Journal articles: 'Kinetics of hot rolled steel'

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Yang, Wang Yue, Long Fei Li, Yun Yang Yin, Zu Qing Sun, and Xi Tao Wang. "Hot-Rolled TRIP Steels Based on Dynamic Transformation of Undercooled Austenite." Materials Science Forum 654-656 (June 2010): 250–53. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.250.

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A novel thermomechanical process to manufacture hot-rolled transformation-induced plasticity (TRIP) steels was developed based on dynamic transformation of undercooled austenite (DTUA). Between DTUA and the isothermal bainitic treatment, only one-step controlled-cooling was required. The microstructure evolution of hot-rolled C-Mn-Si and C-Mn-Al-Si TRIP steels based on DTUA was investigated by hot uniaxial compression tests using a Gleeble1500 simulation test machine. The results indicated that during DTUA, the kinetics of ferrite formation was fast, the volume fraction of ferrite formed was determined by applied strain. In comparison with the process based on static transformation of austenite, a more uniform multiphase microstructure with fine ferrite grains was formed, the bainite packets were small and had relatively random orientations, the retained austenite distributed uniformly and had relatively high volume fraction. Hot-rolled TRIP steels based on DTUA demonstrated better mechanical properties, especially for C-Mn-Al-Si TRIP steel.

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Melo, Tulio M. F., Érica Ribeiro, Lorena Dutra, and Dagoberto Brandão Santos. "Low C High Mn Cold Rolled TWIP Steel: Kinetics of Isothermal Recrystallization." Materials Science Forum 706-709 (January 2012): 2181–86. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2181.

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The increasing demand, mainly from the automobile industry, for materials which combine high strength, high ductility and low specific weight makes steels with the TWIP (TWinning Induced Plasticity) effect a promising material to meet these requirements. This work aimed to study the kinetics of isothermal recrystallization of a TWIP steel (C-0.06%, Mn-25%, Al-3%, Si-2%, and Ni-1%) after cold rolling. The steel was hot and cold-rolled and then annealed at 700°C with soaking times ranging from 10 to 7200 s. Microstructural analysis was performed using light (LM) and scanning electron microscopy (SEM). Furthermore, quantitative metallography was performed in order to evaluate the recrystallized volume fraction and grain size. A JMAK based model was applied to describe the nucleation grain growth process. The restoration of the steel was also evaluated by microhardness tests. A complete recrystallization after 7200 s at 700°C was observed. It was found that with increasing annealing times, the recrystallized volume fraction also increases, while the nucleation and growth rates decrease, in agreement with the results for plain carbon steels.

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Mohanty, R. R., and O. A. Girina. "Effect of Coiling Temperature on Kinetics of Austenite Formation in Cold Rolled Advanced High Strength Steels." Materials Science Forum 706-709 (January 2012): 2112–17. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2112.

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A systematic experimental investigation was conducted using lab processed low carbon 0.08C-2.0Mn-Cr-Mo steel microalloyed with Ti/Nb to evaluate the influence of initial hot-rolled microstructures on the kinetics of austenite formation and decomposition after cold-rolling and subsequent annealing. Coiling temperature as a major hot rolling parameter was used to obtain different types of hot-rolled microstructures. Dilatometer and continuous annealing simulator were employed for austenite formation studies and annealing simulations, respectively. It was found that the coiling temperature affects the processes occurring during heat treatment in continuous annealing lines of full hard material: ferrite recrystallization, austenite formation during continuous heating and austenite decomposition during cooling. A decrease in coiling temperature accelerates the recrystallization of ferrite and nucleation of austenite, which results in formation of refined ferrite-martensite structure. The effect of initial hot rolled structure on final mechanical properties after continuous annealing was also investigated.

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Jain, N. K. "Kinetics of hot deformation in electroslag refined and hot rolled & annealed En 36 steel." High Temperature Technology 3, no. 1 (February 1985): 35–40. http://dx.doi.org/10.1080/02619180.1985.11753277.

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Malta, Paula Oliveira, Iane Dutra Moutinho, Davi Silva Alves, Aline Vasconcelos Ferreira, and Dagoberto Brandão Santos. "Recrystallization Kinetics and Texture Evolution of Nb Stabilized Ferritic 430 Stainless Steel Cold Rolled and Isothermal Annealed." Materials Science Forum 879 (November 2016): 1656–61. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1656.

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The ferritic stainless steel type 430 stabilized with Nb, with and without annealing after hot rolling, was cold rolled and subjected to isothermal annealing at temperatures 650, 700 and 750°C for times ranging between 10 to 86400 s. The recrystallization kinetics was evaluated by JMAK model through microhardness measurements and KAM and GOS parameters. The Avrami exponent data indicate the occurrence of an unidimensional grain growth due only to high angle boundaries migration, with values ranging between 0.9 and 1.2. The nucleation rate and grain growth decreased continuously with time. The evolution of the texture was analyzed via EBSD analysis by ODF maps. The steel recrystallization is based on combination of ON and SG theories, due to presence of {111}<121>, {554}<225> and {111}<112> related to γ fiber. The rotated cube component, feature of the hot rolled steel, decreased with annealing time.

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Rodriguez-Calvillo, Pablo, R. Rouco, and Yvan Houbaert. "Growth Kinetics of Al-Si-Fe Intermetallics during Hot Dipping of Steel." Defect and Diffusion Forum 273-276 (February 2008): 58–62. http://dx.doi.org/10.4028/www.scientific.net/ddf.273-276.58.

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Electrical steels are used in flux carrying machines, divided in grain oriented and non oriented electrical steels mainly used in transformers and electrical motors, respectively. Their industrial production is not always easy due to the alloying elements which produce brittle order structures in the steel. Therefore hot dipping was found to be an alternative way of producing electrical steel with a high concentration of Al and/or Si: in a first series of experiments different steel substrates were coated by immersion in an Al + 23 m.-% Si hypereutectic alloy, followed by a high temperature diffusion annealing. The present contribution reports on the growth kinetics of Al-Si-Fe intermetallics formed during the dipping process in a hypoeutectic Al – 5 m.-% Si bath of Fe-substrates with 3 m.-% Si, previously cold rolled to different thickness. This bath composition allows a liquid phase at temperatures lower than the hypereutectic one with 23 m.-% Si and also less amount of eutectic formation. No Na-addition was made to the bath (the occurrence of a needle-like morphology of the Al-Si eutectic was not relevant for these experiments), furthermore this element might lower the magnetic properties of the steel. The preheating of samples and bath temperatures were not varied and set to 670°C. Short dipping times of 1 to 60 sec. were applied. The different layers formed were characterised by Scanning Electron Microscopy (SEM), using the Back Scattered Electron (BSE) detector and Energy Dispersive Spectroscopy (EDS).

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Rodriguez-Calvillo, Pablo, Lucia Suarez, and Yvan Houbaert. "Al-Si-Fe Intermetallics on Fe-Substrates during Hot-Dipping." Defect and Diffusion Forum 297-301 (April 2010): 1042–47. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.1042.

