ALUMINUM ALLOY SHEET EXCELLENT IN HIGH-SPEED SUPERPLASTIC FORMABILITY AND PROCESS OF FORMING THE SAME

摘要

An alloy containing 3.0 to 8.0 wt.% of Mg, 0.001 to 0.1 wt.% of Ti, and amounts of Fe and Si (as impurities) as small as 0.06 wt.% or less, the balance being Al and unavoidable impurities, wherein the number per square millimeter of grains of an Al-Fe-Si compound having a diameter of 1 mu m or more is 2000 or less, the mean crystal grain diameter is 25 to 200 mu m and the elongation is more than 380% as worked at 350 to 550 DEG C and a strain rate of 10<-2> to 10<0>/s. This alloy may further contain a small amount of Cu, Mn and/or Cr and is formed at 350 to 550 DEG C and a strain rate of 10<-2> to 10<0>/s. An aluminum alloy sheet with excellent high strain rate superplastic formability and therefore capable of being formed at high temperature and high speed is obtained and the use of this sheet shortens the forming time to improve productivity.