Abstract: A surgical implant is disclosed manufactured from cast austenitic stainless steel and cold-forged to a final shape. The endoprosthesis is initially a preform which is cast oversized in shape and dimensions. It is then compressed using the cold-forging process to its final size and shape. Using a cast material as a starting material and then compressing it substantially reduces the porosity of the material and increases its strength compared to a machined product from a wrought material.

Abstract: A surgical implant manufactured from austenitic stainless steel by cold-forging has improved mechanical properties and corrosion fatigue resistance. The grain-size index for the cold-forged 316L stainless steel is increased from an ASTM grain-size index of about 8 to an ASTM grain-size index of about 14 by cold-forging the steel into the desired shape. Further improvement in mechanical properties and corrosion fatigue resistance is obtained by stress relieving the material after cold-forging into the desired configuration. The microstructure of the cold-forged material is characterized by the absence of visible slip planes at 600.times. magnification, in contrast with visible slip planes present in the microstructure of the austenitic stainless steel starting material.

Abstract: A method of chemically polishing medical implants by immersing them in a solution including lactic acid, hydrofluoric acid, and nitric acid to produce smooth, matte finished implants.