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A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: closed (31 January 2023) | Viewed by 13684

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Prof. Dr. Yanling Zhang

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Guest Editor

State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing, China
Interests: research on application of solid waste such as red mud in steelmaking process; research on basic rheology and melt properties of metallurgical slag; steelmaking process technology theory and application; comprehensive utilization of secondary resources
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Prof. Dr. Guoguang Cheng

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Guest Editor

State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing, China
Interests: metal
Special Issues, Collections and Topics in MDPI journals

Zhonghua Zhan

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Guest Editor Assistant

State Key Laboratory of Advanced Metallurgy, University of Science and Technology and Beijing, Beijing, China
Interests: high strength stainless steel steelmaking process optimization; inclusion control of special steel

Special Issue Information

Dear Colleagues,

Non-metallic inclusions have a great influence on the cleanliness and mechanical properties of steel. Controlling the size and composition of inclusions contributes to the excellent properties of “clean steel”. At the same time, in terms of our understanding of inclusions’ behavior using thermodynamics principles, the design and control of the composition, shape, size, and distribution of non-metallic inclusions in different steels can significantly enhance steel properties.

The primary focus of this Special Issue is on recent advances in inclusion engineering that aim at controlling steel cleanliness and microstructure by modeling and experimental work. The particularly interesting research theme of the formation mechanism and evolution control methods of inclusions in the smelting process in laboratory and steel plants is welcomed. The study of the agglomeration and floatation of inclusions and the kinetics of slag adsorption in the process of refining and solidification are also potential themes of contribution.

Topics addressed in this Special Issue may include, but are not limited to, the following aspects:

Formation/evaluation of inclusions during steel smelting/refining/solidification;
Multiphase reaction of steel–slag–inclusion–refractory;
Thermodynamics and kinetics prediction;
Fundamentals on wettability, contact angle, and surface tension, as well as the related basic database;
Inclusion metallurgy in clean steel.

Prof. Dr. Yanling Zhang
Prof. Dr. Guoguang Cheng
Guest Editors

Zhonghua Zhan
Guest Editor Assistant

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Keywords

inclusion
clean steel
multiphase reaction
refining
interface behavior

Published Papers (11 papers)

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Editorial

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2 pages, 166 KiB

Open AccessEditorial

Inclusion Metallurgy

by Yanling Zhang, Guoguang Cheng and Zhonghua Zhan

Metals 2023, 13(5), 827; https://doi.org/10.3390/met13050827 - 23 Apr 2023

Viewed by 778

Abstract

Non-metallic inclusions have a great influence on the cleanliness and mechanical properties of steel [...] Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

Research

Jump to: Editorial

15 pages, 13733 KiB

Open AccessArticle

Effects of Rare Earth La–Ce Alloying Treatment on Modification of Inclusions and Magnetic Properties of W350 Non-Oriented Silicon Steel

by Haijun Wang, Yuhao Niu, Haitao Ling, Jialong Qiao, Yanling Zhang, Wei Zhong and Shengtao Qiu

Metals 2023, 13(3), 626; https://doi.org/10.3390/met13030626 - 21 Mar 2023

Cited by 2 | Viewed by 1307

Abstract

In order to study the effects of rare earth La–Ce alloying treatment on the characteristics of inclusions in non-oriented silicon steels, industrial experiments were conducted studying the composition, morphology, size and quantity of inclusions in W350 non-oriented silicon steel during the RH (Ruhrstahl-Hereaeus) refining process and tundish process, after rare earth treatment. The products were analyzed by means of ICP-MS (inductively coupled plasma mass spectrometry), SEM/EDS (scanning electron microscope-energy dispersive spectrometry), and ASPEX (automated SEM/EDS inclusion analysis). The research results showed that the types of inclusions in experimental steel changed significantly after rare earth treatment. The types of inclusions after RE (rare earth) treatment are typically rare earth composite inclusions that are mainly composed of (La, Ce)Al₂O₃, and conventional inclusions. The addition of rare earth promotes the agglomeration of inclusions; the morphologies of the inclusions are mostly blocky, and some are distributed in long strips. After rare earth treatment during the RH refining process, the number of inclusions with sizes of 1.0~3.5 μm in the experimental steel is increased, and the average size of the inclusions is 2.66 μm. In addition, the number of inclusions larger than 4 μm in the specimens increases due to the collision and growth of inclusions caused by the RH circulation. After rare earth treatment during the tundish process, the number of micro inclusions with sizes of 1.0~2.5 μm in the specimen steels decreases, while the number of inclusions larger than 5 μm increases. The size distribution of micro inclusions in hot-rolled sheets after rare earth treatment was studied using TEM (transmission electron microscopy). In the specimens without rare earth, the content of micro inclusions (≤1 μm) is 51,458.2/mm² and the average size is 0.388 μm. In the specimens with rare earth added, the content of micro inclusions (≤1 μm) is 24,230.2/mm² and the average size is 0.427 μm. Compared to sheet produced by the original process, the iron loss of the 0.35 mm finished experimental sheet is reduced by 0.068 W/kg, and the magnetic induction is increased by 0.007 T. The iron loss of the 0.50 mm finished experimental sheet is reduced by 0.008 W/kg, and the magnetic induction is increased by 0.004 T. After rare earth treatment, the average size of micro inclusions increases and the magnetic properties are obviously improved. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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14 pages, 8123 KiB

