Internship - R&D Engineer - Understanding Grain Refinement for Increasing Recycling H/F

C-TEC RECRUTE  

INTERNSHIP - R&D ENGINEER F/H/X

Constellium is a global leader designing and manufacturing innovative and high value-added aluminum products and solutions for a broad range of applications dedicated primarily to aerospace, automotive and packaging markets. Constellium Technology Center (C-TEC) based in Grenoble (Voreppe - 38) is Constellium’ s European research center with 246 employees and 20 nationalities.

Understanding Grain Refinement for Increasing Recycling of Aluminium alloys

Main objective and key accountabilities

Combine experimental and numerical techniques to understand the effect of the microstructural features of industrial grain refiners on their grain refining efficiency in aluminium alloys.

The knowledge generated in this work will contribute to incorporating higher recycled contents in the production of aluminium alloys for aerospace and automotive applications.

Context & environment

Aluminium alloys have long been crucial to the aerospace industry due to their low density and high mechanical properties.  Nowadays their use is rapidly expanding in the automotive sector for the purpose of light weighting vehicles for reducing the carbon footprint of the industry.

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, generating more runaround scrap and resulting in significant value loss. Our plants are more than ever seeking to reduce their runaround scrap to maximise external scrap content resulting in reduced carbon footprint. Equiaxed grains of well-controlled size help 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 more or less efficient. We have concluded in recent findings, that the presence of nucleating particle agglomerates in industrial grain refiners has a significant negative impact on grain refiner efficiency. In the tested grain refiners, notable metallurgical differences were identified in nominally identical grain refiners coming from different suppliers and even between lots coming from the same supplier.  However, these differences have not yet been unequivocally linked to the resulting grain refining efficiencies of these different refiners. 

In this work, we aim to improve our understanding and perfect the already developed 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.

Expected results:

The candidate will be based at Constellium C-TEC, Voreppe and will perform solidification experiments, optical and SEM characterizations in order to quantify the size distribution of nucleant particles along with other metallurgical features. The candidate will also try to fit the experimental findings with cellular automaton simulations aiming at explaining the physical phenomena at play affecting grain refiner efficiency.

This internship can be decomposed into several stages:

• Familiarization with the principles 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
• Motivated, creative, rigorous, and curious candidate with good communication skills and autonomy.
• Knowledge in Materials science, and desire to develop modelling skills
• Knowledge of Microsoft Office
• Good communication skills in English and French are essential