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1

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.

2

Strip casting using a single roll caster equipped with a scraper

Haga T., Akitsu K., Kamakura K., Kumai S., Watari H.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 1

26--32

EN

Purpose: Purpose of this paper is to investigate the ability of a single roll caster equipped with a scraper. The purpose of the development of the single roll caster equipped with a scraper is casting of the strip without centre line segregation and porosity and with sound free solidified surface. The single roll caster can cast the strip without the centre segregation and porosity. However, the conditions of the free solidified surface and the thickness distribution are not sound. The scraper was adopted in order to improve the free solidified surface. Investigation of the effect of the scraper and the properties of the roll cast strip is the purpose of this paper. Design/methodology/approach: A scraper was developed to improve the free solidified surface condition. The scraper scribed the semisolid metal on the free solidified surface to make the free solidified surface flat. The scraper was made from mild-steel-plate, and it was coated by the insulator sheet of 2 mm-thick. The scraper was pushed to free solidified surface by the constant load. Findings: The scraper was very useful to improve the free solidified surface. AA5182 aluminium alloy strip could be cast at the speed up to 40 m/min. There was no centre segregation and porosity. There was no difference between the roll contact surface and the scribed surface. The mechanical properties of the roll cast strip were as same as those of strip made from D.C. cast slab. Hi-content Al-Mg alloy like Al-10 mass%Mg, which cannot be cast into the strip by the twin roll caster without centre segregation, could be cast into the strip without defect. Research limitations/implications: Metal which was investigated was only aluminium alloy. It is not clear that this process is useful to other alloys like steel, copper et. al. Practical implications: This process may be able to be used instead of the D.C. casting and the twin roll casting. Especially, this caster is useful the strip casting of the Al-Mg alloy. Originality/value: The single roll caster equipped with a scraper is original development. This caster may be useful for aluminium and magnesium sheet making companies.

3

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.

4

Roll casting of 5182 aluminium alloy

Haga T., Mtsuo M., Kunigo D., Hatanaka Y., Nakamuta R., Watari H., Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 34, nr 2

172-179

EN

Purpose: of this paper is investigation of the ability of the high speed roll casting of 5182 aluminium alloy. Appropriate twin roll caster to cast the 5182 strip was researched. Design/methodology/approach: Method used in the present study was an unequal diameter twin roll caster and a vertical type high speed twin roll caster equipped with mild steel rolls without parting material. Findings: are that the vertical type high speed twin roll caster was effective to cast 5182 strip at high speed. 5182 could be cast at 10 times higher speed than a conventional twin roll caster for aluminium alloy. 5182 could be cast by the mild steel roll using no-parting material without sticking. Research limitations/implications: is that ability of casting of the wide strip, that is wider than 600 mm, could not be investigated. Practical implications: 600 mm-width 5182 strip could be cast and this width is enough for some structural parts. 5182 could be cast into the strip at high productivity and low energy using the economy equipment and no-consumable good. Originality/value: The method to make economy sheet metal of aluminium alloy is imported. The economy alloy and economy process are essential to get economy aluminium alloy sheet.

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

Casting of aluminium alloy strip using an unequal diameter twin roll caster

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

Archives of Materials Science and Engineering

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2008

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Vol. 29, nr 2

113-116

EN

Purpose: of this paper is to clear the property and ability of an unequal diameter twin roll caster to cast commercial size strip. Therefore, 400mm-width strip was cast as first step. Surface-condition, microstructure and mechanical property of the strip was investigated. Design/methodology/approach: Method used in the present study was an unequal diameter twin roll caster. This method was devised to realize easy operation of the twin roll casting and increase of casting speed. Findings: are that 400-width-strip of 3084, 5182 and 6022 could be cast at speed of 20 m/min. This strip was about 4 mm-thick. There were some defects on the surface. As cast strip could be cold-rolled down to sheet of 1 mm-thick. 180 degrees bending test was operated on the 6022 sheet after T4 heat treatment. Crack did not occurred at the outer surface when strip was bent at width-direction. Research limitations/implications: is that the quantity of the melt was 21kg and investigation of the properties was not enough for practical use. The larger weight of melt must be cast for production. Practical implications: are as below. The 400mm-width strip can be cast easily by the unequal diameter twin roll caster. This caster can be adapted to 3083, 5182 and 6022. Originality/value: as below. The economy sheet with 400mm width can be produced by the unequal diameter twin roll caster. 3083, 5182 and 6022 can be cast at the speed of 20m/min. The thickness of the strip was about 4mm.

