锅炉水冷壁爆管分析

锅炉水冷壁发生了钝边和无明显塑性变形爆管。通过对失效的锅炉水冷壁管进行宏观检查、化学分析和金相试验以及X射线衍射分析，发现该管向火侧外壁(烟气侧)发生了导致管壁严重减薄的高温硫腐蚀和内壁(水侧)垢下酸性腐蚀，而垢下腐蚀产物为氢原子渗入基体与Fe3C反应生成的CH4，由它引发沿晶微裂纹，最终由氢致裂纹引起管材失效。

FAILURE ANALYSIS OF BOILER WATERWALL TUBE

The boiler waterwall tube failed with thick-lipped rupture which did not exhibit significant ductility. By means of macroscopic inspection, chemical composition analysis, metallgraphic examination and X-ray diffraction, the conclusions were drawn that the failure tube of boiler waterwall had been suffered from fireside high-temperature sulfur corrosion which resulting in tube thickness severely reduction and waterside under-deposited acid corrosion producing atomic hydrogen, some of which caused intergranular microcracks after diffusing into steel and then reacting with Fe_3C in the metal to form CH_4. The mechanism of failure was hydrogen induced cracking.