600MW机组高温集箱铸造三通焊缝裂纹分析及处理

Analysis and Treatment on Casting Three-way Crack of High Temperature Header in 600MW Thermal Power Unit

针对某火电厂600MW亚临界机组高温集箱铸造三通焊缝熔合线出现表面环向裂纹的问题,从宏观应力、材料特性及化学成分等方面分析裂纹产生的原因,认为裂纹属再热裂纹,由焊缝熔合线处复杂应力释放造成。给出采用合理的焊接及热处理工艺修复上述裂纹缺陷的处理措施,并提出对该类三通焊缝的技术监督及处理建议。

According to the problem of casting three-way weld fusion line circular crack of high temperature header in 600 MW subcritical unit,this paper analyzes the reasons from the aspects of macroscopic stress,material properties and chemical composition,it is finally confirmed that the crack belongs to reheat crack,caused by the release of complex stress at the weld fusion line.In this paper,we provide a reasonable welding and heat treatment measure to repair the above crack defects and put forward related suggestions to prevent above crack defects.