Vol 2018, No 10 (2018)

The deformation behavior of metals and rocks is analyzed. The stages of damage accumulation, the formation of deformation localization zones, the length distributions of the number of microcracks in metallic samples and faults in Earth’s crust, and the time dependences of acoustic emission and seismic events before the fracture of specimens and earthquakes are considered. The main laws of the damage accumulation kinetics before the fracture of specimens and the seismicity dynamics before an earthquake are found to be similar.

The accumulation kinetics of rotational and shear primary mesodefects (junction disclinations, planar mesodefects) is studied by computer simulation. The mesodefect strength is shown to increase monotonically and to level off during plastic deformation. The influence of the geometry of lattice slip and the applied stress on the mesodefect strength is analyzed.

The problem of stability of the reverse phase transformation in the support rods of the Shanley column made of a shape memory alloy is analytically solved in quasi-static formulation. The column is in a constrained state. The results of the solution in the double-coupled formulation are compared with the similar data obtained in the single-coupled and uncoupled formulations. The influence of a structural transformation on the result of solving the stability problem during the reverse phase transformation is studied.

The structural evolution in the cylindrical shells made of an AMg6 alloy and loaded by glancing detonation at two different intensities is studied. At a weak action of a detonation wave, the shells are shown not to collapse and only an initial stage of convergence is detected. The shell material is found to be hardened during high-rate deformation. Structural investigations demonstrate that the detonation wave intensity affects the rheology of the deformation behavior of the AMg6 alloy.

The structural evolution of crystalline ceramics and amorphous glasses during high pressure torsion is analyzed. Enhanced consolidation of ceramic powders under high pressure torsion is observed. This phenomenon is explained. The effect of a severe external impact on the powder consolidation, which enlarges the field of application of ceramics, is revealed.

The effect of the deformation axis orientation on the length and the strength of dislocation junctions in fcc single crystals has been studied within the model of interdislocation contact interactions, which includes the formation of a dislocation reaction and a change in a dislocation configuration under stress in three-dimensional space. The probabilities of failure of a dislocation junction under stress, the formation of indestructible dislocation junctions, and the formation of long strength dislocation barriers capable of limiting the shear zone have been determined.

The mechanism of formation and propagation of shear bands on the surface of a model Co₆₉Fe₄Cr₄Si₁₂B₁₁ alloy amorphous wire 90 μm in diameter without a glass cover, which was subjected to different types of loading, such as uniaxial tension, drawing, bending, and torsion, is studied. For all applied loadings, the wire exhibits the ability to forming at a retained amorphous state. Depending on the type of loading, deformation is distributed either uniformly along the wire or is localized in a stress concentration zone. In this case, the contributions of forming mechanisms, namely, elastic deformation, ductile flow in the volume, and formation of shear bands on the wire surface, change. The wire is concluded to exhibit the pseudoplasticity effect.

Based on the results of an experimental investigation of cold-rolled automobile body sheet steels of various strength classes, we developed a mathematical model to predict the recrystallized ferrite grain size as a function of the ferrite grain size after hot rolling and the strain during cold rolling. The model can reproduce the experimental data at a good accuracy.

The effect of preliminary quenching and subsequent aging at 190°C for 10 h on the structure and the strength of the D16 alloy subjected to high-pressure torsion at room temperature is studied. The strength of the preliminarily quenched and the preliminarily aged alloy is shown to be comparable despite the fact that a more developed nanostructure forms in the preliminarily quenched alloy during severe plastic deformation. The nature of the alloy behavior is discussed.

The mechanical properties of the Ti₅₀Ni_49.7Mo_0.3 alloy with 1–4 at % vanadium and niobium have been studied. The best mechanical properties are found to be in the alloys containing 1 at % vanadium and niobium. The further increase in the vanadium concentration leads to a decrease in the strength and ductile properties of the alloy; an increase in the niobium concentration causes an increase in the ductility of the alloy and a decrease in the strength properties.

The service properties of the steels intended for metallic constructions that are regulated by new standards and the standards that have recently been operative are compared. The validity of the transition to impact toughness standardization using specimens with a sharp notch instead of earlier specimens with a semicircular notch (transition from KCU to KCV) is grounded. The correlation of KCV as a structural strength parameter with other service properties of the steels intended for metallic constructions is discussed.