Tetsu-to-Hagane

[title in Japanese]

[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...

1974 Volume 60 Issue 7 Pages 739-740
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_739

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General View of The Continuous Casting Equipment

Tatsuichi OBINATA

1974 Volume 60 Issue 7 Pages 741-754
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_741

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Development of Continuous Casting Operation

Hidetaro NEMOTO

1974 Volume 60 Issue 7 Pages 755-773
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_755

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Cast Structure of Continuously Cast Steel Ingot

Akira SUZUKI

1974 Volume 60 Issue 7 Pages 774-783
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_774

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Causes and Preventions of Continuous Casting Defects

Hisashi Mori

1974 Volume 60 Issue 7 Pages 784-806
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_784

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Model Analysis of Continuous Casting

Hiroshi OOI, Jun-ichi MATSUNO

1974 Volume 60 Issue 7 Pages 807-820
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_807

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Continuous Casting of High Alloy Steels

Fumio HOSHI, Yoshimasa AOYAMA

1974 Volume 60 Issue 7 Pages 821-842
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_821

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Processing and Properties of Continuously Cast Steel

Kiyoto USHIJIMA

1974 Volume 60 Issue 7 Pages 843-859
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_843

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High Speed Casting of Sheet Grade Steel

Shunkichi MIYOSHI, Hideo UCHIBORI, Atushi FUKUTAKE

1974 Volume 60 Issue 7 Pages 860-867
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_860

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Some types of strand guidances of continuous casting machine have been arranged below the mold, and their adaptability to the high-speed casting have been examined.
The following results are obtained.
1) The cooling plate set below the mold is a superior strand guidance method. But it's cooling ability is insufficient.
2) The cooling grid is a satisfactory equipment for both slab supporting and slab cooling ability.
3) Therefore, for the high-speed casting operations of sheet grade steel, the cooling grid or the combination of cooling plate and cooling grid is the most suitable method of slab guidance below the mold.

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Automatic Casting at Continuous Slab Casting Machine Using Slide Gate Nozzle

Hajime NASHIWA, Moriki HASHIO, Makoto TOKUDA, Noriyuki AOKI

1974 Volume 60 Issue 7 Pages 868-874
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_868

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This paper deals with an automatic casting system for a slab caster developed in Wakayama and Kashima Works of Sumitomo Metals Industries Co. Ltd. This automatic casting system is composed of two subsystems described below;
(1) automatic controlling system of the slide gate nozzle for a ladle to keep the molten metal weight in the tundish constant.
(2) automatic controlling system of the slide gate nozzle for a tundish to keep the molten metal level in the mold constant.
This system was completed in October in 1973 after precise analyses and improvements mentioned in the text. Since then, it has resulted in good effects on the operation and the quality as follows;
(1) deviation of the molten metal weight in the tundish can be controlled within 1.0 ton.
(2) deviation of the molten metal level in the mold can be controlled within 5 mm.
(3) stabilized molten metal level in the mold brings better surface quality of a cast slab.
(4) number of operators is reduced.

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Research on In-Line Reduction Process

Eiro TAKEHARA, Daizo YAMASAKI, Makoto TSUNOI, Kanji HAYASHI, Hideki AK ...

1974 Volume 60 Issue 7 Pages 875-884
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_875

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In-Line reduction process is classified into two methods, one is reducing billet with liquid core and the other is reducing billet after complete solidification. For these two methods, the reduction mechanism and material quality have been investigated. An examination has also been made of shaped reduction with similar size to final shape by later method, and the characteristics of products have been made clear.Main results are as follows:
(1) In reducing process with liquid core, as the liquid in mushy zone which is enriched in some solute atom elements is squeezed by reduction, the center of billets after reduction has the tendency of reverse segregation and this tendency changes with the time after start of reduction. It is cleared that the inner cracks with rolling is prevented by enough reduction.
(2) It is shown that the center line shrinkage completely diminishes and cast structure is refined by the reduction after complete solidification, and the similar quality of reduced billet is obtained to that of the bloomed products. Surface cracks are completely prevented by the application of heating furnace and the choice of casting condition in the continuous casting process.
From the results of the shaped reduction test to reduce square billet to round, dog bone and twin bars by 1 or 2 pass, it is shown that the pass schedule of blooming will be simplified and the mill capacity will be compact.

