【摘要】 采用平位横向对接方式对Q500qENH桥梁耐候钢进行CO2气体保护焊接试验，利用光学显微镜（optical microscope,OM）观察了焊接接头的金相组织，结合硬度计、拉伸试验机等设备测试了焊接接头的力学性能.通过周浸试验模拟了熔敷金属在工业大气环境下的腐蚀行为，并采用扫描电子显微镜（scanning electron microscope,SEM）和X射线衍射仪（X-ray diffractometer,XRD）表征了锈层的结构和化学成分组成，测定了熔敷金属的腐蚀失重速率.最后，通过电化学测试对带锈试样进行了耐腐蚀性能评价.结果表明，Q500qENH的淬硬倾向小，焊接冷裂纹敏感性低，接头抗拉强度高于650 MPa，且兼具有良好的抗弯曲性能和低温冲击韧性.熔敷金属在周浸腐蚀48 h后的腐蚀产物为α-FeOOH和γ-FeOOH，腐蚀96 h时，锈层中产生大量黑色的Fe₃O₄，随后逐渐减少，锈层物相转化为稳定的胞状α-FeOOH，其结构相对致密，耐腐蚀性能良好；此外，锈层中的Al₂O₃夹杂物和富Si相会引起锈层的疏松、微裂纹和孔洞的产生，从而对锈层的致密性产生不利影响.更多还原

【Abstract】 The CO₂ gas shielded arc welding test of Q500qENH bridge weathering steel was carried out by horizontal transverse butt welding. The metallographic structure of the welded joint was observed by an OM, and the mechanical properties of the welded joint were tested by a hardness tester and tensile testing machine. The corrosion behavior of deposited metal in the industrial atmosphere was simulated through a cyclic immersion test. The structure and chemical composition of the rust layer were characterized by SEM and XRD, respectively. The corrosion weight loss rate of the deposited metal was measured. Finally, the corrosion resistance of the rusted specimen was evaluated by an electrochemical test. The results show that Q500qENH has a low hardening tendency and cold crack sensitivity during welding. The tensile strength of the joint is higher than 650 MPa, and it has good bending resistance and low-temperature impact toughness. The corrosion products at the deposited metal after cyclic immersion in the corrosive solution for 48 h are α-FeOOH and γ-FeOOH. After 96 h of corrosion, a large amount of black Fe₃O₄ is generated in the rust layer, which then gradually decreases. The phase of the rust layer transforms into a stable lamellar α-FeOOH,which has a relatively dense structure and excellent corrosion resistance. In addition, Al₂O₃ inclusions and Si-rich phases in the rust layer will cause the formation of porosity, micro-cracks, and pores in the rust layer, which will adversely affect the compactness of the rust layer.更多还原