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1

Roll casting of a clad strip consisting of 5182 aluminium alloy

Haga T.

Archives of Materials Science and Engineering

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2015

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Vol. 73, nr 1

33--43

EN

Purpose: The investigation of the casting ability of the two layers and three layers clad strips consisting of the 5182 (Al-Mg) strip by the vertical type twin roll caster equipped with a scraper and the vertical type tandem twin roll caster at the speed higher than 30 m/min is one of the purposes. Another purpose is investigation of the casting conditions that affect the bonding condition of the 5182 strip to another aluminium alloy strip. Design/methodology/approach: A twin roll caster equipped with a scraper and a vertical type tandem twin roll caster were designed, assembled, and the castings of clad strips consisting the 5182 strip were tried. The interface between the strips were observed by the optical microscope. The bonding strength between strips was investigated by the continuous bending test. Findings: In the casting of the 5182 strip and the 3003 strip, the temperature of the 3003 strip influenced the bonding. When the temperature of the 3003 strip was lower, the 5182 strip was not bonded to the 3003 strip. In the casting of the 5182 strip and the 4045 strip, the porosity occurred near the interface. The temperature of the 5182 strip at the roll bite influenced the occurrence of the porosity. When the temperature of the 5182 strip was low, the porosity did not occur. The vertical type twin roll caster equipped with a scraper was suitable for the clad strip consisting of the 5182 and the 3003, and consisting of the 5182 and the 4045. The sound clad strips of the 5182 and the 3003, of the 5182 and 4045 could be cast using the vertical type twin roll caster equipped with a scraper. Research limitations/implications: The size of the roll was laboratory size. Moreover, the amount of the poured molten metal was less 3kg. Therefore, there was no information about the commercial size clad strip in this paper. Practical implications: The aluminium clad strip can be used to make component of the automobile by the press forming. Originality/value: The twin roll casters that could cast two and three layers clad strips were original invention. It is shown that the clad strips consisting of the 5182 (Al-Mg) strip could be cast using the twin roll caster. The elucidation of the casting conditions that affects the bonding and porosity near the interface is original result.

2

A vertical type twin roll caster for an aluminium alloy clad strip

Haga T., Nakamura R., Kumai S., Watari H.

Archives of Materials Science and Engineering

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2013

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Vol. 62, nr 1

36--44

EN

Purpose: of this paper: Twin roll casters that can cast two layers and three layers clad strip of aluminium alloys were invented. One of the purposes of this paper is to report that the two layers and three layers clad strip could be cast by the twin roll caster of this study. The investigation of the characters of these casters and the clad strips was purpose of this paper, too. The connecting at the interface between the strips was most important in the casting of the clad strip. Therefore, the attention was paid on the conditions of the interface. Design/methodology/approach: A vertical type tandem twin roll caster and a twin roll caster equipped with a scraper were designed, assembled and tested. Castings of the two layers clad strip and the three layers clad strip directly from molten metal were tried using these twin roll casters. The connecting strength between strips was investigated by the continuous bending test and the cold rolling. The diffusion and re-melting at the interface was investigated by the SEM-EPMA. Findings: The twin roll casters invented in this study could cast the two layers and three layers clad strips directly from molten metal. These clad strips had clear interface between the strips. This means that the mixing of the two alloys did not occur at the interface. The diffusion of elements of the each strip into another strip did not occur at the interface. The connecting strength was enough to endure the peeling at the interface by continuous bending. The clad ratio could be controlled by the solidification length up to 10:1. Two layers clad strip assembled from Al-Mg alloy strip and another aluminium alloy strip could be cast without defect by the effect of the scraper. The three layers clad strip which base strip had lower melting point than that of the overlay strip could be cast. Practical implications: The three layers clad strip, which base strip is 3003 aluminium alloy and overlay strips are 4045 aluminium alloy, can be used for the brazing sheet of the radiator of the automobile. The twin roll caster of this paper could cast this type of clad strip. The process saving and the energy saving can be attain by the twin roll caster of this paper. The clad ratio between the base strip and the overlay strip was smaller than 10:1. Originality/value: The twin roll casters that could cast two and three layers clad strips were original invention. using the twin roll caster.

