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2 pages, 134 KiB

Open AccessEditorial

5th UK–China Steel Research Forum

by Hanshan Dong, Hongbiao Dong and Zushu Li

Metals 2019, 9(7), 738; https://doi.org/10.3390/met9070738 - 30 Jun 2019

Viewed by 2272

Abstract

Following the past successful four events in Leicester (2010), Wuhan (2012), Oxford (2014) and Chongqing (2016), the 5th UK–China Steel Research Forum, in conjunction with the 16th Conference of Chinese Materials Association in the UK on Materials Science and Engineering, was held at [...] Read more.

Following the past successful four events in Leicester (2010), Wuhan (2012), Oxford (2014) and Chongqing (2016), the 5th UK–China Steel Research Forum, in conjunction with the 16th Conference of Chinese Materials Association in the UK on Materials Science and Engineering, was held at the University of Birmingham, UK on 4–7 July 2018 [...] Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

Research

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12 pages, 3014 KiB

Open AccessArticle

Edge-Drop Control Behavior for Silicon Strip Cold Rolling with a Sendzimir Mill

by Hongbo Li, Zhenwei Zhao, Dawei Dong, Guomin Han, Jie Zhang, Haichao Liu and Xuechang You

Metals 2018, 8(10), 783; https://doi.org/10.3390/met8100783 - 30 Sep 2018

Cited by 17 | Viewed by 4829

Abstract

Edge-drop control is important for silicon strip cold rolling, as the silicon strip is mainly used as a laminated core. Moreover, cold rolling is the key process for the thin strip edge-drop control, and a Sendzimir mill is one of the most popular [...] Read more.

Edge-drop control is important for silicon strip cold rolling, as the silicon strip is mainly used as a laminated core. Moreover, cold rolling is the key process for the thin strip edge-drop control, and a Sendzimir mill is one of the most popular cold rolling mills for silicon strips. Thus, the mastery of edge-drop control behavior for silicon strip cold rolling with a Sendzimir mill is beneficial for the improvement of the strip profile quality. With the finite element method, two models are built to analyze the edge-drop control behavior, one is the roll system and strip integrated elastic-plastic deformation statics model, and the other is the strip plastic deformation dynamics model. The first model provides the roll gap contour for the second model, then the strip profile can be calculated in the second model, which considers the transverse flow of the metal. Firstly, the compositions of edge-drop for the silicon strip are analyzed systematically, which are the edge-drop for work roll bending, the edge-drop for work roll flattening, and the edge-drop for transverse flow of the metal. Secondly, the influence of different rolling process parameters on the three parts are analyzed, such as the entrance thickness, the rolling reduction, the rolling tension, and so on; further, the influence of the roll contours are also analyzed. Finally, the edge-drop control behavior of the different rolling process parameters and roll contours are obtained. The research results provide theoretical guidance for edge drop control in the Sendzimir mill. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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17 pages, 7268 KiB

Open AccessArticle

Initiation of Surface Cracks on Beam Blank in the Mold during Continuous Casting

by Gaiyan Yang, Liguang Zhu, Wei Chen, Xingwang Yu and Baomin He

Metals 2018, 8(9), 712; https://doi.org/10.3390/met8090712 - 11 Sep 2018

Cited by 7 | Viewed by 5660

Abstract

Surface cracking seriously affects the quality of beam blanks, a relatively new blank in the continuous casting in China. In order to study the mechanism of the initiation and propagation of surface cracks, this study established a 2D micro-segmented model of the solidification [...] Read more.

Surface cracking seriously affects the quality of beam blanks, a relatively new blank in the continuous casting in China. In order to study the mechanism of the initiation and propagation of surface cracks, this study established a 2D micro-segmented model of the solidification process for a beam blank in the mold, with a user subroutine DFLUX written in Fortran. Using a contact algorithm, the stress in the shell of the beam was analyzed considering the mechanical properties of the material (Q235B), thermal stress, surface friction force and ferrostatic pressure. The results showed that at the center of the web, surface longitudinal cracks were most likely to initiate at a height of 180 mm from the meniscus; at the fillet, surface longitudinal cracks were most likely to initiate at a height of 200 mm from the meniscus. Moreover, the casting speed showed a greater effect on surface crack initiation than the pouring temperature did. This study reveals the cause of longitudinal crack initiation, and the most likely positions of cracks on the strand. Thus, it is instructive for controlling surface cracks in production. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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13 pages, 5780 KiB

Open AccessArticle

Monitoring Liquid Level of Blast Furnace Hearth and Torpedo Ladle by Electromotive Force Signal

by Ying Li, Lei Zan, Yao Ge, Han Wei, Zhenghao Zhang, Chuanguang Bi, Kaicheng Lu and Yaowei Yu

Metals 2018, 8(9), 665; https://doi.org/10.3390/met8090665 - 25 Aug 2018

Cited by 4 | Viewed by 5168

Abstract

The state of a blast furnace hearth, especially the liquid level of hot metal and slag during the tapping process, is of crucial importance with respect to a long campaign blast furnace. In practice, the state of the hearth is evaluated mainly by [...] Read more.

