, yield/proof strength and elongation specified for bars, wires, rods, sheet and strip across annealed, medium‑hard and hard conditions. Examples:
- Annealed bars (≤80 mm): tensile ≥ 740 MPa, yield ≥ 430 MPa, elongation ≥ 35 %
- Medium‑hard bars (≤20 mm): tensile ≥ 1 000 MPa, yield ≥ 700 MPa, elongation ≥ 20 %
- High‑strength wires/rods: tensile values may reach ~1 800 MPa for small diameters (see standard tables).
- Test methods and sampling: Methods referenced include ISO 377 (sampling), ISO 643 (grain size), ISO 4967 (inclusions), ISO 3651‑2 (intergranular corrosion) and ISO 6892‑1 (tensile testing).
Note: Mechanical properties of finished components can differ from raw-alloy test samples.
Applications
ISO 5832-9:2019 applies to the specification of wrought high‑nitrogen stainless steel for surgical implants where enhanced load-bearing performance and corrosion resistance are critical. Typical users select this material for implants and components that demand high strength and biocompatible corrosion behavior.
Who should use this standard
- Implant manufacturers and material engineers
- Raw‑material suppliers and steel producers
- Quality assurance and testing laboratories
- Regulatory and procurement professionals specifying implant materials
Related standards
Keywords: ISO 5832-9:2019, wrought high nitrogen stainless steel, implants for surgery, surgical implants, corrosion resistance, tensile strength, chemical composition, intergranular corrosion, medical implant materials.
Open preview (PDF)Implants for surgery — Metallic materials — Part 9: Wrought high nitrogen stainless steel