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Steels alloyed with Si and Al are used as core material in flux carrying machines, they are commonly called electrical steels, divided into grain oriented and non-oriented when a material without magnetic anisotropy or not is desired and used in transformer and electrical motors, respectively. The appearance of brittle ordered structures when Si+Al content in steel is above 4 m.-% does not always make its industrial production easy. Therefore hot dipping in a Al-Si bath followed by a diffusion annealing was found to be a productive way of steels with high Si and/or Al concentration and to overcome the creation of fragile structures during deformation processes, such as rolling. The formation of different layered Al-(Si)-Fe intermetallics on the steel substrate depends on diverse processing parameters such as bath temperature and composition, immersion time, preheating of the steel substrate and its composition and cooling down to room temperature. This contribution reports the diffusion kinetics of Fe2Al5 products obtained during the hot dipping process in an Al iron saturated and a hypoeutectic Al – 5 m.-% Si baths of ultra low carbon steel and Fe-substrates with 3 m.-% Si, annealed and cold rolled to different thicknesses. The preheating of the samples and bath temperatures were varied between 670 to750°C. Dipping times between 1 to 600 sec. were applied. The different layers and compounds formed were characterized by Scanning Electron Microscopy (SEM), using Back Scattered Electron (BSE) detector and Energy Dispersive Spectroscopy (EDS). The influence of the substrate and bath chemical composition on the growth kinetics of the Fe2Al5 intermetallics was investigated assuming a parabolic law. Si addition retards the growth kinetics and, as result, raises the activation energy from 71.3 to 159.8 kJmol-1, the obtained results are in agreement with the literature.

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de las Cuevas, F., Mónica Reis, A. Ferraiuolo, G. Pratolongo, L. Pentti Karjalainen, V. García Navas, and J. Gil Sevillano. "Kinetics of Recrystallization and Grain Growth of Cold Rolled TWIP Steel." Advanced Materials Research 89-91 (January 2010): 153–58. http://dx.doi.org/10.4028/www.scientific.net/amr.89-91.153.

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Hot rolled, laboratory-cast, TWIP steel samples (5.4 mm thick) of 22% Mn - 0.6% C (in mass-%) were cold rolled to different reductions (from 40 % to 70 %) and subsequently isothermally annealed for various times at temperatures ranging from 450º C to 1100º C. The evolution of recrystallization and grain growth was followed by control of the softening kinetics complemented by metallographic, OIM and microtexture observations. A map of the recovery, recrystallization and grain growth in the temperature-time space was obtained. In all instances, the grain size at the end of recrystallization was very fine, D ≤ 2 µm and larger grain sizes were the result of grain growth. A range of grain sizes 2 µm ≤ D ≤ 50 µm was covered by the grain growth experiments. A phenomenological grain growth equation that is useful for the annealing control of this steel was derived from the measurements.

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Gutiérrez, Emmanuel J., and Armando Salinas. "Decarburization of Hot-Rolled Non-Oriented Electrical Steels." MRS Proceedings 1485 (2012): 119–24. http://dx.doi.org/10.1557/opl.2013.279.

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ABSTRACTThe high temperature decarburization-oxidation behavior of hot rolled, non-oriented electrical steel strips is investigated during air-annealing treatments. Annealing temperature and time are varied from 700 – 1050 °C and 10 to 150 min, respectively. The experimental results show that uniform external oxidation affects strongly the rate at which carbon can be removed from this material. The thickness of the oxide layer formed after 150 minutes of annealing increases linearly with increasing temperature in the range 828 and 920 °C. The effect of temperature on the thickness of the oxide scale at temperatures outside this range is significantly smaller. These results indicate that the rate of oxidation in this material is strongly influenced by the microstructure of the steel during annealing. Decarburization rates are very slow during annealing at T ≤ 750 °C where the oxide layer is thin and porous. In contrast, fast and intense decarburization of the strips is observed as a result of annealing at temperatures between 800 and 850 °C. Finally, decarburization at T ≥ 875 °C becomes slower as the temperature is increased until at T ≥ 950 °C this process is practically inhibited. Measurements of C content as a function of time and temperature show that the observed decarburization kinetics follows Wagner’s model at 800 and 850 °C. However, at higher annealing temperatures decarburization is slower than that predicted by the model. This behavior is related to the increment of the oxide scale thickness and a transition from cracked to crack-free oxide structure which makes C diffusion through the oxide film very difficult.

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Jacolot, Ronan, Didier Huin, Artem Marmulev, and Eliette Mathey. "Hot Rolled Coil Property Heterogeneities due to Coil Cooling: Impact and Prediction." Key Engineering Materials 622-623 (September 2014): 919–28. http://dx.doi.org/10.4028/www.scientific.net/kem.622-623.919.

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The importance of coil cooling conditions on mechanical properties uniformity of HSLA and AHSS steel grades is discussed. It is namely shown that hot rolled coil under conventional industrial production can be cooled non-uniformly. That is why to predict correctly the final steel microstructure and mechanical properties of hot-rolled products an accurate description of not only run-out table condition but also of coil cooling should be done. Two solutions to provide accurate description of coil cooling were tested. First one is to use 2D finite element (FE) thermal model. When coupled with the ArcelorMittal metallurgical model to predict hot-rolled microstructure and properties (TACSI) it matches well the industrial data within +/-15-20MPa both for the tensile and yield strength. However, this approach is recognized to be heavy and time consuming. A second solution, a new 2D coil cooling simplified model incorporated in TACSI model, proved to be quite efficient, as it leads to performances similar to the more detailed first solution. Moreover, it is able to compute the coupling between the thermal evolution of the hot band and the kinetics of phase transformation during coil coiling and cooling, and will enable a better evaluation of the final mechanical properties especially for the grades for which the phase transformation is not completed before hot band coiling.

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Ariati, Myrna, Azwar Manaf, and Eddy S. Siradj. "Effect of Cooling Rate and Nb Composition on Non-Isothermal Austenite Grain Growth Kinetics in Nb-HSLA Steel during Hot Rolling." Advanced Materials Research 479-481 (February 2012): 414–20. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.414.

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Abstract. The strength of a final product of steel is affected by its final austenite grain size.Almost applied models for grain growth based on Beck and Sellars equation , which has the isothermal condition assumption; whilst most of the materials processing take place under non-isothermal condition. The purpose of this research is to find the effect of Nb and cooling rate to the austenite grain growth model of HSLA-Nb steel to predict the Austenite grain size after hot rolling process in non-isothermal condition .The two composition of 0.019 and 0.056% Nb of HSLA-Nb was hot-rolled about 0.3-0.4 deformation at a temperature of 900-11000 C, followed by cooling rate of 7-11 0 C/s, in a time period of 25-40 second, and quenched by using water jetspray. Austenite final grain size was measured . The work shows that the higher Nb content of steel with higher cooling rate will reduce the final austenite grain size . It was also found that the new non-isothermal austenite grain growth after hot-rolled illustrated as a function of cooling rate,which obtained by modifying the previous established model by a cooling rate parameter 1/Crm, and it was more precision compared to previous grain growth equation.

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Santos, Dagoberto Brandao, Berenice Mendonça Gonzalez, and Elena V. Pereloma. "Recrystallization and Mechanical Behavior of High Mn and Low C Cold Rolled and Annealed Steel with TWIP Effect." Materials Science Forum 715-716 (April 2012): 579–84. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.579.

