X80管线钢环焊缝气体保护焊焊丝的研制

Research on Gas-shielded Welding Wire of Circumferential Weld for X80 Pipeline Steel

针对X80管线钢的组织与性能特点,研究设计了适用于管线钢现场焊接用Mn-Ni-Mo-Ti合金系气体保护焊焊丝;测试了焊缝金属的化学成分、金相组织、冲击韧性、抗拉强度和硬度。该焊丝的熔敷金属屈服强度600 MPa,抗拉强度645 MPa,-30℃夏比冲击功105 J。该焊丝用于X80管线钢现场焊接结果表明,焊缝抗拉强度645 MPa,-10℃夏比冲击功平均值145 J,焊缝具有很好的强韧性匹配。采用金相显微镜和SEM对使用该焊丝焊缝微观组织和断口形貌分析表明,焊缝金相组织主要为针状铁素体、少量的先共析铁素体和粒状贝氏体的组织,断口为韧窝状,呈现典型的塑性断裂特征。

According to the characteristics of the microstructure and properties of X80 pipeline steel, the Mn-Ni-Mo-Ti alloy gas-shielded welding wire was successfully designed and developed for site welding. The chemical composition, metalhn＇gical structure, impact toughness, tensile strength and hardness nfthe weld metal were tested. The yield strength of deposited metal of the welding wire was 600 MPa, tensile strength was 645 MPa, and Charpy impact energy（-30 ℃） was 105 J. The site welding result of X80 pipeline steel showed that the weht was with perfect strength and toughness matching, when the tensile strength of weld was 645 MPa, the average value of Charpy impact energy （-10℃） was t 45 J. The microstructure and fraeture apperance of weld were analyzed by using metallographic microscope and scanning electron microscope（SEM ）,the analysis results indicated that the microstructure of weld mainly are acicular ferrite, a few proeutectoid territe and granular bainite, and the fracture is dimple which presents a typical ductile fracture characteristics.