Direct-rolling of Molten Al-Cu Alloys

Abstract

Regarding the process of direct-rolling of molten metals for directly manufacturing finished products from molten metals as the developed one of the continuous casting, production of half-made products by the process of direct-rolling of molten metals was studied. Using our laboratory machine No.2 (with Bessemer’s twin-roll system), the direct-rolling of molten metals was carried out with Al-Cu alloys which have a wide solidification range and solidify in a pasty manner. The rolling conditions and properties of the direct-rolled plates were examined.
The main results obtained were as follows:
(1) The copper content and the solidification range of Al-Cu alloys have little effect on the upper limit of direct-rollable speed related with the pouring temperature of molten Al-Cu alloys, but its upper limit is lower than that of the pure Al.
(2) The slower the direct-rolling speed, the more strongly segregate copper atoms in the middle of the thickness of plates of Al-5.0%Cu alloys where solidification takes place at last.
(3) Al-Cu alloys are inferior in surface conditions to the pure Al.
(4) The low copper alloys (1.0%Cu, 2.0%Cu) have better mechanical properties at the slower direct-rolling speed, but for the highest Cu alloys (5.0%Cu) it is reverse.
(5) Dendrite subgrain boundaries tend to disappear more completely at a slower direct-rolling speed after the heat treatment (515°C 5 hr WQ, 150°C 5 hr AQ) of the direct-rolled plates.