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Date submitted2021-03-10
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Date accepted2021-05-21
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Date published2021-09-20
Influence of heat treatment on the microstructure of steel coils of a heating tube furnace
- Authors:
- Vladimir Yu. Bazhin
- Bashar Issa
Transportation and refining of heavy metal-bearing oil are associated with the problems of localized destruction of metal structures and elements due to corrosion. In the process of equipment operation, it was revealed that premature failure of steel coils of heating tube furnaces at oil refineries and petrochemical plants was associated with insufficient strength and corrosion resistance of the steelwork. The study of the effect that structure and phase composition of 15KH5M-alloy steel elements of heating furnaces at oil refineries have on the corrosion properties, associated with mass loss and localized destructions in the process of heat treatment, allows to develop protective measures and determine heating modes with a rate-limiting step of oxidation. The rate of various corrosion types of 15KH5M steel is used as an indicator to assess the effectiveness of the applied modes of coil heat treatment in order to increase their corrosion resistance and improve their operational characteristics. Conducted experiments on heat treatment of certain steel coil sections allowed to determine rational heating modes for the studied coils, which made it possible to reduce their mass loss and increase corrosion resistance of working surfaces in the process of operation. Proposed heat treatment of steel coils at specified intervals of their operation in the tube furnaces creates conditions for their stable performance and affects the degree of industrial and environmental safety, as well as reduces material costs associated with the repair and replacement of individual assemblies and parts of tube furnaces.
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Date submitted2019-05-20
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Date accepted2019-07-12
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Date published2019-10-23
Development of Manufacturing Technology for High-Strength Hull Steel Reducing Production Cycle and Providing High-Quality Sheets
The article presents the results of scientific research and industrial experiments aimed at the development of technology to reduce the production cycle of high-strength hull steel. The technology includes an improved reduced heat treatment of ingots made using rare-earth metals and uphill teeming of large sheet ingots. The proposed technology for the preliminary heat treatment of ingots eliminates the high-temperature phase re- crystallization operation, which is unnecessary, according to the authors, since it does not allow partial crushing (grinding) of the metal dendritic structure and homogenization. When using the proposed technology of reduced pre- treatment, phase and structural stresses are sharply reduced. Experiments have shown that the modification of steel with rare-earth metals has a positive effect on the crystallization of ingots, changing the macro- and microstructure of alloy steel. The developed manufacturing technology of high-strength hull steel provides a high level of sheet quality and a reduction in the production cycle time by 10-12 %.
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Date submitted2018-07-21
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Date accepted2018-09-14
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Date published2018-12-21
Natural ventilation of gas space in reservoir with internal floating roof
- Authors:
- M. G. Karavaichenko
- N. M. Fathiev
The article deals with safe operation issues of vertical steel reservoirs with an internal floating roof when storing volatile oil products. The purpose of the work is to study the influence of ventilation openings area and wind speed on the duration of explosive state of vertical reservoirs with an internal floating roof. The influence of ventilation pipes' dimensions and the wind speed on the duration of explosive state of the reservoir has been studied. Method for calculating this time is proposed. It is shown that natural ventilation of the reservoir gas space is caused by the effect of two forces, which are formed due to: 1) the density difference between the vapor-air mixture in the reservoir and outside air; 2) wind pressure occurring on the roof of the reservoir. An algorithm for calculating the duration of reservoir being in an explosive state with wind pressure and no wind is obtained. The greater the difference in geodetic marks of the central and peripheral nozzles, the more efficient the ventilation. This distance will be greatest if the lower ventilation pipes are located on the upper belt of the reservoir or the reservoir is equipped with an air drain. Increase in wind speed of more than 10 m/s does not significantly affect the duration of the reservoir being in an explosive state. Increasing the diameter of the central nozzle from 200 to 500 mm can significantly reduce the duration of the reservoir degassing in windless weather.
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Date submitted2018-05-03
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Date accepted2018-07-07
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Date published2018-10-24
Regularities of material destruction of the impactor in repeated single punch
- Authors:
- V. I. Bolobov
- Le Tkhan' Bin
The technique and the results of experiments on the study of the laws of the process of the cone-shaped tip of a freely falling impactor made of 38HM, U8, H12MF steels, subjected to typical heat treatment and additionally treated with cold, when they apply multiple (up to 10000) single impacts on granite under conditions approaching hydraulic impactor peaks. To explain the processes, we used the values of stresses σ к , arising at the contact area of the impactor and the rock, calculated using the developed mathematical model. It has been established that the process of wear of an impactor with multiple single blows proceeds in three stages separated by critical values, , which correspond to the strength characteristics of the material of the impactor demonstrated in these dynamic conditions. With a small number of strokes (n ≤ n * ) and the small size of the blunting area (stage I interaction) values σ c exceed of steel and it is exposed to local destruction at the contact site, which is recorded as a significant loss of the impactor’s mass; with n * < n ≤ n ** (stage II) the resulting stresses are not enough to destroy the material, but it is enough for its plastic deformation, accompanied by the movement of metal from the central part of the contact area to the peripheral and the destruction of part of the deformed metal by rock; with n > n ** (stage III) arising σ к do not reach the level and the decrease in the mass of the impactor is determined by the resistance of the steel to abrasion by the products of rock destruction, displaced by the impactor from the well. The treatment of impactors from all tested steels with cold leads to an increase in their wear resistance; The total depth of the holes punctured by the cold-treated H12MF steel impactor at the time of the interruption of the rock penetration is four times higher than that of the 38HM steel impactor subjected to typical heat treatment.
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Date submitted2009-08-13
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Date accepted2009-10-29
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Date published2010-02-01
Analysis of statistical data of lecture of the alloyed steels
- Authors:
- R. V. Kurtenkov
Influence of a chemical compound on the carbon contents in a steel is analysed, in the course of processing of month basic data the mathematical model is received, it is offered optimum significances of source parametres at the carbon contents in a steel.
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Date submitted1958-03-29
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Date accepted1958-05-05
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Date published1958-05-09
ЗАВИСИМОСТЬ МИНЕРАЛЬНЫХ АССОЦИАЦИЙ ХРУСТАЛЬНЫХ ГНЕЗД ПРИПОЛЯРНОГО УРАЛА ОТ ХИМИЧЕСКОГО СОСТАВА ВМЕЩАЮЩИХ ПОРОД
- Authors:
- Unknown
Большинство исследователей месторождений горного хрусталя, Приполярного Урала считает, что компоненты, входящие в состав минералов гнезд, вынесены гидротермальными растворами из магматического очага. Посмотрим, насколько это широко распространенное мнение подтверждается фактическим материалом при более или менее детальном исследовании состава вмещающих пород и хрустальных гнезд. Поразительное сходство валового химического состава минералов хрустальных гнезд и вмещающих пород бросается в глаза даже при беглом знакомстве с химическими анализами. Химические анализы показывают, что минералы хрустальных гнезд Приполярного Урала состоят из следующих компонентов: Si 0 2 , А1 2 0 3 , FeO , MgO . CaO , Na 2 0, K 2 O , Fe 2 0 3 , Ti 0 2 , MnO , H 2 0 и C 0 2 . Все эти компоненты входят и в состав пород, вмещающих хрустальные гнезда. Характерно, что количественные соотношения между указанными компонентами почти одинаковы как в общем составе минералов гнездового выполнения, так и во вмещающих хрустальные гнезда породах.