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On the Macro Structure of Carbon Steel Slab Produced by S Type Continuous Wide Slab Casting Machine

Moriyuki ISHIGURO, Kiminari KAWAKAMI, Masaharu ITO, Shunkichi MIYOSHI

1974 Volume 60 Issue 7 Pages 885-893
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_885

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It was observed that the macro structures of carbon steel slab produced by S type continuous wide slab casting machine were asymmetrical, that is, columnar crystal was generated in the upper site of the slab and branched columnar crystal or equiaxed crystal was generated preferentially in the under site.
In order to clarify the cause for above-mentioned asymmetric feature, various investigations, model experiments with water and many operation tests were carried out.
The results obtained are as follows:
(1) The formation of macro structures of continuously cast steel slab was intensitively affected by “Inclination of strand (d.h. gravity)” and “unsolidified steel convection in the shell”. In view of this consideration. The formation process of macro structures was able to be separated into three zones.
(2) Branched columnar crystal formed in the under site of C. C. slab is different from branched columnar crystal formed in steel ingot.
(3) Conditions of equiaxed crystal formation in continuously cast steel slab are formation of lots of nucleus in liquid steel contacted by copper mould and transport of them to the zone of slow freezing rate inside the liquid crater of continuously cast strand.
(4) The formation of center segregation is independent of contact of columnar zone in the center position of continuously cast slab.

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Study on Solidification Behaviour, Solute Segregation and Fluid Flow in Continuously Cast Slab

Kou KUMAI, Koichi ASANO, Tetsuro OHASHI, Etsuo NOMURA, Hiromu FUJII

1974 Volume 60 Issue 7 Pages 894-914
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_894

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Solidification behaviours in the continuously cast slabs of mild steel were determined by addition of radioactive gold and solute distribution in the slabs under various casting conditions was analysed, comparing with the solidification structures.
From these experimental data, the flow velocity in the liquid pool and solute segregation in the center of the slabs were estimated mathematically, using the boundary layer theory and partial mixing model in liquid.
The liquid flow along the shell is composed of the nozzle jet, the natural convection and the bulging flow, the amount of its velocity being 10-40 cm/sec, 1-2.5 cm/sec and2-4 cm/sec. The center segregation is mainly caused of solute redistribution during uni-directional solidification in columnar crystal region, which intensity is strongly dependent on the rate of solidification and the liquid flow, especially the bulging flow.
To reduce the center segregation, increasing the equiaxed crystals and minimizing the bulging were effective, which are related to the amount of cooling water, casting speed, casting temperature, slab thickness and the machine arrangement.

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On the Formation of Centerline Segregation in Continuous-Cast Slab

Shogo TAKAISHI, Tadanoobu KOMAI, Katsuhiko NORO, Yasuhiro AKITA

1974 Volume 60 Issue 7 Pages 915-925
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_915

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The formation mechanism of the centerline segregation of the slabs casted by the curved mold type continuous casting machine, are investigated by means of sulfur-print, X-ray photograph, specific gravity measurement, chemical analysis and EPMA. The results are summarized as follows:
(1) The degree of the centerline segregation can be closely related to the macro-structures of slabs, which are represented by the width of columnar zone and bulging.
(2) The centerline segregation is caused by the accumulation of the microsegregated liquid steel in the interdendrite owing to bulging or bridging at the end of solidification.
(3) The degree of the centerline segregation can be estimated by the volume fraction of the accumulated portion, because the chemical compositions of the enriched portion are constant independently to the different types of solidification.
(4) Elements such as S, P, N, Mn and Si have the same tendency of macro-segregation, which can be explained by the micro-segregation.
(5) The macro-structure shows the tendency of the accumulation of the enriched liquid.
(6) The formation model of the centerline segregation is proposed.

