X80M管线钢双连管预制环焊接头焊接工艺与性能研究
Research on Welding Process and Performance of X80M Pipeline Steel Double-Connected Pipe Prefabricated Circumferential Welding Joint

采用GMAW + SAW焊接工艺和自主研制的移动式自动化预制设备完成了X80M管线钢双连管的预制焊接，总结了焊接操作要点，为下一步现场施工提供指导意见。焊后，对焊接接头焊缝和热影响区组织进行了扫描电镜观察，同时测定了接头拉伸、弯曲、冲击、硬度、CTOD等力学性能。试验结果表明：所采用的焊接装备，可以充分发挥埋弧焊热输入大、焊接效率高的特点，完成双连管的预制焊接工作，该工艺是对长输管道高效焊接的有益探索。焊接接头性能优良，不同焊接位置处性能均匀，满足现行标准要求，但焊缝区粒状贝氏体组织的聚集和内、外埋弧焊道分界线的存在会导致焊缝区韧性下降。
The prefabrication welding of X80M pipeline steel double-connected pipes was completed using GMAW + SAW welding process and self-developed mobile automation prefabrication equipment. The main points of welding operation are summarized to provide guidance for the next field construction. After welding, the microstructure of the weld and heat-affected zone of the welded joint were observed by scanning electron microscopy, and the mechanical properties of the joint, such as tensile, bending, impact, hardness and CTOD were measured. The test results show that the welding equipment adopted can give full play to the characteristics of large heat input and high welding efficiency of submerged arc welding, and complete the pre-welding of double-connected pipes. This process is a beneficial exploration for efficient welding of long-distance pipeline. The welded joint has excellent performance and meets the requirements of current standards. However, the accumulation of granular bainite in the weld zone and the existence of the boundary between the inner and outer submerged arc welds will lead to a decrease in the toughness of the weld zone.