Reproducibility of the Corrosion Resistance of UNS S32205 and UNS S32304 Stainless Steel Reinforcing Bars

One strategy to address the 75-year service life requirement of a number of highway bridge design codes is the use of more corrosion-resistant reinforcement. Over the last few decades, many stainless steel grades have become available for reinforcing concrete. Of these, two duplex alloys, UNS S32205 and UNS S32304, have become the preferred choices for major highway structures in North America. The purpose of the present study was to investigate the consistency, or variability, of the corrosion performance of bars of these grades from different steel manufacturers. Metallography, chemical analysis, corrosion resistance, and corrosion product evaluation were used to evaluate the bars. It was found that micropits exist to varying degree in the as-received conditions of these bars and that was the most dominant factor in determining the corrosion performance of the bars.