Effect of Groove Form on Welding Residual Stress of Q390/Q690 Dissimilar Low Alloy Steel

The effects of groove form (V-shaped, X-shaped and K-shaped) on temperature, stress and residual stress distribution of Q390/Q690 dissimilar low alloy steel melting electrode active gas shielded arc welded joint were studied by using finite element simulation, and were verified by test. The results show that the simulated and test thermal cycle curves and residual stress distribution were similar, and the instantaneous temperature relative error was less than 15%, proving the accuracy of the model. The peak temperature in the weld zone of the K-shaped groove joint was the highest, followed by that of the V-shaped groove, and the X-shaped groove was the lowest. The welds of K-groove, V-groove and X-groove joints all had high stress zones with equivalent stresses higher than 690 MPa, and the areas decreased in sequence. And the longitudinal residual stress was distributed in a zigzag pattern, with peaks appearing at the weld and rapidly transforming into compressive stress in the fusion zone on both sides. The transverse residual stress was distributed in a double hump shape, with peaks appearing in the fusion zone on both sides and rapidly decreasing to near zero at the center of the weld. The groove form had little effect on the peak longitudinal residual tensile stress of the joint. The distribution range of longitudinal residual tensile stress of V-groove and K-groove joints was larger than that of X-groove joints, and the peak transverse residual tensile stress and its distribution range were both larger than those of X-groove joints.