J. Phys. IV France 110 (2003) 9
DOI: 10.1051/jp4:20020662

A new constitutive model for nitrogen austenitic stainless steel

S. Fréchard^{1, 2}, A. Lichtenberger¹, F. Rondot¹, N. Faderl¹, A. Redjaïmia² and M. Adoum<sup>3

1</sup>  ISL, French-German Research Institute of Saint-Louis, BP. 34, 68301 Saint-Louis cedex, France
²  laboratoire de Science et Génie des Surfaces, UMR 7570 du CNRS, École des Mines de Nancy, Parc de Saurupt, 54042 Nancy cedex, France
³  CRIL Technology, ZAC La Plaine, 2 impasse Henry Pitot, 31500 Toulouse, France

Abstract
Quasi-static, quasi-dynamic and dynamic compression tests have been performed on a nitrogen alloyed austenitic stainless steel. For all strain rates, a high strain hardening rate and a good ductility have been achieved. In addition, this steel owns a great strain rate sensitivity. The temperature sensitivity bas been determined between 20 °C and 400 °C. Microstructural analysis has been performed after different loading conditions in relation to the behaviour of the material. Johnson-Cook and Zerilli-Armstrong models have been selected to fit the experimental data into constitutive equations. These models do not reproduce properly the behaviour of this type of steel over the complete range. A new constitutive model that fits very well all the experimental data at different strain, strain rate and temperature has been determined. The model is based on empirical considerations on the separated influence of the main parameters. Single Taylor tests have been realized to validate the models. Live observations of the specimen during impact have been achieved using a special CCD camera set-up. The overall profile at different times are compared to numerical predictions using LS-DYNA code.

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