Medical device compliance under EU MDR 2017/745 and US FDA 21 CFR 820 mandates strict metallurgical composition proof. The two primary international standards governing surgical instrument steel are ASTM F899 (US) and ISO 7153-1 (International).
Surgical Stainless Steel Alloy Specification Table
| Steel Alloy Grade | Microstructure Class | Carbon % | Chromium % | Target Hardness (HRc) | Primary Application |
|---|---|---|---|---|---|
| AISI 410 | Martensitic | 0.09% – 0.15% | 11.5% – 13.5% | 40 – 45 HRc | Retractor blades, handles, speculums |
| AISI 420 (J2) | Martensitic | 0.15% – 0.40% | 12.0% – 14.0% | 50 – 54 HRc | Kelly forceps, Mayo scissors, needle holders |
| AISI 440C (J1) | Martensitic | 0.95% – 1.20% | 16.0% – 18.0% | 56 – 60 HRc | Micro-scissors, osteotomes, scalpel blades |
| AISI 316L | Austenitic | 0.03% Max | 16.5% – 18.5% | 25 – 30 HRc (Work Hardened) | Suction cannulas, hollowware, tray wire |
| Tungsten Carbide (TC) | Cermet Insert | Cobalt Matrix | Sintered Carbide | 70+ HRc Equivalent | Needle holder jaw inserts, TC scissors |
Understanding Chemical Passivation (ASTM A967)
Passivation is the chemical process of immersing clean stainless steel in a nitric or citric acid bath. Acid removes free surface iron particles deposited during CNC milling or grinding, promoting the rapid formation of a protective chromium oxide passive film that shields instruments from surface corrosion during repeated autoclave sterilisation. See our material specifications for the grades used across the range, or browse needle holders and haemostatic forceps forged from these steels.