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Dagoberto Brandão Santos - One of the best experts on this subject based on the ideXlab platform.

  • Mechanical properities of an HSLA bainitic steel subjected to Controlled Rolling with accelerated cooling
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2000
    Co-Authors: P C M Rodrigues, Elena V. Pereloma, Dagoberto Brandão Santos
    Abstract:

    Controlled Rolling followed by accelerated cooling was utilised in laboratory simulations to study the microstructure and mechanical properties of an HSLA low carbon bainitic steel. The effects of processing parameters, such as cooling start temperature and cooling rates, on the final microstructure and mechanical properties were studied. Optical microscopy and transmission electron microscopy were used to evaluate the complex microstructures consisting of polygonal ferrite, pearlite, bainite and martensite/retained austenite constituent. The use of the multiple regression analysis allowed establishment of the relationships between mechanical properties and accelerated cooling variables: cooling rates and cooling start temperatures.

  • simulation of the Controlled Rolling and accelerated cooling of a bainitic steel using torsion testing
    Journal of Materials Processing Technology, 2000
    Co-Authors: Andre Barros Cota, Ronaldo Barbosa, Dagoberto Brandão Santos
    Abstract:

    Controlled Rolling, followed by accelerated cooling, was simulated by means of torsion tests. High-strength low-alloy (HSLA) lowcarbon (0.08%) bainitic steel containing B, recently developed by the industry as a bainitic steel grade of the API X80 class, was examined. The influence of cooling rate and finish-cooling temperature on the microstructure and mechanical properties were studied. The final microstructure was predominantly bainitic. For a finish-cooling temperature of 4008C the microstructure consists of fine laths of bainitic ferrite with interlath MA constituent, and increase in the cooling rate leads to a continuous increase of the tensile and yield strengths of 158 and 183 MPa, respectively. The analysis of the results enabled the establishment of quantitative relationships between the accelerated cooling variables and the mechanical properties of steel. # 2000 Elsevier Science S.A. All rights reserved.

Andre Barros Cota - One of the best experts on this subject based on the ideXlab platform.

  • simulation of the Controlled Rolling and accelerated cooling of a bainitic steel using torsion testing
    Journal of Materials Processing Technology, 2000
    Co-Authors: Andre Barros Cota, Ronaldo Barbosa, Dagoberto Brandão Santos
    Abstract:

    Controlled Rolling, followed by accelerated cooling, was simulated by means of torsion tests. High-strength low-alloy (HSLA) lowcarbon (0.08%) bainitic steel containing B, recently developed by the industry as a bainitic steel grade of the API X80 class, was examined. The influence of cooling rate and finish-cooling temperature on the microstructure and mechanical properties were studied. The final microstructure was predominantly bainitic. For a finish-cooling temperature of 4008C the microstructure consists of fine laths of bainitic ferrite with interlath MA constituent, and increase in the cooling rate leads to a continuous increase of the tensile and yield strengths of 158 and 183 MPa, respectively. The analysis of the results enabled the establishment of quantitative relationships between the accelerated cooling variables and the mechanical properties of steel. # 2000 Elsevier Science S.A. All rights reserved.

L. I. Efron - One of the best experts on this subject based on the ideXlab platform.

  • Effect of deformation regime in main stages of Controlled Rolling on pipe steel microstructure
    Metal Science and Heat Treatment, 2013
    Co-Authors: E. A. Goli-oglu, L. I. Efron, Yu. D. Morozov
    Abstract:

    The effect of Controlled Rolling deformation regimes on features of hot-deformed austenite structure formation and the final microstructure of low-carbon microalloyed pipe steel is studied. The effect of method for performing the Rolling finish stage of grain size and austenite size distribution is established. The effect of deformation level and temperature of the finish Rolling stage on final steel microstructure is studied.