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Study on Large Non-Metallic Inclusion in Continuously Cast Al-Si Killed Steel

Kou KUMAI, Takeshi HIROMOTO, Hisashi MATSUNAGA, Tetsuro OHASHI, Tadayo ...

1974 Volume 60 Issue 7 Pages 926-942
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_926

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Large non-metallic inclusions in the slabs casted continuously by the bow-type machine accumulated within the upper part of slab, that is, the inside radius part of casting machine. Most of such non-metallic inclusions were caused mainly by the erosion of tundish immersion nozzle and by the reoxidation of molten steel secondly. The characteristic accumulation of large non-metallic inclusions were caused by the inclination of the upper shell of steel from the vertical during casting and these phenomena were explained theoretically. Therefore, the bow-type machine had the disadvantage of trapping large non-metallic inclusions compared with the vertical type and the vertical type with bending.
In order to decrease the input of non-metallic inclusions, the following precautions are necessary;
a) Sealing of molten steel stream with Ar gas from ladle to tundish
b) Right selection of temperature and composition of molten steel, in the case of using tundish immersion nozzle made of fused silica.
c) Selection of material of tundish immersion nozzle which excels in antierosion to molten steel.
In order to remove large non-metallic inclusions as much as possible, the following measures are important;
d) The slow speed of molten steel stream at the outlet of tundish immersion nozzle.
e) Selection of the shape of tundish immersion nozzle advantageous to accomplish the good floatation of inclusions in molten steel.

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On the Inner Inclusions in the Slabs Produced by Continuous-Casting Machine of Bending Type

Tsuguharu UEDA, Katsukiyo MARUKAWA, Mamoru TOYODA

1974 Volume 60 Issue 7 Pages 943-952
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_943

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An investigation has been made of the quality of continuous-casting slabs and especially of the inner large inclusions for one year since No 1 continuous-casting machine at Kashima Steel Works started.
The results obtained are summarized as follows:
(1) Number of inclusions in molten metal at tundish increases as the heat proceeds in sequent-casting. For example its ratio at three-heats-casting 1: 3: 10. It is presumed that the principal origin of this increase of ratio is slags in tundish poured out from ladle.
(2) Generally, the inner inclusions of slabs are considered to originate from the following three:
The first is the oxides which are produced when the metal is oxidized by the air in tundish and/or between ladle and tundish. The second is the ladle slag pouered out to tundish and the lining of tundish.
The third is the powder added to the mold. Therefore the inner inclusions in continuous-casting slabs are compounded with those three origins.
(3) The number of the inner inclusions of slabs decreases as the angle of immersed nozzle becomes smaller. It seems, however, that the location of the inner inclusions in the slab is almost the same independent of the angle of immersed nozzle.

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On the Operations of Circular Arc Type Bloom Continuous Casting and Product Qualities

Shujiro ONO, Susumu NARITA, Yukiyoshi ITO, Kunio MIHARA, Tetsuo OSASA

1974 Volume 60 Issue 7 Pages 953-961
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_953

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The No.2 continuous casting machine of NSC Muroran Works is 4 strands circular arc type, which is made by Hitachi Co. and started its operation in Oct 1971.
This machine is so designed as to cast bloom from 244×300 to 165×165 mm, beingsupplied the molten steel from 120 tons BOFs.
The bloom is subsequently rolled to bars, wire rods, bar in coils and shapes.
In this paper, the following items are described.
(1) The systems, adopted in this machine for mold quick changing, computerizationand labour saving.
(2) High productive operation by sizes quick changing method, series casting and high speed casting.
(3) Effective technics on decrease of non-metallic inclusion (Al-Si killed steel)
(4) Improvable methods on internal cracks, central segregation and segregation pattern observed on macro-structure.
(5) Mechanical and fatigue properties, hardinability and sand mark of rolling products.

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Effect of the Penetration Depth of the Casting Stream in the Crater on the Accumulation of Large Non-metallic Inclusions in the Continuously Cast Slab by the Bow Type Machine

Yasuhiro HABU, Hiroshi YOSHI, Hidenari KITAOKA, Yoshiharu IIDA, Takuo ...

