光纤激光-MAG焊复合机理及成形工艺研究

发布时间：2019-03-23 19:33

【摘要】：随着大厚壁工件的在重型机械、大型钢结构、船舶等的广泛应用,其焊接问题成为研究的热点,激光-MAG复合焊接技术作为高效的焊接新技术受到了人们的重视,可用于解决大厚壁工件的焊接问题。激光-MAG复合焊接过程中激光的引入改变了MAG焊电弧导电机制,电弧等离子体和激光致等离子体能量相互耦合,通过高速摄像可以直接观察电弧形态变化。分别以180A小电流和300A大电流进行光纤激光-MAG复合焊接试验,研究激光对MAG焊不同过渡模式(短路过渡模式、喷射过渡模式)的影响规律,通过高速摄像图像和电信号的采集对激光引入前后电弧形态和熔滴过渡变化规律进行分析,给出了激光-MAG复合焊接机理的理论解释。随后以10mm厚Q345B钢板为母材,针对激光-MAG复合焊接主要工艺参数(激光功率PL、焊接电流I、离焦量??、光丝间距DLA、焊接速度Vw、激光电弧相对位置等)对焊缝成形的影响规律开展一系列研究,为复合焊接工艺优化提供实验依据。以10mm厚Q345B钢板Y形坡口(钝边4mm,坡口角度45°)进行了复合焊接工艺试验研究,采用的复合焊接主要工艺参数为:激光功率PL=3.5kW,电流I=240~300A,焊接速VW=600~1000mm/min,并对复合焊缝成形进行分析,实现单面焊双面成形;针对实际焊接生产中组对精度差的问题,开展了激光-MAG复合焊接技术对组对间隙和错边量的工艺适应性研究,复合焊接主要工艺参数为:PL=3.5kW,I=270A,VW=800mm/min,对间隙0~2mm、错边量0~2mm的组对误差进行试焊并研究复合焊缝成形规律。对激光-MAG复合焊焊缝横截面进行了宏观形貌和显微组织观察,复合焊缝横截面几何形貌与单独激光焊和MAG焊均不同,在焊缝熔深方向存在激光电弧作用区和激光作用区。对复合焊缝进行硬度、拉伸、弯曲、冲击等力学性能测试,研究激光-MAG复合焊接工艺对焊缝力学性能影响的规律。
[Abstract]:With the extensive application of large thick wall workpieces in heavy machinery, large steel structures, ships and so on, the welding problem has become a hot spot. Laser-MAG hybrid welding technology has been paid attention to as a new high-efficient welding technology. It can be used to solve the welding problem of large thick wall workpiece. The introduction of laser in the laser-MAG hybrid welding process changes the arc conduction mechanism of MAG welding. The energy of arc plasma and laser-induced plasma are coupled each other. The change of arc shape can be observed directly by high-speed camera. The experiment of fiber laser-MAG hybrid welding with 180A low current and 300A high current is carried out respectively. The influence of laser on different transfer modes (short circuit mode and jet mode) of MAG welding is studied. The change of arc morphology and droplet transition before and after laser introduction is analyzed by collecting high-speed video images and electrical signals, and the theoretical explanation of laser-MAG hybrid welding mechanism is given. Then using 10mm thick Q345B steel plate as base metal, aiming at the main technological parameters of laser-MAG hybrid welding (laser power PL, welding current I, defocus?, wire spacing DLA, welding speed Vw,) A series of studies on the influence of laser arc relative position on weld forming are carried out in order to provide experimental basis for optimization of composite welding process. The hybrid welding process of 10mm thick Q345B steel plate with Y groove (4mm blunt edge, 45 掳groove angle) was studied. The main parameters of hybrid welding were as follows: laser power PL=3.5kW, current I, 240? 300A, welding speed VW=600~1000mm/min,? The composite weld forming is analyzed to realize the single-side welding and double-sided forming. In order to solve the problem of poor accuracy of group pair in actual welding production, the research on the technological adaptability of laser-MAG hybrid welding technology to the clearance and staggered amount of group is carried out. The main technological parameters of composite welding are as follows: PL=3.5kW,I=270A,VW=800mm/min, to gap of 0 ~ 2 mm, The error of the staggered 0~2mm is tested and the forming law of the composite weld is studied. The macroscopic morphology and microstructure of laser-MAG composite welding seam cross section are observed. The cross section geometry of composite weld is different from that of laser welding and MAG welding, and there are laser arc acting zone and laser acting zone in the direction of weld penetration. The effects of laser-MAG hybrid welding process on the mechanical properties of composite welds were studied by testing the mechanical properties of composite welds such as hardness, tensile, bending and impact.
【学位授予单位】：北京石油化工学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.11

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