The structural and thermodynamic features of the elastic-plastic transition in armco iron and its plastic deformation are studied. Energy storage in iron is shown to have a nonlinear character and be accompanied by wavelike heat dissipation. To describe the energy balance in the plastically deformed metal, a theoretical model is proposed based on a statistical description of the evolution of an ensemble of typical mesodefects (microshears). Moreover, a procedure is developed to experimentally determine the dependence of the potential of the medium on the mesodefect density using infrared scanning data.

This paper presents an experimental study of the mechanical and thermal behavior of titanium samples (Grade 2 and Grade 4) with different grain sizes under cyclic loading. The self-heating test demonstrates that the structure of the material has a strong effect on the dissipation ability of titanium. The threshold of energy dissipation corresponding to the transition through the fatigue limit is shown for coarse-grained titanium. On contrary, submicrocrystalline samples exhibit the dependence of continuous energy dissipation on the applied stress amplitude. Analysis of the fatigue properties of titanium in a gigacyclic regime provides evidence that grain grinding improves substantially the fatigue properties of the material.

The mechanical and thermodynamic characteristics of nanocrystalline (NC) titanium have been experimentally studied under the conditions of dynamic compression at a strain rate of (2–5) × 10³ s⁻¹. The samples of NC titanium were cut from a rod processed by equal-channel angular pressing and had a characteristic grain size of 300 nm. It is established that a 25% increase in the dynamic limit of elasticity in the NC titanium (compared to an initial coarse-grained sample) is accompanied by qualitative changes in the process of energy absorption and dissipation in the material. The amount of dissipated energy remains approximately constant and independent of the rate and amplitude of loading in the entire range of strain rates studied.

Laser shock peening (LSP) is used to enhance surface quality of the metallic structures by the generation of compressive residual stresses on it. This work studies the effect of the main LSP parameters on residual stress fields by the finite-element method. The specimen under investigation is a square plate with a thickness of 3 mm made of Ti-6Al-4V. The performed analysis enhances understanding of LSP application to structures manufactured from this material and this information can be useful for a choice of optimal peening parameters. The effect of the spot size and shape, the pulse energy, the number of peen layers, overlapping of spots and temporal variation of the mechanical pressure induced by plasma is considered and analyzed. A 3D finite-element model based on the Johnson-Cook constitutive relation is developed and verified by the results of residual stress measurements performed for the LSP-treated samples under different conditions. From the obtained results the following main conclusions can be drawn: pulse energy provides the more significant effect although the resulting residual stresses profile tends to some saturation curve; temporal pressure pulse shape and its total duration also substantially alter the residual stress field; the least significant parameter is the spot shape.

Modern experimental studies of the temperature evolution at the surface of plastically deformed metals show that processes of energy accumulation and dissipation in the material are nonlinear even in