1974 Volume 60 Issue 7 Pages 962-972
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_962

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In order to understand the mechanism of the accumulation of large non-etallic inclusions under the upper surface of the continuously cast slabs by the bow type machine, slabs, casted by two kinds of submerged nozzles designed to make a different penetration depth of casting stream, were investigated in regard to the distribution and content of large non-metallic inclusions. The resultsobtained are as follows.
1) By use of the nozzle with the shallower penetration depth of the casting stream, the position of maximum amount of large non-metallic inclusions in the accumulated zone and the end point of the accumulated zone shift toward the upper surface and also, their accumulated amount decreases.
2) Total large non-etallic inclusion content in the accumulated zone increases in proportion to the area of “entrapping zone” corresponding to the liquid core between the perpendicular circumscribed with the solidification front at the upper side and the position of the penetration depth of the casting stream in the longitudinal section of the strand during casting.

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Improvement of Surface in CC Slab for Plate and Directly Reheating and Rolling Process without Conditionings

Takanori ANZAI, Atsushi YAMAGAMI, Yoshio MIYASHITA, Eiichi SAKAMOTO, K ...

1974 Volume 60 Issue 7 Pages 973-980
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_973

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The continuous slab caster for plate mill at Keihin works, Nippon kakan has been operating successfully with increased output and improvement of product quality.
As for the surface defects found in continuous casting slab, the causes of the defects were correlated with casting processes and newly adopted operation was proved to give quite fine surface of slab and plate. On the basis of this development, the system of directly reheating and rolling of slab in 40kg/mm² grade steel without conditioning has been adopted since November 1972, with highly excellent results.

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Properties of Continuous-Casting Powders Influencing Surface Defects of Wide Slabs for Plates

Toshihiko EMI, Hakaru NAKATO, Kouji SUZUKI, Yoshiharu IIDA, Tsunehiro ...

1974 Volume 60 Issue 7 Pages 981-989
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_981

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Among many properties of continuous-casting powders, chemical composition, melting rate introduced by the present authors (1/tf), and viscosity (η) have been found to give most significant influences on longitudinal facial cracks and scums on continuously-cast wide slabs for plate use. Laboratory-and industry-scale experiments exhibit that, under the experimental conditions the following properties are required for the powders to make the slabs free from the two surface defects:(1) composition of CaO/SiO₂ 0.6-1.1, Al₂O₃ 7-10%, F-<3%, F-<+CO₃²-<5%, freeC≤5%, S≤4%, and (2)η, tf., andη/tf of 48 poises, 20 sec., 2.4±0.2 at 1250°C, and llpoises, 11sec., 1.0±0.1 at 1400±C, respectively.

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Qualities of Billets Produced by Continuous Casting with In-Line Reduction

Yoshinori SAIGA, Kanichi FUKUI, Yoshinori TSUNEHISA, Takao SHIODA, Shi ...

1974 Volume 60 Issue 7 Pages 990-999
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_990

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A billet continuous casting machine with in-line reduction was installed at the Kishiwada Steel Co. Ltd., and has been in operation since March, 1972. This paper deals with various qualities of the billets produced by this machine during the start-up period. The followings have been found:
1) Center shrinkage cavities and porosities were well cured by the in-line reduction process.
2) The non-metallic inclusions were elongated along the drawing direction throughout the billet by the in-line reduction process, though the inclusions locating at the central parts extended in a greater extent than those at outer layers.
3) Microscopic examinations showed that as-cast billets consist of normal Widmannstatten structures but the in-line reduction improves the structure to some extent.
4) The difference between the tensile properties of the central part and those of the outer layer of the billet was negligible.
It can thus be concluded that the in-line process results in excellent and sound qualities of the billets.

