As results of experimental investigation of elastic‐plastic deformation of the metals (Cu,Ni,Fe, aluminium alloy D16) with various grain size (20 ÷ 200 μm) the violation of the Hall‐Petch relation at pulse duration of 80 ns was found. The increment of the Hugoniot’s and microhardness under increment of the grain size was observed. The reason of the such material behavior under shock loading was determined by measurement of elastic waves velocities along two axes before loading and after it. The main mechanism of plastic flow is rotational for specimen with grain of 20 μm and twinning for the coarse‐grained specimen. In this way plastic flow is determined by various deformation structural scales, depending on correlation of characteristic scales, were ∼ 10 μm for the fine‐grained specimen and apparently ∼ 10 nm for the coarse‐grained specimen. Apparently the appearance of the rotational modes of plastic flow is stipulated by the twinning process under high grain boundaries density in the fine grained specimen. This determines the transition from one structural level of deformation to another one with an essentially larger scale.

This content is only available via PDF.
You do not currently have access to this content.