连铸
Home
|
About Journal
|
Editorial Board
|
Instruction for Authors
|
Subscriptions
|
Advertisement
|
Contacts Us
|
Chinese
Office Online
Author Center
Peer Review
Editor Work
Office Work
Editor-in-chief
Journal Online
Forthcoming Articles
Current Issue
Archive
Read Articles
Download Articles
Email Alert
Quick Search
Advanced Search
2024 Vol. 43 No. 1
Published: 2024-02-20
Technology Exchange
Comprehensive Summarization
Monographic Study
Comprehensive Summarization
1
CHENG Ting, YANG Li, QIU Hao, LI Tong, LIU Heping, MENG Huadong
Review and development of numerical simulation for gas stirring in EAF steelmaking
Numerical simulation has become an effective means to analyze the complex physicochemical phenomena and their mechanism in electric arc furnace (EAF) steelmaking. A review of numerical simulation for gas stirring in EAF steelmaking is performed. The effects of gas stirring on the behavior of flow, heat transfer, and chemical reactions in EAF steelmaking are reviewed from the coherent jet, the side-blowing and the bottom-blowing. The key factors affecting the characteristics of the coherent jet are analyzed. The effects of side-blowing on molten bath in EAF are discussed. The behaviors of molten bath with bottom-blowing in EAF studied based on numerical simulation is reviewed. Finally, the development of numerical simulation for gas stirring in EAF is proposed.
2024 Vol. 43 (1): 1-8 [
Abstract
] (
63
) [
HTML
1KB] [
PDF
0KB] (
140
)
9
SHAO Kaixuan, BAI Xiaolu, JIANG Peng, WANG Haijun, CONG Junqiang, QIU Shengtao
Application of different combustion medium in slab cutting during continuous casting
Under the background of the dual carbon policy, enterprises, and scientific research institutes actively carry out low-cost, high-efficiency, and environmentally friendly steel preparation technology. As one of the supporting processes of continuous casting production, cast billets flame cutting has attracted the attention of many enterprises and researchers. Energy-efficient cutting technology and environmentally friendly cutting methods will be the main direction of future flame-cutting development. Based on the actual demand, the cutting principle of flame cutting different combustion media was summarized, the cutting costs, cutting quality (cutting gap, cutting surface flatness, and dross amount), and cutting efficiency of different cutting media were comparatively analysed, and the research progress of flame cutting of continuous casting billet in iron and steel enterprises and scientific research institutes at domestic and international was summarized. On this basis, combined with the intelligent control hydrogen oxygen cutting technology developed by the author's team, pointed out the shortcomings of the current flame cutting and the future development trend are pointed out.
2024 Vol. 43 (1): 9-17 [
Abstract
] (
47
) [
HTML
1KB] [
PDF
0KB] (
108
)
Monographic Study
18
LU Jingzhou, PAN Weiming, DOU Kun, WANG Wanlin, ZHOU Lejun
Numerical simulation of mold nozzle optimization in slab continuous casting process
To optimize the mold nozzle during the slab continuous casting process to suppress slag entrapment, a three-dimensional model of the stainless-steel slab continuous casting mold was established using ProCAST to study the optimization method of the mold nozzle. By measuring the performance parameters of the protective slag using a laboratory viscosity meter and incorporating them into the empirical formula for the critical surface flow rate of slag entrapment, the critical surface flow rate of molten steel that is prone to slag entrapment can be obtained. Numerical simulation calculates the critical surface flow rate of molten steel before and after optimization, as well as the flow field and temperature field of the mold. The theoretical value of the critical surface velocity of molten steel slag is 0.35 m/s. The numerical simulation results show that the diameter of the middle hole increases from 55 mm to 60 mm, the inclination angle of the side hole decreases from 8 ° to 6 °, the critical surface velocity of the steel in the four feet casting billet decreases from 0.347 m/s to 0.296 m/s, and the critical surface velocity in the five feet casting billet decreases from 0.351 m/s to 0.323 m/s. Under the optimized parameters, the surface flow rate of the molten steel is appropriate, the flow field and temperature field of the mold are reasonable, which is conducive to the melting of the protective slag. The lubrication effect of the billet shell is good, and it can effectively suppress the occurrence of slag entrapment. Therefore, the nozzle of the slab continuous casting mold can be optimized according to this parameter.