The state of a blast furnace hearth, especially the liquid level of hot metal and slag during the tapping process, is of crucial importance with respect to a long campaign blast furnace. In practice, the state of the hearth is evaluated mainly by the experience of operators. In this paper, the electromotive force (EMF) is used to monitor the liquid level of a laboratory scale of blast furnace hearth and the effect of liquid level, EMF sensors position and the thickness of refractory on EMF signals are tested using a single layer of water and double layers of water and oil. After laboratory experiments, the electromotive force (EMF) is used to monitor the liquid level of torpedo ladle successfully. Laboratory experimental results show that the change in liquid level can be characterized by EMF signal. The state of liquid surface and local thermal state cause the EMF signal to vary in the circumferential direction of the vessel. Furthermore, the EMF signal magnitude decreases with the decrease of the thickness of the graphite crucible. Finally, the main conclusions of the laboratory experiment are supported by the torpedo ladle experiment. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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14 pages, 9969 KiB

Open AccessArticle

Multiscale Modeling and Simulation of Directional Solidification Process of Ni-Based Superalloy Turbine Blade Casting

by Qingyan Xu, Cong Yang, Hang Zhang, Xuewei Yan, Ning Tang and Baicheng Liu

Metals 2018, 8(8), 632; https://doi.org/10.3390/met8080632 - 10 Aug 2018

Cited by 20 | Viewed by 8127

Abstract

Ni-based superalloy turbine blades have become indispensable structural parts in modern gas engines. An understanding of the solidification behavior and microstructure formation in directional solidified turbine blades is necessary for improving their high-temperature performance. The multiscale simulation model was developed to simulate the [...] Read more.

Ni-based superalloy turbine blades have become indispensable structural parts in modern gas engines. An understanding of the solidification behavior and microstructure formation in directional solidified turbine blades is necessary for improving their high-temperature performance. The multiscale simulation model was developed to simulate the directional solidification process of superalloy turbine blades. The 3D cellular automaton-finite difference (CA-FD) method was used to calculate heat transfer and grain growth on the macroscopic scale, while the phase-field method was developed to simulate dendrite growth on the microscopic scale. Firstly, the evolution of temperature field of an aero-engine blade and a large industrial gas turbine blade was studied under high-rate solidification (HRS) and liquid-metal cooling (LMC) solidification processes. The varying withdrawal velocity was applied to change the curved mushy zone to a flat shape. Secondly, the grain growth in the aero-engine blade was simulated, and the grain structures in the starter block part and the spiral selector part in the HRS process were compared with those in the LMC process. The simulated grain structures were generally in agreement with experimental results. Finally, the dendrite growth in the typical HRS and LMC solidification process was investigated and the simulation results were compared with the experimental results in terms of dendrite morphology and primary dendritic spacing. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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11 pages, 5115 KiB

Open AccessArticle

Thickness Dependence of Toughness in Ultra-Heavy Low-Alloyed Steel Plate after Quenching and Tempering

by Huibin Liu, Hanqian Zhang and Jinfu Li

Metals 2018, 8(8), 628; https://doi.org/10.3390/met8080628 - 10 Aug 2018

Cited by 19 | Viewed by 4367

Abstract

Due to the limitations of manufacturing techniques, inhomogeneous microstructures and properties along the thickness direction have been a big challenge for heavy and ultra-heavy plates of quenched and tempered low-alloyed steel. In this study, variation in microstructures and mechanical properties were investigated from [...] Read more.

Due to the limitations of manufacturing techniques, inhomogeneous microstructures and properties along the thickness direction have been a big challenge for heavy and ultra-heavy plates of quenched and tempered low-alloyed steel. In this study, variation in microstructures and mechanical properties were investigated from the surface to the center of a 130 mm-thick ultra-heavy steel plate. Emphasis was made on toughness performance including impact toughness and crack resisting ability. It was found that the ultimate tensile strength at the plate surface, quarter and center thickness at room temperature are 715, 643 and 618 MPa, respectively. Meanwhile, the ductile-brittle transition temperature defined by fracture appearance for these three plate positions are −100, −30 and −15 °C, respectively. Moreover, the crack resisting ability represented by the nil-ductility temperature are −40, −25 and −10 °C for these three positions respectively. Investigation by field emission scanning electron microscopy (FE-SEM) and electron backscatter diffraction (EBSD) revealed that the plate surface features finer matrix grain and carbide precipitation, as well as greater frequency of high angle misorientation. These microstructural features contribute to enhancing deformability, retarding cleavage initiation and hindering crack propagation, leading to the pronounced increase in the energy for fracture propagation and the overall impact energy as compared to the other two plate positions. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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10 pages, 3445 KiB

Open AccessArticle

New Process with Argon Injected into Ladle around the Tapping Hole for Controlling Slag Carry-over during Continuous Casting Ladle

by Shuguo Zheng and Miaoyong Zhu

Metals 2018, 8(8), 624; https://doi.org/10.3390/met8080624 - 8 Aug 2018

Cited by 11 | Viewed by 4321

Abstract

A new process with argon injected into the ladle around the tapping hole for controlling slag carry-over in a teeming ladle was presented. Physical modeling was used to study the mechanism of controlling slag carry-over, and the feasibility of the new process was [...] Read more.

