Twin Roll Casting and Secondary Cooling of 6.0 wt.% Silicon Steel

Iron–silicon alloys with up to 6.5 wt.% Si offer an improvement of soft magnetic properties in electrical steels compared to conventional electrical steel grades. However, steels with high Si contents are very brittle and cannot be produced by cold rolling. In addition to solid solution hardening, it is assumed that the B2- and DO3-superlattice structures are responsible for the poor cold workability. In this work, two cast strips with 6.0 wt.% Si were successfully produced by the twin roll strip casting process and cooled differently by secondary cooling. The aim of the different cooling strategies was to suppress the formation of the embrittling superlattice structures and thus enable further processing by cold rolling. A comprehensive material characterization allows for the understanding of the influence of casting parameters and cooling strategies on segregation, microstructure and superlattice structure. The results show that both cooling strategies are not sufficient to prevent the formation of B2- and DO3-structures. Although the dark field images show a condition which is far from equilibrium, the achieved condition is not sufficient to ensure cold processing of the material.

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Effect of Secondary Cooling on Non-Oriented Electrical Steel Strips Produced by Twin-Roll Casting Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.218 ◽

2013 ◽

Vol 690-693 ◽

pp. 218-221

Author(s):

Ting Zhang ◽

Xiao Ming Zhang ◽

Zhi Yuan Guo ◽

Yu Qian Wang ◽

Cheng Gang Li

Keyword(s):

Electrical Steel ◽

Casting Process ◽

Air Cooling ◽

Secondary Cooling ◽

Twin Roll Casting ◽

Steel Strips ◽

Roll Casting ◽

Average Size ◽

Equiaxed Grains ◽

Twin Roll

Effect of secondary cooling on non-oriented electrical steel strips was investigated. The 2.0 mm thick cast strips contain two compositions were produced by twin-roll casting process, cooled in the air or cooled by spraying water. The microstructure was observed by optical microscopy, and EBSD was used to characterize the texture of the cast strips. The results showed that air-cooling cast strips have uniform and equiaxed grains with average size of 250 μm. The microstructure of the water-spraying cast strips compose of most equiaxed grains and a small number of abnormal big grains. At the same time, the secondary cooling rate mildly affects the cast texture strength but has no influence on the texture type.

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Texture Evolution in Non-Oriented Silicon Steel Processed by Twin-Roll Casting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.452-453.7 ◽

2012 ◽

Vol 452-453 ◽

pp. 7-11 ◽

Cited By ~ 1

Author(s):

Wei Pei ◽

Yu Hui Sha ◽

Fang Zhang ◽

Liang Zuo

Keyword(s):

Cold Rolling ◽

Texture Evolution ◽

Casting Process ◽

Rolling Process ◽

Silicon Steel ◽

Recrystallization Annealing ◽

Twin Roll Casting ◽

Steel Sheets ◽

Roll Casting ◽

Twin Roll

In this paper, non-silicon steel sheets were produced by both twin-roll casting method and conventional process. Orientation characteristics and texture evolution of the sheets during casting, cold rolling and recrystallization annealing were investigated for comparison. It was found that the subsurface of twin-roll casting strips are characterized by weak {100} orientation while the central layer by random orientation. Twin-roll casting process can decrease α fiber (//RD) and increase γ fiber (//ND) during cold rolling process. Consequently, the η fiber (//RD) favorable for magnetic properties of non-silicon steels is enhanced and the detrimental {111} component is suppressed after annealing.

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Thermomechanical Treatment of Aluminum Alloy Fin Stock for Heat Exchanger Produced by Twin Roll Strip Casting Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.241 ◽

2010 ◽

Vol 638-642 ◽

pp. 241-246 ◽

Cited By ~ 1

Author(s):

Suk Bong Kang ◽

Dong Bae Kim ◽

Sang Su Jung ◽

Kwang Jun Euh

Keyword(s):

