Techno-economic evaluation of reducing shielding gas consumption in GMAW whilst maintaining weld quality

Abstract

A new method of supplying shielding gases in an alternating manner has been developed to enhance the efficiency of conventional gas metal arc welding (GMAW). However, the available literature on this advanced joining process is very sparse and no cost evaluation has been reported to date. In simple terms, the new method involves discretely supplying two different shielding gases to the weld pool at predetermined frequencies which creates a dynamic action within the liquid pool. In order to assess the potential benefits of this new method from a technical and cost perspective, a comparison has been drawn between the standard shielding gas composition of Ar/20%CO2, which is commonly used in UK and European shipbuilding industries for carbon steels, and a range of four different frequencies alternating between Ar/20%CO2 and helium. The beneficial effects of supplying the weld shielding gases in an alternating manner were found to provide attractive benefits for the manufacturing community. For example, the present study showed that compared with conventional GMAW, a 17 per cent reduction in total welding cost was achieved in the case of the alternating gas method and savings associated with a reduction in the extent of post-weld straightening following plate distortion were also identified. Also, the mechanical properties of the alternating case highlighted some marginal improvements in strength and Charpy impact toughness which were attributed to a more refined weld microstructure

GMAW Shielding Gas Flow Optimisation by Refinement of Nozzle Geometry

“…In a typical shipyard, BAE Systems Surface Ships Ltd. were using an average shielding gas flow rate of 24-26 l/min against a process setting of 18 l/min with a 16 mm nozzle. Studies [2][3][4][5][6][7] have provided confidence that the shielding gas flow rate can be reduced with no loss of coverage and has allowed for flow controllers set at 12 l/min to be installed in the BAE Systems Govan shipyard. To date no defects have been found, and the predicted 50% shielding gas reduction will yield savings in the region of £300k per annum.…”

“…Several studies have investigated the effects of reducing the shielding gas flow rate. Campbell et al [2,3] investigated the effects of using gas saving devices in order to reduce the shielding gas consumption, and determined that the flow rate could be reduced to 6 l/min without detriment to weld quality in a draft free environment. Drafts however, present a significant threat to the shielding gas efficiency and studies [3][4][5][6][7] have been conducted to determine safe working environmental conditions.…”

Artificial neural network prediction of weld distortion rectification using a travelling induction coil

“…This architecture has been previously used successfully in simulations predicting both welding distortion and weld geometry [11,12,20]. The development of the model to predict the distortion rectification due to the travelling induction coil was carried out in 3 distinct stages.…”

“…It is known that the magnitude of distortion is affected by a number of factors including the shielding gas flow rate, weld geometry, plate thickness and welding speed [8][9][10][11]. In particular welding speed has been shown to have a significant impact on distortion as it is one of the primary parameters of controlling heat input during welding [9].…”

“…When supplied with sufficient training data, ANN models are capable of capturing intricate relationships between parameters and detecting subtle trends that other computational approaches may not. These characteristics make ANN models ideally suited to modelling the welding process with its many closely linked parameters and they have been successfully implemented to predict both weld geometry and welding distortion [11,12,20].…”