某超超临界火电机组热交换器BFe10-1-1白铜管运行4 a （年）后发生泄漏失效。通过宏观观察、化学成分分析、金相检验、断口分析、管子内壁沉积物检验等方法对白铜管的失效原因进行了分析。结果表明：白铜管内壁存在明显的沉积物，沉积物下形成氧浓差腐蚀，导致管子内壁产生点腐蚀；点腐蚀坑区域Cl^-存在对于晶界部位的铁元素产生进一步腐蚀使得富集于晶界处的铁元素不断流失而形成空位，空位的不断形成及合并导致晶间裂纹的萌生，最终导致管子发生晶间腐蚀开裂。

Leakage failure of BFe10-1-1 cupronickel tube of heat exchanger in an ultra supercritical thermal power unit occurred after four years operation. By means of macroscopic observation, chemical composition analysis, metallographic examination, fracture analysis and inner wall sediment test, the failure causes of the cupronickel tube were analyzed. The results show that there were obvious deposits on the inner wall of the cupronickel tube, and oxygen concentration corrosion was formed under the deposits, which resulted in pitting corrosion on the inner wall of the tube. Cl^- in the pitting corrosion pit area further corroded the iron elements at the grain boundary, which makes the iron elements enriched at the grain boundary lost continuously and formed vacancy. The continuous formation and combination of vacancy caused to the initiation of intergranular cracks, which eventually led to intergranular corrosion cracking of the tube.