A new process with argon injected into the ladle around the tapping hole for controlling slag carry-over in a teeming ladle was presented. Physical modeling was used to study the mechanism of controlling slag carry-over, and the feasibility of the new process was also investigated by industrial trials. The results show that vortex forms firstly, and then converts to drain sink. With argon injected into the ladle around the tapping hole, an argon ring was formed, and the rotating angular velocity of the melt close to the tapping hole reduced dramatically, and even vanished when the melt passed the argon ring. Therefore, the new controlling slag carry-over process can eliminate the slag carry-over caused by vortex. The velocity of the melt toward the tapping hole was reduced due to the bubble buoyancy as the melt passed the argon ring. So, the new process can decrease the critical height of slag carry-over caused by drain sink. The application feasibility of the new controlling slag carry-over process is verified by the plant trials. Compared to the traditional teeming ladle process, the new controlling slag carry-over process shows much better efficiency on decreasing the steel residual in the poured ladle. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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14 pages, 20171 KiB

Open AccessArticle

Effect of Mg Treatment on Refining the Microstructure and Improving the Toughness of the Heat-Affected Zone in Shipbuilding Steel

by Yan Wang, Liguang Zhu, Qingjun Zhang, Caijun Zhang and Shuoming Wang

Metals 2018, 8(8), 616; https://doi.org/10.3390/met8080616 - 6 Aug 2018

Cited by 11 | Viewed by 5125

Abstract

The effect of Mg treatment on the microstructure and toughness of the heat-affected zone (HAZ) of shipbuilding steel after high-heat-input welding was investigated via laboratory and industrial testing. The welding process and Charpy impact tests were also carried out to evaluate the HAZ [...] Read more.

The effect of Mg treatment on the microstructure and toughness of the heat-affected zone (HAZ) of shipbuilding steel after high-heat-input welding was investigated via laboratory and industrial testing. The welding process and Charpy impact tests were also carried out to evaluate the HAZ toughness of steel plates. First, typical inclusion characteristics were characterised with an ASPEX PSEM Explorer. Then, confocal laser scanning microscopy (CLSM) was used to observe the diameters of austenite grains under different holding times. The results showed that when the addition of microalloy elements were in the order of Al–Mg–Ti, this had an effect on dispersing inclusions, the largest proportion of which were micro-inclusions that had a particle size range of 1.0–1.5 μm. This accounted for 25.4% of the total inclusions, which was the highest amount. The micro inclusion particle size that was mainly distributed in the range of 0.5–3.5 μm accounted for 82.8% of all the micro-inclusions. The inclusion structure induced intragranular acicular ferrite (IAF) in austenite as follows: MgO and Al₂O₃ formed the core and Ti₂O₃ adhered to the Al–Mg complex inclusions to produce smaller particle sizes and dispersions of Al, Mg, and Ti complex inclusions. The 40-mm-thick plate obtained in the industrial test after welding had an average impact absorbed energy 2 mm from the weld joint in the heat-affected zone of 198.9 J at −20 °C, while the welding heat input was 150 kJ/cm, compared with the parent material’s low-temperature performance, which exceeded 88%. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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18 pages, 19943 KiB

Open AccessArticle

Removal Mechanism of Microscale Non-Metallic Inclusions in a Tundish with Multi-Hole-Double-Baffles

by Yan Jin, Xiaosen Dong, Fu Yang, Changgui Cheng, Yang Li and Wei Wang

Metals 2018, 8(8), 611; https://doi.org/10.3390/met8080611 - 6 Aug 2018

Cited by 19 | Viewed by 3634

Abstract

To effectively remove microscale inclusions in the tundish, the Multi-Hole-Double-Baffles (MHDB), a novel flow control device in the tundish for continuous casting, was developed. The hole array mode of the MHDB will directly affect the trajectories of the inclusions. The effect and removal [...] Read more.

