| 摘要 |
PURPOSE:To prepare a high strength super-plastic aluminum alloy having a fine grain structure, by applying heat treatment, hot processing and cold processing to an Al-Zn-Mg alloy ingot having a specific composition in a combined form under a proper condition. CONSTITUTION:An Al-Zn-Mg alloy ingot, containing on a wt. basis, 3-8% Zn and 0.5-3% Mg as essential components and containing one or more of 3% or less Cu, 0.05-2.0% Mn, 0.05-2.0% Cr, 0.05-0.5% Zr, 0.05-0.5% V and 0.15% or less Ti and comprising the remainder of Al and impurities, is subjected to homogenizing heat treatment at 400-550 deg.C. Subsequently, the treated ingot is subjected to hot processing at 350-500 deg.C and, thereafter, first heat holding is performed at 450-550 deg.C for 0.5-10hr. Succeedingly, the hot processed one is cooled to a second heating temp. of 350-450 deg.C and held at that temp. for 0.5- 50hr and, thereafter, cooled at a cooling speed of 30 deg.C/hr or more and subjected to cold processing at least under a draft of 30% or more to obtain a super- plastic aluminum alloy. |
