J. Phys. IV France
Volume 110, September 2003
Page(s) 117 - 122

J. Phys. IV France
110 (2003) 117
DOI: 10.1051/jp4:20020680

Study of high strain rate plastic deformation of low carbon microalloyed steels using experimental observation and computational modeling

J. Majta1, A.K. Zurek2, C.P. Trujillo2 and A. Bator1

1  Akademia Gomiczo-Hutnicza, Metallurgy and Materials Science Department, Mickiewicza 30, 30-059 Krakow, Poland
2  Los Alamos National Laboratory, MST8, MS-G755, Los Alamos, NM, U.S.A.

This work presents validation of the integrated computer model to predict the impact of the microstructure evolution on the mechanical behavior of niobium-microalloyed steels under dynamic loading conditions. The microstructurally based constitutive equations describing the mechanical behavior of the mixed $\alpha$ and $\gamma$ phases are proposed. It is shown that for a given finishing temperature and strain, the Nb steel exhibits strong influence of strain rate on the flow stress and final structure. This tendency is also observed in calculated results obtained using proposed modeling procedures. High strain rates influence the deformation mechanism and reduce the extent of recovery occurring during and after deformation and, in turn, increase the driving force for transformation. On the other hand, the ratio of nucleation rate to growth rate increases for lower strain rates (due to the higher number of nuclei that can be produced during an extended loading time) leading to the refined ferrite structure. However, as it was expected such behavior produces higher inhomogeneity in the final product. Multistage quasistatic compression tests and test using the Hopkinson Pressure Bar under different temperature, strain, and strain rate conditions, are used for verification of the proposed models.

© EDP Sciences 2003