Reason for Cracking of Fillet Weld Between Water Wall and Soot Blower Seal Box in an Ultra-supercritical Boiler
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摘要: 某超超临界锅炉水冷壁D层吹灰器密封盒角焊缝在运行约59 159 h后发生开裂并产生泄漏，采用宏观检查、化学成分检测、显微组织和断口形貌观察、硬度测试、能谱分析等方法分析了该角焊缝的开裂原因。结果表明：角焊缝发生了疲劳断裂。在运行过程中，角焊缝承受着较大的轴向应力，同时角焊缝的焊脚尺寸小于标准要求、焊趾处未圆滑过渡，导致轴向应力增大而萌生裂纹；在锅炉启停、负荷波动过程中，周期性变化的轴向应力促使裂纹扩展而形成疲劳开裂；由于D层温度最高，D层吹灰器密封盒角焊缝最先开裂。Abstract: In an ultra-supercritical boiler, the fillet weld between water wall and soot blower seal box cracked and leaked after 59 159 h service. Reason for cracking of the fillet weld was investigated by macroscopic inspection, chemical composition testing, microstructure and fracture morphology observation, hardness measurement and energy dispersive spectroscopy. The results show that the fillet weld failed by fatigue fracture. The fillet weld was subjected to relatively large axial stresses. The fillet weld leg size was smaller than the standard requirement and the weld toe transition was not smooth, leading to the increase of axial stress, and then cracks initiated. During the process of the boiler start-stop and load fluctuation, the periodical change of axial stresses caused propagation of cracks and formed fatigue cracks. The temperature of the D layer was the highest, resulting in the first cracking of the fillet weld of the D-layer soot blower seal box.
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Keywords:
- water wall /
- seal box /
- fillet weld /
- axial stress /
- fatigue fracture
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[1] 李建锋, 周宏, 吕俊复. 火力发电机组2013年非计划停运统计及分析[J]. 中国电力, 2015, 48(5):1-6. [2] 周昊, 池作和. 根据爆口特征判断爆管原因[J]. 热力发电, 1999(5): 43-45. [3] 范志东, 马翼超, 张志博,等. 超(超)临界锅炉水冷壁管泄漏失效分析[J]. 热加工工艺, 2017(23): 254-258. [4] 李广伟, 孙俊威, 黄启龙. 600 MW对冲燃烧锅炉水冷壁高温腐蚀原因分析及对策[J]. 华电技术, 2016, 38(6):43-46. [5] 李振梁, 江范清, 王曦. 600 MW超临界机组15CrMoG水冷壁管的爆管失效分析[J]. 热加工工艺, 2016(14): 255-256. [6] 李季, 陈志, 唐丽英,等.超超临界二次再热机组高温受热面S30432钢微观组织分析[J]. 热力发电, 2017, 46 (8): 72-76. [7] 国家能源局. 火力发电厂锅炉受热面管监督技术导则: DL/T 939-2016[S]. 北京: 中国电力出版社, 2016. [8] 钟群鹏, 赵子华. 断口学[M]. 北京: 高等教育出版社, 2006. [9] 中国机械工程学会焊接学会. 焊接手册: 第2卷[M]. 北京: 机械工业出版社, 1992: 126-152. [10] MILLS K, DAVIS J R. ASM handbook, volume 12: Fractography[M]. Ohio: ASM International, 1987.
[11] 陈传尧. 疲劳与断裂[M]. 武汉: 华中科技大学出版社, 2002. [12] 张小东. 应力集中对焊接接头疲劳性能影响的有限元分析[D]. 南昌: 华东交通大学, 2012. [13] 王立君, 张彦华. 焊趾应力集中系数的统计特性[J]. 焊接学报, 1992(2): 29-35. [14] 李庆芬. 断裂力学及其工程应用[M]. 哈尔滨: 哈尔滨工程大学出版社, 2007. [15] 施振球, 赵廷元. 动力管道设计手册[M]. 北京: 机械工业出版社, 2006.
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