The Development and Validation of a Model for the Electron Beam Welding of Aero-Engine Components

Experiments designed for the purpose of validating, verifying and calibrating a process model for the simulation of the electron beam welding of Waspaloy are described. The residual stress state in two autogeneous electron beam welds have been determined using X-ray & neutron diffraction and a hole drilling method. Furthermore, estimates of the weld-induced angular distortion are reported. These experimental data are compared with the predictions of the process model, which is based upon a sequentially coupled thermal-mechanical finite-element analysis. The heat source is modelled phenomenologically with no attempt made to simulate plasma, convection and stirring effects in the weld pool, It is shown that the experimental and theoretical results are in broad agreement. With the aid of the model, the effect of a non-penetrating cosmetic pass on the weld-induced distortion has been rationalised. It is shown that such cosmetic passes induce considerable further angular distortion, which is particularly sensitive to the extent by which the beam is defocused away from the surface of the weld preparation, i.e. the 'beam defocus'.