Open AccessArticle

Modification of Rare Earth Ce on Inclusions in W350 Non-Oriented Silicon Steel

by Haijun Wang, Yuhao Niu, Haitao Ling, Jialong Qiao, Yanling Zhang, Wei Zhong and Shengtao Qiu

Metals 2023, 13(3), 453; https://doi.org/10.3390/met13030453 - 22 Feb 2023

Cited by 3 | Viewed by 1064

Abstract

In this paper, the effect of rare earth Ce content on the morphology, composition, type and size distribution of inclusions in W350 non-oriented silicon steel was investigated by means of ICP-MS (inductively coupled plasma mass spectrometry), SEM/EDS (scanning electron microscope-energy Dispersive Spectrometer), and ASPEX (automated SEM/EDS inclusion analysis). The results showed that with the increase of Ce content in the steel, the modification sequence of inclusions was CeAlO₃→Ce₂O₂S→Ce_xS_y. The type and size distribution of inclusions in the steel obviously changed with the difference in added Ce content. When the added Ce content in the steel was 10 ppm, 14 ppm, 20 ppm and 30 ppm respectively, the rare earth inclusions were mainly CeAlO₃-Ce₂O₂S. Furthermore, when the added Ce content increased to 60 ppm, the rare earth inclusions were mainly Ce₂O₂S with a small amount of CeAlO₃ contained in part inclusions. When the added Ce content increased continually to 95 ppm, the rare earth inclusions were mainly Ce_xS_y-Ce₂O₂S. The critical Ce content for the conversion between CeAlO₃ and Ce₂O₂S was 41 ppm. To ensure that inclusions transform from CeAlO₃ to Ce₂O₂S, the Ce content in the steel should be greater than 41 ppm. Under the current experimental conditions, it was found that when the Ce content was 20 ppm, the number density and proportion of inclusions in the steel were lower, and their average size was larger. When the added Ce content increased to 95 ppm, the number density of inclusions in the steel significantly increased, which deteriorated the steel cleanliness. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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16 pages, 7636 KiB

Open AccessArticle

Study of Process Parameters on Solidification Structure and Centre Grain Size of 2311 in 420 mm Extra-Thick Continuously Cast Slabs

by Lijun Xu, Pan Zhang, Yong Shuai, Pengzhao Shi, Zhonghua Zhan and Minglin Wang

Metals 2023, 13(1), 47; https://doi.org/10.3390/met13010047 - 24 Dec 2022

Cited by 2 | Viewed by 1389

Abstract

Based on the solidification heat transfer model and the CAFE model, the solidification behavior and structure of 2311 die steel, with a cross-section dimension of 415 × 2270 mm at different casting speeds, specific water flow and superheat, is numerically simulated. Nail-shooting and acid-etching experiments are carried out on the slab to verify the model’s macroscopic size. With the increase in casting speed, the slab’s central equiaxed grain ratio (ECR) decreases and the average grain size increases. The increase in superheat promotes the growth of columnar grains and inhibits the growth of central equiaxed grains. When the superheat increases from 23 to 38 K, the ECR decreases from 43.2 to 29.64%, and the average radius of grains increases from 0.89 to 1.01 mm. With the increase in specific water flow, the ECR decreases, and the average grain radius is the smallest when the specific water content is 0.32 L kg⁻¹. Finally, the slab quality is improved by process optimization, and the central segregation index of carbon decreases from mean value of 1.15 to 1.05. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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18 pages, 19894 KiB

