The 13th Global Conference on
Materials Science and Engineering (CMSE 2024)

Abstract: The formation of shear bands at extremely high strain rates directly precedes the fracture of metals. Their appearance in the structure signals a reduction or complete loss of the load-bearing properties of a metallic parts. This paper analyses the crystallographic aspects of the mechanism responsible for the occurrence of this form of unstable metal flow under model conditions. The study examined copper single crystals with unstable orientations of C(112)[11-1] and S(346)[63-5], which were deformed up to 60% in a channel-die, with the punch driven by explosive energy to achieve a strain rate of 4 × 10⁵ s⁻¹. Microstructure and texture evolutions were characterized in a wide range of scales, primarily using scanning and transmission electron microscopy techniques. In both orientations analysed, the extremely high strain rate leads to intense nucleation of deformation twins, forming on all four {111} planes in two generation. The appearance of compact twin bundles directly precedes the formation of shear bands. In each case, rigid-body rotation of the twin bundles within the band region, combined with twinning in the reoriented matrix, leads to the formation of texture components close to the G{110}<001> orientation. Finally, crystallographic model for the formation of shear bands in fcc metals deformed at high strain rates were proposed.

Keywords: Adiabatic shear bands, twinning, high strain rates, copper, titanium, SEM/EBSD.

Biography: Professor Henryk Paul received his Doctor of Engineering degree from the Institute of Metallurgy and Materials Science (IMMS) at the Polish Academy of Sciences in Kraków, Poland, in 1989. After serving as an assistant professor, he was promoted to associate professor in 2003 and to full professor in 2010, all at IMMS. He has completed numerous fellowships and internships at French institutions, including an extended stay at the École des Mines de Saint-Étienne and several study visits to LLB Saclay and Université Paris-Sud. He has authored over 280 original papers, 22 book chapters, and 22 review papers on various aspects of phase transformations. His research interests include explosive welding technology, the formation of plastic flow instabilities during the deformation of metallic materials, recovery and recrystallization, phenomena associated with high strain rate deformation of metals, and phase transformations. He has been a plenary, keynote, or invited speaker at 42 international conferences. His publications have been cited over 2,300 times, and he has an h-index of 31.