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ncreasing demand for automotive vehicles with reduced weight, improved crashworthiness and passengers safety has steamed the research of new Twinning Induced Plasticity (TWIP) steels. In this work the effect of annealing between 400 and 900°C on the microstructure and mechanical properties of hot and cold rolled 0.06C-24Mn-3Al-2Si-1Ni (wt%) steel with TWIP effect was investigated. The results have shown that steel exhibits fast recrystallization kinetics with a low amount of recovery, which results in a high driving force for the former. Mechanical properties were determined using Vickers microhardness and tensile tests. Tensile strength of 670 MPa with 54% of total elongation, and strain hardening exponent of 0.57 were reached after annealing at 900°C.

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Siqueira, Rodrigo P., Hugo Ricardo Zschommler Sandim, and Tarcisio R. Oliveira. "Recrystallization of Coarse-Grained Nb-Containing AISI-430 Ferritic Stainless Steel." Materials Science Forum 638-642 (January 2010): 3009–14. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.3009.

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Ferritic stainless steels (FSSs) have excellent corrosion resistance and good mechanical properties. Applications include heaters, houseware, and automotive exhaust systems. Alloying, even in small amounts, affects the recrystallization behavior of FSSs by selective dragging or pinning effects. In the present study, we present the main results regarding the recrystallization of a coarse-grained Nb-containing AISI 430 ferritic stainless steel. The material was processed by hot rolling and further annealed at 1250oC for 2 h to promote secondary recrystallization. Following, the material was cold rolled to a 80% reduction in thickness and annealed at 400-1000oC for 15 min. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were used to characterize the microstructure. Recrystallization of this steel begins at 700oC. Important orientation effects were observed in both as-rolled and annealed conditions. Recrystallization kinetics was strongly dependent on the initial orientation of the coarse grains. Results show that grain boundaries, transition bands and coarse Nb(C,N) particles are preferential sites for nucleation at moderate annealing temperatures.

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Yu, Xianglong, Zhengyi Jiang, Dongbin Wei, Xiaodong Wang, and Quan Yang. "Modelling of Temperature-Dependent Growth Kinetics of Oxide Scale on Hot-Rolled Steel Strip." Advanced Science Letters 13, no. 1 (June 30, 2012): 219–23. http://dx.doi.org/10.1166/asl.2012.3771.

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Sun, Bin, Lei Cheng, Chong-Yang Du, Jing-Ke Zhang, Yong-Quan He, and Guang-Ming Cao. "Effect of Oxide Scale Microstructure on Atmospheric Corrosion Behavior of Hot Rolled Steel Strip." Coatings 11, no. 5 (April 28, 2021): 517. http://dx.doi.org/10.3390/coatings11050517.

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The atmospheric corrosion behavior of a hot-rolled strip with four types (I–IV) of oxide scale was investigated using the accelerated wet–dry cycle corrosion test. Corrosion resistance and porosity of oxide scale were studied by potentiometric polarization measurements. Characterization of samples after 80 cycles of the wet–dry corrosion test showed that scale comprised wüstite and magnetite had strongest corrosion resistance. Oxide scale composed of inner magnetite/iron (>70%) and an outer magnetite layer had the weakest corrosion resistance. The corrosion kinetics (weight gain) of each type of oxide scale followed an initial linear and then parabolic (at middle to late corrosion) relationship. This could be predicted by a simple kinetic model which showed good agreement with the experimental results. Analysis of the potentiometric polarization curves, obtained from oxide coated steel electrodes, revealed that the type I oxide scale had the highest porosity, and the corrosion mechanism resulted from the joint effects of electrochemical behavior and the porosity of the oxide scale. In the initial stage of corrosion, the corrosion product nucleated and an outer rust layer formed. As the thickness of outer rust layer increased, the corrosion product developed on the scale defects. An inner rust layer then formed in the localized pits as crack growth of the scale. This attacked the scale and expanded into the substrate during the later stage of corrosion. At this stage, the protective effect of the oxide scale was lost.

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Karjalainen, L. Pentti, Mahesh C. Somani, and Atef S. Hamada. "Application of Physical Simulation for Developing New Steel Types." Materials Science Forum 575-578 (April 2008): 1002–7. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1002.

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Processing of a large number of novel steel types, such as DP, TRIP, CP and TWIP, and high-strength low-carbon bainitic and martensitic DQ-T steels, have been developed based on physical simulation and modelling studies. Among stainless steels, guidelines for processing of ultra-fine grained austenitic stainless steels have been created. Physical simulation has been used by employing a Gleeble thermo-mechanical simulator to reveal the phenomena occurring in the hot rolling stage (the flow resistance, recrystallization kinetics and microstructure evolution), and in the cooling stage (CCT diagrams) for carbon steels and in short-term annealing of cold rolled metastable austenitic steels. Connecting these data with microstructures examined in optical and electron microscopes and resultant mechanical properties have improved the understanding on complex phenomena occurring in the processing of these steels and the role of numerous process variables in the optimization of enhanced mechanical properties.

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Altamirano-Guerrero, Gerardo, Emmanuel J. Gutiérrez-Castañeda, Omar García-Rincón, and Armando Salinas-Rodríguez. "Experimental Determination of Continuous Cooling Transformation Diagrams of Hot-Rolled Heat Treatable Steel Plates Using Quenching Dilatometry." MRS Proceedings 1812 (2016): 129–34. http://dx.doi.org/10.1557/opl.2016.29.

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ABSTRACTThis article outlines the use of quenching dilatometry in phase transformation kinetics research in steels under continuous cooling conditions. For this purpose, the phase transformation behavior of a hot-rolled heat treatable steel was investigated over the cooling rate range of 0.1 to 200 °C/s. The start and finish points of the austenite transformation were identified from the dilatometric curves and then the continuous cooling transformation (CCT) diagrams were constructed. The experimental CCT diagrams were verified by microstructural characterization using scanning electron microscopy (SEM) and Vickers micro-hardness. In general, results revealed that the quenching dilatometry technique is a powerful tool for the characterization and study of solid-solid phase transformations in steels. For cooling rates between 200 and 25 °C/s the final microstructure consists on plate-like martensite with the highest hardness values. By contrast, a mixture of phases of ferrite, bainite and pearlite predominated for slower cooling rates (10-0.1 °C/s).

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Herrera, Clara, Dirk Ponge, and Dierk Raabe. "Recrystallization during Annealing of a Cold Rolled Lean Duplex Stainless Steel." Materials Science Forum 715-716 (April 2012): 550. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.550.

