Intership - Understanding Aluminium grain refinement for increasing end of life recycling-H/F/X

Constellium is a world leader in the development and manufacture of high value-added aluminum products and solutions for a wide range of markets and applications, focusing in particular on aerospace, automotive and packaging. Constellium also has nearly 12,000 employees worldwide.

We are committed to minimizing the environmental impact of our operations and improving the environmental footprint of aluminum throughout the value chain.

In our company, safety is essential, it is one of our core values. Our Research and Technology Center, C-TEC Constellium Technology Center, employs about 240 people. Our research is mainly in the field of casting, aluminum transformation and surface treatment.

By joining our company, you will discover a multicultural company which is committed to diversity and the well-being of its employees.

Intership's topic: Understanding Aluminium grain refinement for increasing end of life recycling

Main objective and key accountabilities

Combine numerical and experimental techniques to test, validate and optimize a recently developed cellular automaton model to predict the grain refining efficiency of different type of grain refiners and describe new generation grain refiners and incorporate end of life scrap in the production of aluminium alloys.

Context & environment

Aluminium alloys have always been essential, among other fields, to the aeronautic industry due to their low density and high mechanical properties and nowadays their use is experiencing significant growth in the automotive sector for the purpose of light weighting vehicles.

Grain size control during casting of aluminium alloys has always been essential to ensure sound cast quality and guarantee the desired properties of the final product. A non-reliable solidification microstructure control during direct chill (DC) casting reduces production yield, resulting in significant value loss. This increases the plants’ runaround scrap in an industry where recycling is key. A plant is more than ever seeking to reduce its runaround scrap to maximise external scrap content resulting in reduced carbon footprint of the alloy. A well-controlled equiaxed grain size, helps increase production yields by reducing the risk of hot tearing and shrinkage porosities in cast products. This results from enhanced liquid feeding between the solidifying α-Al grains.

Although grain refinement in aluminium alloys is well known from the fundamental and experimental point of view, grain size control is still not always guaranteed at the industrial scale. This depends largely on the nature and fabrication quality of the grain refiner rod. There are sometimes debates in the industrial community about what makes a grain refiner less or more efficient.

In this work we aim at developing a cellular automaton model that can establish a link between the grain refiner nucleant particle size distribution and grain refining efficiency and fading in aluminium alloys.

The candidate will be based at Constellium C-TEC, Voreppe and will perform cellular automaton simulation of aluminum alloy solidification experiments. The candidate will also be involved in SEM characterization of grain refiner aluminium rods and casting experiments in order to quantify the size distribution of nucleant particles and test the efficiency of industrial grain refiners.

Expected results:

The candidate will simulate solidification experiments by means of latest state-of-the-art cellular automaton method. He will gather the experimental parameters required to simulate the experiments and optimize the cellular automaton model to describe the physics involved in the grain nucleation and growth during solidification under different casting conditions. The candidate mission will be to find a link between the casting parameters (cooling rate, temperature gradient, grain refiner type/nature …) and the microstructure formation in order to predict the final microstructure morphology obtained at the end of solidification.

This internship decomposes into several stages:

• Familiarization with the principle of solidification of metallic alloys
• Familiarization with the cellular automaton model
• Take into consideration the globular to dendritic transition during the growth of aluminium grains
• Study the effect of grain refiner type/nature on the final grain size
• Study the effect of nucleant particle size distribution on the final solidified microstructure
• Use numerical modelling to propose improved specifications on grain refiners for aluminium alloys

Profile: 

Education level: Bac+5 / M.Sc.

Mechanical Engineering - Physics or Material Science

Competencies & technical & soft skills requirement:

• Engineering student (last year) or Masters (M2) of Physics or Material Science
• Candidate motivated, creative, rigorous, curious, good communication skills and autonomous.
• Knowledge in Material science, and eager to develop modelling skills
• Knowledge of Microsoft Office
• Good communication skills in English and French are essential