Stress Corrosion Tests for Prestressing Steels—Part 2: Susceptibility of Quenched and Tempered Wires—Influence of Chromium

ABSTRACT Due to the risk of failure in existing prestressed concrete bridges, the assessment of the susceptibility of prestressing steel to hydrogen‐induced stress corrosion cracking will become more important in the future. At present, the used normative ISO 15630‐3 test gives unpersuasive and diverging results using a free corrosion approach for the needed hydrogen charging for stress corrosion cracking initiation. A newly developed test method uses the cathodic polarization to control the supply of electrons for hydrogen charging instead of an uncontrolled and variable supply of electrons by metal dissolution during free corrosion. Experimental data shows a reliable differentiation between highly susceptible known quenched and tempered wires and robust cold‐drawn wires with this new test. A round robin with eight participating testing institutes demonstrated the reproducibility of results testing a cold‐drawn wire batch of St 1470/1670. In contrast to previously reported experience in the literature, the new method ranks the Cr‐alloyed quenched and tempered (“new‐type”) wires as highly‐susceptible as the “old‐type” wires without Cr‐alloy.