The ASTM F139 standard was created to unify the production and quality control of wrought stainless steel sheets and strips employed in surgical implantations. It is a chemically identical alloy, UNS S31673, that is manufactured with much stricter guidelines to ensure that it contains a low level of carbon, few inclusions, and is highly resistant to corrosion compared to Type 316 stainless steel. It is composed of 18 percent chromium, 14 percent nickel, and 2.5 percent molybdenum, which offers good pitting and crevice-corrosion protection in chloride and fluid body environments as found in human body fluids. The standard regulates chemical composition, mechanical property, melting practice, surface condition, and testing processes in order to provide biocompatibility. It is utilized in the manufacture of orthopedic components, surgical clips, cardiovascular components, and dental apparatuses in which flexibility, surface finish, and cleanliness are vital.
ASTM F139 Test Method
| Chemical composition analysis | The alloy shall contain 17.0–19.0 % Cr, 13.0–15.0 % Ni, 2.25–3.00 % Mo, with maximum limits of 0.03 % C, 0.025 % P, and 0.010 % S, verified by spectrochemical or wet chemical analysis. |
| Mechanical property verification | Tensile strength to be minimum 860 MPa, yield strength at least 520 MPa, and elongation minimum 40 %. Hardness values shall comply with the limits prescribed for the annealed condition. |
| Corrosion and microstructure evaluation | The microstructure shall be fully austenitic with no carbide precipitation. Corrosion resistance is checked by immersion tests such as those described in ASTM F745 or equivalent. |