Microstructure, texture and mechanical properties of Ti-43Al-9V-0.2Y alloy hot-rolled at various temperatures

Using the hot-pack rolling method, beta-solidifying Ti-43Al-9V-0.2Y alloy sheets were rolled (thickness reduction: 85%) within the alpha(alpha(2) ) + beta + gamma ternary-phase region at temperatures ranging from 1100 degrees C to 1200 degrees C. The microstructure and texture evolution occurring during dynamic recrystallization of the gamma phase and their effect on the mechanical properties were systematically investigated. After hot-rolling, residual lamellar structures of the as-forged TiAl alloy were completely broken down and the fraction of dynamically recrystallized grains increased significantly with increasing rolling temperature. Lower-temperature and higher-temperature rolling were conducive for dynamic-recrystallization nucleation and growth, respectively, of the gamma grains. At 1100 degrees C, the precipitation of numerous fine (thickness: similar to 200 nm) gamma laths from the beta-phase ribbon was accompanied by the emergence of gamma twins in the new grains. The texture evolution was also strongly dependent on the hot-rolling temperature, as evidenced by the transformation of recrystallization textures into random deformation components when the temperature was increased to 1200 degrees C. Moreover, compared with those rolled at higher temperatures, the sheet hot-rolled at 1100 degrees C had a significantly higher tensile strength (ultimate tensile strength (UTS): 945 MPa, yield strength (YS): 840 MPa) at room temperature. A good combination of high strength (UTS: 550 MPa, YS: 480 MPa) and sufficient ductility (80%) of this alloy sheet was also achieved at 750 degrees C. (C) 2018 Elsevier B.V. All rights reserved.