2024 Vol. 43 (1): 18-25 [
Abstract
] (
43
) [
HTML
1KB] [
PDF
0KB] (
102
)
26
GAO Jiang, WANG Leyao, YANG Wen, ZHANG Lifeng, LI Quanhui, LI Ming
Transformation of inclusions during the solidification and cooling process of Al-killed Ca treated structural steels
In order to study the transformation mechanism and influencing factors of inclusions during the solidification and cooling process of aluminum deoxidized calcium treated steel, the transformation phenomenon of inclusions in steel with different cleanliness levels was analyzed by taking molten steel samples in tundish and continuous casting slab samples of S335 structural steel. It was found that during the production process of Al-killed Ca treated S335 structural steels, inclusions underwent a transformation from homogeneous CaO-Al
2
O
3
to multiphase Al
2
O
3
+CaS from the molten steel in tundish to the continuous casting slab, accompanied by an increase in the number density and size of inclusions. The transformation mechanism of inclusions during the solidification and cooling process of steel was revealed through thermodynamic calculations. It was found that with the decrease of
w
(T.[Ca])/
w
(T.[O]) and the increase of
w
(T.[O])/
w
(T.[S]) in the steel, the weight percent of CaO in inclusions in the molten steel decreased. At the same time, the precipitation temperature and precipitation amount of CaS in inclusions decreased during the solidification and cooling process. Based on the transformation phenomenon of inclusions during the solidification and cooling of steels, it could be concluded that when analyzing the composition of inclusions in molten steel, rapid cooling must be carried out after taking out the molten steel sample to avoid the transformation of inclusions during the solidification and cooling process and improve the accuracy of detection.
2024 Vol. 43 (1): 26-31 [
Abstract
] (
45
) [
HTML
1KB] [
PDF
0KB] (
51
)
32
JIANG Ye, LI Ming, WU Jianyong, MAO Naixu, SONG Sicheng, SUN Yanhui
Optimization of retaining wall for four stream large round billet tundish
In order to solve the problem that the quality of the casting billet in the middle two strands is significantly lower than that in the edge two strands during poor production conditions in a steel plant, improve the consistency of each strand in the tundish, and reduce the proportion of dead zones in the tundish, we designed three methods on the same retaining wall, and obtained the time residence distribution (RTD) curves of each scheme through water model physical experiments. After analyzing the RTD curves, the corresponding proportions of dead zone, piston flow zone, and fully mixed flow zone for each scheme were obtained. At the same time, taking into account the peaks of the RTD curve and the consistency between various strands, the optimal production plan was obtained. The research results indicate that the B1 scheme with a single hole on the side has the best flow field, with an aperture of 140 mm and a vertical angle of 20°. The consistency between its two strands is very good, with a dead zone ratio of 19.95%, and the RTD curve has no peaks or double peaks.
2024 Vol. 43 (1): 32-37 [
Abstract
] (
37
) [
HTML
0KB] [
PDF
0KB] (
6
)
38
LONG Hu, QIU Wensheng, LIU Dong, GUO Junyu, LI Fuqiang, LIU Zhilong
Mechanism of ZrO
2
containing nozzle clogging in continuous casting of calcium treated aluminum killed steel
Calcium treatment is an important way to reduce the clogging of aluminum-killed steel during continuous casting. However, in industrial practice, deposition still occurs after calcium treatment.The morphology, composition and element distribution of the clogging and the large size inclusion at the crack initiation were detected and analyzed by scanning electron microscopy, to study the inclusion clogging behavior of aluminum-killed steel treated with calcium at the the Zr-containing bowl and the inner wall without Zr-containing of the nozzle. Results show that CaO-MgO-Al
2
O
3
were the main components of both the accumulation of the nozzle and the large size inclusions in the center of the rolled wire, and the mass fraction of 1%-3% ZrO
2
was also detected. It was indicated that there were lots of complex calcium-aluminate inclusions in the steel with the Al
2
O
3
percentage larger than 75% at high melting temperature, easy to accumulate in the nozzle during casting. At the same time, the reduction reaction between ZrO
2
, SiO
2
contained in the bowl of the nozzle and graphite C occured, generating SiO, ZrO and other gases, and diffusing outwards into the accumulated calcium-magnesium-aluminate inclusions, hence, the composite reservoir containing ZrO
2
was formed. The attachments of the Zr-containing clogging melted and fell down, part of them accumulated to the inner wall of the nozzle, and part of them entered into the liquid steel and gathered further during the solidification process. The key is to improve the purity of molten steel and appropriately reduce the content of Als and Ca in steel to decrease the inclusions, especially calcium aluminate. It is also necessary to optimize the material of nozzle to reduce its reactivity.
