摘要
为了确保发电设备的安全运行,预防因水冷壁管泄露事故造成发电企业非计划停运,通过宏观检查、显微组织分析、硬度试验、化学成分分析、扫描电镜能谱分析和断口分析,对电站锅炉15Cr Mo钢水冷壁管横向裂纹的成因进行了分析研究.研究结果表明:15Cr Mo钢水冷壁管弯管工艺不合理引起弯管段部分表面产生微裂纹,这种微裂纹在交变热应力作用下从表面向内部扩展成热疲劳横向裂纹.锅炉启停导致弯管永久变形产生的残余拉应力通过降低材料的疲劳极限加速了热疲劳裂纹的扩展;燃烧带来的腐蚀性烟气和裂纹内的管材发生氧化腐蚀反应,这样的腐蚀作用对热疲劳裂纹的延伸起到了推动作用.
Transverse crack on 15 Cr Mo water cooling tube of a power plant was studied by means of observing macrostruacture,microstructure analysis,hardness testing,scanning electron microscopy（ SEM）,energy dispersive spectroscopy（ EDS） and fracture analysis to ensure safe operation of power equipment and regular working of power generation enterprises. The results show that the microcracks on the surface of the elbow,caused by unreasonable bending process of 15 Cr Mo water cooling tube,expand into the thermal fatigue transverse cracks under the action of alternating thermal stress. The corrosive flue gas formed by the combustion accelerates the expansion of the thermal fatigue crack by etching the cracked area. The residual tensile stress formed by the boiler＇s start and stop also accelerates the expansion of the thermal fatigue crack by reducing the fatigue limit of the material.
作者
户如意
陈建
要玉宏
金耀华
HU Ruyi;CHEN J ian;YAO Yuhong;J IN Yaohua(School of Materials and Chemical Engineering, Xi ＇ an Technological University, Xi ＇ an 710021, China)
出处
《西安工业大学学报》
CAS
2018年第2期121-126,共6页
Journal of Xi’an Technological University
基金
国家自然科学基金(51571155
51671150)
陕西省重点科技项目(2012K07-08)
关键词
水冷壁管
横向裂纹
热疲劳
腐蚀性烟气
water cooling tube
transverse cracks
thermal fatigue
corrosion flue gas
