Surgical stainless steel
Surgical stainless steel is an informal term which refers to certain grades of stainless steel that are used in biomedical applications. The most common "surgical steels" are austenitic 316 stainless and martensitic 440 and 420 stainless steels. There is no formal definition on what contitutes a "surgical stainless steel", so product manufacturers and distributors apply the term to refer to any grade of corrosion resistant steel.
316 stainless steel, also referred to as marine grade stainless steel, is a chromium, nickel, molybdenum alloy of steel that exhibits relatively good strength and corrosion resistance. Along with the titanium alloy Ti6Al4V, 316 stainless is a common choice of material for biomedical implants. Although Ti6Al4V provides greater strength per weight and corrosion resistance, 316 stainless components can be more economical to produce. However, immune system reaction to nickel is a potential complication of 316. Implants and equipment that are put under pressure (bone fixation screws, prostheses, body piercing jewelry) are made out of austenitic steel, often 316L and 316LVM compliant to ASTM F138,. 316 surgical steel is used in the manufacture and handling of food and pharmaceutical products where it is often required in order to minimize metallic contamination. ASTM F138-compliant steel is also used in the manufacture of body piercing jewellery and body modification implants.
440 and 420 stainless steels, known also by the name "Cutlery Stainless Steel", are high carbon steels alloyed with chromium. They have very good corrosion resistance compared to other cutlery steels, but their corrosion resistance is inferior to 316 stainless. Biomedical cutting instruments are often made from 440 or 420 stainless due to its high hardness coupled with acceptable corrosion resistance. This type of stainless steel may be a touch magnet.
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- Thomas, P.; Thomsen, M. (2010). "Implantatallergien" [Implant allergies]. Der Hautarzt (in German). 61 (3): 255–62; quiz 263–4. doi:10.1007/s00105-009-1907-x. PMID 20204719.
- ASTM F138 standard
- Association of Professional Piercers official standards for body jewelry