Étude expérimentale assistée par simulation numérique du formage par ligne de chauffe de l'acier inoxydable austénitique AISI 304L

Abstract

Line heating forming is an industrial process that allows bending metal plate only by the introduction of thermal stresses along a heating line. Several mechanisms take part in the process depending on plate size and heating conditions. The present work deals with the so called “Temperature Gradient Mechanism”, which is dominant when the heat source diameter is smaller than the metal plate thickness. The first part of the project was to design an experimental procedure that allowed getting data to later validate numerical simulations that have been performed with the commercial software SYSWELD. The measurements of the deformations have been done thanks to a LVDT and measurements of the temperature field have been done using thermocouples. Different heating sources have been used for this project. At the ÉTS, a series of experiments using a torch fueled with an oxygen/acetylene mix in one hand and induction heating on the other hand has been performed. Then, a second series of tests have been done with a 3kW fiber laser at the AMTC, Montreal, which is a governmental research center, specialized in manufacturing processes for the aerospace industry. The material that has been chosen for the samples is the AISI 304L stainless steel since its physical properties gives better deformations, and the fact that there is no martensitic transformation simplifies the modeling. The heat sources have been modeled with Gaussian 2D and 3D conical and double-ellipsoid sources, or by a constant heat flux in the case of induction heating. The results show a difference of about 10% between simulated and measured temperatures, and about 25% for the deformation. Our knowledge of SYSWELD allowed us to carry out simulations with virtual heat sources that cannot be performed experimentally either because of the cost of these experiments, or because these sources cannot be reproduced in a laboratory yet. The results show that volume sources are more efficient than the 2D ones as they can build higher deformation at a lower temperature. These results have been then used in the simulation of the so-called “double sources” process. This process improves the final deformation that would be obtained with only one source.

Date	25 Oct 2013
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Tan Pham (Supervisor) & Jean Luc Fihey (Co-supervisor)