Open AccessArticle

Evolution and Formation of Non-Metallic Inclusions during Electroslag Remelting of Ce-Bearing 15Cr-22Ni-1Nb Austenitic Heat-Resistant Steel

by Zhongwei Wang, Chengbin Shi, Shijun Wang, Jing Li and Xin Zhu

Metals 2022, 12(12), 2094; https://doi.org/10.3390/met12122094 - 06 Dec 2022

Cited by 3 | Viewed by 1053

Abstract

The evolution of inclusions in austenitic heat-resistant steel with different Ce content during protective argon gas atmosphere electroslag remelting (ESR) was studied. All oxide inclusions in the Ce-free consumable electrode are MgO·Al₂O₃. A part of these MgO·Al₂O₃ inclusions was removed before metal droplets entered the liquid metal pool during the ESR. The soluble oxygen (arising from the reoxidation) reacted with soluble aluminum, calcium, and magnesium in liquid steel to form MgO·Al₂O₃ and CaO–Al₂O₃ inclusions in liquid steel. All oxide inclusions in the electrode with 0.016 mass% Ce are Ce₂O₂S. A portion of these Ce₂O₂S inclusions was dissociated into soluble oxygen, cerium, and sulfur in liquid steel during the ESR process, whereas the others were removed by absorbing them into molten slag. The oxide inclusions in the liquid metal pool and remelted ingot were Ce₂O₃, CeAlO₃, and Ce₂O₂S. The CeAlO₃ and Ce₂O₃ inclusions were reoxidation products formed by the chemical reaction between the soluble oxygen, soluble aluminum, and cerium. The oxide inclusions in the electrode with 0.300 mass% Ce are CeS and Ce₂O₂S. These CeS inclusions were removed by molten slag adsorption during the ESR. A part of these Ce₂O₂S inclusions was removed by slag adsorption, and the remaining entered into the liquid metal pool. The oxide inclusions in the liquid metal pool and the ingot were Ce₂O₃ and Ce₂O₂S. The Ce₂O₃ inclusions were formed through the chemical reaction between the soluble oxygen and cerium in the liquid metal pool. The Ce₂O₂S inclusions in the liquid pool originate from reoxidation products during the ESR process and the relics from the electrode. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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17 pages, 10040 KiB

Open AccessArticle

Formation and Removal Mechanism of Nonmetallic Inclusions in 42CrMo4 Steel during the Steelmaking Process

by Tong Qiao, Guoguang Cheng, Yu Huang, Yao Li, Yanling Zhang and Zhanchun Li

Metals 2022, 12(9), 1505; https://doi.org/10.3390/met12091505 - 11 Sep 2022

Cited by 7 | Viewed by 1593

Abstract

Nonmetallic inclusions are harmful to the quality of 42CrMo4 steel. Therefore, the formation and removal mechanism of inclusions in 42CrMo4 steel during the steelmaking process is investigated by industrial trials. The characteristics of inclusions in specimens were analyzed by scanning electron microscopy and energy dispersive spectroscopy. The main type of inclusions in molten steel in the early stage of ladle furnace (LF) refining is MgO-Al₂O₃ inclusions of irregular shape. CaO begins to appear in MgO-Al₂O₃ inclusions in the middle and late stages of LF. In the vacuum degassing (VD) refining stage, the inclusions in molten steel completely change into low-melting-point CaO-MgO-Al₂O₃ inclusions. The existence of [Mg] in molten steel is the fundamental reason for the formation of a large number of MgO-Al₂O₃ inclusions. Thermodynamic calculation shows that the refractory mainly transfers [Mg] to the liquid steel in the LF refining stage, whereas the slag mainly transfers [Mg] to the liquid steel in the VD refining stage. Kinetic calculation indicates that MgO-Al₂O₃ inclusions could be removed from molten steel faster than low-melting-point CaO-MgO-Al₂O₃ inclusions. The fundamental reason for the different removal behavior of the two types of inclusions is that the interfacial tension between the low-melting-point CaO-MgO-Al₂O₃ inclusions and the liquid steel is 50% lower than that of the MgO-Al₂O₃ inclusions. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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13 pages, 4805 KiB