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Duplex stainless steels (DSSs) are based on the Fe-Cr-Ni system and formed by ferrite (30-70%) and austenite. They have high tensile strength, good toughness and weldability and excellent corrosion resistance including stress-corrosion cracking and resistance to localized corrosion. The increase of the raw materials of the last years, there has been a motivation to develop new stainless steels with lower contents of nickel and molybdenum. Lean duplex stainless steels (LDSSs) are almost Mo free and nickel content lower than 4%. The lean duplex grades are expected to substitute not only 304/316 grades but also other duplex stainless steel grades. LDSSs are used for structural applications and for the less corrosion conditions such as liquor tanks and suction rolls. The aim of the present work was to study the kinetics of recovery and recrystallization of the lean duplex stainless steel 1.4362 during annealing treatment. The material was subjected to hot rolling and cold rolling of 70%, annealing treatment for different times at temperatures from 1000 to 1100°C and subsequently water quenched. Optical microscopy and electron back scattering diffraction (EBSD) were employed to study the evolution of the microstructure during the annealing treatment. After cold rolling austenite exhibited more strain hardening than ferrite. Consequently, the driving force of the austenite for recrystallization is higher. During annealing, recovery took place in ferrite, while the austenite remained nearly unrecovered until beginning of recrystallization. The layered grain morphology produced during cold rolling remained after the annealing treatment. The volume fraction of the phases did not show significant changes with the annealing time. Nevertheless, the volume fraction of austenite decline with an increasing of annealing temperature. After 60 seconds at 1100°C, annealing primary recrystallization had progressed in both phases, which show a bamboo-structure where the grain boundaries ran perpendicular to the phase boundaries. Grain growth progressed for longer annealing times. After 600 seconds, the bamboo-structure started to change for a more globular grain structure, pearl-structure. It continued and became more pronounced at longer annealing times. At lower temperatures, the recrystallization behavior is similar; however, the structure was refined. Recovery is favored by the high stacking fault energy of ferrite and the layered grain morphology. The lean duplex stainless steel 1.4362 shows a similar recrystallization kinetics compare with standard duplex stainless steels.

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Hosseini, Vahid A., Kristina Lindgren, Mattias Thuvander, Daniel Gonzalez, James Oliver, and Leif Karlsson. "Nanoscale phase separations in as-fabricated thick super duplex stainless steels." Journal of Materials Science 56, no. 21 (April 19, 2021): 12475–85. http://dx.doi.org/10.1007/s10853-021-06056-0.

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AbstractNanoscale phase separations, and effects of these, were studied for thick super duplex stainless steel products by atom probe tomography and mechanical testing. Although nanoscale phase separations typically occur during long-time service at intermediate temperatures (300–500° C, our results show that slowly cooled products start to develop Fe and Cr separation and/or precipitation of Cu-rich particles already during fabrication. Copper significantly slowed down the kinetics at the expense of Cu-rich particle precipitation, where the high-copper material subjected to hot isostatic pressing (HIP), with Δt500–400 of 160 s and the low-copper hot-rolled plate with Δt500–400 of 2 s had the same level of Fe and Cr separation. The phase separations resulted in lower toughness and higher hardness of the HIP material than for hot-rolled plate. Therefore, both local cooling rate dependent and alloy composition governed variations of phase separations can be expected in as-fabricated condition.

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Reyes Barragan, Jose Luis, Roberto Ademar Rodriguez Diaz, Maria Luisa Ojeda Martinez, Silvia Gaona Jimenez, and Julio Alberto Juarez Islas. "Effect of Isothermal Treatment on Microstructure and Mechanical Properties of Cold-Deformed IF Steel." Advances in Materials Science and Engineering 2019 (March 12, 2019): 1–13. http://dx.doi.org/10.1155/2019/8674323.

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In this study, we investigated the recrystallisation kinetics of Ti-stabilised interstitial-free (IF) steel manufactured by the Mexican steel industry through the route of electric arc furnace with vacuum degassing, secondary refining, and subsequent continuous casting. The IF steel was hot-rolled at 950°C and then cold-rolled until deformation of 94% was attained, followed by recrystallisation at different times at a constant temperature of 780°C. In addition, the mechanical properties of the IF steel were assessed as a function of recrystallisation time. The results obtained from the mechanical property tests were presented in the form of plots of microhardness, yield strength, ultimate tensile stress, and deformation percent as functions of the recrystallised fraction with an indirect dependence on recrystallisation time. A graphical model of the recrystallisation behaviour showed the evolution of the microstructure, including phase transformations, hardness, and the mechanical properties determined from the tensile tests. In view of subsequent recovery and recrystallisation, stored energy analysis derived from the strain induced by deformation was presented. Furthermore, we determined the precipitates formed in the different processing stages of IF steel.

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Zaitsev, A. I. "Perspective directions of metallurgy and steel metal science development." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 75, no. 4 (May 18, 2019): 417–25. http://dx.doi.org/10.32339/0135-5910-2019-4-417-425.

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The task of principal (multiple) increase of complex of service parameters (often being hard compatible) and steel quality under conditions of costs decrease becomes more and more actual. The solution is possible by creation and application of new principles and approaches based, first of all, on adequate physical and chemical predicting methods and effective technological skill of control non-metallic inclusions, forms of impurities, phase isolations, structure state, including homogeneity of the metal volume. A complex approach to prediction, analysis of phase composition, structure state and steel properties elaborated to implement this progressive direction. It has an important feature like elaborated in details scientific principles. The principles allow not only to make effective the development of new steel and technologies of their production at minimum costs, but also to reveal the content, directions and intensity of processes having place during metal processing. It was illustrated at the example of microalloyed (stabilized) by titanium super-high-carbon IF steel. Importance of accounting of regularity of phase isolations forming kinetics shown, that can result in considerable change of their characteristics and steel properties. This circumstance can be used for unification of chemical composition or development of cassette technologies production, for example, from IF-steels of the same chemical composition, of rolled products of different assortment or strength class. It was shown, that the complex phase isolations forming takes place with participation impurities and elements presented in the steel. Therefore there arose wide possibilities of considerable increase of complex of properties at decreasing of costs. Presence of deformation considerably accelerates the processes of nano-size phase isolations forming not only during rolling, but also during parts manufacturing by hot stamping, combined with steel quenching. This allows to increase their strength by 300–400 MPa additionally to martensitic structure. It is possible, apart from principal perfection of parameters of service characteristics stability, to reach considerable increase of composition homogeneity, structure and properties in the whole metal volume by non-metallic inclusions forming control. Forming of silicate glassy inclusions in low-alloyed steels improves principally the macro- and microstructure of CC billet and impact toughness of rolled products KCV–40 (420–445 J/сm2 ). Their presence in the steel stipulated by kinetic reasons. Additional substantial increase of composition homogeneity, structure and microalloyed steels properties can be reached during the rolling process by return redistribution of components from the axis zone to the surface of the rolled product. High efficiency of the above-mentioned approaches at present has been confirmed by development an array of pipe, structural, automobile steels and highly efficient technologies of their production.

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Jansto, Steven G. "Reheat Furnace Thermodynamic, Kinetic and Combustion Considerations for TMCP Processing." Materials Science Forum 941 (December 2018): 608–13. http://dx.doi.org/10.4028/www.scientific.net/msf.941.608.