2024 Vol. 43 (1): 38-45 [
Abstract
] (
44
) [
HTML
0KB] [
PDF
0KB] (
6
)
46
LIAN Tianlong, HE Bo, WANG Wenxue, HOU Kaikai
Simulation on the flow field and inclusions in slab con-cast tundish
As an intermediate step in con-cast production, the tundish enables the pouring of molten steel to shift from intermittent to continuous operation, and its role as a metallurgical reaction vessel is crucial in improving steel production capacity and quality. Multiple optimization schemes for the shape of the tundish in a case study are proposed. Then through the simulation calculation, the law of inclusion removal rate, RTD curve data, velocity field and temperature field under different schemes is studied, the advantages and disadvantages of the proposed schemes are evaluated, and the best improvement scheme is proposed. Finally, some of the technical measures proposed can provide references and guidance for steel production companies to improve product quality.
2024 Vol. 43 (1): 46-54 [
Abstract
] (
49
) [
HTML
0KB] [
PDF
0KB] (
6
)
55
CAO Longqiong, XIA Jinkui, JIN Haibing, YAN Min, WANG Zixian, ZHANG Liqiang
Control practices for edge cracking after rolling of 300 mm thick wide-section plain plates
Egang Steel's slab casting equipment has been in operation for over ten years. However, since the second half of 2020, discontinuous cracks deviating from the edge by 50-100 mm have been observed in 300 mm thick slabs. The cracking ratio of the rolled steel plates with a thickness of 300 mm reached 19.8%, resulting in a significant amount of slabs that could not be delivered as hot-rolled plates after edge cutting. Upon identifying the crucial factors through multiple rounds of testing and analysis, it was found that the increase in speed, steel composition, and nitrogen content had a certain impact on the formation of steel plate cracks. By modifying the process parameters, adjusting the molten steel composition, and controlling the nitrogen content, the deviating edge cracks on the 300 mm thick hot-rolled plates were essentially eliminated, and the edge crack rate was controlled to below 2%.
2024 Vol. 43 (1): 55-61 [
Abstract
] (
36
) [
HTML
0KB] [
PDF
0KB] (
5
)
Technology Exchange
62
LI Shengcun, MIAO Chengliang, TIAN Guichang
Microstructure uniformity control of low carbon steel in short process continuous casting and rolling
The low carbon steel products with thickness of 2.0 mm and below produced in the short process of continuous casting and rolling are in great demand in the market. However, due to the factors such as rolling process and equipment capacity, the microstructure uniformity is poor, which further affects the product performance.The causes of the uneven microstructure of low carbon steel produced by ferritic rolling process are analyzed. It is found that the uneven microstructure of strip steel gradually increases with the thickness thinning. The strip steel with a thickness of 1.8 mm has uniform microstructure, but the uneven microstructure begins to appear from 1.5 mm, and the microstructure is obviously stratified when the thickness is reduced to 1.3 mm. When the thickness is reduced to 1.1 mm, the stratification gradually intensifies, showing a clear “sandwich” structure.The coiling temperature is increased from 650 ℃ to 680 ℃ by adopting the air cooling mode in the layer cooling section and putting in the insulation cover equipment. There is also a reduction in the thickness of the intermediate billet, the use of 70%-85% of the reduction rate and other measures, so that the uniformity of the organization has been significantly improved, compared with the previous performance, the yield is reduced by 3%-5%, the tensile strength is reduced by less than 3%, and the elongation is increased by 12%-29%.
2024 Vol. 43 (1): 62-66 [
Abstract
] (
39
) [
HTML
0KB] [
PDF
0KB] (
7
)
67
LI Zhe, YANG Xiaojiang, TIAN Wei, ZHANG Dayong, XIAO Pengcheng, LI Hongbin
Optimization of continuous casting process for peritectic high alumina steel 590DH
590DH belongs to peritectic high-alumina steel, and has the technical difficulties of both peritectic steel and high-alumina steel. At the initial stage of production, the bond alarm is frequent in the casting process, and the longitudinal crack of continuous casting billet occurs from time to time, accompanied by the transverse crack of the corner. By adding Li
2
O to the slag, increasing R and reducing C content, the heat transfer and lubrication effects of the slag are improved. Change the SEN Angle down 25° to 15°, and reduce the insertion depth of the SEN port from 135 mm to 120 mm. Casting speed is optimized. The liquid level of the mold is active, the melting of the protective slag is promoted, and the inflow of the slag is improved. Through the implementation of the above measures, the stability of the slag is improved, the heat transfer and lubrication effect are improved, the bonding alarm problem is solved, the longitudinal cracks are eliminated, and the surface quality of the slab is improved.
