CT110连续油管环焊工艺对焊接接头组织性能的影响

Effect of Girth Welding Process on Microstructure and Properties of CT110 Coiled Tubing Welded Joint

为了确保连续油管现场修复对接焊缝性能,提高连续油管的使用寿命,设计了两种CT110连续油管环焊对接工艺方案,并进行了焊接试验。采用金相组织分析、显微硬度测试、拉伸性能检测及疲劳试验等方法,分析了两种工艺方案下焊接接头的组织与力学性能。结果显示,两种工艺下所焊CT110连续油管焊接接头的焊缝及热影响区粗晶区组织均以铁素体和粒状贝氏体为主,显微硬度及抗拉强度相当,但工艺方案二所焊接头均匀变形能力更强,疲劳寿命相对提高92%。研究表明,采用工艺方案二将盖面层改为两道焊的工艺措施,能够降低因焊接热作用引起的热影响区回复与再结晶程度,提高焊接接头均匀变形能力,从而提高接头抗低周疲劳性能。

In order to ensure the performance of field repair butt weld of coiled tubing and improve the service life of coiled tubing,two kinds of circumferential butt welding process schemes of CT110 coiled tubing were designed,and welding tests were carried out.The microstructure and mechanical properties of the welded joint under the two processes were analyzed by means of metallographic structure analysis,microhardness test,tensile property test and fatigue test.The results show that ferrite and granular bainite are the main microstructure in weld and HAZ of CT110 coiled tubing welded joint under the two processes,and the microhardness and tensile strength are similar.But in the second scheme,the uniform deformation ability of welded joint is stronger,and the fatigue life is increased by 92%.The results show that the recovery and recrystallization degree of HAZ caused by welding heat can be reduced by changing the cover layer into two pass welding in the second scheme.The uniform deformation ability of welded joint is improved,so as to improve the low cycle fatigue resistance of welded joint.