9

High speed twin roll casting of recycled Al-3Si-0.6Mg strip

Haga T., Ikawa M., Watari H., Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 21, nr 1

7-12

EN

Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of recycled Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast recycled Al-3%Si-0.6%Mg strip was purpose, too. Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed. Findings: Findings are that recycled Al-3%Si-0.6%Mg was could be cast at speed of 60 m/min. This strip was 3.1 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 occured at the outer surface. This result means the roll cast recycled Al-3%Si-0.6%Mg can be used as the body of the auto mobile. Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties was not enough for practical use. Wider strip must be cast using the twin roll caster of the size for production. Practical implications: Practical implications are as below. The economy sheet for the auto mobile can be produced by the high speed twin roll caster. Al-3%Si-0.6%Mg can be used both the casting and plastic forming. Therefore, fractionation in the recycle of the aluminium alloy will becomes easy. The content of Fe in the recycled aluminium alloy increases. Fe becomes intermetallic of AlSiFe. Si for Mg2Si becomes deficient. 3%Si was enough for Mg2Si if AlSiFe was precipitated. Al-3%Si-0.6%Mg is suitable for recycle. Originality/value: The economy sheet of Al-3%Si-0.6%Mg can be made by the high productivity of the HSTRC. The result of this report contributes to make the economy aluminium alloy sheet for the automobile.

10

High speed twin roll casting of 6016 aluminium alloy strip

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

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

495-498

EN

Purpose: of this paper is to clear the possibility of high speed roll casting of aluminium alloy strip. In the body of the automobiles, a sheet of 6016 aluminium alloy is adopted for the outer panel. Therefore, casting of 6016 was tried in this study. Characteristics of roll cast 6016 were investigated. Design/methodology/approach: was a high speed twin roll caster. The high speed twin roll caster was designed to overcome the low castability of the twin roll caster. Findings: are as below. 6016 alloy could be cast into the strip continuously at the speed of 60 m/min. The thickness of the strip was 3.4 mm. The microstructure at as-cast and after T4 heat treatment was shown. The microstructure was very fine. The mechanical properties were investigated by the tensile test and 180 degrees vending test. The as-cast strip could be cold rolled without homogenization to 1 mm. Result of tensile test was tensile strength was 230MPa, 0.2% proof stress was 118MPa and elongation was 33%. 6016 strip of T4 heat treatment could be bent 180 degrees without occurrence of crack at the outer surface or breaking. Research limitations/implications: is the width of the strip was 100 mm. It is necesarry to test twin roll caster equipped wide rolls. Practical implications: are as below. The mechanical properites of the roll-cast 6016 were enough for the sheet metal for the automobile. The low productivity of the twin roller caster could be improved. Originality/value: is that 6016 strip could be cast continuously at speed 60 m/min and this strip had good mechanical properties.

11

High speed twin roll caster for aluminum alloy thin strip

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

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

365-371

EN

Purpose: In the present study, effectiveness of a high-speed twin roll caster for recycling aluminum alloy was investigated. Design/methodology/approach: The effects of the high-speed twin roll caster on alleviating the deterioration of mechanical properties by impurities were investigated. Properties of the cast strip were investigated by metallography, a tension test, and a bending test. Findings: A vertical type twin roll caster for strip casting of aluminum alloys was devised. The strip, which was thinner than 3 mm, could be cast at speeds higher than 60 m/min. Features of the twin roll casters are as below. Copper rolls were used and lubricant was not used in order to increase the casting speed. A casting nozzle was used to set the solidification length precisely. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Separating force was very small in order to prevent sticking of the strip to the roll. Low superheat casting was carried out in order to improve microstructure of the strip. In the present study, effectiveness of a high-speed and high-cooling rate twin roll caster of the present study for recycling aluminum alloy was investigated. Fe was added as impurity to 6063 and A356. The roll caster of the present study was useful to decrease the influence of impurity of Fe. Research limitations/implications: A high-speed twin roll caster of vertical type was designed and assembled to cast aluminum alloy thin strip. Originality/value: The results demonstrate that the high-speed twin roll caster can improve the deterioration by impurities.

