A. K. Divakov

Shock-induced α-ω phase transition and mechanisms of spallation in shock loaded titanium alloys

A study of the shock-induced α-ωphase transformations and spallation in Titanium alloys has been performed by using the interferometric velocity measurements and post-shocked SEM-investigations. Maximum spall-strength relates to rotational mechanism of spall fracture at the mesolevel. Shock tests revealed forward α→ω and reverse ω→α phase transitions.

Formation of Rotation in Titanium Alloys at Shock Loading

TEM and X‐ray diffraction analyses are used to investigate the structural and phase changes occurring in a material of planar target samples of VT‐6 two‐phase titanium alloy, tested over the impact velocity range of 400 to 600 m/s. It is shown that the compressional plastic deformation wave modulates the material structure, breaking it up into micro‐blocks of 4 to 40 μm in size. Along the boundaries of these blocks, the unloading wave produces a coordinated displacement of blocks relative to each other in such a way that the smaller the blocks and the closer they are to the center of rotation, the greater the mutual displacements of the blocks.

Comparative analysis of uniaxial strain shock tests and Taylor tests for maraging steels

High-strength constructional 38XH3MΦA steel and three kinds of maraging steel were tested to determine the yield stress under dynamic loading. The 38XH3MΦA steel was used as central test material to work out the experimental technique and compare the results obtained in different test methods. Results obtained in the plane shock tests under uniaxial strain condition show roughly the same yield stress values as those obtained in Taylor tests.

Comparative Analysis of Uniaxial Strain Shock Tests and Taylor Tests for Armor and Maraging Steels

High‐strength constructional 38KhN3MFA steel and 02H18К9M5‐BИ maraging steel were tested to determine the yield stress under dynamic loading. The 38KhN3MFA steel was used as central test material to work out the experimental technique. For both kinds of steel the results obtained in the plane shock tests under uniaxial strain condition show approximately the identical yield stress values as those obtained in Taylor tests. Cracking of maraging steel occurs along the shock‐induced austenite bands where microhardness is much smaller than that for the rest of the matrix.

Kinetics of Mesostructure and Reloading Behavior of Dynamically Compressed Solids

Experimental study of shock reloading processes during the uniaxial strain loading of aluminum alloy targets reveals a dependence of reloading response of material on the particle velocity dispersion behavior. This response is found to be elastic‐plastic in case the velocity dispersion at the plateau of compressive pulse equals zero. In the presence of the velocity dispersion the reloading response is pure plastic. This phenomenon is considered from the position of non‐local hydrodynamic theory developed for description of high‐nonequilibrium processes in heterogeneous media.