The Effect of Surface Treatment on Corrosion Resistance of Austenitic Biomaterial

This paper focuses on the effect of surface treatment (grinding, electrochemical polishing) on the corrosion resistance of AISI 316L, a Cr-Ni-Mo low-carbon austenitic surgical stainless steel, in a physiological solution at the temperature of 37 °C. The influence of a surface defect and of sensitization by heat treatment on the corrosion behaviour of electrochemically polished surface is also studied. The evaluation is based on the results of cyclic potentiodynamic polarization tests and on the microscopic observation of specimen surfaces after performed tests. The analysis of cyclic potentiodynamic curves showed the highest pitting corrosion resistance of electrochemically polished specimens regardless of the previous sensitization. The as-received specimen showed the highest susceptibility to pitting, which was microscopically confirmed. Based on the performed experiments we can conclude that electrochemical polishing is an efficient chemical surface treatment to increase the resistance of AISI 316L to pitting corrosion; the resistance to pitting corrosion of electrochemically polished surface can by markedly decreased by the presence of mechanical defects; the as-received surface and the ground surface showed lower resistance to pitting corrosion than electrochemically polished ones; sensitization induced by heat treatment (700 °C/10 hours) does not decrease resistance to pitting corrosion