Processing Platinum Enhanced Radiopaque Stainless Steel (PERSS ) for Use as Balloon-Expandable Coronary Stents
SourceA platinum-enhanced variant of UNS S31673 stainless steel has been eveloped for use in fabricating balloon-expandable coronary stents. PERSS® is sufficiently radiopaque to be detected by current radiographic methods and maintains compliance with ASTM requirements. Boston Scientific Corporation/Interventional Technologies (BSC/IVT) has implemented a pilot program for the development of PERSS with the intent of achieving vertical integration of the manufacturing process. PERSS ingots containing 5 wt% platinum were cast by vacuum induction melting, refined by vacuum arc remelting, upset in a forge, then hot and cold-rolled into sheet and foil. The sheet was cold-rolled on a 20-high cluster mill to a foil thickness of less than 0.25 mm (0.01 inches). While the final product otherwise meets the ASTM specification for UNS S31673 alloys, intentional addition of unspecified additional elements precludes its compliance with same.