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The reheat furnace process step has a profound effect on the TMCP performance, final hot rolled steel quality and mechanical property consistency during the production of hot rolled steels. The uniformity of heating applied across the entire width and length of the slab or billet is critical in the achievement of customer properties regardless of the chemistry. The resultant ferrite grain size in the final hot rolled product is significantly governed by the initial prior austenite grain size. Numerous reheat furnace process metallurgy and combustion parameters in actual operation affect mill productivity, microstructure, austenite grain size, scrap rate and diverts. This reheating step in the steelmaking process often receives low priority in the evaluation of product quality and mechanical property performance, especially the toughness through the plate thickness. Heat transfer conditions of radiation, convection and conduction affect furnace heating efficiency. In laboratory studies, the furnace heating step is typically quite uniform resulting in a homogeneous and fine prior austenite grain size. During production, it is much more difficult to control the uniformity of heating and heat transfer consistency along the entire length and through the thickness of the work piece. The furnace conditions are correlated to product quality via furnace process variables such as the air to gas ratio, furnace burner condition, furnace pressure, energy efficiency, adiabatic flame temperature (AFT) and furnace refractory condition. Operational practice recommendations are presented to minimize inhomogeneous heating which results in inferior product quality, hot rolling model anomalies and toughness variations in the through-thickness-direction.

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Maubane, Dannis Rorisang Nkarapa, Charles Witness Siyasiya, Kevin Mark Banks, and Waldo Edmund Stumpf. "Critical Strain for Complete Austenite Recrystallisation during Rough Rolling of C-Mn Steel and Nb-Ti-V Microalloyed Steel." Materials Science Forum 941 (December 2018): 46–51. http://dx.doi.org/10.4028/www.scientific.net/msf.941.46.

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The influence of roughing strain on the extent of austenite recrystallisation in plain carbon steel and Nb-Ti-V microalloyed steel was investigated. Reheating and roughing simulations were conducted on a deformation dilatometer using industrial heating, soaking times, strain and strain rates. The roughing schedules comprised of varying the pass strain magnitude within a typical roughing temperature range. The double stroke method was used to determine the austenite softening fraction. The austenite grain size, prior to and after rolling, was measured on quenched specimens. Grain refinement was achieved in both steels after all rolling schedules. An applied pass strain of 0.15 was sufficient to completely soften the austenite after the first pass and produced the finest recrystallised grain size. This was attributed to sufficient nucleation sites and driving force for recrystallisation compared to lower strains. Partial recrystallisation occurred after the first pass due to the relatively coarse initial grain size. The steel chemistry played an insignificant role in controlling the recrystallisation kinetics at high roughing temperatures. The through-thickness strain distribution calculated from FEM simulations showed that, for a given applied strain, a similar magnitude of deformation is achieved at the centre of a hot-rolled plate.

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Sharma, Sandeep, Tarun Nanda, Manashi Adhikary, Venugopalan T., and Ravi Kumar B. "A simulation study of pearlite-to-austenite transformation kinetics in rapidly heated hot-rolled low carbon steel." Materials & Design 107 (October 2016): 65–73. http://dx.doi.org/10.1016/j.matdes.2016.06.025.

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Mecozzi, Maria Giuseppina, C. Bos, and J. Sietsma. "Microstructure Modelling of Solid-State Transformations in Low-Alloy Steel Production ." Materials Science Forum 706-709 (January 2012): 2782–87. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2782.

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In this work the formation of microstructural banding in a dual-phase steel is investigated by using a three-dimensional cellular automata model for phase transformations. Originally developed for describing the metallurgical processes occurring during the annealing stage of cold-rolled strips, this model is presently applied to investigate microstructural-band formation during the austenite-to-ferrite transformation kinetics during cooling after hot rolling. The recent incorporation in the model of an inhomogeneous concentration of Mn, the alloying element most responsible for the development of microstructural banding, and the local nucleation behaviour dependent on the Mn concentration allows the study of the effect of material and process parameters on the banding formation.

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26

Patra, Sudipta, and Lokesh Kumar Singhal. "Production of High Nitrogen Stainless Steel X8CrMnN18-18 through EAF-AOD-LRF-CC-Steckel Mill Route and its Hot Deformation Study by Gleeble Thermomechanical Simulator." Advanced Materials Research 794 (September 2013): 429–40. http://dx.doi.org/10.4028/www.scientific.net/amr.794.429.

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High nitrogen containing austenitic stainless steel X8CrMnN18-18 exhibits attractive combination of high strength, toughness and corrosion resistance.This grade containing more than 5000 ppm of nitrogen was produced commercially through EAF-AOD-LRF-CC-Steckel mill route and its microstructure and mechanical properties were studied. Excellent combination of strength,ductility and toughness is achieved in the entire range of 6mm to 50mm thick hot rolled plates. Uniaxial compression tests were carried out to understand the hot deformation behavior by varying temperature and strain rate. Softening behavior during deformation was analyzed from flow stress strain curves and microstructural analysis. Dynamic recrystallization (DRX) behavior of the material was observed during thermo mechanical processing. Critical strain related to DRX and Avrami kinetics of DRX was calculated by analyzing the flow curve data. Microstructural characterization was done by optical microscopy and EBSD analysis. Extensive grain refinement can be achieved by thermo-mechanical processing controlled by DRX. Keywords: High nitrogen stainless steel, Strength and toughness, DRX, Grain refinement, TMCP

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Piston, Michael, Laura Bartlett, Krista R. Limmer, and Daniel M. Field. "Microstructural Influence on Mechanical Properties of a Lightweight Ultrahigh Strength Fe-18Mn-10Al-0.9C-5Ni (wt%) Steel." Metals 10, no. 10 (September 29, 2020): 1305. http://dx.doi.org/10.3390/met10101305.

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This study evaluates the role of thermomechanical processing and heat treatment on the microstructure and mechanical properties of a hot rolled, annealed, and aged Fe-18Mn-10Al-0.9C-5Ni (wt%) steel. The steel exhibited rapid age hardening kinetics when aged in the temperature range of 500–600 °C for up to 50 h, which has been shown in other work to be the result of B2 ordering in the ferrite and κ-carbide precipitation within the austenite matrix. The ultimate tensile strength increased from 1120 MPa in the annealed condition to 1230 MPa after 2 h of aging at 570 °C. Charpy V-notch toughness was evaluated at −40 °C in sub-sized specimens with a maximum in the annealed and quenched condition of 28.5 J in the L-T orientation.

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Mucsi, András. "Effect of hot rolled grain size on the precipitation kinetics of nitrides in low carbon Al-killed steel." Journal of Materials Processing Technology 214, no. 8 (August 2014): 1536–45. http://dx.doi.org/10.1016/j.jmatprotec.2014.02.024.

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29

Hao, Liang, Tuanjie Li, Zhongliang Xie, Qingjuan Duan, and Guoyuan Zhang. "The Oxidation Behaviors of Indefinite Chill Roll and High Speed Steel Materials." Metals 10, no. 8 (August 13, 2020): 1095. http://dx.doi.org/10.3390/met10081095.

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Indefinite chill (IC) roll and high speed steel (HSS) materials have been widely employed to manufacture work rolls as latter and former stands in hot rolling mills. The oxidation of work rolls is of importance for the surface quality of the rolled workpieces. The isothermal oxidation of the IC and HSS materials was conducted at 650 °C and 700 °C in both dry air and humid air. The isothermal oxidation curves indicate that HSS shows faster kinetics than the IC materials in dry air, whereas the opposite occurred in humid air. The oxide scales of the IC materials after the oxidation in both dry air and humid air are made up of two oxide phases. Two oxide phases were found when the HSS oxidized in the dry air and three oxide phases were found when oxidized in the humid air.

