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Rybin V.V.,Saint Petersburg State University | Zolotorevskii N.Y.,Saint Petersburg State University | Ushanova E.A.,Central Research Institute of Structural Materials Prometey
Technical Physics

The existing concepts of the mechanisms of forming fragmented structures under the conditions of severe plastic deformation of crystalline solids are analytically reviewed. The translational and rotational plasticity modes that develop at micro- and mesoscopic structural levels, respectively, are sequentially taken into account. This allows us to correctly describe the morphological features of the evolution of fragmented structures, to predict misorientation spectra for various fragmentation mechanisms, and to determine the partial contribution of each mechanism in the cases where several deformation grain refinement mechanisms are involved in fragmentation. The computer simulation of deformation-induced misorientation spectra that was developed using these concepts is a new method for studying the physical nature of structure formation processes, and this method can be applied for various materials, temperature-rate deformation conditions, and technological loading schemes. As an example, we comprehensively consider the formation of fragmented structures under the extreme conditions of explosion welding of commercial-purity copper plates. A comparison of the model misorientation spectra calculated for a reference structure and the fragmented structure in the near-contact zone of the welded joint with the existing experimental data demonstrates the efficiency and reliability of the proposed method. © 2014, Pleiades Publishing, Ltd. Source

Zolotorevsky N.Y.,Polytechnic University of Mozambique | Panpurin S.N.,Polytechnic University of Mozambique | Zisman A.A.,Central University of Costa Rica | Petrov S.N.,Central Research Institute of Structural Materials Prometey
Materials Characterization

A method to determine the orientation relationship (OR) in bainitic and martensitic transformations has been employed that does not use reconstruction of prior austenite grains. It is shown that the method keeps accuracy regardless of orientation non-uniformity induced inside austenite grains by hot deformation. The revealed OR behavior for bainite formed under continuous cooling agrees with its temperature dependence previously found in case of isothermal transformation. Ausforming effect on the OR detected in martensite is presumably due to deformation induced subgrains separated by low-angle dislocation boundaries. © 2015 Elsevier Inc. All rights reserved. Source

Margolin B.,Central Research Institute of Structural Materials Prometey | Sorokin A.,Central Research Institute of Structural Materials Prometey
Journal of Nuclear Materials

A drastic decrease in the ultimate tensile strength of irradiated austenitic steels with high swelling values is considered. The physical-mechanical model proposed in Part 1 of the present paper is applied for the prediction of a drastic decrease in ultimate tensile strength. The mechanism called by the authors the "running collapse mechanism" is used for modeling the material ductile fracture when stresses are less than the yield strength. This ductile mechanism is similar to brittle fracture when crack propagates unstable manner. Running collapse mechanism occurs due to evolution of vacancy voids resulting in irradiation swelling. Nanoscale of vacancy voids (void sizes, distance between voids) results in the possibility of ductile fracture in very small zones whose size is considerably smaller than the grain size. © 2014 Elsevier B.V. All rights reserved. Source

Il'In A.V.,Central Research Institute of Structural Materials Prometey | Sadkin K.E.,Central Research Institute of Structural Materials Prometey
Inorganic Materials: Applied Research

According to the current standards, predominantly two methods are used to evaluate the fatigue strength of welded joints: the method of the S-N curves that involves every type of welded joints and the so- called hot-spot-stress method that uses a common fatigue curve for a butt-welded joint and a procedure to assess the structural stress concentration for the joints of other types. The numerical finite element analysis using three-dimensional elements with an exact simulation of the geometry of hull structure welded joints showed mutual disagreement of both methods and the possibility to refine the calculation procedures based on interpolation formulas for assessment of the stress concentration in welded joints. Original Russian Text © M.L. Fedoseev, A.V. Ptashnik, S.N. Petrov, B.K. Barakhtin, Yu.A. Utkin, 2013. Source

Vaynerman A.A.,Central Research Institute of Structural Materials Prometey | Vaynerman A.E.,Central Research Institute of Structural Materials Prometey
Tsvetnye Metally

Nowadays, new austenite nitrogenous steel (Fe-Cr-Ni-Mn-N composition) is more applied to manufacturing of sea technical equipment structures, which obtaining requires copper alloy welding with this steel. Copper alloy welding with new austenite nitrogenous steel has the following peculiarities: eventual boiling of weld pool; nitrogen emission; formation of cracks in steel; partially contained copper alloy and formation nitrides in weld metal. Application of sublayer, cladded by EW-263ESR wire on this steel, together with scraping of base metal and acid-etching of filler metal, are necessary for receiving of qualitative welded joints of copper alloys with new austenite nitrogenous steel. Optimum conditions of TIG-welding deposition of sublayer, cladded by EW-263ESR wire on the steel was researched and installed together with amount of cladded layers of this sublayer metal, its optimum composition and metal structure, providing the absence of cracks and other defects, values of tensile strength and impact strength at steel level. There is shown the necessity of second sublayer, cladded by CuNiFeSiTi 5-1-0,2-0,2 wire on sublayer, cladded by EW-263ESR wire on Cr-Ni-Mn-N composition. On the basis of these researches, there was developed the process of TIG-welding of CuNiFe 5-1 grade alloy with new austenite nitrogenous steel composition thickness up to 15 mm grade, providing the quality of weld, tensile strength (CuNiFe 5-1 grade alloy) and high values of impact strength. Source

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