To effectively remove microscale inclusions in the tundish, the Multi-Hole-Double-Baffles (MHDB), a novel flow control device in the tundish for continuous casting, was developed. The hole array mode of the MHDB will directly affect the trajectories of the inclusions. The effect and removal mechanism of the inclusions with sizes of 1 µm to 50 μm in the tundish with MHDB were studied by numerical simulation. The hole array mode of MHDB could affect the inclusions’ trajectories and distribution, and the mechanism underlying the effect of the MHDB was investigated using the discrete phase model (DPM). A 1:2.5 physical model was built to verify the accuracy of numerical simulation. The results showed that micro-inclusions were primarily driven by the drag force exerted by the molten steel flow, micro-inclusion trajectories followed the molten steel streamlines almost exactly, but buoyancy still played a role in the removal of the micro-inclusions near the molten steel surface; the hole array mode affected the trajectories of the micro-inclusions and controlled and decelerated the flow of molten steel, increasing the residence time of the molten steel flow a the value that is 15 times larger than the theoretical value; and “upper-in-lower-out” type MHDB showed the most efficient removal of micro-inclusions, with the removal rate being increased by 13–49% compared to the removal rates for the other type MHDB. The results of numerical simulation were well verified by physical simulation. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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12 pages, 3940 KiB

Open AccessArticle

The In-Plane Structure and Dynamic Property of the Homogeneous Al-Al Solid-Liquid Interface

by Rui Yan, Sida Ma, Tao Jing and Hongbiao Dong

Metals 2018, 8(8), 602; https://doi.org/10.3390/met8080602 - 2 Aug 2018

Cited by 7 | Viewed by 3285

Abstract

Using molecular dynamics simulation and a newly developed COMB3 potential, the in-plane ordering and diffusion constant profiles at the homogeneous (100), (110), and (111) interfaces between solid and liquid Al have been examined. We found that the in-plane ordering characterized by 2-D density [...] Read more.

Using molecular dynamics simulation and a newly developed COMB3 potential, the in-plane ordering and diffusion constant profiles at the homogeneous (100), (110), and (111) interfaces between solid and liquid Al have been examined. We found that the in-plane ordering characterized by 2-D density maps and 2-D structure factors existed in the first 6, 10, and 3 out-of-plane layers at the (100), (110), and (111) interfaces, respectively, showing a strong dependence on substrate orientation. In layers with in-plane ordering, the diffusion constant is greatly reduced relative to its value in the bulk liquid, while the influence of layers without in-plane ordering is negligible. The three diffusivity components turn out to be isotropic at the homogeneous interfaces. The Al-Al interfaces studied here will serve as an important reference in comparisons of the structure and properties of different solid-liquid interfaces, which will greatly support the design of grain refiners. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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10 pages, 2342 KiB

Open AccessArticle

Key Intelligent Technology of Steel Strip Production through Process

by Jie Sun, Wen Peng, Jingguo Ding, Xu Li and Dianhua Zhang

Metals 2018, 8(8), 597; https://doi.org/10.3390/met8080597 - 31 Jul 2018

Cited by 14 | Viewed by 4813

Abstract

Because of the complexity of procedure interface and working conditions, the further improvement of steel strip quality and production efficiency is limited. Realizing the optimization of product quality and production process in multi-process, system-level through intelligent key technology is one of the strategic [...] Read more.

Because of the complexity of procedure interface and working conditions, the further improvement of steel strip quality and production efficiency is limited. Realizing the optimization of product quality and production process in multi-process, system-level through intelligent key technology is one of the strategic directions in steel strip production. (1) Collaborative intelligent optimization and dynamic scheduling technology for steel manufacturing supply chain oriented to customized production, reducing the cost of raw material purchase and production operations and improving production efficiency and precision service ability; (2) Online monitoring, diagnosis and optimization technology of product quality. Getting through the process information flow of product, the correlation analysis of process quality parameters, the tracing of quality anomalies, the reverse optimization of process parameters and the optimization of process route will be realized; (3) Multi-process coordination optimization and quality control based on CPS architecture. The precise control technology of process quality parameters will be developed; the structure of multi-process coordination optimization system is established and optimization of key quality parameters in the through process will be realized; and (4) Microstructure and mechanical property optimization and surface quality intelligent control technology in the hot strip rolling process. Intelligent prediction of microstructure and mechanical properties, rapid dynamic design and steel grade merging technology will be formed and green process design technology of oxide scale will be developed. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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14 pages, 8926 KiB

Open AccessArticle

Behavior Characteristics of Argon Bubbles on Inner Surface of Upper Tundish Nozzle during Argon Blowing Process

by Yang Li, Changgui Cheng, Minglei Yang, Zhixuan Dong and Zhengliang Xue

Metals 2018, 8(8), 590; https://doi.org/10.3390/met8080590 - 30 Jul 2018

Cited by 11 | Viewed by 4104

Abstract

During continuous casting of aluminum-killed steel, clogging of tundish nozzle frequently occurs, which seriously disrupts the normal casting sequences and deteriorates strand quality. Generally, argon blowing technology in the form of a stable and continuous argon film on the inner surface of the [...] Read more.

