Missions

The study will consist of adapting and improving an existing laboratory model describing Electro Slag Remelting (ESR), and then applying it to the quantitative prediction of the chemical composition of remelted steel ingots.
This numerical simulation work will be based on an experimental component consisting of the characterisation of a 20 t ingot of type 300M special steel remelted by Aubert & Duval under known and controlled process conditions, as well as the characterisation of an electrode of the same grade which includes:
 Measurements of the chemistry and metallurgy of the electrode and/or ingot, carried out by Framatome,
 Ingot solidification structure size measurements carried out by the IJL.

The study will focus on the quantitative comparison of the measurements made and the numerical predictions with regard to macrosegregation in the remelted ingot. On the basis of this comparison, the model will be developed to arrive at proposals for operating procedures aimed at minimising radial segregation in particular.
In parallel, the IJL ("Solidification" team) will implement a series of TDS (Template-Directed Solidification) measurements of the size of solidification structures (grain sizes, interdendritic spacing), with a view to feeding the permeability models of the mushy zone.

Activités

- Testing the SOLECS code on ingot geometries of 120 t or more
- Specifically developing a macro-segregation model by gathering the necessary information already available and listing the data to be collected
- Integrating the segregation model into the SOLECS code, resulting in a new optimised version.
- Comparing experimental results and model predictions for macro-segregation
- Developing a model to establish a procedure minimising radial segregation in particular and extrapolate the results to 18MND5 steel ingots up to 250 t
- Developing the basis for assessing the risk of formation of freckle-like mesosegregations (or segregated veins)
- Measuring the size of the solidification structures by TDS, comparing them with measurements on ingots in order to feed the permeability models of the mushy zone

Compétences

- Expertise in the field of materials, particularly with regard to metal alloys
- Good knowledge of numerical simulation and programming
- Aptitude for experimental activities and numerical simulation
- Ability to lead a project and interact with academic and industrial partners

Contexte de travail

The Institut Jean Lamour (IJL) is a joint research unit (UMR 7198) of CNRS and Université de Lorraine It is linked to the Institute of Chemistry of CNRS.
Focused on materials and processes science and engineering, it covers: materials, metallurgy, plasmas, surfaces, nanomaterials and electronics.
It regroups 183 researchers/lecturers, 91 engineers/technicians/administrative staff, 150 doctoral students and 25 post-doctoral fellows.
Partnerships exist with 150 companies and our research groups collaborate with more than 30 countries
throughout the world.
Its exceptional instrumental platforms are spread over 4 sites; the main one is located on Artem campus in Nancy.
The project will be carried out within the Elaboration Processes team.

Among other things, the Institut Jean Lamour carries out mathematical modelling and numerical simulation studies of the ESR process for the production of nickel-based steels and superalloys. The main result of these studies has been the development and subsequent improvement of the SOLECS numerical simulation software.
The SOLECS model is based on the coupled resolution, in 2D axisymmetric geometry, of the equations for the conservation of energy, mass and momentum in the slag and in the secondary ingot during growth and cooling. The development of this model is carried out at the IJL (Elaboration Processes team - A. Jardy and B. Dussoubs) within the framework of a Users' Club which includes, in addition to the laboratory, the following companies:
- Aubert & Duval (Eramet group)
- Timet (PCC group)
- Aperam Alloys
- Framatome

At Framatome, since the creation of the Users' Club in 2002, the Component Research Centre (CRC) in Ugine has been involved in the studies, due to its specific interest in the arc remelting of zirconium alloys. Recently, Framatome has expressed its desire to become involved in the simulation of slag remelting of large steel ingots, in particular to quantify the phenomenon of macrosegregation in alloying elements.

At present, the SOLECS code does not specifically address segregation in steels. The aim of the study is to develop models to better understand the segregation phenomena at work in the production of large ingots (up to 250 t) of low-alloy steel, based on experimental results obtained specifically, and then to incorporate them into SOLECS. This new version of the code will make it possible to carry out numerical simulations of the ESR remelting of large steel ingots and to characterise the influence of the operating parameters on the macro-segregation phenomena as well as on the possible formation of "freckles" (or segregated veins).

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

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Informations complémentaires

The candidates will possess a Ph. D in the field of materials or materials chemistry. Strong knowledge in numerical simulation would be a plus.