Fabrication of High Aluminum Content Mg alloys using a Horizontal Twin Roll Caster
This study was aimed for investigating of manufacturing high aluminum content Mg alloys using a horizontal twin roll caster. Recently, weight saving has been key issues for lighter transport equipments as well as electronic componen t parts. As alternative materials to aluminum alloys, developin g magnesium alloy with higher strength has been expected. Normally hi gh Aluminum content Mg alloy has poor ductility and is difficul t to be rolled because of its high strength. However, twin roll casting pr ocess is suitable for manufacturing wrought Mg alloys because materials can be cast directly from molten metal. In this study, manufact uring of high aluminum content magnesium alloy sheet using the roll casting process has been carried out. Effects of manufactur ing parameter, such as roll velocity, pouring temperature and roll gap, on casting was investigated. A microscopic observation of the crys tals of cross section of as cast strip as well as rolled strip was conduc ted. Keywords—AZ91, AZ111, AZ121, Magnesium alloys, Twin roll casting
Development of manufacturing process of wrou- ght magnesium alloy sheets by twin roll casting
AbstrAct Purpose: The purpose of the work is to development of a strip casting technology for manufacturing magnesium alloy sheets. The aim of the work is to establish a manufacturing process and technology to facilitate the economical manufacture of high-strength magnesium sheet alloys. Design/methodology/approach: A horizontal type twin roll caster was used to manufacture magnesium alloy sheets. Pair of copper alloy roll, pure copper roll and steel roll was used for the horizontal type twin roll caster. The diameter of the rolls was 300mm and the width of rolls was 100 and 150mm. Findings: The magnesium alloy sheets could be succcessfully manufactured by the horizontal twin roll caster. The product sheet thickness in the present experiment was 2.0 to 5.0mm. The equiaxed microstrucure was observed in cast magnesium alloys when a pair of copper and cupper aolly rolls were used. The mean grain size of the cast magnesium alloys strip was from 30 to 60 micrometers. After hot rolling process, the grain size was reduced to about 10 micrometers. The obtained magnesium alloy sheet indicated a good plastic formability by a warm-drawing test.
Formability of Magnesium Alloy Sheets Manufactured by Semi-Solid Roll Strip Casting
An experimental investigation was performed into the formability of magnesium alloy sheets that were hot-rolled after a semi-solid roll strip casting process. Semi-solid forming helps reduce the total product weight if the semi-solid material produced by light metals, such as aluminum and magnesium can be used to replace conventional iron and steel products. However, the problems of utilizing magnesium alloys are still related to high manufacturing costs. This means that improved quality must be balanced by economic validity. Magnesium alloy AZ31B was used in this experiment to ascertain the effectiveness of semi-solid roll strip casting for producing magnesium alloy sheets. The temperature of the molten magnesium, and the roll speeds of the upper and lower rolls, (which could be changed independently), were varied to find an appropriate manufacturing condition. Rolling conditions and heat treatment were changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microscopic observation of the crystals of the finished products was performed. It has been found that a limiting drawing ratio of 2.4 was possible in a deep drawing process of the cast magnesium alloy sheets.