Determination of optimum welding sequence and distortion forces in steel lattice beams

Distortion is the main problem of welding industry. This problem can be managed by variety of techniques including rigid fixing, heat sink and welding sequence (WS). The aim of this study was to investigate the effect of various welding sequences on welding distortion in steel lattice beams. Welding distortion tendencies in the lattice beams were determined by means of distortion forces. These forces were measured by using force measuring plates (FMPs). The plates were placed between the rigid frame and the lattice beam. Distortion forces created by different applications of WS in the lattice beam were transferred to data-logger and then to a personal computer. The relationship between WS and distortion forces was analyzed by using AMR Win Control programme. Effects of 20 various combinations of WS on distortion forces in the lattice beam were investigated. It was found that minimum distortion tendencies were observed for WS which had homogenous heat gradient. Welding sequences in which welding joint points arranged far from to each other and initial welding points where chosen with the distance from centre of the beam exhibited minimum distortion tendency. WS started from the centre of the beam and connection points which were welded consecutively showed intensive distortion tendencies.