During continuous casting of aluminum-killed steel, clogging of tundish nozzle frequently occurs, which seriously disrupts the normal casting sequences and deteriorates strand quality. Generally, argon blowing technology in the form of a stable and continuous argon film on the inner surface of the upper nozzle is employed to prevent the upper nozzle from clogging in the production. To explore the formation mechanism and influence factors of this argon film, a water model of the upper nozzle with blowing argon with a similarity ratio of 1:1 was built. The results show that the number of bubble chains increases gradually with increasing argon flow rate and casting speed, and the argon gas curtain appears at the bottom half of the upper nozzle. For a given argon flow rate, the velocity of argon gas bubbles increased gradually with increasing casting speed, and decreased gradually with increasing distance from the upper nozzle top. For a given casting speed, the average velocity of argon gas bubbles was largest at a distance from the upper nozzle top of 6 mm with argon flow rate of 150 L/h. The results could provide theoretical and technical basis for the optimization of blowing argon parameters in order to prevent the clogging of upper nozzle and improve strand quality. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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12 pages, 5375 KiB

Open AccessArticle

Formation Analysis of Edge Cracks of 33MnCrTiB Fork Steel

by Shuo Zhao, Yangyang Ge, Liang Ma, Tao Yan, Jingcai Lyu and Zushu Li

Metals 2018, 8(8), 587; https://doi.org/10.3390/met8080587 - 27 Jul 2018

Cited by 2 | Viewed by 4550

Abstract

A 33MnCrTiB is a high-strength low alloy steel used for a forklift truck. This study investigates the root causes of the edge cracks in 33MnCrTiB steel produced by a steel manufacturer. After sampling, inspecting and analyzing the 33MnCrTiB flat steel with edge cracks [...] Read more.

A 33MnCrTiB is a high-strength low alloy steel used for a forklift truck. This study investigates the root causes of the edge cracks in 33MnCrTiB steel produced by a steel manufacturer. After sampling, inspecting and analyzing the 33MnCrTiB flat steel with edge cracks taken from the plant, it was found that the crack and porosity contain similar residues to the deoxidation products and continuous casting mold flux. It can be concluded that the edge surface cracking in the flat steel are mainly caused by the non-deformable inclusions in steel, slag sticking and surface cracks on the original billet. At the same time, the further expansion of cracks is closely related to the serious decarburization during the heating treatment in the billet heating process, and the improper rolling deformation system during the rolling process. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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14 pages, 3145 KiB

Open AccessArticle

Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition

by Hui-rong Li, Li-gen Sun, Li-guang Zhu, Yun-song Liu and Yun-gang Li

Metals 2018, 8(8), 584; https://doi.org/10.3390/met8080584 - 26 Jul 2018

Cited by 8 | Viewed by 3534

Abstract

The welding performance of shipbuilding steel under large heat input could be improved greatly by the addition of Mg to the steel, but the impact toughness of the heat affect zone (HAZ) is not stable. According to the three different thickness steel plates [...] Read more.

The welding performance of shipbuilding steel under large heat input could be improved greatly by the addition of Mg to the steel, but the impact toughness of the heat affect zone (HAZ) is not stable. According to the three different thickness steel plates obtained in the industrial experiment, the large heat input welding was carried out by different heat input, and the impact toughness analysis, impact fracture analysis, metallographic microstructure analysis and inclusions analysis were carried out. The results showed that, the HAZ of three kinds of thickness plates induced much intragranular acicular ferrite (IAF); with Mg addition, the inclusion dimension had been reduced effectively, and the IAF-induced ability of the inclusions had also been improved. The difference of HAZ impact toughness with different welding heat input and different impact temperature is significant; considering the influence of welding heat input and metallographic microstructure on the impact toughness of HAZ, the welding heat load had a far greater effect than the metallographic microstructure on ductile–brittle transition temperature. At the same time, if the original metallographic microstructure of steel was coarse, the pinning effect of the inclusions would be reduced significantly, and the microstructure of HAZ would be coarsened and the impact toughness of HAZ would be decreased, so there is a certain matching relationship between the metallographic microstructure and the inclusion dimension. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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13 pages, 3435 KiB

Open AccessArticle

Surface Characterization and Secondary Electron Emission Properties of Alumina Containing MgO Film on Ag-Mg-Al Alloy

by Fan Zhou, Quan Zhang, Feifei Wang, Jing Wang, Yunfei Yang, Chen Lai, Wei Liu and Jinshu Wang

Metals 2018, 8(8), 570; https://doi.org/10.3390/met8080570 - 25 Jul 2018

Cited by 15 | Viewed by 5306

Abstract

Ag-Mg alloy is used as a dynode material in electron multiplier tubes due to the high secondary electron yields (δ) of the surface of MgO film. However, MgO film is readily degraded under strong electron or ion bombardment, which results in [...] Read more.

