No abstract

This work studied the influence law of gas-metal-arc welding process parameters on the morphologies and performance to improve the morphologies and performance. The mixed orthogonal surfacing test was carried out by taking the preheating temperature, welding voltage, current, speed, and wire extension as GMAW process parameters. The aspect ratio decreased with increasing welding voltage, and it first increased and then decreased with increasing welding current. The hardness increased with increasing preheating temperature and welding speed and decreased with increasing welding voltage, current, and wire extension. Residual stress increased with the increased preheating temperature. In addition, it first decreased and then increased with increasing welding voltage and speed. Based on the regression model, the nondominated sorting genetic algorithm II (NSGA-II) was used for multiobjective optimization. After that, experiments were conducted to verify the noninferior solutions among the aspect ratio, hardness, and residual stress. Errors between the predicted and experimental results by the three output indices were all less than 10%, indicating the feasibility of the optimization method. The research results provide a theoretical direction for multiobjective optimization and refined applications of arc welding.

The work focused on the forming quality of surface-groove backing welds of gas metal arc welding (GMAW). The Box-Behnken design in response surface methodology (RSM) was used to explore the effects of welding voltages, welding currents, welding speeds, and surface radians on the properties of welded joints. The mathematical model was established among process parameters and response indices of welded joints. Experimental results showed that the unmelted gap decreased with the increased welding voltage, welding current, welding speed, and surface radian. Tensile strength increased with the increased welding voltage and welding speed and decreased after increasing with the increased surface radian. Elongation first increased and then decreased with the increased welding voltage, welding speed, and surface radian. Optimal process parameters were obtained by minimizing the unmelted gap and maximizing the tensile strength and elongation: welding voltage = 32 V; welding current = 224 A; welding speed = 32 cm/min; surface radian = 14/36π rad. The errors of the unmelted gap, tensile strength, and elongation were 1.71%, 5.69%, and 1.27%, respectively, by comparing the predicted and actual values. Research results have essential theoretic guidance for improving the penetration and mechanical properties of complex surface grooves welded joints.