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Theoretical Analysis on the Solidification Profiles of Slab in Straight Type Continuous Casting Machine

Ken-ichi MIYAZAWA, Iwao MUCHI

1974 Volume 60 Issue 7 Pages 1000-1006
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_1000

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A mathematical model for the estimation of the solidification profiles of the slab in the continuous casting machine with a straight mold has been developed with the aid of integral-profile method. In this model, a mushy zone is taken into account and the heat transfer from the pool of molten steel to the mushy zone is described in terms of the heat transfer coefficient on the surface of liquidus line.
The general varidity of the model mentioned above has been confirmed by comparing the empirical data obtained by the other investigators with the profiles of mushy zone calculated from this model.
Effects of the casting speed and the cooling conditions on the solidification profiles have been determined by the use of the model proposed in this paper.

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Theoretical Analysis on the Solidification Profiles of Slab in Circular-arc Type Continuous Casting Machine

Ken-ichi MIYAZAWA, Iwao MUCHI

1974 Volume 60 Issue 7 Pages 1007-1012
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_1007

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Taking the mushy zone into considerations, a mathematical model for estimating the solidification profiles of slab in the circular-arc type continuous casting machine has been developed by the use of the integral profile method. This work represents the first published attempt to predict the solidification process in the machine like this.
The results calculated from the model proposed in this paper show that the nonsymmetry in solidification profiles between the upper side and the lower side of the slab is considerably small if the both sides of the slab are kept at the same cooling condition, and that the effects of the curvature of the machine on the nonsymmetry mentioned above are negligibly small.

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Mathematical Analysis of Heat Transfer Phenomena in Continuous Casting

Toshio NANJO, Toshiyuki FUKAI, Hidetoshi KOMORI, Kanji KIZAKI

1974 Volume 60 Issue 7 Pages 1013-1022
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_1013

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The continuous casting of steel is rapidly expanding its scope of influence in the field of steel making, because the process is superior to the conventional ingot making process from the view point of the product quality, working environment, and automation.
The main problem of continuous casting is how to control heat transfer phenomena skillfully.
Therefore, this report describes the results which were calculated by mathematical models of the heat transfer in each step from the tapping of steel to the transfer table as described below:
(1) The relation between the elapsed time and the temperature of molten steel in the ladle.
(2) The relation between the elapsed time and the temperature of molten steel in the tundish.
(3) Temperature distributions of the billet in the mold, and the secondary cooling and air cooling zones.
(4) Temperature distribution of the billet in the soaking furnace.
(5) Temperature drop of the billet due to in-line reduction.
(6) Temperature distribution of the billet on the transfer table.
In these cases, calculations were performed sequentialy by algebraic equations by the use of finite difference techniques.

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An Analysis of Solidification Rate and Surface temperature of Continuous Casting Slabs

Jvn-ichi MATSUNO, Hakaru NAKATO, Hiroshi OOI

1974 Volume 60 Issue 7 Pages 1023-1032
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_1023

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The cooling and solidification of continuous casting slabs were analysed by a new mathematical model, in which heat transfer coefficients on the slab surface both in the mould and in the spray zone were deter-mined semi-empirically from operational data. The effect of air gap between the slab surface and the mould was taken into account in the estimation of the heat transfer coefficient, and the point of complete sepera tion of the slab surface from the mould was determined as a function of the withdrawal rate. The heat transfer coefficient in the spray zone was obtained from modification of an empirical formula on spray cooling of steel plates. The results of analysis made clear the effects of operational conditions, that is, the solidification profile depends mainly on the withdrawal rate, while the surface temperature is affected much more by the water ratio in the cooling zone.

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Some Study on Cooling Capacity Analysis of Walking Bar Indirect Cooling Type Curvilinear Continuous Casting Machine and Quality of the Slab

Takasuke MORI, Yutaka NAGAOKA, Kenzo AYATA, Toshiyuki SOEZIMA

1974 Volume 60 Issue 7 Pages 1033-1040
Published: June 01, 1974
Released on J-STAGE: December 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_1033

