DEVELOPMENT OF PROCESS MAPS FOR SUPERPLASTIC FORMING OF WELDALITE(TM)-049

The activation energy under superplastic forming (SPF) conditions for the Al-Cu-Li alloy Weldalite(TM) 049 (W049) had been reported in a few publications with insufficient information to establish the material constitutive equation. In the present work, the constitutive equation of the alloy was developed through superplastic uniaxial testing with the main axis of the specimen parallel, perpendicular, and at 45 degre es to the rolling direction. The results of the investigation showed t hat the activation energy was not a function of orientation with respe ct to the rolling direction, but a function of the strain rate. The da ta generated from the tests was used to generate process maps for W049 which correlate the processing conditions to the available formabilit y and the developed microstructure. The formability map shows that the alloy exhibits its maximum formability in the region bounded bq a tem perature of 485 degrees C and a strain rate of 5 x 10(-4) s(-1). The f ormability drops to much lower values, at slower strain rates. (C) 199 8 Elsevier Science S.A. All rights reserved.