Nouveaux aciers à gradient de propriétés (Graded Composite Steels Design) – GRACOS

In this joint ANR/NSERC project, we propose to investigate the design of hybrid composite steel sheets with a graded structure from surface to center. This graded structure will be achieved through the use physical vapour deposition (PVD) combined with controlled thermal treatment. The goal of this project is to control the steel structure at the meso, the micro, and the nanoscopic scale. The central question that will be assed in this project is: ‘Can we achieve a gradient of alloying elements (C, Cr, Mn) in ultra-low carbon steel sheets that leads to (i) increased yield strength and (ii) suppression of Lüdering’? Physical vapour deposition as a metallurgical processing route for sheet steel provides opportunities to develop far from equilibrium nanostructured materials (e.g: up to a few tens of percent of C in Fe) and can also be considered as a way of modifying both the near surface and bulk properties of steel sheet. This work will focus on the coating of packaging steels (low carbon or manganese steel) provided by ArcelorMittal with Fe-C, Fe-Mn-C and Fe-Cr-C films followed by diffusion annealing to achieve the desired graded hybrid composite microstructures. In this particular proposal we aim at three specific objectives: (i) produce and characterize the microstructure (microscopy, tomographic atom probe) and mechanical properties of graded steel sheets; (ii) develop predictive physical models capable of describing the relationship between processing, microstructure and mechanical properties; (iii) Evaluate the compatibility of the processing routes devised in this work within the context of steel processing. This project involves two French and two Canadian partners: (P1) Univ. Rouen ? GPM (Fr), (P2) Univ. Lyon ? MATEIS (Fr), (P3) Univ. British Columbia (Ca) and (P4) Univ. Ottawa (Ca). It is divided in four tasks: (T1) material synthesis (Leader C. Sinclair ? Vancouver); (T2) mechanical characterization (Leader A. Weck ? Ottawa); (T3) microstructural characterization (Leader X. Sauvage ? Rouen) and (T4) physical modelling (Leader M. Perez ? Lyon). The project will involve 3 PhD projects supported by ANR and NSERC: (PhD1) Production and Modelling of Graded Fe-C Based Packaging Steels - Supervisor: C. W. Sinclair, Co-supervisor: M. Perez ; (PhD2) Mechanical Properties of Graded Fe-C Steels - Supervisor: A. Weck, Co-supervisor: X. Sauvage and (PhD3) Observation and Modelling of Microstructures in Highly Supersaturated Fe-C-X (X=Cr,Mn) Materials - Supervisor: X. Sauvage, Co-supervisor: M. Perez. Close communication over the period of this project is the key to the success of such a joint international proposal. This will be aided by the fact that C. Sinclair will spend a study leave in Europe commencing in the summer of 2009 and finishing in the summer of 2010 and M. Perez will spend a 6 month study leave at UBC during 2011. Moreover, two workshops will be organized in France and in Canada and all PhD projects will be co-supervised by partners in both France and Canada with travel for students between institutions an important component of the proposal.