CREVICE CORROSION BEHAVIORS OF Q235 WELD JOINT

As a candidate package material for high level radiation waste disposal, the crevice corrosion behavior of Q235 low carbon steel weld joint was investigated in a solution simulated to the groundwater in the northwest part of China. The influences of temperature and oxygen content were evaluated. The microstructure of the weld joint was observed by OM, and SEM and surface profile were employed to analyze the crevice corrosion behavior of the weld joint. Open circuit potential of different regions of the weld joint was measured by electrochemical method. Experimental results indicated that the increases of temperature and oxygen content could promote the occurrence of crevice corrosion, and facilitate the corrosion processes both inside and outside the crevice. Fusion zone with a microstructure of clustered ferrite was the most severe corroded area in the weld joint, followed by weld metal, which was characterized by a coarse widmanstaetten structure. The microstructures of base metal and heat affected zone were fine and homogeneous, so these two regions underwent slighter corrosion.