FCAW-S工艺条件下X80环焊接头性能及安全运行影响因素研究

Study on the Influencing Factors of Performance and Safe Operation of X80 Girth Welding Joint under FCAW-S Welding Process

为了提高油气输送管道工程环焊缝质量,保证高钢级管道建设的安全施工和运营,通过常规性能测试和微测试方法,对X80油气输送管道自保护药芯半自动焊接工艺(FCAW-S)的环焊接头组织和性能进行了研究,并利用数值模拟方法分析了在役管道环焊缝在工作应力、组对应力、土壤约束应力和焊后残余应力共同作用下,不同强度匹配的环焊接头的起裂韧性。研究结果显示,X80管道FCAW-S环焊工艺,焊接热输入量变化较大,对接环焊接头冲击韧性不稳定,存在韧性较低值;FCAW-S环焊接头的根焊强度和硬度远低于管体母材,为整个环焊接头的薄弱环节;热煨弯管-直管连接的环焊接头轴向应力最大;不同缺陷深度和不同强度匹配对裂纹驱动力有显著的影响。研究结果为解决X80管线钢环焊接头FCAW-S焊接工艺的起裂韧性指标问题和缺陷容限提供了技术和理论支持。

In order to improve the quality of girth welding joint of oil and gas pipeline engineering and ensure the safe construction and operation of high-grade pipeline construction,the microstructure and properties of girth weld of X80 oil and gas pipeline with self shielded flux cored semi-automatic welding process(FCAW-S)were studied by conventional performance test and micro test methods.The crack initiation toughness of girth welding joints with different strength matching under the combined action of working stress,group stress,soil restraint stress and residual stress after welding are analyzed by numerical simulation method.The results show that the welding heat input of FCAW-S girth welding process for X80 pipeline changes greatly,and the impact toughness of girth welding joint is unstable with low toughness;the root welding strength and hardness of FCAW-S girth welding joint are far lower than the base metal of pipe body,which is the weak link of the whole girth welding joint;the axial stress of the girth weld joint of hot bend pipe-straight pipe connection is the largest;different defect depth and different strength matching have significant influence on the crack driving force.The research results provide technical and theoretical support for solving the crack initiation toughness index and defect tolerance of FCAW-S welding process of X80 pipeline steel girth welding joint.