Biography
Biography: Yuta Kashitani
Abstract
This paper describes a horizontal type twin roll strip casting process for producing aluminum alloy strip of A7075. Twin roll casting process is able to produce a strip from molten metal directly. Thus this process has a possibility to reduce total cost of sheet making comparing to conventional rolling process. Strip casting process has some disadvantages. Casting speed depends on the material properties. It is difficult to determine the casting conditions. Aluminum alloy A7075 has high tensile strength, and it is known as a material for aerospace application. The sheet is manufactured in small quantities comparing to the other sheet aluminum alloy. Because A7075 alloy sheet is generally needed to a number of rolling and annealing process after hot extrusion. It is supposed that the demand of high tensile strength aluminum sheet such as A7075 is going to increase for weight saving of structural material. In this study, the effect of pouring temperature on the strip was investigated. Castability, surface conditions microstructure and strip thickness were estimated. It was possible to produce strip at any pouring temperature by horizontal twin roll strip casting process. Each surfaces of produced strip were transcribed form the roll surface, and the surfaces had a metallic luster. Minor cracks occurred at pouring temperature 710°C. Solidification cracking occurred at a pouring temperature of 740℃. Generally, the strip thickness tends to decrease as the pouring temperature increases. However, the strip thickness of pouring temperature of 710℃ and 740℃ increased compared with the pouring temperature of 680℃. Moreover, the strip thickness decreased at the pouring temperature of 770℃. As a result of observing the microstructure, equiaxed crystals were produced at any pouring temperature.