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30

Morawiec, Mateusz, Adam Grajcar, Władysław Zalecki, Carlos Garcia-Mateo, and Marek Opiela. "Dilatometric Study of Phase Transformations in 5 Mn Steel Subjected to Different Heat Treatments." Materials 13, no. 4 (February 21, 2020): 958. http://dx.doi.org/10.3390/ma13040958.

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The work presents results of phase transformation kinetics of hot-rolled 5% Mn steel subjected to different heat treatments. Three different schedules were introduced: isothermal holding in a bainite region, coiling simulation and intercritical annealing. The evolution of microstructure components was investigated using dilatometric and metallographic analyses. According to obtained results, the medium-Mn steel exhibits high resistance for γ/α transformation during the bainite transformation and coiling simulation (upon cooling from the austenite region). During 5 h isothermal holding, no bainite and/or ferrite formation was detected. This results in the formation of martensite upon cooling to room temperature. Differently, when the steel was subjected to the intercritical annealing at 720 and 700 °C (upon heating from room temperature), a final microstructure consisted of ferrite, martensite and retained austenite. At 700 °C, no fresh martensite formation was detected upon cooling to room temperature. This means that the austenite was enriched in carbon during the intercritical annealing step enough to keep its thermal stability.

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31

Zisman, A. A., T. V. Soshina, and E. I. Khlusova. "Revealing prior austenite grains and analysis of the metadynamic recrystallization kinetics of austenite in hot rolled low carbon steel." Letters on Materials 2, no. 1 (2012): 3–8. http://dx.doi.org/10.22226/2410-3535-2012-1-3-8.

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32

Chandra-ambhorn, Somrerk, Supati Ieamsupapong, V. Thanateponake, and Walairat Suksamai. "Effect of Coiling Temperature on the Formation and Pickling Behaviour of Tertiary Scale on Hot-Rolled Carbon Steel Strip." Key Engineering Materials 410-411 (March 2009): 669–76. http://dx.doi.org/10.4028/www.scientific.net/kem.410-411.669.

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Steel strips covered by a tertiary thermal oxide scale from a hot rolling process were studied in this research work. In case that the clean strip is required, i.e. for the cold rolling process, this tertiary scale formed on the steel surface is typically removed by a pickling process. In this work, a finishing temperature – the temperature at the exit of strip from a finishing mill – was kept constant at 830 °C. A coiling temperature – the temperature that the strip was coiled at a down coiler – was varied in a real hot rolling line to obtain different types of tertiary scales formed on low carbon steel strips. Physico-chemical characteristics and pickling behaviour of the scales were further investigated. It was found from a scanning electron microscope (SEM) that the thickness of scale at the centre of strip was in the range of 3-5 m and reduced with the decrease in coiling temperature. A laser Raman spectroscopy was also applied to make a depth profile of scale. Additionally, with the results observed from SEM and X-ray diffraction (XRD), it is concluded that the tertiary scale is a non-homogeneous single layer of a eutectoid structure consisting of magnetite and iron. Moreover, the samples were further immersed in a 10%v/v HCl pickling solution at 80 °C. It was found that the time needed to remove the tertiary scale was reduced with the decreased scale thickness, which was obtained by lowering the coiling temperature. Kinetics of scale removal during pickling is discussed in the paper.

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Gsellmann, Bernadette, Dilek Halici, Mihaela Albu, Coline Beal, and Bernhard Sonderegger. "Combination of Microstructural Investigation and Simulation during the Heat Treatment of a Creep Resistant 11% Cr-Steel." Materials Science Forum 879 (November 2016): 625–30. http://dx.doi.org/10.4028/www.scientific.net/msf.879.625.

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This work deals with the microstructural evolution of creep resistant martensitic/ferritic 11% Cr-steel during thermomechanical treatment from an experimental as well as modeling point of view. The creep resistance of this material group is highly dependent on the precipitate status. The initial precipitate status is controlled by the chemical composition of the alloy and the heat treatment after casting or hot rolling. It is therefore of utmost interest to understand and model the precipitate kinetics during this process. Once the microstructural evolution has been modeled successfully, only minimum effort is required to computationally test variants in the composition or heat treatment in order to optimize the process. In this work, the material was hot rolled, austenitized and subsequently annealed. All heat treatments have been performed during dilatometry tests. In order to investigate the microstructural evolution during the process, specimens were extracted at definite stages of the treatment. The specimens were then investigated applying various microscopical techniques in order to quantify the microstructural features (grain size, martensite lath width and precipitate data). The experimental data were then compared to thermodynamic simulations (MatCalc). General data such as nucleation sites for precipitates were taken from literature, grain size and martensite lath widths from the experimental data. Simulations include equilibrium calculations and precipitate kinetic simulations. In general, the simulations showed good agreement with the experimental findings, with minor room for improvements. The work thus lays a solid ground for future improvements of the heat treatment process.

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MATSUMURA, Yoshikazu, Shirou SANAGI, Yasumitsu ONOE, and Hiroshi KATOH. "Precipitation Kinetics in Cast Steels Prior to Hot Rolling and Mechanical Properties of Rolled Products." Tetsu-to-Hagane 74, no. 7 (1988): 1470–77. http://dx.doi.org/10.2355/tetsutohagane1955.74.7_1470.

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35

Duggan, B. J., Y. Y. Tse, and G. J. Shen. "An Impingement – Spheroidisation Theory for Nucleation and Grain Growth." Materials Science Forum 467-470 (October 2004): 45–50. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.45.

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In an investigation of nucleation of recrystallisation in an Interstitial Free steel it was found that new crystals were almost always contained within the rolled-out hot band grain envelopes and were mostly equiaxed. At a later stage they grew and had an aspect ratio of 2:1 but at the completion of recrystallisation were again equiaxed. This is explained by the notion that nucleation occurs relatively frequently in certain grains, that these nuclei have very similar orientations and are thus orientation pinned within the solute and precipitate containing envelopes of the hot band grains. Provided the misorientation is small the impinged group are capable of spheroidisation provided the driving force across the pinned boundary is sufficient to overcome the pinning, because, by definition, this pinned boundary is of high angle character. The theory, as it is presented as coalescence, relies on a form of Östwald ripening and therefore provides a possible explanation of why grain growth kinetics obeys a time exponent of between 1/2 and 1/3. A similar observation of high aspect ratio grains has been made many times in the case of cold rolled copper which forms cube texture. Again, nuclei are formed in the cube bands, but these are prevented from lengthening because of orientation pinning. However, when the length of a group of such impinged nuclei is sufficient, spheroidisation will produce equiaxed grains.

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36

da Cruz, José Alberto, Thiara Francis Mateus Rodrigues, Virgínia Dutra Costa Viana, and Dagoberto Brandão Santos. "Bainite Formation at Low Temperatures in High C-Si Steel and its Mechanical Behavior." Materials Science Forum 706-709 (January 2012): 173–80. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.173.

