Research Of Triple-Wire High Speed GMAW Welding Technology On Ship Plates

As one of the key welding technologies in hull construction, gas metal arc welding (GMAW) plays an important role in shipbuilding industry. The welding efficiency and weld quality are desired to be improved to cope with the recent development of shipbuilding industry, which requires an innovation and application of high speed welding technologies. For GMAW in shipbuilding, a primary issue is that the onset of geometric defects such as humping or discontinuous weld beads frequently limits the use of higher welding speeds and increased productivity. In the present study, the newest triple-wire high speed GMAW technology which can achieve weld beam with good quality at speed of 1.8m/min is developed and studied ,covering the effect of welding parameters on beam formation and geometry and weld joint microstructure characteristics.The triple-wire high speed GMAW experimental system platform was established successfully, in which the experimental work were performed efficiently. Besides, the real-time welding current and voltage data was acquired based on LabVIEW data acquisition system to analyze the whole welding process stability through variation coefficients.The key factor to achieve stable welding process and good weld formation used triple-wire high speed GMAW technology has been observed and studied. With CO2-shielded,opposite direct current is added to the middle wire between the leading and trailing wire by applying DCEP/DCEN/DCEP and DCEN/DCEP/DCEN polarity combinations, which is useful to decrease welding defects inducing by increasing welding speed, and obtain good weld qualities.In triple-wire high speed GMAW, the arc interruption caused by the electromagnetic forces occurs among leading wire, middle wire and trailing wire. And it has been found that the total heat input of triple wires influence the welding process. In order to obtain good weld formation, the total welding heat input should be in the range of 250A/250A/250A and 550/450/450A with right currents combination in DCEP/DCEN/DCEP welding. Based on what is mentioned above, welding condition parameters combination experiments were performed to predict the weld quality and geometry.Space location parameters effect on weld formation and geometry parameters has been studied, such as such as tilt angle and inter-wire distance. It has been found that the wire offset have great effect on the weld quality when the other welding condition parameters are the same.A comparative analysis has been made on welding speed, heat input, weld formation, joint microstructures among triple-wire, double-wire and single-wire welding process. The results show that, the proportional relationship of all the three technologies on welding speed is approximately 1:2:3, and there is no essential difference in joint microstructure.