The Influence On Heat-iuput And Weld Deam By Welding Parameters Of Dual-electrode Gas Metal Arc Welding

Efficient, high-quality, low consumption is the development direction of welding technology. High welding current produces high heat input, and brings about bad weld shape, that is the restrict in high efficient conventional MIG/MAG welding. In the welding of the new materials and ultra thin steel, high welding current but low heat input is also required for. To realize efficient welding and low heat-input welding, lots new method were put forward on the base of traditional welding. Dual-electrode Gas Metal Arc Welding (DE-GMAW for short) is one of the new welding methods; it has many unique advantages in efficient welding and low heat-input welding.Dual-electrode Gas Metal Welding has many forms: DE-GMAW, pulse DE- GMAW, double wire DE-GMAW, and each form have its unique advantages. This paper reflected on the characteristics of the three type DE-GMAW methods that mentioned above. Firstly, to study the influence on weld seam shape by bypass current, a series of welding joins were obtained by DE-GMAW overlay welding on different value combinations of bypass current and base-metal current. Compared to the conventional MIG welding, the influence law of different bypass current on the weld shape size, the microstructure in HAZ, and the width of HAZ were analyzed.Secondly, in view of the character of low and controlled heat input of Pulse DE-GMAW, jointing of platinum and steel was carried by Pulse DE-GMAW and CMT(Cold Metal Transfer)method. And the aluminium/steel joints were researched and compared by microstructure analysis and electron probe element analysis. Results showed that the IMC (inter-metallic compound) layer in the aluminium/steel joint of Pulse DE-GNAW is about 8μm less than 10μm,which is the generally accepted critical thickness. And the microstructures are similar in the Pulse DE-GMAW joint and CMT joint, but the Pulse DE-GMAW has the higher deposition rate.Finally, the overlay welding by double wire DE-GMAW and traditional MIG welding were conduct, and the welding thermal cycles were measured in the condition of the welding process with different welding parameters. And the character of the welding thermal cycles and the microstructure in the HAZ under different welding parameters were analyzed and compared with the traditional MIG welding. Results showed that double wire DE-GMAW had low base-metal heat-input and high thermal efficiency had high deposition rate.