Research on multi-objective optimization of GMAW welding of DH36 steel

Weld bead morphology plays an important role in welding procedure specification and welding process planning. In order to obtain the quantitative relationship between process parameters and weld morphology of DH36 marine steel plate, grey correlation method was used to study multiple morphology characteristics simultaneously. Eighteen experimental runs were proposed according to orthogonal method. With grey correlation theory, three response objectives, aspect ratio, depth of penetration and weld were transformed into a single grey correlation grade (GRG). The process parameters were quantitatively correlated to the GRG value and optimized with the target of maximum aspect ratio, minimum depth of penetration and maximum weld area. The results show that the optimized weld bead morphology is better than other weld bead morphology. The relative error of the predicted GRG with respect to the actual value is 5.06%, which further verifies the accuracy of the established model. The microstructure and hardness analysis suggests that the optimized welded joint has obtained required mechanical properties.The research outcomes provide a theoretical basis for multi-objective optimization of arc welding morphology in practical applications.