Stress corrosion cracking behavior of welding joint of high strength steel

Nowadays, high-strength steel structures are increasingly being used in marine or soil environments, but low attention has been paid on the corrosion and stress corrosion cracking problem. In this paper, the susceptibility to stress corrosion cracking (SCC) of butt-welding joints of Strenx (R) 700 (S690QL high strength steel) both in marine and acid-polluted marine atmospheres was studied, by using slow strain rate tensile (SSRT) test. The seawater corrosion environment was considered and it was prepared following the ASTM D1141. To study the influence of the environment pH, NaOH 0,1M solutions and pure H2SO4 were used to adjust the pH of the simulated seawater solution to 8 and 4, respectively. The slow strain rate tensile tests (SSRT) with a crosshead speed of 0.000017 mm/s were carried out at room temperature (approximately 25 degrees C). After failure, the SCC susceptibility was evaluated acquiring the elongation loss rate and the reduction-in-area loss rate. The fracture surfaces were analyzed by SEM observation.