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Rupture à chaud dans les aciers au cours de leur solidification : caractérisation expérimentale et modélisation thermomécanique

Abstract : Hot tearing is a major defect in castings or semi-finished cast products. It consists in the opening of cracks in the mushy zone and more precisely in the areas with high fraction of solid (typically 0.9 and beyond), when the material is subjected to deformations leading to local tensile stress. Various kinds of criteria have been previously developed to highlight a risk of formation of hot tears. The aim of this study is to evaluate their capability to predict the occurrence of hot tears correctly. In order to do so, two kinds of tests have been analyzed with the use of a thermomechanical model in which criteria have been implemented. A new constrained solidification testing apparatus has then been designed and contructed. This laboratory set-up proved to be discriminating because the generation of hot tears did occur, or not, depending on the configuration of the test. These defects are quite similar to those detected in industrial processes. Another evaluation has been performed on a semi industrial scale test, which consists in bending a semi-solid steel ingot. These comparisons succeeded in revealing that accumulated strain is a key parameter in hot tearing problems. Thus, the most significant criterion has been improved in order to predict more accurately the occurrence of hot tears in industrial configuration.
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Submitted on : Tuesday, February 5, 2008 - 9:59:07 AM
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  • HAL Id : tel-00239189, version 1

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Olivier Cerri. Rupture à chaud dans les aciers au cours de leur solidification : caractérisation expérimentale et modélisation thermomécanique. Mécanique [physics.med-ph]. École Nationale Supérieure des Mines de Paris, 2007. Français. ⟨NNT : 2007ENMP1494⟩. ⟨tel-00239189⟩

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