INFLUENCE OF POST-SUPERPLASTIC FORMING PRACTICES ON THE TENSILE PROPERTIES OF ALUMINUM-LITHIUM ALLOYS

The effect of thermal processing following superplastic forming on the tensile properties of aluminum-lithium alloys is addressed, The starting materials consisted of alloys 8090, 2090, and X2095 (a Weldalite(TM) 049 variant) in the form of commercial-grade superplastic sheet. Experience dictates that post-forming practices aimed at a slightly underaged T6 temper produce balanced engineering properties in these alloys. The objective of this study was to assess the potential to use a TS-type temper by eliminating the solution heat treatment and/or cold water quenching steps characteristic of T6 processing, The experimental procedures adopted ensured that the tensile properties compiled were representative of the bulk material Initially, the strengthening behavior of each alloy as a function of temper selection was established, Subsequently, aging practices that resulted in peak strength and balanced properties were identified for the baseline T6 temper and two T5 tempers, The implications for replacing a T6 temper with a T5-type temper, including rapid and slow cooling following forming, are discussed on the basis of the results.