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Samoilovich Y.A.,Research Institute of Metallurgical Heat Engineering VNIIMT
Metallurgist | Year: 2015

Roll steel with a high chromium content (steel 45Kh5MF) is characterized by good hardenability, which provides an opportunity to significantly increase the durability of rolling-mill rolls. Here, the surface layer (working layer) of the rolls is strengthened thanks to the use of a heat treatment that forms a structure of lower bainite while blocking the pearlite transformation of austenite. At the same time, occurrence of the bainite transformation in high-chromium steel requires that the steel be kept in the narrow temperature range associated with this conversion (290–410°C) for a considerable length of time. Large rolls made of steel 45Kh5MF are quenched on a horizontal unit in two stages: intensive water-air cooling for 30–35 min (stage 1); cooling with compressed air for 4–5 h (Stage 2). Such quenching blocks the conversion of austenite to pearlite and ensures the formation of a satisfactorily developed bainitic structure. Efficient regimes for quenching and tempering large rolling-mill rolls were found by using integrated software that makes it possible to track the dynamics of the formation of temporary and residual stresses in rolls. © 2015, Springer Science+Business Media New York. Source


Butkarev A.A.,Research Institute of Metallurgical Heat Engineering VNIIMT
Metallurgist | Year: 2011

Results are presented from practical application of VNIIMT methodology for optimizing the heat-engineering schemes of conveyor-type roasting machines at different combines. Technical innovations that will improve the performance indices of these machines are presented. One example cited is the modernization of roasting machine No. 5 at the Sokolovo-Sarbaiskii Mining-Beneficiation Association, which increased the productivity of the machine by 24.6%, reduced the consumption of natural gas by more than half, and lowered electricpower consumption on the draft equipment by 21.3%.© 2011 Springer Science+Business Media, Inc. Source


Samoilovich Yu.A.,Research Institute of Metallurgical Heat Engineering VNIIMT
Metallurgist | Year: 2012

A method has been developed for calculating the stresses and strains created during the quenching of railroad rails. The use of a generalized heat-conduction equation of the hyperbolic type made it possible to determine the oscillatory character of the changes in temperature, stress, and strain during the thermal shock that accompanies the initial stage of quenching. Another innovative feature of the mathematical model that was constructed is that it accounts for the kinetics of the transformations of austenite into pearlite and martensite during the quenching operation. The results obtained from calculations of the stresses formed during the bulk quenching of rails in oil agree satisfactorily with the experimental data. © 2012 Springer Science+Business Media, Inc. Source


Samoilovich Yu.A.,Research Institute of Metallurgical Heat Engineering VNIIMT
Metallurgist | Year: 2012

Calculation analysis is performed for temperature, strains, and stresses within railway rails during differential quenching for lower bainite. The possibility is demonstrated of a radical reduction in rail buckling with a choice of rational cooling regimes for a rail head and foot. © 2012 Springer Science+Business Media, Inc. Source


Samoilovich Yu.A.,Research Institute of Metallurgical Heat Engineering VNIIMT
Metallurgist | Year: 2011

A mathematical model is presented to describe the thermal stress state of the solidifying skin of the ingot during the continuous casting of peritectic low-carbon steel. A theoretical analysis performed with the use of the proposed model revealed that the magnitude of the tensile stresses in the ingot skin is significantly affected by the increased amount of shrinkage which occurs due to the ω→γ phase transformation. This effect is particularly strong during the intensive heat exchange that takes place near the top edge of the mold. The calculated thermal stresses in the skin are 1.5-2 times greater than the ultimate strength of the steel at temperatures close to the alloy's solidus, which accounts for the high probability of rupture of the skin. © 2011 Springer Science+Business Media, Inc. Source

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