某火电厂多次发生水冷壁管爆管事故。采用宏观观察、化学成分分析、力学性能测试、腐蚀产物分析、扫描电镜分析、金相检验等方法分析了水冷壁管爆管的原因。结果表明:爆管位置均位于水冷壁管迎风面上,钢管内表面均存在腐蚀凹槽,凹槽中存在硬且脆的腐蚀产物,在腐蚀产物中检测出了NaFeO₂,Na₂FeO₂等中间产物,说明水冷壁管爆管的原因为碱腐蚀引起的应力腐蚀开裂。

The water wall tube burst accident occurred many times in a thermal power plant. The reasons for the explosion of water wall tube were analyzed by macroscopic observation, chemical composition analysis, mechanical property testing, corrosion product analysis, scanning electron microscopy analysis and metallographic examination. The results show that the positions of the burst pipes were all located on the windward surface of the water wall tube, and there were corrosion grooves on the inner surface of the steel pipes. There were hard and brittle corrosion products in the grooves, and intermediate products such as NaFeO₂ and Na₂FeO₂ were detected in the corrosion products, indicated that the cause of the burst pipes of the water wall tube was stress corrosion cracking caused by alkali corrosion.