  • Nonuniformity of steel plate mechanical properties after Controlled Rolling with accelerated cooling
    Metallurgist, 2013
    Co-Authors: E. A. Goli-oglu, L. I. Efron
    Abstract:

    The effect of temperature regimes for accelerated cooling in the range 820–590°C on low-carbon microalloyed steel plate microstructure and properties is studied. Microstructure formation features are determined with unequal cooling conditions over a workpiece length during manufacture by Controlled Rolling technology with accelerated cooling. Recommendations are made for improving property uniformity over the length during industrial production.

  • a study of the microstructure of niobium microalloyed pipe steel after different modes of Controlled Rolling with accelerated cooling
    Metal Science and Heat Treatment, 2008
    Co-Authors: Yu M Matrosov, L. I. Efron, A A Kichkina, I V Lyasotskii
    Abstract:

    The phase composition and mechanical properties of rolled thick sheets from pipe steel 05G1MB produced by different modes of Controlled Rolling with accelerated cooling are studied. The effects of the temperature and deformation regime, of the final Rolling temperature, and of the temperature of the start of accelerated cooling on the phase composition of the rolled sheets are considered. The temperature range in which intense reduction during Rolling should be avoided in order to keep niobium in the solid solution of the γ-phase and to ensure subsequent segregation of fine niobium carbides in ferrite is determined.

  • simulating structure forming processes in tube steels during Controlled Rolling with accelerated cooling
    Metallurgist, 2007
    Co-Authors: Yu. I. Matrosov, L. I. Efron, A A Kichkina, A A Efimov, O A Bagmet
    Abstract:

    The technology of combining Controlled Rolling with accelerated cooling (CR + AC) makes it possible to produce thick plates having a unique combination of strength, toughness, cold resistance, and weldability. This technology is characterized by several key parameters (cooling rate, the temperature at which accelerated cooling is ended, etc.), which should be determined and substantiated from the viewpoint of the structure-forming processes that take place in the plate metal. Values of the parameters for CR + AC were obtained by analyzing the results from a study of the phase transformations and structure-forming processes which occur during accelerated cooling.

  • Controlled Rolling OF SKELP ON LOW-POWER MILLS
    Metallurgist, 2004
    Co-Authors: Yu. D. Morozov, L. I. Efron, A. M. Stepashin, I. P. Shabalov
    Abstract:

    Large-diameter pipes are one of the most metal-intensive products that are made. Russian industry annually produces 700,000‐1,000,000 tons of such pipe just to fill the orders placed by Gazpom. The metal of these pipes must meet exacting standards for strength characteristics, low-temperature toughness, ductility, weldability, and cold resistance. The last property is particularly important, and obtaining it requires the use of a special technology. Cold resistance is determined from the results of drop-weight tear tests (DWTT) of specimens of normal thickness. The percentage of the tough component in the fracture of DWTT specimens tested at the service temperature should be at least 85%. After this requirement was incorporated into existing standards, the number of fractures of gas pipelines decreased sharply, brittle fractures longer than one pipe length were completely eliminated (the number of such fractures previously totalled 100 m or more), and it became possible to transport gas in 1420-mm-diam. pipes with a working pressure of 7.5‐10.0 MPa. A special Rolling operation was developed to satisfy the standards on the percentage of the tough component in DWTT specimens. The new technology involved the use of a variable thermomechanical treatment and was given the name Controlled Rolling. This energy-saving technology almost completely replaces the previously used method, which involved quenching, tempering, and double heating. In addition, thanks to the exceptionally fine-grained microstructure of the metal and the presence of texture from the Rolling operation, the new technology is more advantageous that the earlier method in terms of its ability to satisfy the specifications on cold resistance. Controlled Rolling is usually done on specialized reversing mills with an allowable unit load of 1.5‐2.0 tons/mm roll body. The finishing temperature is within the range 700‐800°C. Such characteristics are typical of the finishing stands of modern 5000 mills such as those operated in Japan, Germany, and Italy. In the USSR, the special 3000 mill at the Il’ich Metallurgical Plant has capabilities similar to the above (the allowable pressure on the rolls is 7000 tons). The 3600 mill at the Azovstal’ plant has slightly lower characteristics. In controll ed Rolling, the finishing temperature on the mills may be as low as 670‐690°C. Both of the Mariupol’ mills were left in Ukraine after the breakup of the Soviet Union. Controlled Rolling was not done on reversing mills in Russia due to the low power of the 2800 mills (such as the one at the Ural’skaya Stal’ (Orsk-Khalilovo Metallurgical Combine (OKhMK)) and Severstal’ OAO), while the 5000 mill at the factory in Kolpino required a major overhaul. The first research into Controlled-Rolling regimes for the low-power 2800 mill at the OKhMK (allowable unit load of 2800 tons) was begun in 1993. Following the recommendations of one of the founders of Russian metallurgy ‐ I. P. Bardin ‐ on taking a multi-faceted approach to research, a group of scientists at different institutes (TsNIIchermet, the All-Russia Scientific Research Institute of Hard Alloys (VNIIST ), and the All-Russia Scientific Research Institute of Natural Gas (VNIIGaz)) collaborated with factory specialists at Ural Steel and the Chelyabinsk Pipe Plant (ChTPZ) to conduct studies.

