1999 Volume 17 Issue 2 Pages 301-309
In this study, a new method to control the welding distortion of fillet welds which is especially substantial in thin aluminum alloy was proposed. This is the method to effectively reduce the angular distortion during the welding process, which is conducted by TIG heating on the back surface of welding plate going ahead of MIG welding arc. The advantage of this method was experimentally demonstrated, because it was confirmed that the angular distortion could be completely reduced by this method in comparison with the TIG heating applied before and after welding.
By using a thermo-elastic-plastic FEM, the main effect of the TIG heating preceding to MIG welding on the decrease of angular distortion was analyzed. Consequently, the large reduction of angular distortion by this method resulted from the two main effects. One effect is that the TIG heating on back surface provides reverse angular distortion by thermal strain. Another one is the preheating effect, which is provided as a result of pre-set temperature distribution of the plate in thickness direction by the TIG heating and the following MIG welding. Accordingly, the decrease of angular distortion sensitively depends on the condition of TIG heating, such as the distance from MIG to TIG torch, the TIG heat input and the width of TIG heat source. In order to maintain the reduction effect stably, keeping a distance to some extent between TIG and MIG torch is more effective. But, it is necessary to select appropriate TIG heat input.
