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 rust during 1,000+ autoclave sterilization cycles. Learn more about Sialcraft's certified material specifications.