Ag-Mg alloy is used as a dynode material in electron multiplier tubes due to the high secondary electron yields (δ) of the surface of MgO film. However, MgO film is readily degraded under strong electron or ion bombardment, which results in a decrease in the lifetime of devices. In this study, alumina-containing MgO films of ~50–150 nm were developed on a Ag-2Mg-2Al alloy (silver alloy containing 2 wt % Mg and 2 wt % Al) after a thermal activation process performed at 500–600 °C under low oxygen pressures of 5.0–20.0 Pa. Auger electron spectroscopy and X-ray photoelectron spectroscopy analyses reveal that the film consists of a thin layer of pure MgO and a relatively thicker layer of alumina-containing MgO located beneath the top MgO layer. The alumina-containing MgO film exhibits high δ value of 7.7 at a primary electron energy of 580 eV and a much better stability under energetic electron bombardment than pure MgO film on Ag-Mg alloy. Alumina has higher bond dissociation energy than MgO, and the presence of alumina in the film contributes to mitigating the dissociation of the MgO film under electron bombardment. The Ag-2Mg-2Al alloy with alumina-containing MgO film is a promising candidate as a dynode material for electron multiplier tubes. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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15 pages, 7475 KiB

Open AccessArticle

Production of Clean Steel Using the Nitrogen Elevating and Reducing Method

by Jie Zhang, Jianhua Liu, Saijian Yu, Daxi Dong, Gongliang Wang and Shiqi Li

Metals 2018, 8(7), 560; https://doi.org/10.3390/met8070560 - 21 Jul 2018

Cited by 10 | Viewed by 4631

Abstract

Nitrogen Elevating and Reducing Method (NERM) is a new technology developed to remove inclusions and oxygen in molten steel. The principle that underlies it is that nitrogenizing molten steel under low or normal pressure initially elevates the nitrogen content. Then, when the vacuum [...] Read more.

Nitrogen Elevating and Reducing Method (NERM) is a new technology developed to remove inclusions and oxygen in molten steel. The principle that underlies it is that nitrogenizing molten steel under low or normal pressure initially elevates the nitrogen content. Then, when the vacuum treatment is started, the nitrogen bubbles can nucleate on the surface of the inclusions and carry them to slag, reducing the number of inclusions in steel significantly. The removal effects between the new method and the conventional method were compared by industrial trials in this paper. The results show that the average oxygen content of the billet produced by the conventional method was 16 ppm, while that produced by the new method dropped to 11.5 ppm. Besides, the new method shows better removal effect of inclusions, and the number of inclusions decreased by 52.8% compared to the conventional method. The new method has obvious removal effects on inclusions in different sizes. In addition, the differences between NERM and the Pressure Elevating and Reducing Method (PERM) were compared, and the mechanism of each method was analyzed in this paper. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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10 pages, 5184 KiB

Open AccessArticle

Inclusion Evolution Behavior of Ti-Mg Oxide Metallurgy Steel and Its Effect on a High Heat Input Welding HAZ

by Hao-Nan Lou, Chao Wang, Bing-Xing Wang, Zhao-Dong Wang, Yu-Qian Li and Zi-Gang Chen

Metals 2018, 8(7), 534; https://doi.org/10.3390/met8070534 - 11 Jul 2018

Cited by 24 | Viewed by 4353

Abstract

We have studied here the evolution of inclusions in ladle furnace (LF), Ruhrstahl & Heraeus furnace (RH), and simulated welded samples during Ti-Mg oxide metallurgy treatment and the mechanical properties of the heat-affected zone (HAZ) after high heat input welding. The study indicated [...] Read more.

We have studied here the evolution of inclusions in ladle furnace (LF), Ruhrstahl & Heraeus furnace (RH), and simulated welded samples during Ti-Mg oxide metallurgy treatment and the mechanical properties of the heat-affected zone (HAZ) after high heat input welding. The study indicated that inclusions in an LF furnace station are silicomanganate and MnS of size range ~0.8–1.0 μm. After Mg addition, fine Ti-Ca-Mg-O-MnS complex oxides were obtained, which were conducive to the nucleation of acicular ferrite (AF). The corresponding microstructure changed from ferrite side plate (FSP) and polygonal ferrite (PF) to AF, PF, and grain boundary ferrite (GBF). After a simulated welding thermal cycle of 200 kJ/cm, disordered arrangements of acicular ferrite plates, fine size cleavage facets, small inclusions, and dimples all promoted high impact toughness. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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14 pages, 2763 KiB

Open AccessArticle

The Effect of Pressurized Decarbonization of CO on Inhibiting the Adhesion of Fine Iron Ore Particles

by Qiyan Xu, Zhiping Li, Zhuangzhuang Liu, Jianjun Wang and Haichuan Wang

Metals 2018, 8(7), 525; https://doi.org/10.3390/met8070525 - 6 Jul 2018

Cited by 13 | Viewed by 3437

Abstract

In this research, Australian fine iron ore is reduced by pressured carbon monoxide in a fluidized bed. This research aims to obtain the influence law of gas linear velocity, reduction pressure, reduction temperature, particle size, and reduction time on the reduction effect and [...] Read more.

