【課題】 高強度・高靱性で耐蝕性に富むアルミニウム 合金板を低廉なコストで提供することである。
【解決手段】 ２．０〜６．０ｗｔ％のＭｇを含有する Ａｌ合金材を異周速圧延機で圧延する圧延工程と、前記 圧延されたＡｌ合金材を、該Ａｌ合金の再結晶温度以上 で、固相線温度より５℃以上低い温度に加熱する加熱工 程と、前記加熱工程の後、冷却する冷却工程とを具備す るアルミニウム合金板の製造方法。
PROBLEM TO BE SOLVED: To form a fine crystal structure in steel at a low cost without requiring complex treating stages and precise control and to improve the strength and corrosion resistance thereof by rolling an Al alloy material having a specified Mg content by a different peripheral speed rolling mill, next executing heating treatment at a specified temp. and thereafter subjecting it to cooling. SOLUTION: An Al alloy material contg., by weight, 2.0 to 6.0% Mg, furthermore contg., at need, 0.05 to 0.5% Cu or one or more kinds among 0.05 to 1.0% Mn, 0.05 to 0.35% Cr, 0.05 to 0.25% Zr and 0.001 to 0.2% Ti is rolled at the temperature equal to or below the recovering temp. thereof, preferably at a room temp. to 150 deg.C by a different peripheral speed rolling mill at a rolling ratio of 80 to 97%. This rolling mill is preferably the one in which the rotary peripheral speed ratio between the upper and lower rolls is 1.1 to 1.8, by which sufficient shear deformation can be obtd. As to the obtd. Al alloy sheet, the temp. is raised to the recrystallization temp. to the solidus temp. -5 deg.C at >=1 deg.C/sec, and it is held to 280 to 400 deg.C. This is cooled to <=100 deg.C at >=5 deg.C/sec to obtain a desired Al alloy sheet.