Microstructure and Mechanical Properties of High Aluminum Content Magnesium Alloys Fabricated by Twin-Roll Casting Process

This paper describes the twin roll casting technology of magnesium alloys that contains relatively high weight ratio of aluminum, such as AM60, AZ91 and AZ121. The cast magnesium alloy sheets were hot-rolled in an elevated temperature to investigate the appropriate hot-rolling conditions for producing high-quality strip using a purpose-built strip-casting mill. The influences of such process parameters as materials of roll, casting temperature, and roll speed are ascertained. A simple method of predicting the convection heat transfer coefficient between casting rolls and molten metal is introduced. The microstructure of the manufactured wrought alloy sheets was observed to investigate the effects of the hot-rolling and heat-treatment conditions on crystal growth in the cast products. It is found that manufacturing thin magnesium alloy sheet was possible at a roll speed of 110m/min by a vertical type roll caster. The grain size of the manufactured wrought magnesium alloys sheet was less than 30 micrometers due to rapid solidification in the proposed process.

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SUPERPLASTIC FORMABILITY OF AZ31 MAGNESIUM ALLOY SHEETS PRODUCED BY TWIN ROLL CASTING AND SEQUENTIAL HOT ROLLING

Modern Physics Letters B ◽

10.1142/s0217984913410200 ◽

2013 ◽

Vol 27 (19) ◽

pp. 1341020

Author(s):

YANDONG YU ◽

KAI LIN ◽

PENG JIANG

Keyword(s):

Magnesium Alloy ◽

Magnesium Alloys ◽

Hot Rolling ◽

Tensile Testing ◽

Az31 Magnesium Alloy ◽

Twin Roll Casting ◽

Roll Casting ◽

Three Stages ◽

The Common ◽

Twin Roll

In this paper, superplastic tensile testing and gas bulging forming of AZ31 and AZ31 + Y + Sr magnesium alloys produced by twin roll casting (TRC) and sequential hot rolling were carried out. At 673 K, the superplastic formability of the TRC AZ31 magnesium alloy sheets added Y and Sr elements has improved significantly compared to the common TRC AZ31 sheets. Formations of cavities on the bulging part go through three stages of the nucleation, growth and aggregation, finally cavities merging lead to rupture at the top of the bulging part.

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Kiss-Point Position Control of Solidification Layer and Process Optimization for Twin-Roll Casting of Magnesium Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3844 ◽

2011 ◽

Vol 189-193 ◽

pp. 3844-3851

Author(s):

Wen Ping Weng ◽

Kang Deng ◽

Zhong Ming Ren ◽

Qi Chen ◽

Zhi Dong Chi ◽

...

Keyword(s):

Magnesium Alloy ◽

Magnesium Alloys ◽

Process Optimization ◽

Strip Thickness ◽

Alloy Strip ◽

Roll Speed ◽

Twin Roll Casting ◽

Roll Casting ◽

Twin Roll

The solidification and process optimization for twin-roll casting of magnesium alloys have been studied. Effects of roll speed, roller diameter, setback length and strip thickness on the position of the solidification front and the surface quality of strip were analyzed through experiments. A kiss-point model which considers the strip thickness, set-back length and roll speed was established to optimize process and enhance the surface quality of magnesium alloy strip. Results showed that the twin-roll casting process could be effectively stabilized and optimized under the direction of the model, and the defectless magnesium alloy strip was obtained.

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The Development of Superplastic Magnesium Alloy Sheet

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.433.273 ◽

2010 ◽

Vol 433 ◽

pp. 273-279 ◽

Cited By ~ 4

Author(s):

Richard J. Dashwood ◽

David Klaumunzer ◽

Martin Jackson ◽

Zhong Yun Fan ◽

Roger Grimes

Keyword(s):

Magnesium Alloy ◽

Magnesium Alloys ◽

Warm Rolling ◽

Alloy Sheet ◽

Magnesium Alloy Sheet ◽

Twin Roll Casting ◽

Roll Casting ◽

Strip Cast ◽

Twin Roll ◽

Cast Condition

While magnesium alloys are routinely used in engineering applications in the form of net shape castings, applications for sheet product have been limited due to the poor cold formability of magnesium combined with the perceived expense of sheet. The issues associated with poor cold formability could largely be overcome if magnesium alloys were to be superplastically formed. Superplasticity in magnesium is well established with research papers on the subject dating back to the late 1960s. In recent years, interest in this area has grown to the point where a number of companies have successfully superplastically formed prototype automotive panels from magnesium alloy sheet. Concurrent to this the scientific community have demonstrated superplasticity in a wide range of magnesium alloys using processing techniques ranging from the exotic (severe plastic deformation) to the mundane (traditional warm rolling). Work by the current authors has shown, rather surprisingly, that superplasticity can be achieved in magnesium alloys in the as-cast condition. This has led to some initial exploratory work involving twin roll casting. The concept being that affordable superplastic magnesium sheet could be produced via twin roll casting with only limited rolling reduction to final gauge. This paper describes the superplastic behaviour (in uniaxial tension) and microstructure of sheet processed from strip cast AZ31 and AZ91. The experimental material has included strip cast AZ91 subjected to large shear strains immediately prior to casting. The material was tested in the as-cast condition and after warm rolling to a number of gauges. Industrially useful superplastic capability was demonstrated in the strip cast alloys. Furthermore, good superplastic capability was also demonstrated in sheet subsequently rolled from the cast metal and rolling strain did not significantly influence the ductilities obtained. The mechanism for achieving superplasticity in as-cast magnesium alloys will be considered and the contrasting deformation characteristics of AZ31 and AZ91 will be discussed in terms of m value analysis and microstructural characterisation.