3

Development of a twin roll caster for light metals

Haga T.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 1

393--402

EN

Purpose: Purpose of this paper is to show the development of a twin roll caster for aluminium alloy. One of the developments was the increase of the roll speed. The increase of the roll speed was essential to improve the low productivity of the twin roll caster. Limitation of the alloys, which can be cast into the strip, could be enlarged by the method to increase the roll speed. The method to increase the roll speed was useful to increase the cooling rate of the cast strip. The devices to increase the roll speed were shown in this paper. Other development was invention of the twin roll caster to cast clad strip. The twin roll casters to cast two layers clad strip, three layers clad strip and five layers clad strip were invented. Design/methodology/approach: Increase of roll speed was attained by the use of a copper roll and a nozzle, operation of the low temperature casting and non-use of parting material. A scraper was adopted to the twin roll caster for clad strip to prevent the mixture of the molten metals and to control the surface condition. The devices to increase the roll speed were useful for the roll caster to cast clad strip. Findings: The aluminium alloy strip could be cast at the speeds up to 90 m/min. The aluminium alloy which has wide freezing zone like Al-25%Si could be cast into the strip. Two layers, three layers and five layers of clad strips could be cast. Research limitations/implications: The roll casters were laboratory size. Therefore, it was not clear of the ability of the casting of the long size and wide size strips. Practical implications: The productivity of aluminium alloy strip is increased. The property of the aluminium alloy strip is improved. The aluminium alloy, which was too brittle to be formed into the plate, will be cast into strip directly from melt. The process and energy to make the brazing sheet will be saved by the roll caster of the present study. Originality/value: The invented roll casters, devices for casting and properties of the cast strips are original.

4

Roll caster for the three-layer clad-strip

Nakamura R., Yamabayashi T., Haga T., Kumai S., Watari H.

Archives of Materials Science and Engineering

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2010

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Vol. 41, nr 2

112-120

EN

Purpose: of this paper is to show the characteristics of two kinds of roll casters for three-layer clad strip of aluminium alloys. Moreover, the characteristics of these twin roll casters were compeered with the early type of roll casters for clad strip. Design/methodology/approach: Design was tried to attain the fabrication of the roll casters to cast the three-layers-clad-strip. One caster was an unequal diameter roll caster equipped with a scraper. The scraper was adopted to prevent the mixture of different kinds of melts of the alloys. The scraper was used to cast the clad strip with clear interfaces between each strip. The other caster was a tandem type roll caster assembled from two vertical type twin roll casters. A vertical type of twin roll was mounted on the other vertical type of a twin roll caster. Findings: Three layers of clad strips could be cast by two kinds of the roll casters developed in the present study. The casting speed was 20 m/min. This speed was much higher at the conventional twin roll caster for the aluminium alloys. Each strip of three layers clad strip was connected strictly. The element of clad strip did not peel at the interface by continuous bending. The as-cast clad strip could be cold-rolled. The element of alloys did not mix at the connecting interface of the strips. The casting conditions which affected the connecting of the strips and condition of interface were investigated and shown in this paper. Research limitations/implications: The width of the strip was from 30 mm to 50 mm. The casting of the wide strip was not investigated. The alloy used in the present study was only aluminium alloys. The length of the cast strip was 3 m. The thickness of element strip was from 0.8 mm to 1.5 mm. The difference of the melting temperature of the alloys was within 50°C. The number of the layers was less than three layers. Practical implications: The roll caster invented in the present study can be used for the fabrication of the clad strip. The clad strip is, for example, used for the brazing sheet of the radiator for the automotive industry. Originality/value: There was not a report concerning the roll caster for three layers clad strip. The roll casters for clad strips shown in this paper were of an original process. Especially, the use of the scraper in the roll casting was original.

5

Clad strip casting by a twin roll caster

Haga T., Nakamura R., Kumai S., Watari H.

Archives of Materials Science and Engineering

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2009

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Vol. 37, nr 2

117-124

EN

Purpose: Of this paper is to realize the casting of the clad strip by only one process. Therefore, the investigation of the ability of the casting of the clad strip by a vertical type twin roll caster was operated. The aim of the use of the twin roll caster to make clad strip was in the reduction of the production-energy of the clad strip. Design/methodology/approach: Used in the present study was a vertical type twin roll caster with the scriber. The scriber was used to prevent the mixture of the two kinds of the melts. The scriber was set at roll-bite, and the scriber contacted to the one of solidification layer. The melt was stopped by the scriber and the only the solidification layer was dragged by the roll. Findings: The clad strip with the clear interface could be by the vertical type twin roll caster with the scriber. The scriber was useful to drag only the solid and semisolid layer. The two kinds of strips were connected strictly at the interface of the clad strip. The clad strip was not broken at the interface by the continuous bending. Research limitations/implications: Are that 100 mm width-strip was cast in the present study. Ability of the clad strip that is wider than 100 mm was not clear. The control of the clad ratio was not investigated. Practical implications: The twin roll caster devised and investigated in this report is useful to cast clad strip like the brazing sheet for the radiator of the automobile. Originality/value: The vertical type twin roll cater to cast clad strip is original process. The scriber was used to prevent the mixture of the two kinds of melts. The scriber was not used in the previous research to cast clad strip at the twin roll caster, and use of the scriber was the first try.

