The microstructure and mechanical properties of squeeze cast aluminium alloy 7010
The microstructure and mechanical properties of squeeze cast aluminium alloy 7010
The cast structures of an experimental Al-Zn-Mg-Cu alloy and the commercial equivalent, 7010 Al-alloy, were studied under a combination of squeeze casting conditions. For the 7010 alloy composition, castings of a beaker form were investigated. In all of the castings studied a pressure of 50 MPa was found to be sufficient to produce pore free castings. The relationship between the magnitude of squeeze cast pressure and heat transfer coefficient was established. The solidification behaviour of the 7010 Al-alloy composition responded in the same way to the casting variables as the Al-Zn-Mg-Cu alloy, except that a finer grained structure was always observed in the former alloy. This was attributed to the Ti and Zr grain controllers being present in the 7010 alloy. For both the quaternary and the 7010 composition alloys, the effect of pressure on cast structure was found to be significant only when the pouring temperature was extremely high which in this study was 780oC. Columnar grains only formed when both the pressure and pouring temperature were high. With a pouring temperature lower than 680oC, the casting consisted of fine equiaxed grains and no effect of pressure on grain size was observed. However, the pouring temperature was found to be the most effective single casting parameter in controlling grain structure. Lowering the pouring temperature always resulted in a refinement of grain size, and with a pouring temperature of 630oC, i.e. close to the liquidus temperature, the structure was found to consist of extremely fine cellular grains (50 μm-100 μm in diameter). The relationship between the mechanical properties and grain size of the commercial 7010 alloy composition in squeeze cast material has been established and the properties compared to those of rolled plate and gravity cast material. The mechanical properties studied included: tensile properties, fatigue strength, fatigue crack propagation resistance and fracture toughness. In both the peak aged (T6) and overaged (T73) conditions the mechanical properties of the fine grain size squeeze cast material usually fell between the longitudinal and short transverse properties of the plate material and were always superior to those of the gravity cast material. The casting conditions necessary to give a good combination of mechanical properties for the 7010 composition Al-alloy have been proposed.
University of Southampton
1987
Yue, Tai-Man
(1987)
The microstructure and mechanical properties of squeeze cast aluminium alloy 7010.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The cast structures of an experimental Al-Zn-Mg-Cu alloy and the commercial equivalent, 7010 Al-alloy, were studied under a combination of squeeze casting conditions. For the 7010 alloy composition, castings of a beaker form were investigated. In all of the castings studied a pressure of 50 MPa was found to be sufficient to produce pore free castings. The relationship between the magnitude of squeeze cast pressure and heat transfer coefficient was established. The solidification behaviour of the 7010 Al-alloy composition responded in the same way to the casting variables as the Al-Zn-Mg-Cu alloy, except that a finer grained structure was always observed in the former alloy. This was attributed to the Ti and Zr grain controllers being present in the 7010 alloy. For both the quaternary and the 7010 composition alloys, the effect of pressure on cast structure was found to be significant only when the pouring temperature was extremely high which in this study was 780oC. Columnar grains only formed when both the pressure and pouring temperature were high. With a pouring temperature lower than 680oC, the casting consisted of fine equiaxed grains and no effect of pressure on grain size was observed. However, the pouring temperature was found to be the most effective single casting parameter in controlling grain structure. Lowering the pouring temperature always resulted in a refinement of grain size, and with a pouring temperature of 630oC, i.e. close to the liquidus temperature, the structure was found to consist of extremely fine cellular grains (50 μm-100 μm in diameter). The relationship between the mechanical properties and grain size of the commercial 7010 alloy composition in squeeze cast material has been established and the properties compared to those of rolled plate and gravity cast material. The mechanical properties studied included: tensile properties, fatigue strength, fatigue crack propagation resistance and fracture toughness. In both the peak aged (T6) and overaged (T73) conditions the mechanical properties of the fine grain size squeeze cast material usually fell between the longitudinal and short transverse properties of the plate material and were always superior to those of the gravity cast material. The casting conditions necessary to give a good combination of mechanical properties for the 7010 composition Al-alloy have been proposed.
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Published date: 1987
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Local EPrints ID: 461805
URI: http://eprints.soton.ac.uk/id/eprint/461805
PURE UUID: dc0b73cb-1dea-4ac3-ad4f-791e4ac6578d
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Date deposited: 04 Jul 2022 18:55
Last modified: 04 Jul 2022 18:55
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Author:
Tai-Man Yue
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