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Mechanical Properties and Metallurgical Qualities of High Aluminum Content Magnesium Alloys Fabricated by Twin-Roll Casting

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1440 ◽

2010 ◽

Vol 654-656 ◽

pp. 1440-1443 ◽

Cited By ~ 1

Author(s):

Hisaki Watari ◽

Yoshimasa Nishio ◽

Mayumi Suzuki ◽

Ryoji Nakamura ◽

Nobuhio Koga ◽

...

Keyword(s):

Magnesium Alloy ◽

Magnesium Alloys ◽

Aluminum Content ◽

Mg Alloys ◽

Roll Speed ◽

Twin Roll Casting ◽

Roll Casting ◽

High Aluminum Content ◽

Twin Roll ◽

High Aluminum

This paper describes the twin-roll casting technology of magnesium alloys that contain relatively high weight ratios of aluminum, such as AZ91, AZ101 and AZ111. The magnesium alloy sheets were cast by a horizontal twin roll caster to manufacture relatively high-strength Mg alloys with high aluminum content. The influences of such process parameters as casting temperature and roll speed were ascertained. The microstructures of cast magnesium alloy sheets are observed to investigate the effects of roll-casting conditions on crystal growth in the cast products. It was found that Mg alloys with high aluminum content can be fabricated at a roll speed of 15 m/min with a horizontal-roll caster. The grain size of the manufactured wrought magnesium alloy sheet was about 10 micrometers due to rapid solidification in the proposed process.

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Effects of Aluminum Content on Plastic Formability of Wrought Mg Alloy Sheet Produced by Twin-Roll Casting Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.675-677.667 ◽

2011 ◽

Vol 675-677 ◽

pp. 667-670 ◽

Cited By ~ 3

Author(s):

Hisaki Watari ◽

Yoshimasa Nishio ◽

Mayumi Suzuki ◽

Toshio Haga ◽

Keith Davey ◽

...

Keyword(s):

Magnesium Alloy ◽

Aluminum Content ◽

Alloy Sheet ◽

Mg Alloys ◽

Roll Speed ◽

Twin Roll Casting ◽

Roll Casting ◽

High Aluminum Content ◽

Twin Roll ◽

High Aluminum

A total weight reduction approach has been key issue for car manufacturers to cope with more and more stringent requirements for fuel economy. This paper describes the twin-roll casting technology of magnesium alloys that contain relatively high weight ratios of aluminum, such as AZ91,AZ101 and AZ111. The magnesium alloy sheets were cast by a horizontal twin roll caster to manufacture relatively high-strength Mg alloys with high aluminum content. The influences of such process parameters as casting temperature and roll speed were ascertained. The microstructures of cast magnesium alloy sheets were observed to investigate the effects of roll-casting conditions on crystal growth in the cast products. It was found that Mg alloys with high aluminum content can be fabricated at a roll speed of 15 m/min with a horizontal-roll caster. The grain size of the manufactured wrought magnesium alloy sheet was about 10 μm due to rapid solidification in the proposed process.

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Microstructures and Mechanical Properties of AZ31+Sr+Y Magnesium Alloy Sheets Produced by Twin-Roll Casting and Sequential Hot Rolling

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.765-767.3176 ◽

2013 ◽

Vol 765-767 ◽

pp. 3176-3179 ◽

Cited By ~ 1

Author(s):

Yan Dong Yu ◽

Qiong Hu ◽

Peng Jiang

Keyword(s):

Magnesium Alloy ◽

Hot Rolling ◽

Room Temperature ◽

Dominant Role ◽

Boundary Slip ◽

Twin Roll Casting ◽

Roll Casting ◽

Deformation Properties ◽

Increasing Temperature ◽

Twin Roll

In this paper, the deformation properties of AZ31+Sr+Y magnesium alloy sheets produced by twin-roll casting (TRC) and sequential hot rolling were studied by the tensile testing at a strain rate of 7×10-4s-1and various temperatures: room temperature (RT), 200°C, 300°C and 400°C, respectively. The result shows that the microstructure of AZ31+Sr+Y alloy was refined obviously by adding elements Sr and Y, the elongation of the alloy increased with increasing temperature, and the fracture behavior of the alloy changed from brittle fracture to ductile fracture with increasing temperature. During the process of plastic deformation of AZ31+Sr+Y alloy, the twin plays a leading role at room temperature; the dislocation movement is regarded as the main deformation mechanism at 200° C; at the higher temperature (above 300°C) the grain boundary slip (GBS) plays a dominant role .

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