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A significant amout of stabilized austenite can be obtained in high carbon steel containing high amounts of manganese and silicon (1.5-2 %). At relatively low temperatures the bainite plates formed are extremely thin, making the material very strong. In this study, the influence of the thermal cycle of austempering on the mechanical behavior of a spring steel 0.56C-1.43Si-0.58Mn-0.47Cr (wt. %), with TRIP effect was investigated. The thermal cycle consisted of heating three groups of hot-rolled wire steel at austenite field of 900°C for 300 s, and quickly transferring those to a metallic bath maintained at 200, 220 or 270°C, respectively, for different heat treatment times. The samples were then tested in tension and their microstructures were examined by scanning and transmission electron microscopy. The samples treated at 220°C showed higher elongation, yield strength and tensile strength than those maintained at 200 or 270°C. The high level of strength and ductility is due to a mixture of martensite and very fine bainitic ferrite with interlath film of retained austenite. The temperature has shown a strong influence on bainite formation kinetics. The fracture behavior of the steel was also evaluated using SEM fractography.

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37

Yang, Hai Li, Chang Wei Cui, Yun Gang Li, Guo Zhang Tang, and Yu Zhu Zhang. "Growth Kinetics and Microstructure of Siliconized Layer by Molten Salt Electrodeposition." Advanced Materials Research 214 (February 2011): 434–38. http://dx.doi.org/10.4028/www.scientific.net/amr.214.434.

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The siliconized layers were formed on the surface of hot rolled grain oriented silicon steel using a molten salt pulse electrodeposition method. The process was performed in the temperature range 1023-1123 K and with varying deposition time (60-180 min). The profile distribution of Si in the siliconized layer was measured using the glow discharge spectrometry (GDS) and the depth from the surface to the substrate was taken as the layer thickness. The morphology and structure were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that a longer deposition time tended to produce a larger grain and a looser, rougher layer. The phase structure of the layer was composed of Fe3Si with (110) preferred orientation in the experimental range. The longer deposition time resulted in an increase in thickness layer and the thickness of the layers ranged from 17 to 165m. Kinetic studies showed that the siliconized layer grew with a parabolic rate law, indicating the diffusion controlled growth. The activation energy for growth of siliconized layer was about 242 kJ/mol.

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38

Varela-Castro, Gonzalo, Jose María Cabrera, and Jose Manuel Prado. "Influence of Manganese on the Hot Working Behaviour of Construction Steels." Advanced Materials Research 89-91 (January 2010): 580–85. http://dx.doi.org/10.4028/www.scientific.net/amr.89-91.580.

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The microstructural control of rolled products is based on managing the austenite phase transformations during and after hot deformation to attain the desired microstructure after the cooling step. Therefore, it is very important an appropriate description of the kinetics of the hardening and softening phenomena taking place during the deformation at high temperatures, namely, dynamic recovery (DRV) and recrystallization (DRX). This investigation examines the effect of manganese contents on the hot flow behaviour of plain carbon steels. For this purpose, uniaxial hot compression tests were carried out in carbon steels in an extensive range of temperatures, from 1123 to 1373 K and strain rates, from 510-4 to 110-1 s-1. This work is focused in determining the physically-based constitutive equations that govern the plastic behaviour of plain carbon steels. Experimental results were compared with the predictions of the model and an excellent agreement over a broad range of temperatures and strain rates was obtained.

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Pereda, Beatriz, Felipe Bastos, Beatriz López, and J. M. Rodriguez-Ibabe. "Effect of Nb on the Austenite Microstructural Homogeneity of Hot Rolled Rebars." Materials Science Forum 1016 (January 2021): 1127–33. http://dx.doi.org/10.4028/www.scientific.net/msf.1016.1127.

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While the role of Nb in flat rolling of low carbon steels has been investigated in many works, the information about the use of Nb in rebar rolling of higher carbon grades is more limited. Rebar rolling presents differences relative to flat rolling that can affect the role of Nb, such as the application of higher number of rolling passes, higher strain rates, lower interpass times, and, consequently, enhanced adiabatic heating. Increasing the number of passes can contribute to austenite grain refinement. However, the high finishing temperatures in rebar rolling can lead also to significant austenite grain growth and microstructural heterogeneity development before phase transformation. This phenomenon will directly influence the final grain size and can also lead to the appearance of second hard phases in the final product. One of the options to avoid austenite grain growth is to add microalloying elements that retard grain growth kinetics, either in solid solution or as precipitates. This can open new roles for the application of Nb in rebar rolling. To analyze this, in this work laboratory torsion tests were performed with two 0.2%C steels microalloyed with two different Nb contents (0.029% and 0.015%). Soaking temperatures from 1100°C to 1250°C were applied to obtain different amounts of Nb in solid solution before grain growth study. The study shows that not only finish rolling temperature and cooling time, but also reheating temperature and the amount of Nb remaining in the form of undissolved precipitates are important factors controlling austenite grain growth.

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40

Gokhale, A. M. "Application of microstructure modeling to the kinetics of proeutectoid ferrite transformation in hot-rolled microalloyed steels." Metallurgical Transactions A 17, no. 9 (September 1986): 1625–29. http://dx.doi.org/10.1007/bf02650099.

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41

Graux, Alexis, Sophie Cazottes, David De Castro, David San-Martín, Carlos Capdevila, Jose Maria Cabrera, Sílvia Molas, et al. "Design and Development of Complex Phase Steels with Improved Combination of Strength and Stretch-Flangeability." Metals 10, no. 6 (June 20, 2020): 824. http://dx.doi.org/10.3390/met10060824.

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This study presents the design and development of a hot-rolled bainitic steel, presenting a good combination of strength and stretch-flangeability, for automotive applications. Ti, Nb, and Mo were added in the steel composition in order to control austenite grain sizes, enhance precipitation hardening, and promote the formation of bainite. This study focuses on the effect of process parameters on final microstructures and mechanical properties. These parameters are the finishing rolling temperature, which conditions the austenite microstructure before its decomposition, and the coiling temperature, which conditions the nature and morphology of the ferritic phases transformed. A preliminary study allowed to determine the austenite grain growth behavior during reheating, the recrystallization kinetics, and the continuous cooling transformation curves of the studied steel. Then, a first set of parameters was tested at a semi-industrial scale, which confirmed that the best elongation properties were obtained for homogeneous bainitic lath/granular microstructures, that can be produced by choosing a coiling temperature of 500 ∘ C . When choosing those parameters for the final industrial trial, the microstructure obtained consisted of a homogeneous lath/granular bainite mixture that presented a Ultimate Tensile Strength of 830 MPa and a Hole Expansion Ratio exceeding 70%.

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42

Buchmayr, Bruno, and Thomas Antretter. "Thermo-Mechanical Behaviour of Dual-Phase Steels in Various Structural Morphologies: Experiments and Modelling." Materials Science Forum 706-709 (January 2012): 2072–77. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2072.

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The thermo-mechanical behaviour of the hot rolled dual-phase steel 10MnSi7 has been determined as a function of temperature and time within the two-phase field α+γ as well as at lower deformation temperatures down to Ms-temperature. The corresponding microstructures, phase hardness, state of recrystallisation have been determined using quantitative metallography. Using this information, a finite element model of a representative volume element (RVE) has been set up. Each element represents a subdomain of a grain that transforms according to the kinetics found in the measurements. The RVE has been subjected to the same loading history as in the accompanying experiments and the overall stress-strain response is monitored during ongoing transformation. The effect of a preferred orientation of the two phase structure has been studied taking into account the effects of a significant plastic deformation. The model is validated by comparison with the experimental evidence.

