Pulse and DC Electropolishing of Stainless Steel for Stents and Other Devices

This paper describes optimized conditions for the electropolishing of austenitic type 304 and 316L stainless steels in commercially-available EPS 4000 solution (based on a mixture of phosphoric and sulfuric acids) for use in cardiac stenting applications. Electropolishing parameters such as electrolyte temperature and concentration, current density, polishing duration, use of pulsed current and ultrasonic agitation have been explored and optimal conditions have been found. Quality of the polishing was determined on the average surface roughness, amount of thickness reduction, and overall surface appearance. Samples polished in an ultrasonic bath with pulsed currents of 50 Hz, and 60degC achieved the lowest surface roughness with little or no evidence of surface defects which were present in other recipes. Similar results were seen in both types 304 and 316L stainless steels