6

High speed twin roll casting of 6061 alloy strips

Haga T., Sakaguchi H., Watari H., Kumai S.

Archives of Materials Science and Engineering

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2008

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Vol. 31, nr 1

49-52

EN

Purpose: of this paper is to clear the possibility of high speed roll casting of thin strips of two aluminum alloys: 6061 and recycled 6061. Mechanical properties of the roll cast 6061 and recycled 6061 strips were investigated in the frame of this purpose. Design/methodology/approach: Methods used in the present study were high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification and increase the casting speed. Findings: are that 6061 and recycled 6061 could be cast at speed of 60 m/min. Casted strips were about 3 mm thick. As cast strip could be cold-rolled down to sheet of 1 mm thick. 180 degrees bending test was operated on the sheet after T4 heat treatment and crack was not worse than 6022 which is typical aluminum alloy for sheet of the automobile. This result means the roll cast 6061 can be used as a sheet for body of the automobile instead of 6022. Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties were enough for practical use. Wider strip must be cast using the twin roll caster of the size for production. Originality/value: The economy sheet of the 6061 for the auto mobile can be produced by the high speed twin roll caster. 6061 is typical wrought aluminum alloy of 6000 series. Therefore, the sheet of 6061 will become economy. 6061 can be recycled at two times when the 6061 is cast into strip by the high speed roll casting.

7

Grooved roll for a high speed twin roll caster

Haga T., Hirooka K., Watari H., Kumai S.

Archives of Materials Science and Engineering

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2008

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Vol. 30, nr 2

117-120

EN

Purpose: Purpose of this paper is investigation of the effect of roll-surface on the strip-surface. Improvement of small cracks on the strip-surface was tried and effect of groove at the roll surface on the strip surface was shown. Design/methodology/approach: Method used in the present study was high speed twin roll caster with grooved roll. Two kinds of grooves were used: one was parallel groove and the other was cross groove machined by knurling and bite attached to a lathe. Findings: Findings of this research are that grooved roll was effective to eliminate the small cracks on the strip surface. The contact condition between the roll and the melt became uniform by the small groove on the roll surface. Contact area became small, and heat transfer between the melt and roll became small, too. As the result, chill structure did not become columnar, and crack did not occur. Groove pattern on the strip surface could be erased by the cold rolling. Research limitations/implications: Research limitation is that groove life could not be investigated. Practical implications: Practical implications are as below. The roll load was small and strip was not hot-rolled in a high speed twin roll caster. The grooved roll made strip-surface sound. Grooved 600mm width roll was tested, and usefulness of the grooved roll was shown. Originality/value: In the present study effect of the grooved roll on a high speed twin roll caster was investigated.

8

Twin roll casting of magnesium alloys with high aluminum contents

Watari H., Haga T., Shibue Y., Davey K., Koga N.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

