This study mainly focused on seeking the causes of cracks in the repair-welded layer of a boiler's water-cooled wall in an actual power plant.The observations and tests employed in the study were macroscopic inspection,non-destruc-tive testing,composition analysis,metallographic analysis,hardness testing,and micro-area energy spectroscopy.It was found high mass fraction of C element in the welded seam metal,resulting in enriching of S and P elements at the grain boundary and the formation of low-melting-point eutectics.This could be attributed to the incomplete polishing of tube surface coating prior to the repair welding process.The low-melting-point eutectics and the high welding thermal stress to-gether led to welding cracks along the grain boundary.
维普
万方数据