DYMAT 2009 (2009) 971-976
DOI: 10.1051/dymat/2009136

Soft recovery of a ferrous alloy: Structural modification and properties

T. d'Almeida¹, D.J. Chapman¹, W.G. Proud¹, P.J. Gould², P.D. Church², M. Reynolds², R. Wheeler², H.J. MacGillivray³, M. Di Michiel⁴ and J.M. Merino<sup>5

1</sup>  SMF Group, Cavendish Laboratory, JJ Thomson Avenue, University of Cambridge CB30HE, UK
²  QinetiQ, Fort Halstead, Sevenoaks, Kent TN 14 7BP, UK
³  Imperial College London, UK
⁴  European Synchrotron Radiation Facility, BP. 220, 38034 Grenoble Cedex, France
⁵  Universidad Autonoma de Madrid, Departamento de Fisica Aplicada, 28049 Madrid, Spain

Published online: 15 September 2009

Abstract
The passage of a shock wave through a material causes the properties of the post-impact, recovered material to change. This may be through the action of void formation, shear banding or the introduction of dislocations. This has a major effect on the properties of the materials as some processes soften the material while other harden the sample – overall it is difficult to determine which effects will dominate, without experimental data. In this study a ferrous alloy was shocked into its high pressure, epsilon phase. In the series of plate impact experiments, samples are taken to shock stresses of 16 GPa. The phase transformation stress is in the region of 12.8 GPa. The sample material is mounted in an impedance matched cell which permits the target to be recovered with minimal additional damage. Iron and its alloys are well known for their propensity to display shock induced twins and dislocations, thus modifying the mechanical properties of the recovered material. In this paper the recovered material is sectioned and subjected to two forms of analysis – (1) tensile testing and (2) X-ray diffraction. The data is then analysed to populate the Goldthorpe Path Dependent Model and comparison made to other ferrous systems.

© EDP Sciences 2009