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The Kobe Steel has built a W. B.*-curvilinear type continuous casting machine at Kakogawa plant; this machine has a special indirect cooling system named W. B. in it's upper part of the secondary cooling zone.
Solidification constants, K's of this machine are as follows:
(i) Mold zone K_M=-29.8 (mm min^-1/2)
(ii) W. B. zone K_W.B.=23.9 (mm min^-1/2)
(iii) Roller zone K_R=21.9 (mm min^-1/2)
An analytical simulation of cooling capacity has been made by a computer.
As a result, the average heat transfer coefficient of W. B. zone is found about 320 kcal/m² hr°C, and the average heat transfer coefficient of W. B. is 360 kcal/m²hr°C when it contacts with the slab surface. The components of them are as follows:
(i) Radiation 270 kcal/m²hr°C
(ii) Convection (gas) 48 kcal/m² hr°C
(iii) Contact 42 kcal/m²hr°C
Concerning the quality of the product, the following characteristics are obtained:
(i) The slab is kept in good uniformity, so the error in the weight per unit length is within a 0.5% deviation.
(ii) The equiaxial crystal zone occupy about 30% of the slab width in a usual slab.
(iii) The centerline segregation is slight.
(iv) Few large inclusions can be found.

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An Analysis of Fluid Flow and Mixing Phenomena in Liquid Pool of a Continuous Casting

Tetsuya FUJII, Jun-ichi MATSUNO, Hiroshi OOI

1974 Volume 60 Issue 7 Pages 1041-1051
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_1041

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In order to make clear the fluid flow and mixing phenomena of the liquid pool in a continuous casting process, experimental studies were done by casting successively two melts which were different in the composition. The fluid flow and the mixing intensity of the molten steel were obtained based on the measured values of concentration changes at the jointed part of the two heats. Furthermore, the solidification rate of the molten steel was calculated considering the mixing effect on the heat transfer.
The results obtained are as follows.
(1) Molten steel in the mould region is observed to be perfectly mixed.
(2) It can be considered that the curvature of the continuous casting machine has no effect on the mixing phenomena of molten steel.
(3) The mixing phenomena of molten steel can be well simulated by the diffusion model which is known to be often satisfactory for the evaluation of the dispersion in mixing experiments on the assumption that the process takes place by eddy diffusion. The distribution of the back mixing coefficient in liquid pool is evaluated based on this model.
(4) The effect of the pouring temperature on the thickness of mushy zone is calculated considering the mixing effect of molten steel on heat transfer. The relation between the pouring temperature and the solidified structure of a cast slab is discussed.
(5) A good agreement is found between the calculated solidification rate of solidus line and the experimental one. It is found, however, that there is a significant difference between the calculated and experimental solidification rates of the liquidus line. The reason of this difference is discussed.

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Continuous Casting of Sulfur Type Free-Machining Stainless Steel Blooms

Toshio KISHIDA, Susumu SHINAGWA, Hisao ISHIZUKA, Masatoshi OZAWA, Shiz ...

1974 Volume 60 Issue 7 Pages 1052-1062
Published: June 01, 1974
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.60.7_1052

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Free-machining stainless steel containing sulfur has been continuously cast in square shape of 165 mm×165 mm and its surface grade and hot-workability as well as mechanical property have been tested under various casting conditions.
The results are summarized as follows;
(1) The increase in sulfur content in the range 0.014 to 0.32 wt% decreased the surface quality. The number of transverse cracks on the surface depended on the property of mold powders used. The mold powders with slow melting property and low viscosity after melting decreased remarkably the number of the surface cracks.
(2) The number of the longitudinal cracks was related to the carbon content and to the secondary cooling rate. When the carbon content was more than 0.09 wt% and the secondary cooling rate was 0.8 1/kg, internal cracks have been observed in the as-cast blooms.
(3) Surface smoothing by mechanical polishers was very effective for the improvement of the hotworkability of the cast blooms. A deep oscillation mark behaved as a notch upon hot rolling. A succssful hot-rolling was practiced, only when the ratio of manganese content to sulfur content was more than 9.0 and the oxygen content was less than 130ppm.
(4) The bars hot-rolled from the blooms continuously cast showed same mechanical properties as the conventional ones. Because the forging ratio of the continuous-cast bars is smaller than that of the conventional ones, the non-metallic inclusions are not elongated and thus, the former has shown the better machinability.

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