2024 Vol. 43 (1): 67-72 [
Abstract
] (
42
) [
HTML
0KB] [
PDF
0KB] (
4
)
73
YE Gaoqi, HAN Xiaoqiang, LI Sheng, MA Yunfei
Analysis and improvement of wide band edge crack defect in Q235B steel
By tracking the continuous casting billet, it is found that the distribution of the upper edge crack of the hot rolled strip is very consistent with the distribution of the transverse corner crack of the continuous casting billet.The results of energy spectrum analysis showed that K and Na were typical components of mold powder, which proved that the defect originated in the mold of continuous casting machine. Then take Q235B molten steel as an example, the carbon content should be controlled in the range of 0.15%-0.20%,
w
([Mn])/
w
([S])>20 standard. By avoiding the crack sensitive region of carbon content and
w
([Mn])/
w
([S]), the proportion of furnace times in the crack sensitive region of carbon content and
w
([Mn])/
w
([S]) and the value of the opening of the foot roll of continuous casting mold are adjusted to 0 mm、0.4 mm、0.8 mm.Two-side and middle-three-point tests were used to test the arc-foot roller and sector roller in the mould. Each checkpoint detects four sets of values, and the test control standard was (1±0.15) mm The edge crack rate of hot rolled steel strip was reduced from 0.46% to 0.04% by optimizing and improving the nozzle insertion depth of continuous casting mold to 120-150 mm.
2024 Vol. 43 (1): 73-77 [
Abstract
] (
34
) [
HTML
0KB] [
PDF
0KB] (
6
)
78
KANG Wei, LI Hong, LIAO Xiangwei, ZHU Xiaolei, YANG Ji
Application and development of inclusion control and removal technology in Ansteel
Inclusions have significant impact on the performance and surface quality of steel.Various attempts and studies have been made focus on inclusion control and removal. Such as injecting ultrafine CaO powder into molten steel,adding ultrafine powder composite balls into molten steel, as well as industrial trial on injecting ultrafine CaO powder into molten steel and adding composite balls into molten steel at RH.Circular composite inclusions are formed in the molten steel by injecting ultrafine CaO powder into molten steel or adding ultrafine powder composite balls,and most of them aggregating and floating out of steel.Most of inclusions in the slab are circular and size around 2 μm after injecting ultra-fine CaO powder, the numerical density and area percentage content of the inclusions decrease significantly of EH36 steel. T[O] significantly decrease after adding composite balls into automobile plate steel, the lowest T[O] reach 0.001 3% in tundish and 0.000 5% in the slab.
2024 Vol. 43 (1): 78-84 [
Abstract
] (
29
) [
HTML
1KB] [
PDF
0KB] (
175
)
85
CHENG Hongbo
Practice to reduce metal charge consumption in BOF
In order to effectively reduce the consumption of metal materials in the converter, the main factors affecting the consumption of metal materials in the converter are studied, and the scheme to reduce the consumption of metal materials is put forward.By adjusting the structure of raw and auxiliary materials in the converter, such as increasing the application of iron containing materials, optimizing production processes and technologies such as smelting, slagging, endpoint control, and continuous casting production, strengthening the control of the converter process to achieve the ultimate control of metal charge consumption. Through practice, in 2022, the metal material consumption of the converter at Shiheng Steelmaking Plant decreased by 2.24 kg/t, effectively reducing steel material consumption and steelmaking production costs, and achieving good economic benefits.
2024 Vol. 43 (1): 85-92 [
Abstract
] (
39
) [
HTML
1KB] [
PDF
0KB] (
90
)
连铸
News
·
Indexed-in
·
·
·
·
More
Author Center
Instruction for Authors
Template
Copyright Agreement
Links
·
Links
·
·
·
·
·
More
Copyright © CONTINUOUS CASTING
Supported by: Beijing Magtech