Open AccessArticle

Source and Transformation of MgO-Based Inclusions in Si-Mn-Killed Steel with Lime-Silicate Slag

by Jiaqi Zhao, Jianhua Chu, Xin Liu, Min Wang, Xiaofeng Cai, Han Ma and Yanping Bao

Metals 2022, 12(8), 1323; https://doi.org/10.3390/met12081323 - 07 Aug 2022

Cited by 2 | Viewed by 1432

Abstract

The origin, evolution, and formation mechanism of MgO-based inclusions in Si-Mn-killed steel were studied in industrial trials with systematical samplings of the refining ladle, casting tundish, and as-cast bloom. In the present study, there were large numbers of MgO-based non-metallic inclusions, which started to form in the LF final process, and the MgO content in the lime-silicate slag increases from LF to VD process. The reason for the formation of MgO-based inclusions in refining process was analyzed using FactSage8.1 software. It was found that MgO-based inclusions were caused by the violent reaction between the slag and steel and the serious erosion of MgO-C refractory. The MgO solubility decreased in the lime-silicate slag and precipitated the periclase phase with basicity increasing. The solubility of MgO increased with an increase in the temperature. Measures were taken to optimize the refining process based on the above result. By increasing the slag basicity and increasing the content of MgO in the slag, erosion of the MgO-C refractory was reduced and the number of MgO-based non-metallic inclusions decreased from 0.2 to 0.04 per square millimeter. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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13 pages, 4404 KiB

Open AccessArticle

Effect of Rare Earth Cerium Content on Manganese Sulfide in U75V Heavy Rail Steel

by Chao Zhuo, Rui Liu, Zirong Zhao, Yulei Zhang, Xiaoshuai Hao, Huajie Wu and Yanhui Sun

Metals 2022, 12(6), 1012; https://doi.org/10.3390/met12061012 - 14 Jun 2022

Cited by 9 | Viewed by 1849

Abstract

To study the effect of Ce on the morphology of manganese sulfide, we added different contents of Ce into U75V heavy rail steel. The composition and morphology of sulfide in steel were analyzed. The inclusions’ number, size, and aspect ratio were analyzed by automatic scanning electron microscope ASPEX. The results show that the inclusions in heavy rail steel without Ce are elongated MnS and irregular Al-Si-Ca-O inclusions. With the increase of Ce from 52 ppm to 340 ppm, the composition of main inclusions changes along the route of Ce₂O₂S-MnS → Ce₂O₂S-MnS-Ce₂S₃ → Ce₂O₂S-Ce₃S₄-Ce₂S₃ → Ce₂O₂S-Ce₃S₄-CeS. Ce has a noticeable spheroidization effect on MnS, which can make inclusions finely dispersed. When Ce content is 139 ppm, the average size of inclusions is the smallest. The mechanism of Ce-modified MnS was discussed by combining experimental results with thermodynamic calculations. Finally, the effect of Ce treatment on inhibiting MnS deformation was verified by simulated rolling. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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22 pages, 14790 KiB

Open AccessArticle

Evolution of Inclusions and Cleanliness in Ti-Bearing IF Steel Produced via the BOF–LF–RH–CC Process

by Baohui Yuan, Jianhua Liu, Jianhua Zeng, Min Zhang, Jihong Huang and Xiaodong Yang

Metals 2022, 12(3), 434; https://doi.org/10.3390/met12030434 - 01 Mar 2022

Cited by 10 | Viewed by 2462

Abstract

Owing to the insufficient converter heat, IF steel is produced via the BOF–LF–RH–CC process in Pangang Group Xichang Steel and Vanadium Co., Ltd. To clarify the evolution of inclusions and the control strategy to improve the cleanliness of molten steel in Ti-bearing IF steel produced via the long process, scanning electron microscopy with energy spectroscopy analysis and automatic scanning electron microscopy were employed to analyze the number, size, type and morphology of inclusions in IF steel from RH to tundish. The results show that the characteristics of inclusions are similar in two heats during RH treatment. In the tundish sample of Heat 2, the number density (ND) and area fraction (AF) of Al₂O₃ and Al₂O₃·TiO_x inclusions increase significantly, and the size of Al₂O₃ inclusions decreases obviously, which is closely related to the serious reoxidation of molten steel caused by the slag with high oxidability during the holding process. Meanwhile, a new method of determining the number of cluster inclusions is used to evaluate the cleanliness of IF steel in this paper, and the obtained number of inclusion clusters is consistent with the trend of ND and AF of inclusions. The effects of reoxidation on the morphology, number and other indexes of Al₂O₃ and Al₂O₃·TiO_x inclusions are discussed in detail, and there are two ways of forming Al₂O₃·TiO_x inclusions in the case of serious reoxidation. To weaken the reoxidation process and enhance the cleanliness of IF steel produced via the long process, reducing the oxygen content in molten steel before Al deoxidation, minimizing the holding time and reducing the oxidability of slag after RH are helpful. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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19 pages, 18829 KiB

