厚板高强钢Q690E机器人双丝MAG焊工艺研究

发布时间：2018-06-09 15:09

  本文选题：机器人双丝MAG焊 + 低合金高强钢　； 参考：《上海交通大学》2014年硕士论文

【摘要】：随着海洋钻井平台逐步向深海发展，平台用钢的强度等级越来越高、厚度越来越大。而钻井平台桩腿的焊接作为平台建造最为关键的步骤之一，对焊接效率和焊接质量的要求也越来越高。针对我国海洋平台建设起步晚、技术水平相对落后的状况，本文重点研究了自升式钻井平台桩腿用大厚度Q690E低合金高强钢机器人双丝MAG焊接工艺。 本文首先采用ABAQUS有限元分析软件，模拟计算了不同焊丝间距的Q690E双丝焊温度场和焊接接头热循环曲线，并与单丝焊温度场进行对比分析，探索低合金高强钢机器人双丝MAG焊接接头热循环曲线特点，为后续工艺试验提供理论指导。然后通过平板单层单道堆焊试验，以及对焊道截面的宏观分析，探索不同焊接电源模式（脉冲模式和恒压模式）以及焊接速度对机器人双丝MAG焊缝成形的影响。最后结合以上试验结果，对50mm厚的Q690E高强钢进行机器人双丝MAG对接焊工艺试验，通过对焊接接头的力学性能测试、微观组织观察以及冲击断口的扫描电镜照片分析，研究了焊接热输入、焊接规范（大电流高速焊和小电流低速焊）以及保护气体对Q690E机器人双丝MAG焊焊接接头组织性能的影响。 最终研究结果表明： （1）当双丝间距大于20mm时，焊接熔池中部出现缩颈，焊缝中心热循环曲线出现了两个波峰；当双丝间距为25mm时，焊缝区T8/3增大到71.6s，冷却速度降低； （2）在其他焊接条件相同时，两种电源模式所得焊缝的熔深均为4.7mm，但脉冲电源模式下焊缝熔宽为16.0mm，余高为3.5mm，均大于恒压模式下所得焊缝熔宽和余高；随着焊接速度的增大，双丝脉冲MAG焊缝熔深先增大后减小，在焊接速度为9.2mm/s时，焊缝熔深最大，为5.9mm； （3）对于低合金高强钢Q690E的机器人双丝MAG焊接工艺，当焊接电源采用脉冲模式，焊接热输入控制在1.57KJ/mm左右，保护气体为20%CO2+80%Ar的混合气体时，，能够获得满足标准规定、综合力学性能优良的焊接接头，接头强度大于770MPa，-40℃低温冲击功大于69J。
[Abstract]:With the development of offshore drilling platform into the deep sea, the strength and thickness of platform steel are higher and higher. As one of the most critical steps in platform construction, the welding of pile leg of drilling platform requires more and more high welding efficiency and welding quality. In view of the situation that the construction of offshore platforms in China started late and the level of technology was relatively backward, In this paper, the welding process of large thickness Q690E low alloy high strength steel robot dual wire MAG for pile leg of jack-up drilling platform is mainly studied. Firstly, Abaqus finite element analysis software is used in this paper. The temperature field of Q690E double wire welding and the thermal cycle curve of welding joint were simulated and calculated with different wire spacing, and compared with single wire welding temperature field, the characteristics of thermal cycle curve of low alloy high strength steel robot double wire MAG welding joint were explored. To provide theoretical guidance for subsequent process testing. Then, through the single-pass surfacing test and the macroscopic analysis of the welding pass section, the effects of different welding power modes (pulse mode and constant voltage mode) and welding speed on the weld formation of robot double-wire MAG are explored. Finally, combined with the above experimental results, the robot double-wire MAG butt welding process of Q690E high-strength steel with 50mm thickness was tested. The mechanical properties of the welded joints, the microstructure observation and the SEM photos of the impact fracture were analyzed. The effects of welding heat input, welding specifications (high current high speed welding and low current low speed welding) and shielding gas on the microstructure and properties of Q690E robot double wire MAG welding joint were studied. The necking appears in the middle of the weld pool, and two peaks appear in the heat cycle curve of the weld. When the distance between the two wires is 25mm, the T8 / 3 of the weld zone increases to 71.6 s, and the cooling rate decreases, and the cooling rate decreases when the other welding conditions are the same. The weld penetration depth of the two power modes is 4.7 mm, but the weld width is 16.0mm and the residual height is 3.5mm in the pulsed power mode, which is larger than the weld width and the residual height under the constant voltage mode, and with the increase of welding speed, the weld penetration depth of the weld is 4.7mm, but the weld width is 16.0mm and the residual height is 3.5mm. The weld penetration of double wire pulse MAG increases first and then decreases. When the welding speed is 9.2mm/s, the weld penetration is the largest, 5.9 mm; for the robot double wire MAG welding process of low alloy high strength steel Q690E, when the welding power source is pulse mode, When the welding heat input is controlled at about 1.57KJ / mm and the protective gas is 20CO2 80%Ar, the welded joints which meet the standard requirements and have excellent comprehensive mechanical properties can be obtained. The joint strength is greater than 770MPa- 40 鈩

本文编号：2000146