In this research, Australian fine iron ore is reduced by pressured carbon monoxide in a fluidized bed. This research aims to obtain the influence law of gas linear velocity, reduction pressure, reduction temperature, particle size, and reduction time on the reduction effect and the economic, convenient, and effective operating parameters, as well as clarify the effect of the pressurized decarbonization of CO, which inhibits the adhesion of fine iron ore particles during the reduction process. The experimental results show that the preferable operating parameters are a linear velocity of 0.8 m/s, reduction pressure of 0.2 MPa, reduction temperature of 1023 K, and particle size of 0.18 mm–0.66 mm. The graphite produced by the carbon precipitation reaction of carbon monoxide hinders the diffusion of iron atoms and avoids the direct contact between the iron atoms, thereby effectively controlling the sticking. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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17 pages, 3846 KiB

Open AccessArticle

The Effect of Carbon Dissection of Waste Plastics on Inhibiting the Adhesion of Fine Iron Ore Particles during Hydrogen Reduction

by Qiyan Xu, Zhuangzhuang Liu, Zhiping Li, Jianjun Wang and Li Zhou

Metals 2018, 8(7), 523; https://doi.org/10.3390/met8070523 - 6 Jul 2018

Cited by 8 | Viewed by 3254

Abstract

In this research, Australian fine iron ore was reduced by combining pressurized and energy-bearing waste plastics in a fluidized bed. This research aims to obtain preferable operating parameters by synthetically researching the effect of temperature, linear velocity, pressure, size, and mass content of [...] Read more.

In this research, Australian fine iron ore was reduced by combining pressurized and energy-bearing waste plastics in a fluidized bed. This research aims to obtain preferable operating parameters by synthetically researching the effect of temperature, linear velocity, pressure, size, and mass content of energetic waste plastics, and to clarify the sticking mechanism and the inhibitory mechanism of fine iron ore during the reduction process. The experimental results show that the preferable operating parameters include a reduction temperature of 923–973 K, linear velocity of 0.8 m/s, reduction pressure of 0.15 MPa, particle size of energetic waste plastics of 0.18–0.66 mm, and mass content of energetic waste plastics of 8%. Under the conditions of theses preferable operating parameters, the sticking mechanism of fine iron ore is caused by the reunion of the metal iron atoms. The occurrence states of carbons deposited from waste plastics can be divided into two types: graphite and carbon from Fe₃C. Carbon from Fe₃C reduces the sticking of fine iron ore, while the graphite hinders the direct contact of iron atoms, thereby effectively controlling the sticking. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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17 pages, 4199 KiB

Open AccessArticle

Substrate-Induced Liquid Layering: A New Insight into the Heterogeneous Nucleation of Liquid Metals

by Sida Ma, Rui Yan, Tao Jing and Hongbiao Dong

Metals 2018, 8(7), 521; https://doi.org/10.3390/met8070521 - 6 Jul 2018

Cited by 13 | Viewed by 3690

Abstract

Liquid layering, which is a general phenomenon adjacent to the solid substrates, is less understood for its role in heterogeneous nucleation. In this work, the structural features and dynamics of the liquid Al layers induced by the (0001) sapphire and the (0001) TiB [...] Read more.

Liquid layering, which is a general phenomenon adjacent to the solid substrates, is less understood for its role in heterogeneous nucleation. In this work, the structural features and dynamics of the liquid Al layers induced by the (0001) sapphire and the (0001) TiB₂ substrates, respectively, are quantitatively compared based on the ab initio molecular dynamics simulations. An almost fully ordered liquid Al layer is observed adjacent to the TiB₂ substrate above the Al melting point, while the liquid layers near the sapphire substrate are weakly ordered with virtually no in-plane translational symmetry. Further liquid layering is facilitated by the ordered liquid layer near the TiB₂ substrate, while impeded by the low in-plane ordering of the liquid layers near the sapphire substrate, resulting in different nucleation behaviors for the two systems. The difference in the liquid layering is caused, in part, by the lower adsorption strength at the sapphire–liquid Al interface than that at the TiB₂–liquid Al interface. Additionally, the compressive stress imposed on the liquid layers seriously hinders the sapphire-induced liquid layering. We conclude from this work that the interfacial adsorption strength and mismatch alter the heterogeneous nucleation by influencing the features of the substrate-induced liquid layering. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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12 pages, 2074 KiB

Open AccessArticle

Optimal Charge Planning Model of Steelmaking Based on Multi-Objective Evolutionary Algorithm

by Jianping Yang, Bailin Wang, Caoyun Zou, Xiang Li, Tieke Li and Qing Liu

Metals 2018, 8(7), 483; https://doi.org/10.3390/met8070483 - 25 Jun 2018

Cited by 9 | Viewed by 3410

Abstract

As having an important part of coordination control in steelmaking process, traditional production planning and scheduling technologies are developed with little consideration of the metallurgy mechanism, leading to lower feasibility for actual production. Based on current situation and requirements of steel plants, this [...] Read more.

