On-site repair of heat exchange tubes with Nd：YAG laser
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摘要: 介绍了可用于受损管件现场修复的内衬管环形Nd：YAG激光深熔焊结构及装置。内衬管设计成内凹状,以减小轴向变形拘束度,降低焊接残余应力,从而降低应力腐蚀倾向。光导纤维将激光导入内衬管内,旋转斜面镜将激光反射到内衬管内壁并产生一深熔环形焊道。熔化金属凝固后将内衬管与外管连接在一起,并防止液体渗入损坏的外管部分。实验结果表明,激光焊母材热影响区晶粒长大较小,激光脉冲峰值影响焊缝连接宽度,而连接宽度影响拉伸剪切强度。焊接接头的拉伸剪切强度约为Inconel600管拉伸强度的62%。Abstract: In the paper,the composition and equipment for on-site repair of damaged tubes by circular Nd：YAG laser deep penetration welding of inner sleeves are introduced.The inner sleeve is designed to be concave to reduce their axial constraints so that the residual stress of the welded part can be reduced and the tendency of stress corrosion can be decreased.Laser light is transmitted into the inner sleeve through an optical fiber,then reflected by a rotating mirror onto the inner wall;finally a circular weld of deep penetration is produced.The melted metal connects the inner sleeve with the outer tube,and prevents liquid seeping to the damaged part of the tube.Experimental results indicate that the grain growth of heat affected zone of parent metal caused by laser welding is small,the connection width is influenced by pulse power and that the tensile shear strength is influenced by pulse power and that the tensile shear strength is influenced by connection width.The tensile shear strength of the welded joint is about 62% of the tensile strength of Inconel 600 tube.
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Keywords:
- Nd：YAG laser /
- pulsed welding /
- heat exchange tube /
- inner sleeve
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