US 6,602,364 B1Granted

Aluminium alloy containing magnesium and silicon

AssigneeNorsk Hydro a.s.

InventorsUlf Tundal, Reiso Oddvin

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Abstract

An aluminum alloy and a process for treating the aluminum alloy. The alloy contains 0.5 to 2.5% by weight of an alloying mixture of magnesium and silicon, in which the molar ratio of Mg/Si is 0.70 to 1.25, the alloy optionally containing an additional amount of silicon up to about ⅓ of any iron, manganese and chromium in the alloy, as expressed by weight percent, the balance of the alloy being aluminum, optional alloying elements and unavoidable impurities. The process entails an ageing technique that includes a first stage in which an extrusion of the aluminum alloy is heated at a rate above 100° C./hour to 100-170° C., a second stage in which the extrusion is heated at a rate of 5 to 50° C./hour to a final hold temperature, wherein the total ageing operation is performed in 3 to 24 hours.

Claims20

Dependent claims

A process of treating an aluminium alloy comprising 0.5 to 2.5 percent by weight of an alloying mixture of magnesium and silicon, the molar ratio of Mg/Si being 0.70 to 1.25, optionally an additional amount of Si equal to about ⅓ by weight percent of any amount of Fe, Mn and Cr in the alloy, unavoidable impurities, and balance aluminum, the process comprising the steps of:

casting, cooling, homogenising, preheating and extruding the alloy;
and then
ageing the alloy with a dual step ageing operation to a final hold temperature of 160° C. to 220° C., the dual step ageing operation comprising a first stage in which the alloy is heated at a heating rate above 100° C./hour to a temperature of 100 to 170° C., and comprises a second stage in which the alloy is heated at a heating rate of 5 to 50° C./hour to the final hold temperature, the ageing operation being performed in a time of 3 to 24 hours.

Dependencies are inferred from the claim text.