Medical stainless selection centres on corrosion resistance, strength, cleanability and sterilisation:

• 316L (1.4404): good corrosion resistance and biocompatibility; used for instrument handles, frames, implant aids and stainless tubing; inclusion content and surface quality matter. • 17-4PH (630): precipitation hardening, tensile strength above 1000 MPa; used for orthopaedic instruments and high-strength parts; apply in the specified condition (H900/H1025). • 420/440C martensitic: high hardness for scalpel blades and scissors; lower corrosion resistance, so rust management is essential.

Key requirements:

1) Cleaning and sterilisation: repeated autoclave cycles require stable material and cleanable surfaces. 2) Surface quality: lower Ra reduces bacterial retention; mirror polishing and passivation are key. 3) Biocompatibility: body-contact parts assessed per ISO 10993. 4) Traceability: heat numbers, material certificates and process records.

Purchasing reminder: do not stop at the grade — specify surface roughness, passivation and cleanliness; medical suppliers usually need ISO 13485.