| 摘要 |
<p>A high-strength aluminum alloy plate which is suitable for use as structural materials such as ones for domestic electrical appliances and exterior automotive sheets and combines excellent unsusceptibility to surface roughening and formability; and a process for producing the plate. The high-strength aluminum alloy plate has a chemical composition containing 2.0-3.3 mass% Mg, 0.1-0.5 mass% Mn, and 0.2-1.0 mass% Fe, the remainder being unavoidable impurities and Al and the unavoidable impurities containing less than 0.20 mass% Si. In the plate, intermetallic compounds have an average diameter in terms of equivalent-circle diameter of 1 mum or smaller and an areal proportion of 1.2% or higher, recrystallized grains have an average grain diameter of 10 mum or smaller, and the tensile strength is 220 MPa or higher. An aluminum alloy melt having the chemical composition is poured into a twin-belt casting machine to continuously produce, by casting, a thin slab having a thickness of 6-15 mm at a cooling rate of 50-200 °C/sec as measured in a position corresponding to 1/4 the slab thickness. The cast is wound into a coil and then cold-rolled at a cold rolling reduction of 60-98%. The resultant plate is subjected to final annealing with a continuous annealing furnace in which the plate is heated at a rate of 100 °C/min or higher and held at a temperature of 400-520°C for a period of 5 minutes or shorter to produce the high-strength aluminum alloy plate.</p> |