Alireza Fallahi - One of the best experts on this subject based on the ideXlab platform.

  • microstructure properties correlation of dual phase steels produced by Controlled Rolling process
    Journal of Materials Science & Technology, 2009
    Co-Authors: Alireza Fallahi
    Abstract:

    The purpose of this research is to quantify the effects of compositional and processing parameters on the microstructure and properties of dual phase steel produced directly by hot Rolling and rapid cooling. Steels with the basecomposition of 0.1%C, 1.4%Si, and 1.0%Mn with additions of 0.5%Cr to influence hardenability, 0.04%Nb to retard recrystallization in the latter stages of Rolling, or 0.02%Ti to inhibit grain growth during and after reheatingwere investigated. Investigation was made to predict microstructure evolution and to correlate microstructure withprocessing parameters. The effects of the important microstructure parameters such as ferrite grain size, martensitevolume fraction (VM) and morphology (polygonal or fibrous) on the tensile and impact properties are discussed.Multiple linear regression analysis of the ultimate tensile strength has shown that, increasing VM and martensitemicrohardness and grain refinement of ferrite are the major contributions to increase the strength of the steel. It wasfound that the dual-phase steel produced by Controlled Rolling process, with a microstructure which consisted of finegrained ferrite (4μm) and 35%～40% fibrous martensite, presented optimum tensile and impact properties becauseof enhanced resistance to crack propagation.

J. Snopek - One of the best experts on this subject based on the ideXlab platform.

  • Physical simulation of Controlled Rolling and accelerated cooling for ultrafine-grained steel plates
    Archives of Metallurgy and Materials, 2011
    Co-Authors: H. Dyja, Marcin Knapiński, Marcin Kwapisz, J. Snopek
    Abstract:

    Physical Simulation of Controlled Rolling and Accelerated Cooling for Ultrafine-Grained Steel Plates The work shows the possibilities of obtaining ultrafine-grained ferrite-pearlite and ferrite-bainite structures in the process of Controlled Rolling of sheet metal using immediate accelerated cooling after the final pass. Low-carbon steel without micro-alloy additives was analyzed. The analysis was conducted using the Gleeble 3800 device with Hydrawedge II MCU module which enabled a multiple cycle of fast compression of the material. During the test, 10×15×20 mm rectangular parallelepiped specimens were deformed in flat anvils gaining the flat state of deformation in the zone of compression. Then the influence of the used scheme of deformation, cooling rate, time of break between the last deformation and the beginning of the accelerated cooling was analyzed as well as the temperature at the end of accelerated cooling of the structure and the mechanical properties of the final item.