电站汽轮机高压缸疏水管焊缝断裂研究
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摘要
对发生断裂的汽轮机高压内缸疏水管角焊缝进行了宏观检查、显微形貌分析、金相组织检验、布氏硬度及显微维氏硬度检查。检验结果表明:疏水管与缸体间的角焊缝根部存在连续未焊透缺陷,焊缝、热影响区的布氏硬度和局部显微硬度偏高,未焊透位置的焊缝形状突变处显微硬度最高,此处为主裂纹的起源位置。疏水管断裂的原因是焊接控制不当,角焊缝根部产生连续未焊透缺陷,导致应力集中,在长期高温环境中,高环向应力作用下,裂纹在未焊透位置的焊缝形状突变处萌生并向外壁和周向延伸扩展,致使接头断裂失效。重视和控制好焊接质量并采取有效措施消除焊接残余应力是避免此类问题的关键。分析结果对电站汽轮机组的安全运行具有重要指导意义。
Macroscopic examination,micro-morphology analysis,metallographic examination,Brinell hardness and micro-Vickers hardness test were carried out for the fillet weld of the steam turbine high pressure inner cylinder drain pipe. The results showed that there were continuous incomplete penetration defects at the root of the fillet weld between the drain tube and the cylinder block,and the Brinell hardness and local microhardness of weld,heat affected zone were high,especially near the fracture surface of weld generally higher,the microhardness at the abrupt change of weld shape in the impermeable position was the highest,where the main crack originated. The reason for the fracture of the drain pipe was the improper welding control,continuous incomplete penetration defects were occurred at the root of fillet weld,which leaded to stress concentration. Under the long-term high temperature environment and high circumferential stress,the crack initiated at the abrupt change of the weld shape in the incomplete penetration position and extended to the outer wall and circumferential direction,resulting in the fracture failure of the joint. Attaching importance to and controlling welding quality and taking effective measures to eliminate welding residual stress was the key to avoid such problems. The analysis results of this paper are of great significance to the safe operation of power station steam turbine.
Macroscopic examination,micro-morphology analysis,metallographic examination,Brinell hardness and micro-Vickers hardness test were carried out for the fillet weld of the steam turbine high pressure inner cylinder drain pipe. The results showed that there were continuous incomplete penetration defects at the root of the fillet weld between the drain tube and the cylinder block,and the Brinell hardness and local microhardness of weld,heat affected zone were high,especially near the fracture surface of weld generally higher,the microhardness at the abrupt change of weld shape in the impermeable position was the highest,where the main crack originated. The reason for the fracture of the drain pipe was the improper welding control,continuous incomplete penetration defects were occurred at the root of fillet weld,which leaded to stress concentration. Under the long-term high temperature environment and high circumferential stress,the crack initiated at the abrupt change of the weld shape in the incomplete penetration position and extended to the outer wall and circumferential direction,resulting in the fracture failure of the joint. Attaching importance to and controlling welding quality and taking effective measures to eliminate welding residual stress was the key to avoid such problems. The analysis results of this paper are of great significance to the safe operation of power station steam turbine.
引文
[1]周春林,于洪.汽轮机主蒸汽疏水管爆管失效分析[J].管道技术与设备,2013(06):20-21.
[2]李建杰,石春生,庾博园,等.汽轮机主蒸汽疏水管裂纹原因分析及处理措施[J].河北电力技术,2013,32(06):50-51.
[3]李彦林.锅炉热管失效分折及预防[M].北京:中国电力出版社,2007.
[4]赵永堂,邱玉堂.火力发电厂金属监督[M].北京:中国电力力出版社,2005.
[5]陈汉明,方可伟.某汽轮机抽汽疏水弯管泄漏失效分析[J].理化检验-物理分册,2015(51):593-595.
[6]周春林,于洪.汽轮机主蒸汽疏水管弯头爆破原因分析[J].河北电力技术,2013,28(01):35-36.
[2]李建杰,石春生,庾博园,等.汽轮机主蒸汽疏水管裂纹原因分析及处理措施[J].河北电力技术,2013,32(06):50-51.
[3]李彦林.锅炉热管失效分折及预防[M].北京:中国电力出版社,2007.
[4]赵永堂,邱玉堂.火力发电厂金属监督[M].北京:中国电力力出版社,2005.
[5]陈汉明,方可伟.某汽轮机抽汽疏水弯管泄漏失效分析[J].理化检验-物理分册,2015(51):593-595.
[6]周春林,于洪.汽轮机主蒸汽疏水管弯头爆破原因分析[J].河北电力技术,2013,28(01):35-36.