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2.5万瓩中压汽轮机组叶轮相继发生开裂现象,经过仔细的电子显微镜断口分析和金相显微裂纹的观察,以及断口产物的X光,电子探针等的分析,判断了叶轮的开裂是以应力腐蚀开裂SCC方式扩展的脆性断裂。通过对开裂叶轮上的盐垢成份分析、断面腐蚀产物成份的分析及SCC试验,确定腐蚀因子是蒸汽中的NaOH,证明34CrNi3Mo钢在NaOH溶液中的SCC是属于阳极活性通道溶解型(APC型)的。最后,提出了设计材料热处理和大修的建议。
25000 瓩 medium pressure steam turbine impeller cracking occurred in succession, after careful analysis of electron microscopy and microscopic microscopic cracks, as well as the fracture of the product X-ray, electron probe analysis, to determine the impeller cracking is stress corrosion Cracking SCC Extended brittle fracture. The results showed that the SCC of 34CrNi3Mo steel in NaOH solution belongs to the active channel dissolution type (APC type) through the analysis of the scale components on the split impeller, the analysis of the corrosion products and the SCC test, of. Finally, the proposal of designing materials for heat treatment and overhaul was put forward.