Thermal Conductivity ◽

Aluminum Alloy ◽

Heat Exchanger ◽

Cold Rolling ◽

Heat Exchangers ◽

Casting Process ◽

Strip Casting ◽

Manufacturing Cost ◽

Intermediate Annealing ◽

Twin Roll

Aluminum alloys are commonly used as a material for heat exchangers due to their higher thermal conductivity and specific strength among various metallic materials. The lightweightening heat exchangers for automobile application are requisite for reducing the evolution of CO2 and improving the efficiency of fuel. The twin roll strip casting process is considered to produce the high quality and low manufacturing cost aluminum alloy fin stock for automobile heat exchangers. Thermomechamical treatment has carried out to obtain optimum processes for initial cold rolling, intermediate annealing and final cold rolling, which can meet the requirements for high strength and high thermal conductivity after brazing heat treatment. Mechanical properties and thermal condutivity have been evaluated before and after simulated brazing process. The nuclei of recrystallization might be formed along shear deformation bands during initial cold rolling and should be grown during intermediate annealing to enhance the permeation of molten brazings for the following brazing process. Final cold rolling has allowed strain hardening and controlling of sagging amount as fin stock materials of heat exchanger. In the present study the suitable thermomechnical treatment was suggested to balance the properties of strength, thermal conductivity, brazing behavior and sagging in Al-Fe-Mn-Si-Zn based alloys produced by twin roll strip casting process.

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Casted Strip Character of Twin-Roll Casted High Strength Non-Oriented Electrical Steel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.582 ◽

2013 ◽

Vol 690-693 ◽

pp. 582-585

Author(s):

Yu Qian Wang ◽

Xiao Ming Zhang ◽

Ting Zhang ◽

Zhong Mian Fan

Keyword(s):

Electrical Steel ◽

High Strength ◽

Casting Process ◽

Main Role ◽

Secondary Cooling ◽

Cooling Process ◽

Cast Strip ◽

Roll Casting ◽

Columnar Grains ◽

Twin Roll

A twin-roll casting process was used to produce high strength non-oriented electrical steel casted strips. The typical character in chemical composition is the adding of Ni and Cr.The main role of Ni and Cr is solution strengthening. MEM, SEM, and TEM were used to observe microstructure, texture, and precipitate characteristics of a casted strip. The casted strip character under different secondary cooling process was compared. The results show that water-cooled as-cast strip is composed of the equiaxed grains, air-cooled as-cast strip is characterized by a mixture of the quiaxed and columnar grains. The texture of water-cooled as-cast strip is weaker and diffuser than air-cooled as-cast strip. Precipitates mostly are AlN and MnS, which mostly precipitate in the grain. The precipitates of Ni and Cr is not observed. The size distinction of MnS between two secondary cooling process is not remarkable. The size of AlN in water-cooled process is smaller than in air-cooled process.

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Effect of Copper Variation and Thermomechanical Treatment on Microstructure and Properties in Aluminum Alloy Fin Stock for Heat Exchanger

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.311 ◽

2012 ◽

Vol 706-709 ◽

pp. 311-316 ◽

Cited By ~ 2

Author(s):

Suk Bong Kang ◽

Dong Bae Kim ◽

Jae Hyung Cho

Keyword(s):

Thermal Conductivity ◽

Aluminum Alloy ◽

Heat Exchanger ◽

Cold Rolling ◽

Heat Exchangers ◽

Casting Process ◽

Strip Casting ◽

Intermediate Annealing ◽

Effect Of Copper ◽

Twin Roll

Aluminum alloys are commonly used as a material for heat exchangers due to their higher thermal conductivity and specific strength among various metallic materials. Twin roll strip casting process is considered to produce the high quality and low manufacturing cost aluminum alloy fin stock for automobile heat exchangers. Thermomechamical treatment has carried out to obtain optimum processes for initial cold rolling, intermediate annealing and final cold rolling, which can meet the requirements for high strength and high thermal conductivity after brazing heat treatment. Additionally the effect of copper element variation was considered to determine the optimum content of copper element in Al-Zn-Mn-Si-Fe-Cu based alloys produced by twin roll strip casting process. Mechanical properties and thermal condutivity have been evaluated before and after simulated brazing process. The nuclei of recrystallization might be formed along shear deformation bands during initial cold rolling and should be grown during intermediate annealing to enhance the permeation of molten brazings for the following brazing process. Final cold rolling has allowed strain hardening and controlling of sagging amount as fin stock materials of heat exchanger. In the present study the suitable thermomechnical treatment and optimum copper content was suggested to balance the properties of strength, thermal conductivity, brazing behaviour, corrosion resistance and sagging resistance in Al-Zn-Mn-Si-Fe-Cu based alloys produced by twin roll strip casting process.

