Corrosion resistance of stainless-steel surgical tools in enzymatic and alkaline detergent

Metallic surgical instruments are subject to corrosion, which can be accelerated when there is an attack on the passive layer formed on the stainless-steel surfaces. Corrosion can create defects on the metal surface, which can retain residues and promote microbiological growth, leading to infections in surgeries and contamination of medical devices. Since these applications require a high degree of cleaning and sterilization, such items undergo recurrent cleaning cycles using water and detergents. This study aims to test two types of detergents, alkaline and enzymatic, comparing their effects on corrosion resistance of AISI 304 L, 316 L and 420 stainless steels (SS), commonly used in surgical instruments. The electrochemical impedance spectroscopy, and cyclic polarization tests were used to evaluate the corrosion resistance of stainless steels in detergents. Scanning electron microscopy was used to study the morphology of the steel surfaces after corrosion tests. The AISI 304 L steel showed the highest corrosion resistance in the enzymatic medium among the three stainless steels tested. The AISI 316 L stainless steel had an intermediate behavior in enzymatic medium, and lower impedance when immersed in alkaline detergent, while the AISI 420 steel showed deeper corrosion marks on its surface in alkaline medium when compared to the enzymatic solution. The enzymatic detergent is the less aggressive medium to the steels, and the AISI 304 L SS was the most corrosion resistant in alkaline and enzymatic detergents.