This thesis focuses on the simulation of the welding process in 13Cr-4Ni (CA6NM) martensitic stainless steels by incorporating phase transformations. These transformations must be considered when simulating 13Cr-4Ni steels, used in turbine manufacturing, since they undergo both austenitic and martensitic phase transformations and exhibit transformation-induced plasticity during the martensitic transformation.
The work addresses the characterization of the thermophysical and mechanical properties of S41500 steel and E410NiMo filler metal. These characterizations serve multiple purposes : first, they provide the material properties required for the simulation software; second, they are used, in particular the dilatometric tests, to determine the parameters of phase transformation kinetics models during welding. For this purpose, a quenching dilatometer is employed to reproduce thermal histories similar to those encountered during welding. Dilatometric tests are used to calibrate diffusive transformation models of the JMAK type and displacive transformation models of the Koistinen-Marburger type. Dilatometry is also used to characterize transformation-induced plasticity. A specific configuration of the quenching dilatometer enables measurement of deformation during martensitic transformation under applied stress.
The simulation algorithm integrating these material phenomena is presented. The expression of the tangent modulus required to evaluate material hardening during phase transformations is developed. Thermal simulation of welding on an instrumented plate with thermocouples is described, allowing accurate calculation of heat distribution and the evolution of transformed fractions at every point in the model. The experimental measurements required for validation are also presented.
| Date | 12 Jan 2026 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Henri Champliaud (Supervisor) & Jacques Lanteigne (Co-supervisor) |
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Lévesque, J.-B. (Author),
Champliaud, H. (Supervisor) & Lanteigne, J. (Co-supervisor),
12 Jan 2026Student thesis: Doctoral thesis › Doctorate in Engineering: Engineering