Furukawa-sky Aluminum Corporation

Nippon Steel Sumitomo Metal Corporation

Koji Ichitani

Toshio Komatsubara

Ken Takata

Tsutomu Tagata

Akira Hibino

An aluminum alloy material for high-temperature/high-speed molding containing 2.0 to 8.0 mass % of Mg, 0.05 to 1.0 mass % of Mn, 0.01 to 0.3 mass % of Zr, 0.06 to 0.4 mass % of Si and 0.06 to 0.4 mass % of Fe, with the balance being made of aluminum and inevitable impurities; an aluminum alloy material for high-temperature/high-speed molding containing 2.0 to 8.0% of Mg, 0.05 to 1.5% of Mn and 0.05 to 0.4% of Cr, Fe being restricted to 0.4% or less and Si being restricted to 0.4% or less, the grain diameter of a Cr-base intermetallic compound formed by melt-casting being 20 &#x3bc;m or less, and grains of intermetallic compounds with a grain diameter in the range from 50 to 1,000 nm as Mn-base and Cr-base precipitates being present in a distribution density of 350,000 grains/mmor more, the aluminum alloy material being used for high-temperature/high-speed molding by subjecting the alloy material to cooling at a cooling rate of 20&#xb0; C./min or more immediately after molding at a temperature range from 200 to 550&#xb0; C. and at a strain rate from 10to 10/sec; and a method of producing the aluminum alloy material.

Aluminum alloy material for high-temperature/high-speed molding, method of producing the same, and method of producing a molded article of an aluminum alloy

An Al&#x2014;Mg&#x2014;Si based aluminum alloy sheet having undergone normal-temperature aging (or being in a underaged state) after a solution treatment thereof is, before press forming, subjected to a heating treatment (partial reversion heating treatment) in which the alloy sheet is partially heated to a temperature in the range of 150 to 350&#xb0; C. for a time of not more than 5 minutes so that the difference in strength (difference in 0.2% proof stress) between the heated part and the non-heated part will be not less than 10 MPa. The alloy sheet thus treated is subjected to cold press forming in the condition where the heated part with low strength is put in contact with a wrinkle holding-down appliance of the press and the non-heated part with high strength is put in contact with the shoulder part (radius) of the punch. In the partial reversion heating treatment, the temperature rise rate and the cooling rate in cooling down to 100&#xb0; C. or below are set to be not less than 30&#xb0; C./min. Further, the period for which the alloy sheet is left to stand at normal temperature after the partial reversion heating treatment until the cold press forming is set to be within 30 days.

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Tokyo, Japan

Koji Ichitani