12

High speed twin roll casting of Al-3Si-0.6Mg strip

Haga T., Ikawa M., Watari H., Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

337--340

EN

Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast Al-3%Si-0.6%Mg strip was purpose, too. Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed. Findings: Findings are that Al-3%Si-0.6%Mg was could be cast at speed of 60 m/min. This strip was 3.1 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 occurred at the outer surface. Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties was not enough for practical use. Wider strip must be cast using the twin roll caster of the size for production. Practical implications: Practical implications are as below. The economy sheet for the auto mobile can be produced by the high speed twin roll caster. Al-3%Si-0.6%Mg can be used both the casting and plastic forming. Therefore, fractionation in the recycle of the aluminum alloy will becomes easy. The content of Fe in the recycled aluminum alloy increases. Fe becomes intermetallic of AlSiFe. Si for Mg2Si becomes deficient. 3%Si was enough for Mg2Si if AlSiFe was precipitated. Al-3%Si-0.6%Mg is suitable for recycle. Originality/value: The result means the roll cast Al-3%Si-0.6%Mg has ability to be used as the body sheet of the auto mobile.

13

High speed twin roll casting of 6016 strip

Haga T., Ikawa M., Watari H., Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

371--374

EN

Purpose: of this paper is to clear the possibility of high speed roll casting of thin aluminum alloy strip. 6016 aluminum alloy is used for sheet metal of the automobile. Therefore, casting of 6016 was tried in this study. Castability and characteristics of roll cast 6016 strip were investigated. Design/methodology/approach: was a high speed twin roll caster. The high speed twin roll caster was designed to overcome the low castability of the twin roll caster. Findings: are as below. The 6016 could be cast at speed of 60 m/min. The thickness of the 6016 was 3 mm. The microstructure at as-cast and after T6 heat treatment was shown. The microstructure was very fine by the effect of the rapid solidification. The mechanical properties were investigated by the tension test and 180 degrees bending test. The as-cast strip could be cold rolled down to 1 mm without homogenization. The result of tension test (gage length 50mm) of T4 strip was as below, tensile stress was 242 MPa, proof stress was 123 MPa and elongation was 26%. There was no crack at the outer surface of 180-degree-bent strip until contact. This shows the strip endure the hem forming. Research limitations/implications: is the width of the strip was 100 mm. The test using a large scale twin roll caster must be operated. Practical implications: are as below. The mechanical properties of the roll-cast 6016 were enough for the sheet metal for the automobile. The low productivity of the twin roll caster could be improved, and economy 6016 strip was able to produce. Originality/value: is that 6016 strip could be cast at speed 60 m/min and this strip had good mechanical properties.

14

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.

15

Aluminum alloy semisolid strip casting using an unequal diameter twin roll caster

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

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 14, nr 1-2

157--162

EN

Purpose: A Purpose of the present study was to break through the disadvantage of the twin roll caster for aluminum alloy. They were slow casting speed and limitation of alloy. For example, the casting speed was slower than 5 m/min, and casting of hypereutectic Al-Si alloy was difficult. In order to break through the disadvantages, semisolid casting using an unequal diameter twin roll caster was tested its ability. Design/methodology/approach: The specification of the unequal diameter twin roll caster is as below. The diameter of the upper roll was 250 mm, and that of the lower roll was 1000 mm. The width of the roll was 100 mm. The semisolid slurry was made by a cooling slope. Findings: The microstructure of the strip became very fine. Especially, primary and eutectic Si became very fine. This was the effect of rapid solidification. As the result, the ductility of Al-16%Si was improved. Research limitations/implications: 6111 aluminum alloy strip was cast at speeds of 5, 10 and 20 m/min. This caster could cast the strip at the speeds higher than the conventional twin roll caster. Start of casting was very easy. The hypereutectic Al-16%Si alloy, which has wide freezing zone, could be cast in to the strip by the unequal diameter twin roll caster. This was the effect of the cooling of the strip on the lower roll. Originality/value: The roll cast Al-16mass%Si strip had good ductility, and could be cold rolled. Annealed 0.5 mm thick Al-16mass%Si could be bent at radius of 0.75mm.