MANUFACTURE OF HIGH-STRENGTH AL-CU-LI-MG-ZR SUPERPLASTIC SHEET

摘要

PURPOSE:To manufacture an Al alloy sheet reduced in anisotropy, having high strength, and capable of plastic deformation by subjecting an ingot of an Al alloy containing specific amounts of Li, Cu, Mg, Zr, and Ti to homogenizing treatment or further to solution heat treatment and then applying rolling to the above under specific conditions. CONSTITUTION:An ingot of an Al alloy having a composition containing, by weight, 1.7-2.3% Li, 1.8-3.0% Cu, 1.1-3.0% Mg, 0.05-0.20% Zr, and 0.01-0.10% Ti is subjected to single-stage or multistage homogenizing treatment at 450-540 deg.C for 1-50h. Subsequently, the above ingot is subjected to solution heat treatment at =460 deg.C and then to heating at 300-450 deg.C for 1-50h to undergo precipitation treatment and successively rolled at the above temp. so as to be worked into a metal sheet. At this time, rolling is carried out while regulating the equivalent strain rate represented by equation I to =10S-1. By this method, the high-strength superplastic Al alloy sheet reduced in anisotropy at high temp. in the range of strain rate where deformation rate is extremely high can be manufactured.