Corrosion Cracking and Hydrogen Embrittlement of Thermally Hardened Reinforcement of Prestressed Reinforced-Concrete Structures

Abstract : Steel samples with the composition C 0.15-0.25, Mn 0.25-1.5, Si 0.67- 1.36% and also some alloys having V 0.12, Al 0.1 and Ti 0.11% have been studied during thermal-mechanical hardening. Testing time ranged 2.5-21 hr. Steel tempered at temperatures lower than annealing had an increased tendency to corrosion cracking. Even at high temperatures (470-600 degrees) it did not acquire satisfactory corrosion stability. All specimens of the thermally hardened steels broke down in brittle pieces without the formation of any visual corrosion products in 40-50 min. when subjected to a H2S saturated aqueous solution at room temperature. High stable cold worked steel specimens were unaffected even after 200 hr in the above solution. The disintegration is due to H embrittlement as shown by cathodic polarization curves.