水冷壁焊口裂纹失效原因分析

Analysis of Failure Causes of Welding Joint Cracks on Water Wall

文章以某国外项目水冷壁焊口裂纹失效案列为依据对试样进行试验分析,确定了裂纹类型为应力主导型延迟裂纹。结合现场实际情况,有针对性地研究焊口对口及打底过程中焊缝的详细受力情况及环境中氢来源的因素,进行试验并分析了焊缝硬度与焊接预热方式之间的关系,间接地证明了稳定的预热温度(比如电加热)可以有效地辅助氢扩散,避免出现应力集中,从而大大降低了焊缝及热影响区硬度。文章通过分析裂纹原因,找出对策并给出了预防建议,用于指导现场施工,取得了良好的效果。

Based on the failure case of a welded joint of a foreign project,the test analysis of the sample is carried out,and the crack type is determined to be the stress-dominant delayed crack.Combining with the actual situation on site,research the detailed stress of the weld joint and the welding seam during the bottoming process and the factors of the hydrogen source in the environment,conduct experiments and analyze the relationship between the welding seam hardness and the welding preheating method,Indirectly proves that a stable preheating temperature(such as electric heating)can effectively assist the diffusion of hydrogen,avoid stress concentration,and greatly reduce the hardness of the weld and the heat-affected zone.The article analyzes the causes of cracks,finds out countermeasures and gives preventive suggestions,which are used to guide on-site construction,and good results have been achieved.