Casting of thin magnesium strip using a high-speed-semisolid-roll-casting and its mechanical properties

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16560641
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Material processing/treatments
• Research Institution: Osaka Institute of Technology
• Principal Investigator: HAGA Toshio Osaka Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (00212134)
• Project Period (FY): 2004 – 2005
• Keywords: roll casting / twin roll caster / thin strip / continuous casting / magnesium alloy / AZ91 / AM60 / AZ31

Research Abstract

Hot-rolling is essential to make Magnesium alloy sheet from slab. Heating of magnesium alloy is needed on every ho-rolling pass. Therefore, magnesium alloy sheet is very expensive. Reducing number of hot-rolling is very useful to make the magnesium sheet economy. Thin strip, which is thinner than 5mm, can be cast by a twin roll caster. If the magnesium alloy strip can be cast using the twin roll caster, the twin roll caster is very useful to reduce the cost of magnesium sheet. Sheet of AM60 and AZ91 for commercial is not existed. The reason that hot roll of AM60 and AZ91 from slab is difficult. Products made from AM60 and AZ91 sheet became stronger than that of AZ31 sheet. If AZ91 sheet could be used for press product, fractionation of magnesium alloys in recycle becomes easy. Most of magnesium alloy products can be made from AZ91 alloy. Sheet forming of AZ91 alloy was tried in the present study. A vertical type high speed twin roll caster was used in the present study to cast thin str ip. The high speed twin roll caster (HSTRC) can cast the aluminum alloy strip at speeds higher than 60m/min. Magnesium alloy was cast at speeds higher than 60m/min. Low temperature casting was adopted on the casting. The low superheat casting was useful to increase the casting speed and safety. In the present study, ability of roll casting of magnesium alloy, and mechanical properties of roll cast strip were investigated. 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. A vertical type high speed twin roll caster was used. The roll casting was operated in the air atmosphere. The casting speed was from 60m/min up to 180m/min. Low temperature casting was adopted to realize high speed casting. Strip thinner 3mm 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 0.5mm. AZ31 as-cast strip could be thinner down to 0.5mm only by three times of hot rolling. Deep drawing was operated with three kinds of Mg alloy at 250℃, and LDR value was larger than 2.0. It was shown that deep drawing of AZ91 alloy for casting was possible. There was tendency that cracks occurred at the center in the thickness direction as Al content increased. Sheet metal forming of magnesium alloy with high content Al can be realized. It was shown that possibility of high speed roll casting of magnesium alloy, and warm deep drawing of roll cast AZ91 strip.