Defect induced structural transitions, instability and plastic strain localization in dynamically loaded metals

摘要

We present an experimental and theoretical study of the mechanisms of plastic strain instability in metals subjected to dynamic loading. A special sample shape was proposed to realize pure shear strain localization state using Hopkinson-Kolsky bar apparatus. The lateral strain localization area was studied in-situ using a high-speed infra-red camera CEDIP Silver 450M with sensitivity ～25 mK. (at 300K), spectral range 3-5 mkm, maximum frame size 320×240 pixels and temporal resolution 1KHz. The temperature field distribution obtained at different time allowed us to trace the evolution of plastic strain localization and support theoretical results concerning the leading role of defect-induced structural transitions in the mechanisms of plastic strain localization.