Industrial innovative casting processes for the aeronautical industry – PRINCIPIA

The project PRINCIPIA aims at contributing significantly to the definition of innovative new melting and ingot casting processes for the production of thick plates in high performance aluminium alloys (7xxx and 2xxx families, including the new AlCuLi alloys) for the civil aircraft industry
- through the understanding of factors allowing the reduction of porosity and inclusions in DC cast ingots for the rolling and forging stock
- through the multi-physics and multi-scale modelling of melting and solidification processes and their integration in an industrial dedicated softawer
- through the evaluation, both at lab-scale and on an industrial pilot, of improvement or innovative solutions delivered from the project tasks.

The production of high quality aluminium solutions (in terms of inclusion cleanliness, low porosity level, homogeneous metallurgical structure) and improved properties (light weighting, increased durability) for heavy gage products is a major target for Alcan Engineered Products and his customers from the aerospace industry.

In the case of thick rolled products porosities potentially present in the as-cast state may not be fully closed during further processing. Technical challenges associated to the casting of thick gage rolling ingots are particularly critical for the new alloys of the AlCuLi family with enhanced specific properties (e.g. 2050). The high tendency to oxidation results in an increased inclusion risk associated to a higher gas content in molten metal, leading to porosity formation in the as-cast product which is increased by almost an order of magnitude as compared to Li-free alloys.

The project associates 2 industrial partners and 5 public research teams, collaborating on 4 technical tasks (in addition to the management and industrial transfer activities).
- Improvement in the molten metal cleanliness
o Hydrodynamic modelling and inclusion capture assessment for an optimum casting furnace process
- Reduction of porosity
o Understanding of the impact of refractory materials on the hydric exchanges with molten aluminium and definition of new multi-functional refractory solutions.
o Understanding of the link between the as-cast DC structure (macrosegregation and grain morphology) and the size of the pores, and of the impact of process parameters on the structure by multi-scale and multi-physics modelling associated to trials
o Exploration of innovative routes for the reduction of hydrogen content in molten metal

This project has a significant economic impact on the strengthening of the world competitive positioning of Alcan Engineered Products (Global Aeronautic, Transport and Industry business group, European leader and n°2 worldwide for the production of semi-products for the aircraft industry), on the long term activity of Issoire plant with Alcan CRV support. It will provide a support to the current industrial developments for this industry, with the perspective of a new process generation.

Aside from answering the industrial needs in terms of refractory materials for the aluminium application the project will provide to Saint Gobain CREE and additional knowledge in the area of the functionalising of specialty refractory materials, which is a differentiation factor on the metallurgical market.