TWI Industrial Member Report Summary 95/1979
By F R Coe and J Moreton
An hypothesis based on chemical thermodynamics relating oxygen derived from the shielding gas to the oxygen content of the weld metal is postulated for the solid wire gas-shielded welding of steel, and is tested against published data. New experiments employing both carbon dioxide-rich and argon-rich shielding gases, a range of filler wires and careful analysis of the weld metals for oxygen contents, have produced an encouraging degree of agreement between prediction and observation. Further experiments are envisaged to test the hypothesis over a wider range of consumables.
The possibility of using the reaction equations in graphical form for selecting wire-gas shielding combinations to achieve specific weld metal oxygen levels thus becomes feasible. Careful examination of weld oxygen levels necessary in this work has highlighted the importance of correct sampling strategy in order to obtain reliable and representative results.