Microstructure Evolution and Anisotropy Effect During Low Temperature Cross Rolling and Annealing of Ti6Al4V

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 54; no. 9; pp. 3550 - 3562
• Main Authors: Zhu, Wen-Guang, Pu, Jiao, Zhang, Cong-Hui, Wang, Qin-Bo, Wang, Yi-Lei, Shu, Ting-Chuan, Wang, Xiao-Xiang, Wang, Jian
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2023; Springer Nature B.V
• Subjects: Anisotropy; Annealing; Beta phase; Characterization and Evaluation of Materials; Chemistry and Materials Science; Continuous annealing; Cross rolling; Dynamic recrystallization; Electron back scatter; Evolution; Grain size; Low temperature; Materials Science; Metal plates; Metallic Materials; Microstructure; Nanotechnology; Original Research Article; Structural Materials; Surfaces and Interfaces; Tensile properties; Tensile tests; Texture; Thin Films; Titanium alloys; Titanium base alloys; Ultrafines
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-023-07112-x

In order to obtain ultrafine isotropic titanium alloy plate, β phase quenching and the subsequent low temperature α / β phase cross rolling are employed in this paper. The microstructure evolution, texture variation and recrystallization behavior are characterized by scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). Tensile properties of the as cross rolled and annealed plates were investigated. The microstructure dependences of strength difference in TD and RD samples were discussed in detail. The results suggest that discontinuous dynamic recrystallization (DDRX) takes place incompletely which results in a refined but inhomogeneous microstructure after first cross rolling. After second cross rolling, a refined grain with average size ~ 1.24  μ m is obtained. The texture is transformed into a B-type ([0001]//ND) texture which results in limited strength differences between TD and RD sample. During subsequent annealing treatment, continuous static recrystallization (CSRX) generates an equiaxed uniform microstructure and the grain size increases with increasing annealing temperature. Tensile tests suggest that TD samples exhibit a higher strength than that of the RD sample in both cross rolling and annealing condition. The strength difference is decreasing with increasing annealing temperature. Finally, the Schmid law is used to analyze the strength difference in TD and RD direction. The RD sample displayed highest SF value for prismatic and pyramidal  〈 a 〉 slip system which is the origin of the lower yield strength. With increasing annealing temperature, SF value difference of prismatic  〈 a 〉 slip system between RD and TD sample is decreasing which is beneficial to reduce anisotropy of Ti6Al4V plates.