Effect of Microstructure on the Stress Corrosion Cracking of X-80 Pipeline Steel in Diluted Sodium Bicarbonate Solutions

An investigation was carried out on the effect of heat treatments on the stress corrosion cracking (SCC) resistance of X-80 pipeline steel in 0.01 M and 0.05 M sodium bicarbonate (NaHCO₃) solutions using the slow strain rate testing (SSRT) technique. The heat treatments were either water-quenched, water-quenched and tempered, water-sprayed, or kept in the as-received condition at room temperature. The results indicate that this steel is highly susceptible to SCC in 0.01 M NaHCO₃ solution. The most susceptible steel was the quenched steel followed by the quenched and tempered steel, whereas the least susceptible was the as-received steel. The cracking mechanism is discussed in terms of the anodic dissolution and film rupture.