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Observation of GaAs/AlAs Superlattice Structures in both Secondary and Backscattcred Electron Imaging Modes with an Ultrahigh Resolution Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010018077x ◽

1990 ◽

Vol 48 (1) ◽

pp. 404-405

Author(s):

K. Ogura ◽

A. Ono ◽

S. Franchi ◽

P.G. Merli ◽

A. Migliori

Keyword(s):

Gaas Layer ◽

Objective Lens ◽

Superlattice Structure ◽

Backscattered Electron ◽

Instrumental Resolution ◽

Electron Microscopes ◽

Superlattice Structures ◽

Electron Imaging ◽

Scanning Electron Microscopes ◽

Scanning Electron

In the last few years the development of Scanning Electron Microscopes (SEM), equipped with a Field Emission Gun (FEG) and using in-lens specimen position, has allowed a significant improvement of the instrumental resolution . This is a result of the fine and bright probe provided by the FEG and by the reduced aberration coefficients of the strongly excited objective lens. The smaller specimen size required by in-lens instruments (about 1 cm, in comparison to 15 or 20 cm of a conventional SEM) doesn’t represent a serious limitation in the evaluation of semiconductor process techniques, where the demand of high resolution is continuosly increasing. In this field one of the more interesting applications, already described (1), is the observation of superlattice structures.In this note we report a comparison between secondary electron (SE) and backscattered electron (BSE) images of a GaAs / AlAs superlattice structure, whose cross section is reported in fig. 1. The structure consist of a 3 nm GaAs layer and 10 pairs of 7 nm GaAs / 15 nm AlAs layers grown on GaAs substrate. Fig. 2, 3 and 4 are SE images of this structure made with a JEOL JSM 890 SEM operating at an accelerating voltage of 3, 15 and 25 kV respectively. Fig. 5 is a 25 kV BSE image of the same specimen. It can be noticed that the 3nm layer is always visible and that the 3 kV SE image, in spite of the poorer resolution, shows the same contrast of the BSE image. In the SE mode, an increase of the accelerating voltage produces a contrast inversion. On the contrary, when observed with BSE, the layers of GaAs are always brighter than the AlAs ones , independently of the beam energy.

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Applying Crystallographic Orientation Analysis for Exploring Deformation Mechanism of 6.5 wt.% Si Electrical Strip During Twin-roll Thin Strip Casting Process

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2021.06.002 ◽

2021 ◽

Author(s):

W.L. Hu ◽

Y.X. Zhang ◽

G. Yuan ◽

X.M. Zhang ◽

J.H. Zhao ◽

...

Keyword(s):

Deformation Mechanism ◽

Crystallographic Orientation ◽

Casting Process ◽

Strip Casting ◽

Thin Strip ◽

Orientation Analysis ◽

Twin Roll

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Comparison of Optimization-Regulation Algorithms for Secondary Cooling in Continuous Steel Casting

Metals ◽

10.3390/met11020237 ◽

2021 ◽

Vol 11 (2) ◽

pp. 237

Author(s):

Michal Brezina ◽

Tomas Mauder ◽

Lubomir Klimes ◽

Josef Stetina

Keyword(s):

Convergence Rate ◽

Water Flow ◽

Steel Casting ◽

Casting Process ◽

Continuous Steel Casting ◽

Continuous Steel ◽

Cooling Zone ◽

Secondary Cooling ◽

Flow Rates ◽

Secondary Cooling Zone

The paper presents the comparison of optimization-regulation algorithms applied to the secondary cooling zone in continuous steel casting where the semi-product withdraws most of its thermal energy. In steel production, requirements towards obtaining defect-free semi-products are increasing day-by-day and the products, which would satisfy requirements of the consumers a few decades ago, are now far below the minimum required quality. To fulfill the quality demands towards minimum occurrence of defects in secondary cooling as possible, some regulation in the casting process is needed. The main concept of this paper is to analyze and compare the most known metaheuristic optimization approaches applied to the continuous steel casting process. Heat transfer and solidification phenomena are solved by using a fast 2.5D slice numerical model. The objective function is set to minimize the surface temperature differences in secondary cooling zones between calculated and targeted surface temperatures by suitable water flow rates through cooling nozzles. Obtained optimization results are discussed and the most suitable algorithm for this type of optimization problem is identified. Temperature deviations and cooling water flow rates in the secondary cooling zone, together with convergence rate and operation times needed to reach the stop criterium for each optimization approach, are analyzed and compared to target casting conditions based on a required temperature distribution of the strand. The paper also contains a brief description of applied heuristic algorithms. Some of the algorithms exhibited faster convergence rate than others, but the optimal solution was reached in every optimization run by only one algorithm.

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