Stress Corrosion Cracking Behaviour of Lean-Duplex Stainless Steel Reinforcements in Chloride Contaminated Concrete Pore Solution

摘要

Use of duplex stainless steel reinforcements provides a great advantage for reinforced concretestructures, when it comes to corrosion control. Corrosion chlorides threshold is found to be at leastthree times higher for stainless steel reinforced concrete. In the presence of applied loads orremaining stresses this corrosion chloride threshold can decrease dramatically. In this study,stress corrosion cracking (SCC) susceptibility of stainless steel reinforcements is been studied insimulated concrete pore solution. Life time in service for stainless steel reinforcements is predictedto be twice the value of the carbon steel ones. This work seeks to understand the stress corrosioncracking mechanisms of lean-duplex stainless steel reinforcements exposed to chloridecontaminatedenvironments, where reinforcements become much prone to suffer from pittingcorrosion. Duplex stainless steel (SS) grades are studied, SS2001, SS2304 and SS2205.Corrosion monitoring by electrochemical techniques was performed by cyclic potentiodynamicpolarization (CPP) and electrochemical impedance spectroscopy (EIS). Results showed SCCsusceptibility for SS2001, in high chloride contaminated concrete pore solution, while SS2304 didnot presented pitting after testing. Surface analysis by XPS revealed different composition of thepassive layer for the different duplex stainless steel grades, it was found for SS2001 a lower Crcontent on the passive film.