419--422

EN

Purpose: The purpose of the work is to establish a manufacturing process and technology to facilitate the economical manufacture of high-quality magnesium sheet alloys with high aluminum contents, such as AZ61 and AZ91. The aim of the work is to establish a twin roll casting technology to facilitate the manufacture of AZ61 and AZ91 magnesium sheet alloys economically whilst maintaining high quality. Design/methodology/approach: A horizontal type twin roll caster was used to manufacture thin magnesium alloy sheets of AZ61 and AZ91. Pair of copper alloy roll and pure copper roll was used for the horizontal type twin roll caster. A closed type tundish was set to the roll caster to keep stable contact of molten magnesium with upper and lower rolls. Findings: The experiment results clarified that AZ61 and AZ91 sheets can be manufactured by twin roll casting process. The product sheet thickness in the present experiment is 2.0 to 4.5 mm for AZ91, 2.5 to 5.0mm for AZ61. Mill stiffness and a method of predicting the cast sheet’s thickness were investigated to determine the appropriate manufacturing conditions. The microstructure of AZ61 cast strips was equiaxed structure and the crystal sizes are different depending on cross section observed. The dendric and equiaxed microstructure were seen in the microstructure of AZ91 cross section. The intermetllic Mg17Al12 was seen in the grain boundary in AZ91 when roll speed was very slow. The grain size of the manufactured wrought magnesium alloys sheet was less than 10 micrometers. The obtained magnesium alloy sheet exhibited an equivalent limiting drawing ratio in a warm-drawing test. The limiting drawing ratio of AZ61 was 2.6 and 2.4 for AZ91. Research limitations/implications: The suitable roll speed was from 9m/min to 15m/min in manufacturing AZ91 and AZ61 strip using copper alloy rolls. When in use of pure copper roll, strips were cast between 6m/min and 20m/min for manufacturing AZ61 and AZ91. The superheats in the experiment were 15ºC and 30ºC. The cast strips should be hot rolled at 300ºC. Originality/value: value In this experiment, it is clarified that AZ61, AZ91 sheets can be manufactured by twin roll casting. These cast sheet can be hot rolled and the manufacturing process by twin roll casting enable to manufacure thin magnesium sheet alloys with high aluminum contents. It has been found that the manufactured cast AZ61 and AZ91 have good formability by a warm deep drawing test.

9

High speed roll casting of Mg alloy strip by a vertical type twin roll caster

Haga T., Watari H., Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 15, nr 1-2

186--192

EN

Purpose: The possibility of high speed roll casting of AZ31, AM60 and AZ91 was investigated. Warm deep drawing of roll cast magnesium alloy was operated. and formability of roll cast magnesium strip was cleared. Design/methodology/approach: A vertical type high speed twin roll caster was used. The roll casting was operated in the air atmosphere. The casting speed was from 60 m/min up to 180 m/min. Low temperature casting was adopted to realize high speed casting. Findings: Strip thinner 3 mm with 100 width could be cast continuously. The casting ability became better with increasing content of Al. Roll cast Mg alloy strips could be hot-rolled down to 0.5 mm. AZ31 as-cast strip could be thinner down to 0.5 mm only by three times of hot rolling. Deep drawing was operated with three kinds of Mg alloy at 250°C, and LDR value was larger than 2.0. It was shown that deep drawing of AZ91 alloy for casting was possible. Research limitations/implications: There was tendency that cracks occurred at the center in the thickness direction as Al content increased. Practical implications: Sheet metal forming of magnesium alloy with high content Al can be realized. Originality/value: It was shown that possibility of high speed roll casting of magnesium alloy, and warm deep drawing of roll cast AZ91 strip.

10

Effects of production parameters on characteristics of magnesium alloy sheets manufactured by twin-roll casting

Watari H., Haga T., Davey K., Koga N., Yamazaki T.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 16, nr 1-2

171--176

EN

Purpose: The purpose of the work is to establish a manufacturing process and technology to facilitate the economical manufacture of high-quality magnesium sheet alloys. Design/methodology/approach: Magnesium alloy AZ31B was used to investigate the appropriate manufacturing conditions for use in twin-roll strip casting. Temperatures of the molten materials and roll speeds were varied to find the appropriate manufacturing conditions. The effects of manufacturing conditions on possible forming were clarified in terms of roll speeds and roll gaps between upper and lower rolls. Findings: In the hot-rolling process, a temperature exceeding 200°C was chosen to keep cast products from cracking. An appropriate annealing temperature was effective for homogenizing the microstructure of the rolled cast sheets after the strip casting process. The grain size of the manufactured wrought magnesium alloys sheet was less than 10 micrometers. The obtained magnesium alloy sheet exhibited an equivalent limiting drawing ratio in a warm-drawing test. Research limitations/implications: AZ31 were used to investigate the appropriate manufacturing conditions for use in twin-roll strip casting. Casting temperatures were varied from 630°C to 670°C to find the best casting conditions. Roll casting speeds were varied from 5m/min to 30 m/min in order to examine which roll speed was appropriate for solidifying the molten magnesium. Practical implications: It was found that the cast magnesium sheet manufactured by roll strip casting could be used for plastic forming if the appropriate magnesium sheets were produced after the roll casting process. Originality/value: This paper showed the effectiveness of twin roll casting for magnesium alloys by a horizontal roll caster.