Static grain growth in an austenitic stainless steel subjected to intense plastic straining

The post-dynamic recrystallization of an ultrafine grained 304-type austenitic stainless steel was studied during annealing at 800 and 1000°C for 7.5 to 480 minutes. The initial ultrafine grained microstructures have been developed by continuous dynamic recrystallization during isothermal multidirectional forging to a total strain of ~4 at temperatures ranging from 500 to 800°C. The post-dynamic recrystallization involves a rapid softening at early stage of annealing followed by a sluggish decrease of hardness upon further annealing. A transient recrystallization at early annealing stage results in somewhat heterogeneous microstructures in the samples subjected to previous deformation at relatively low temperatures of 500-600°C. This structural heterogeneity disappears with increasing the annealing tim

Microstructure and mechanical properties of austenitic stainless steels after dynamic and post-dynamic recrystallization treatment

The effects of dynamic and post-dynamic recrystallization (DRX and post-DRX) on the microstructure and mechanical properties of austenitic stainless steels are critically reviewed. Particularly, the paper is focused on the grain refinement and strengthening by large strain deformation including severe plastic deformation conditions. The DRX and post-DRX microstructures are considered with close relation to the operative recrystallization mechanism

Properties of bright squeezed vacuum at increasing brightness

A bright squeezed vacuum (BSV) is a nonclassical macroscopic state of light, which is generated through high-gain parametric down-conversion or four-wave mixing. Although the BSV is an important tool in quantum optics and has a lot of applications, its theoretical description is still not complete. In particular, the existing description in terms of Schmidt modes with gain-independent shapes fails to explain the spectral broadening observed in the experiment as the mean number of photons increases. Meanwhile, the semiclassical description accounting for the broadening does not allow us to decouple the intermodal photon-number correlations. In this work, we present a new generalized theoretical approach to describe the spatial properties of a multimode BSV. In the multimode case, one has to take into account the complicated interplay between all involved modes: each plane-wave mode interacts with all other modes, which complicates the problem significantly. The developed approach is based on exchanging the (k, t ) and (ω, z) representations and solving a system of integrodifferential equations. Our approach predicts correctly the dynamics of the Schmidt modes and the broadening of the angular distribution with the increase in the BSV mean photon number due to a stronger pumping. Moreover, the model correctly describes various properties of a widely used experimental configuration with two crystals and an air gap between them, namely, an SU(1,1) interferometer. In particular, it predicts the narrowing of the intensity distribution, the reduction and shift of the side lobes, and the decline in the interference visibility as the mean photon number increases due to stronger pumping. The presented experimental results confirm the validity of the new approach. The model can be easily extended to the case of the frequency spectrum, frequency Schmidt modes, and other experimental configurations

Projective filtering of a single spatial radiation eigenmode

Lossless filtering of a single coherent (Schmidt) mode from spatially multimode radiation is a problem crucial for optics in general and for quantum optics in particular. It becomes especially important in the case of nonclassical light that is fragile to optical losses. An example is bright squeezed vacuum generated via high-gain parametric down conversion or four-wave mixing. Its highly multiphoton and multimode structure offers a huge increase in the information capacity provided that each mode can be addressed separately. However, the nonclassical signature of bright squeezed vacuum, photon-number correlations, are highly susceptible to losses. Here we demonstrate lossless filtering of a single spatial Schmidt mode by projecting the spatial spectrum of bright squeezed vacuum on the eigenmode of a single-mode fiber. Moreover, we show that the first Schmidt mode can be captured by simply maximizing the fiber-coupled intensity. Importantly, the projection operation does not affect the targeted mode and leaves it usable for further applications.Comment: 10 pages, 9 figure

Kinetics of grain refinemet in metallic materials during large strain deformation

The development of ultrafine grained microstructures in austenitic stainless steel and pure titanium subjected to large strain deformation was comparatively studied. The change in the volume fractions of newly developed ultrafine grains was used to quantify the progress in grain refinement during plastic deformatio

Dynamically recrystallized microstructures, textures, and tensile properties of a hot worked high-Mn steel

The deformation microstructures and mechanical properties were studied in a high-Mn steel subjected to hot compression. The deformation microstructures resulted from the development of dynamic recrystallization (DRX). Two DRX mechanisms, namely discontinuous and continuous, operated during warm-to-hot workin

The assessment of research and technical potential in the framework of the innovative model of development of regional economy

This article considers the research and technological potential and the innovative activity in a specific region of Russia — the Kaliningrad region. The authors assess its research and technological potential, and the achieved level of innovative activity in the Kaliningrad region as prerequisites necessary for the implementation of an innovative model of economy. This work identifies the problems of the research and technological potential development of the region, as well as a low level of development of the innovative activity in the Kaliningrad region in general and compared to the Baltic Sea region states. The authors also focus on the prerequisites for the development of research and technological cooperation between the Kaliningrad region and the Baltic Sea region countries. Special attention is paid to the opportunities for the creation of innovative clusters in the Baltic region states

Tensile behavior of an austenitic stainless steel subjected to multidirectional forging

The mechanical behavior of a chromium -nickel austenitic stainless steel with submicrocrystalline structures produced by multidirectional forging (MDF) to a total strain of ∼ 4 at temperatures of 700 and 600° C was studied. This processing resulted in the formation of uniform ultrafine grained structure with an average crystallite size of 360 and 300 nm, respectively, and high dislocation density. The tensile tests were carried out in a wide temperature range 20 -650° C. At ambient temperature, the yield stress (YS) comprised 900 MPa and 730 MPa in the samples subjected to MDF at 600 and 700° C, respectively. It should be noted that this strength was achieved along with elongations of 16% and 22% in the samples subjected to MDF at 600 and 700° C. The YS decreased and elongati on-to-failure tends to increase with increasing test temperature and approaching 235 MPa and 51%, respectively, at 650° C. Effect of temperature on mechanical behavior of stainless steel with submicrocrystalline structure is discusse

Effect of warm to hot rolling on microstructure, texture and mechanical properties of an advanced medium-Mn Steel

The deformation microstructures and mechanical properties were studied in a medium-Mn austenitic steel subjected to warm-to-hot rollin