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43

Lottey, K. R., and Matthias Militzer. "Microstructure Evolution in Fine-Grained Microalloyed Steels." Materials Science Forum 500-501 (November 2005): 347–54. http://dx.doi.org/10.4028/www.scientific.net/msf.500-501.347.

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There is an increasing emphasis to develop novel hot-rolled high strength steels with fine and ultra fine grain sizes for structural and other applications. Traditionally the concept of microalloying has been employed to refine microstructures thereby obtaining increased strength levels. For example, employing an alloying strategy with Nb, Ti and Mo is promising to attain yield strength levels of 700MPa and beyond. In the present study, the transformation behaviour is investigated for a HSLA steel containing 0.05wt%C-1.65wt%Mn-0.20wt%Mo-0.07wt%Nb- 0.02wt%Ti. The ferrite formation from work-hardened austenite has been studied for simulated run-out table cooling conditions employing a Gleeble 3500 thermomechanical simulator equipped with a dilatometer. The effects of cooling rate and initial austenite microstructure, i.e. austenite grain size and degree of work hardening, on the austenite decomposition kinetics and resulting ferrite grain size have been quantified. Based on the experimental results, a phenomenological transformation and ferrite grain size model is proposed for run-out table cooling conditions. The transformation model includes submodels for transformation start and ferrite growth. The latter is described using a Johnson-Mehl-Avrami-Kolmogorov approach. The degree of work hardening is incorporated by introducing an effective austenite grain size as a function of the strain applied under no-recrystallization condition. The ferrite grain size can be predicted as a function of the transformation start temperature. Increasing both cooling rate and amount of work hardening can optimize ferrite grain refinement. In the present steel, ferrite grain sizes of as low as 2µm have been obtained in this way. The results observed for the present steel are compared to the transformation behaviour in previously studied Nb-Ti HSLA steels of similar strength levels.

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Li, Yun Jie, Dong Chen, Jian Kang, Xiao Lei Li, Guo Yuan, Raja Devesh Kumar Misra, and Guo Dong Wang. "Kinetics of Carbon Partitioning during Non‐Isothermal Treatment and Mechanical Properties of the First Industrial Coils of Hot Rolled Quenched and Partitioned Steel." steel research international 90, no. 8 (May 31, 2019): 1900122. http://dx.doi.org/10.1002/srin.201900122.

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45

Muszka, Krzysztof, Janusz Majta, and Marcin Gliwinski. "Through-Scale Analysis of Strain Path Effects in Microalloyed Austenite Subjected to Reverse Rolling." Materials Science Forum 941 (December 2018): 89–94. http://dx.doi.org/10.4028/www.scientific.net/msf.941.89.

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Thermomechanical hot rolling processes are often realized using reverse rolling stands, where the rolled stock is fed forward and backward through the rolling gap. During those processes, material undergoes several strain reversals that significantly alter microstructure evolution of austenite with respect to continuously rolled counterparts. In Nb-microalloyed steels, where precipitation hardening is usually expected, the effects of strain reversal are especially complex. When rolling direction is reversed, both static recrystallization (SRX) kinetics and strain-induced precipitation (SIP) processes are slowed down due to decreasing dislocation density. It affects the competition between driving force for SRX and pinning pressure for SIP and, in turn, changes the non-recrystallization temperature (Tnr), compared to the case where strain path is linear. In the present paper, detailed through-scale analysis of strain path effects in microalloyed austenite will be presented. Physical simulation and detailed microstructural analysis will be employed to study global and local effects in microalloyed austenite after complex deformation histories. Conclusions regarding the influence of strain path changes on the interactions between SRX and SIP will be drawn.

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Malta, Paula Oliveira, Camila Magalhães Gonçalves, Davi Silva Alves, Aline Oliveira Vasconcelos Ferreira, Iane Dutra Moutinho, and Dagoberto Brandão Santos. "The influence of hot band annealing on recrystallization kinetics and texture evolution in a cold-rolled Nb-stabilized ferritic stainless steel during isothermal annealing." Journal of Materials Research 31, no. 18 (August 30, 2016): 2838–49. http://dx.doi.org/10.1557/jmr.2016.296.

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47

Ma, M., H. Ding, R. D. K. Misra, Z. Y. Tang, H. B. Li, and G. W. Fan. "A study on precipitation kinetics of sigma phase in a hot-rolled super duplex stainless steel during isothermal aging based on the Johnson–Mehl–Avrami model." Ironmaking & Steelmaking 44, no. 4 (August 17, 2016): 311–18. http://dx.doi.org/10.1080/03019233.2016.1210912.

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48

Hu, Jun, Lin-Xiu Du, Hui Xie, Fu-Tao Dong, and R. D. K. Misra. "Effect of weld peak temperature on the microstructure, hardness, and transformation kinetics of simulated heat affected zone of hot rolled ultra-low carbon high strength Ti–Mo ferritic steel." Materials & Design 60 (August 2014): 302–9. http://dx.doi.org/10.1016/j.matdes.2014.04.003.

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49

Alina, A. A., V. Y. Kulikov, P. V. Kovalev, and A. M. Dostayeva. "Study of thermal resistance of cold mixtures with clay addition." Kompleksnoe ispolʹzovanie mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik shikisattardy Keshendi Paidalanu 316, no. 1 (March 15, 2021): 91–97. http://dx.doi.org/10.31643/2021/6445.11.

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The article analyzes the results of heat resistance of cold-harmful mixtures with the addition of clay. The article presents the results of an experimental laboratory study of the properties of samples from CTS, obtained by various methods. The scientific novelty of the technology lies in the fact that the technology of casting in cold-rolled steel ensures high quality of the casting surface, the absence of gas defects and blockages in the casting. The selection of the composition and technological parameters for the manufacture of the mold, contributing to the production of high-quality defect-free castings, will significantly reduce their cost, which will have a positive effect on the economy of our country. The study of the change in density over time depending on the applied load was studied in a series of experiments. The density of the mixture was determined every thirty seconds during the entire time of the formation of the dispersed medium. These experiments showed that at the beginning of the formation of the shell, its density increases significantly. In works on the thermal stability of polymers, the general laws of thermal decomposition and carbonization of cyclic, spatially crosslinked hot curing polymers were investigated and it was shown that the kinetics of destruction, the composition of gaseous products, the amount of coke formed and its properties depend on the properties of the initial polymers - the degree of crosslinking of molecular chains, chemical structure, the presence of impurities of catalysts and other curing conditions, as well as the heating conditions - speed and temperature. The article summarizes some of the results of the study, which is most appropriate for thin-walled steel castings to use the following mixture composition: filler - quartz sand; binder - clay of the Kazakhstani deposit, epoxy resin, hardener.

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50

Dillon, Barry. "Transit damage and hot rolled steel." Practical Failure Analysis 2, no. 4 (August 2002): 7–13. http://dx.doi.org/10.1007/bf02715443.

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Journal articles on the topic 'Kinetics of hot rolled steel'

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