Thermo-mechanical processing of a cast 7XXX Al alloy modified with Sc

AI alloys modified with Sc offer significant enhancements in mechanical properties and are attracting attention for aerospace applications. Thermo-mechanical processing (TMP) is an important step in the shape-forming of these alloys to obtain desired shape, microstructure, and mechanical property combinations. The Sc addition is expected to affect the TMP response of AI alloys and an understanding of these effects would help in the design and optimization of the process sequences. In this paper, we describe the TMP response of an advanced Sc-modified 7XXX AI alloy produced via direct chill continuous casting. Hot compression tests were conducted in the temperature range of 250 - 500 degrees C and strain rate range of 3 x 10(-4)-10s(-1). A processing map for hot working has been generated based on the analyses of temperature and strain rate sensitivity of the flow stress over the above ranges. Hot deformation mechanisms were identified and correlated with the microstructures and hot tensile properties. The influence of Sc on the hot workability of the alloy was established, and the optimum parameters for TMP are discussed.