Influence of Laser Forging on Residual Stress and Weld Morphology of Laser Forged Coupled Arc Welded E690 Marine Steel
W-L. Cai, Y-K. Zhang and J-H Liu
Welding residual stress and welding deformation of marine engineering steel structure will be caused by welding process, welding environment and other factors. Taking E690 marine high strength steel (HSS) as the research object, the new technology of laser forging coupled arc welding is adopted. According to the X-ray diffraction (XRD) principle, the measurement method of inclination fixed φ is adopted and the peak determination method of cross-correlation method is selected to study the influence of process parameters such as different groove widths and different distances between the laser beam and the weld arc on the residual stress of weld section fusion zone (FZ), weld zone (WZ), heat affected zone (HAZ) and base metal zone (BMZ). The experimental results show that the maximum residual compressive stress is -541 MPa in the FZ when the groove width is 5 mm and the distance between laser and arc is 6 mm, and the maximum residual compressive stress is -536.1 MPa in the WZ when the distance between laser and arc is 10 mm. Whether the groove width is 5 or 8 mm, the residual stress increases first and then decreases. Observe the section morphology, and the weld shape is in V-shape, showing a trend of wide at the top and narrow at the bottom. Martensite structure is produced in the FZ and with the distance from the WZ, the martensite grain is gradually refined, greatly enhancing the mechanical property of the material and making the fusion effect better.
Keywords: Nd:YAG laser, E690 marine steel, laser forging, arc welding, X-ray diffraction (XRD), morphology, residual stress