As having an important part of coordination control in steelmaking process, traditional production planning and scheduling technologies are developed with little consideration of the metallurgy mechanism, leading to lower feasibility for actual production. Based on current situation and requirements of steel plants, this paper focuses on the investigation of the charge plan from the view of metallurgy and establishes a charge planning model concerning the minimization of both the open order amount and the difference in due dates of the orders in each charge. A modified multi-objective evolutionary algorithm is proposed to solve the charge planning model of steelmaking process. By presenting a new fitness function, based on the rule of target ranking and introducing the Elitism strategy to construct the non-inferior solution set, the quality of solutions is improved effectively and the convergence of the algorithm is enhanced remarkably. Simulation experiments are carried out on the orders from actual production, and the proposed algorithm produces a group of optimized charge plans in a short time. The quality of the solutions is better than those produced by a genetic algorithm, modified partheno-genetic algorithm, and those produced manually to some extent. The simulation results demonstrate the feasibility and effectiveness of the proposed model and the algorithm. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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18 pages, 3780 KiB

Open AccessArticle

Formation of Multi-Type Inclusions during the Cooling and Solidification of Steel: A Trend Model

by Dali You, Susanne K. Michelic and Christian Bernhard

Metals 2018, 8(6), 452; https://doi.org/10.3390/met8060452 - 13 Jun 2018

Cited by 9 | Viewed by 4286

Abstract

This paper presents a trend model of the competitive formation of multi-type inclusions during the cooling and solidification of steel. The model is able to predict the evolution of various inclusions, including their type, composition and size distribution. In the calculations, the thermodynamic [...] Read more.

This paper presents a trend model of the competitive formation of multi-type inclusions during the cooling and solidification of steel. The model is able to predict the evolution of various inclusions, including their type, composition and size distribution. In the calculations, the thermodynamic library, ChemApp, was applied to perform a thermodynamic equilibrium calculation. Homogeneous nucleation, diffusion-controlled growth and dissolution were employed to simulate the size distribution evolution. At the same time, the collision of inclusions of the same type were considered in a simplified way. The inclusion stabilities were validated by laboratory experiments, which offered a strong basis for the simulations. Using the proposed model, the influence of alloying temperature and oxygen content on the formation of multi-type inclusions was investigated. The results indicated that decreasing the alloying temperature resulted in a higher number density and finer size of different oxides. The oxygen content affected the formation of various oxides in different ways. The predictions, based on the mechanism of competitive nucleation and growth, are discussed and explained. It is believed that the calculations deepen the understanding of the competitive formation of multi-type inclusions. The predicted trends provide a valuable reference for inclusion control and experiment design. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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Review

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16 pages, 2674 KiB

Open AccessReview

Management of Lime in Steel

by Sanjeev Manocha and François Ponchon

Metals 2018, 8(9), 686; https://doi.org/10.3390/met8090686 - 31 Aug 2018

Cited by 38 | Viewed by 10470

Abstract

The EU28 total lime demand in 2017 was estimated at about 20 million tons, out of which about 40% are consumed in the iron and steel industry. Steel remains the major consumer after environment and construction. The lime industry is quite mature and [...] Read more.

The EU28 total lime demand in 2017 was estimated at about 20 million tons, out of which about 40% are consumed in the iron and steel industry. Steel remains the major consumer after environment and construction. The lime industry is quite mature and consolidated in developed countries, with enough reserves and production to serve regional markets while being fragmented in developing nations where steel producers rely on local sourcing. There is relatively very little trade for lime worldwide. Lime has a critical role at different steps of the steelmaking process, and especially to make a good slag facilitating the removal of sulphur and phosphorus, and for providing a safer platform to withstand high intensity arc plasma in the electric arc furnace (EAF), and violent reactions in the basic oxygen furnace (BOF). Lime quality and quantity has a direct effect on slag quality, which affects metallurgical results, refractory life, liquid metal yield, and productivity, and therefore the total cost of the steel production. In this paper, we present the importance of careful selection in the limestone and calcination process, which influences critical lime quality characteristics. We shall further elaborate on the impact of lime characteristics in the optimization of the steelmaking process, metallurgical benefits, overall cost impact, potential savings, and environmental benefits. Full article

(This article belongs to the Special Issue 5th UK-China Steel Research Forum)

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