Nickel-base superalloy welding - models for residual stress, distortion, and weldability

摘要

In this paper we present finite element based models for the welding of nickel-base superalloys common to many aeroengine components. Two welding processes are modelled; Electron Beam Welding (EBW) commonly employed in the joining of turbine discs and Tungsten Inert Gas (TIG) welding for combuster liner and casings applications. Both models share the common basis of a thermal model sequentially coupled to an elasto-plastic mechanical model. For the TIG welding process a microstructural model for the diffusion of the alloying elements has also been added to provide some measure of 'weldability'. The approach developed enables the weld engineer to predict the appropriate welding conditions to minimise weld induced distortion and the likelihood of cracking due to solidification or liquation and provides valuable residual stress input for component lifing calculations.