Papers by Keyword: Microstructural Modeling

Abstract: Two models to predict the microstructural evolution and post-weld properties of friction stir welds in aerospace aluminium alloys are presented. The first model is a develop- ment of an existing semi-empirical method for the prediction of hardness profiles after welding, calibrated using isothermal hardness data. Post-weld natural ageing is accounted for, and a new method that predicts natural ageing kinetics is introduced. Once calibrated, the model is shown to accurately predict weld hardness profiles. However, this model does not explicitly predict the microstructure and therefore cannot readily be extended to model other properties. It can also only be applied to alloys welded in peak or overaged conditions. The second model aims to explicitly predict the heterogeneous precipitate distributions obtained after welding for any initial condition. It is based on classical kinetic theory and the numerical framework of Kampmann and Wagner. Multiple nucleation sites and multiple phases are accounted for. This model provides detailed microstructural information required for prediction of complex properties.

Abstract: The microstructural evolution during the hot rolling of coarse grain sized austenite has been modeled taking into consideration all the microstructural mechanisms (dynamic, static and metadynamic recrystallization, strain induced precipitation) that could take place during the industrial TSDR production of a Nb microalloyed steel. Based on the results obtained from the model, processing maps have been drawn for a 0.035%Nb microalloyed steel. Optimum processing conditions to exploit all the benefits of Nb microalloying have been defined considering a final gauge thickness range between 1.5 and 12.65 mm.