Open AccessArticle

Formation Mechanism and Improvement of Magnetic Particle Inspection Defects in Cr5 Backup Roller Forged Ingot

by Weifeng Zhang, Guanbo Wang, Yanling Zhang, Guoguang Cheng and Zhonghua Zhan

Metals 2022, 12(2), 295; https://doi.org/10.3390/met12020295 - 08 Feb 2022

Cited by 4 | Viewed by 1386

Abstract

Industrial tests and thermodynamic calculations were utilized to investigate the source and formation of magnetic particle inspection defects identified on the near-surface of the Cr5 back-up roll forged ingot, which was used in large cold rolling mills. The results showed that the linear aggregating SiO₂-MnO-Al₂O₃ liquid inclusions up to 3 mm led to the flaw detection failure. SiO₂-MnO-Al₂O₃ liquid inclusions were firstly formed in the inductive furnace. Due to its low contact angle, a huge amount of SiO₂-MnO-Al₂O₃ liquid inclusions were inherited into the forged ingot. The formation of SiO₂-MnO-Al₂O₃ liquid inclusions was attributed to the over-oxidation and relatively low aluminum content in the molten steel, as calculated by Factsage 8.1. Controlling the amount of aluminum in molten steel during the smelting process could modify the formation of SiO₂-MnO-Al₂O₃ and CaO-SiO₂-Al₂O₃ liquid oxide into solid Al₂O₃ type inclusions that were easily removed. Besides, the CaO-SiO₂-Al₂O₃ liquid oxide could be transformed from CaO-Al₂O₃ type oxide by the significant loss of aluminum content during the VD process or slag entrapment. Certain content of aluminum in the molten steel could improve the flaw detection caused by the aggregating SiO₂-MnO-Al₂O₃ inclusions effectively. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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16 pages, 10804 KiB

Open AccessArticle

Effect of Sulfur Content on the Inclusion and Mechanical Properties in Ce-Mg Treated Resulfurized SCr420H Steel

by Meng Sun, Zhouhua Jiang, Yang Li, Changyong Chen, Shuai Ma, Yongshuai Ji, Ju Wang and Hang Liu

Metals 2022, 12(1), 136; https://doi.org/10.3390/met12010136 - 11 Jan 2022

Cited by 10 | Viewed by 2149

Abstract

To clarify the effect of sulfur on inclusions and mechanical properties of Ce-Mg treated resulfurized SCr420H steel. Laboratory experiments were conducted to prepare steels with sulfur contents as 0.01%, 0.06%, and 0.132%. Inclusion evolution in liquid steel, MnS precipitation during solidification, and tensile test results of steel after quenching and tempering were investigated. The results showed that due to the limitation of mass transfer in molten steel, composite inclusion that Ce-O-S wrapped by Ce-Ca-Mg-Al-Si-O, which was named transition state inclusions, can form quickly after adding Ce-Mg lump to the molten steel. As the homogenization of molten steel, the difference of sulfur content in steel can lead to the transition state inclusions transformed into different inclusions. With the increase of sulfur content, the quantity of MnS increased significantly, and the morphology of MnS transformed from “stick” to “dendritic + fishbone”, and then to “fishbone”. Tensile test results and fracture analysis indicate that the decline of inclusion spacing as the increase of sulfur content leads to a shorter physical path of crack propagation in steel. Therefore, the increase of sulfur content can bring about a decrease in the strength and plasticity of the steel. From the perspective of inclusion control, making the MnS inclusion precipitate more dispersive and increasing the distance between inclusions can be considered as a method for preventing the decline of mechanical properties in steel with high sulfur content. Full article

(This article belongs to the Special Issue Inclusion Metallurgy)

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