Roberto Moreira Schroeder

Stress corrosion cracking and hydrogen embrittlement susceptibility of an eutectoid steel employed in prestressed concrete

The stress corrosion and hydrogen embrittlement behavior of AISI 1080 steel employed in concrete prestressing tendons was studied with different experimental techniques. A simulated concrete pore solution, with and without contaminants such as chloride, sulfate and thiocyanate ions was used. For comparison purposes the standard 20% ammonium thiocyanate solution was also employed. Polarization curves, slow strain rate tests and fracture mechanics tests were used to evaluate the influence of parameters such as potential, temperature (between 0 and 100 °C), and tempering temperature of the steel. The results have shown that the fracture mechanism of the stress corrosion cracking process is associated with hydrogen action.

The characterization of the sulphide stress-corrosion susceptibility of high-strength low-alloy steels in standardized solutions

Abstract Medium and high-strength steels with yield strengths from 390 to 870 MPa were tested by constant elongation-rate tests in two solutions: acidified chloride solution saturated with H 2 S, pH 3.5–3.8 (NACE standard TM-01/77-86) and H 2 S-saturated artificial sea water, pH 5 (NACE standard TM-02/84). All steels exhibited some degradation of mechanical properties (elongation, ultimate tensile strength), in both solutions, at corrosion potentials and at 50 mV above and below it. Increasing deterioration was observed in a sequence which demonstrated that hydrogen embrittlement did not have the same importance in both solutions. The influence of spheroidization of inclusions in welded specimens could only be detected in the pH 5 sea water solution.

Temperature influence on SCC behaviour of duplex stainless steel

Some studies have related damages in duplex stainless steel (DSS) structures due to stress corrosion cracking (SCC), however, different mechanisms are observed depending of the electrolyte, temperature, electrochemical potential and steel composition. Wherefore, the SCC mechanisms of the AISI 318 DSS in a 115 000 ppm of chloride solution at 25 and 70°C were investigated. The results showed that the SCC cracks propagated in both phases, ferrite and austenite. A reduction in elongation was observed at anodic potentials caused by electrochemical dissolution and at cathodic potentials below −650 mVECS at 70°C and −750 mVECS at 25°C related to SCC mechanism. Accordingly, the more susceptible and protective potentials were determined for DSS in both temperatures.