Mathematical Modelling of Materials Processing
Models for DC-casting (DirectChill-) of aluminium extrusion ingots and sheet ingots include:
- calculations of complex waterfilm boundary conditions,
- heat and fluid flow,
- solidification and
- thermal stresses and deformations.
The models also include constitutive modelling of elastoviscoplastic material characteristics which depends on:
- strain and
- rate of strain.
The development is a co-operation between several research institutes financed by European aluminium industry including Elkem Aluminium and Hydro Aluminium. IFE has developed the new simulation programme ALSIM4, where temperature, fluid flow, mechanical stresses and deformations are calculated as coupled phenomena. The program is a unique tool for continuous casting of aluminium. In the project VirCast, financed by the European Union, new models for simulation of the solidification zone as a multiphase medium have been developed, and these are to be included in the future. Coupling to microstructure calculations of precipitation and growth of hardening particles will be further developed in a strategic institute programme.
There has been a close co-operation between IFE and Hydro Automotive regarding development of mathematical models for different welding processes. These models calculate temperatures, mechanical deformations and development of microstructure for agehardening aluminium alloys in the heat affected zone for conventional welding processes (MIG/GMAW) as well as for electron beam welding (EB). For the automotive industry the model are also used to calculate deformations in aluminium frameworks during welding.
For the steel industry the models include casting, heat treatment and rolling. The heat treatment model includes calculation of gas flow with burners and the coupling between the gas flow and the steel ingots. In this area it is a close co-operation between IFE and the research institute MEFOS in Luleå, Sweden. The models are used both for design studies and on-line control of the furnaces.
For the aluminium electrolysis process there has been developed a system of models in co-operation with Hydro Aluminium. These models are used for design and maintenance of the aluminium cells. The models include calculations of magneto-hydrodynamic instabilities that may occur in the reduction cells.