Evaluation of Passivation Process for Stainless Steel Hypotubes Used in Coronary Angioplasty Technique

In the manufacturing of hypotubes for coronary applications, austenitic steels types 304, or 316 L are being used. The process involves bending steel strips into tubes and continuous longitudinal welding tubes. Manufacturing also includes heat treatments stretching operations to achieve an external/internal diameter 0.35/0.23 mm, with a tolerance +/? 0.01 mm. Austenitic sensitive localized corrosion (pitting, crevice, intergranular) that results from various treatments. An extremely important step is cleaning internal external passivation hypotube surface. During patient interventions, there high risk metal cations released in contact human blood. aim this study was evaluate state resistance by using electrochemical methods specific intergranular tests (the Strauss test). There were difficulties passivating assessing phenomena interior Assessments made plotting open circuit potential curves exploring polarization Tafel domain range ?50 mV vs. Ecorr (redox potential) +150 saturated calomel electrode (SCE, reference micro-electrode) both surfaces hypotubes. tested did not exhibit corrosion, as mass losses low and, general, close limit analytical balance. Electrochemical techniques differentiation possible. measured currents order nano–pico amperes, quantities electrical charges consumed micro–nano coulombs.