ISO 5832-1:2024

Overview

ISO 5832-1:2024 - Implants for surgery - Metallic materials - Part 1: Wrought stainless steel specifies the chemical, microstructural and mechanical characteristics, and associated test methods, for wrought austenitic stainless steel used in the manufacture of surgical implants. The alloy corresponds to UNS S31673 (ASTM F138 / F139) and the document applies to raw implant materials (bars, wires, sheet and strip), not finished medical devices.

Key topics and requirements

• Chemical composition: Limits for major elements are specified (examples: C ≤ 0.030%; Si ≤ 0.75%; Mn ≤ 2.0%; Cr 17.0–19.0%; Mo 2.25–3.00%; Ni 13.0–15.0%; N ≤ 0.10%; Cu ≤ 0.50%; Co < 0.10%; Fe balance). The alloy must satisfy the chromium/molybdenum effectiveness index: C = 3.3·w(Mo) + w(Cr) ≥ 26.
• Microstructure: Austenitic grain size shall be no coarser than grade No. 5. The steel must be free from delta ferrite, chi or sigma phases in the fully annealed condition.
• Inclusion cleanliness: Non‑metallic inclusion limits are defined (sulfides, aluminates, silicates, oxides) with specified size/abundance limits; vacuum or electroslag melting may be required to meet cleanliness.
• Mechanical properties: Tensile strength, proof/yield strength and minimum elongation are specified for bars, wires, sheet and strip in annealed, cold‑worked and extra‑hard conditions (e.g., annealed bars Rm 490–690 MPa, Rp0.2 ≥190 MPa, A ≥40%).
• Test methods and sampling: Prescribed test standards are referenced (ISO 377, ISO 404, ISO 439, ISO 629, ISO 643, ISO 671, ISO 4967, ISO 6892‑1, ISO 10714). Gauge length and sampling instructions for tensile tests are defined.
• Notes: Mechanical properties of finished devices can differ from raw material values; the standard focuses on raw material conformity.

Applications

• Material specification for orthopaedic implants, dental implants, trauma devices and other surgical implants where wrought 316L-type stainless steel is used.
• Supplier acceptance criteria for bars, wires, sheet and strip destined for medical device manufacture.
• Basis for material testing and quality control in medical device manufacturing and metallurgical laboratories.

Who uses this standard

• Implant manufacturers and design engineers
• Raw material suppliers and steel mills
• Quality assurance and regulatory teams in medical device companies
• Testing and certification laboratories
• Procurement and conformity assessment bodies

Related standards

• ASTM F138 / F139 (UNS S31673) - closely related specifications for surgical implant stainless steel
• Other parts of the ISO 5832 series covering alternative metallic implant materials

Keywords: ISO 5832-1, wrought stainless steel, surgical implants, UNS S31673, ASTM F138, chemical composition, mechanical properties, microstructure, inclusion content, implant material standards.