Strength and structure variation of 2195 Al-Li alloy caused by different deformation processes of hot extrusion and cold-rolling
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China;
4. Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education, Central South University, Changsha 410083, China)
2. Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China;
4. Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education, Central South University, Changsha 410083, China)
Abstract: 2195 Al-Li alloy was deformed through extrusion followed by cold-rolling. The textures of the extruded plate and cold-rolled sheet after solutionization were investigated. The longitudinal strength and precipitates after T8 aging were measured and observed, respectively. Compared to those in the sheet, T1(Al2CuLi) precipitates in the extruded plate after T8 aging are non-uniform, and their incubation time is shorter. The extruded plate after solutionization is not recrystallized and contains 55.28% deformation textures of Brass and S. In the cold-rolled sheet after solutionization, massive recrystallization occurs and S component disappears. Due to the higher fraction of Brass and S textures with higher Schmid factor and lower equivalent sliding system number, the extruded plate possesses an yield strength not higher or even lower, but a tensile strength higher, than the cold-rolled sheet after solutionization. In addition, during the aging after pre-stretch, these textures promote T1 precipitation on preferred sliding planes of cold-rolled sheet and cause its higher yield strength and tensile strength after T8 aging.
Key words: Al-Li alloy; cold-rolling; extrusion; texture; precipitate; strength