A process model for the distortion induced by the electron-beam welding of a nickel-based superalloy

A process model suitable for the prediction of the distortion induced during the electron-beam welding of nickel-based superalloys is described. For the purposes of model validation, processing trials on WASPALOY have been carried out using an industrial-scale welding apparatus. Particular emphasis has been placed on the effect of altering the focal position of the beam. The heat transfer occurring during welding has been characterized, and values of the thermal efficiency are reported. The thermal cycles experienced by material in the heat-affected zone (HAZ) are reproduced accurately. The resulting modes of distortion, both angular and camber, have been analyzed. For one of the welds, the residual-stress state has been determined using the neutron diffraction technique, and it is shown that the predictions are in reasonable agreement with the observations. While there are some discrepancies, the model is capable of rationalizing the modes and extent of distortion and the manner in which these depend upon the focal position of the beam.