Stress Corrosion Behavior of X65 Steel Welded Joint in Marine Environment

摘要

The short-term stress corrosion cracking (SCC) behavior of X65 pipeline steel welded joints insimulated deep (1000 m) and shallow sea was studied by the immersion of U-shaped bend samples,electrochemistry, and scanning electron microscope observation of fracture surfaces. Results showedthat a crack existed near the fusion line in deep sea, whereas no crack occurred in shallow sea. Tafelslope and corrosion potential of welded joint was low in deep sea environment indicting there excitedhydrogen evolution reactions. Cathodic polarization was controlled by both oxygen reduction andhydrogen evolution reactions in deep sea, but only oxygen reduction reactions in shallow sea. Thesensitivity of the SCC of the welded joint in deep sea was higher than that in shallow sea.