Hot Deformation Behavior and Microstructural Evolution Characteristics of Ti-44Al-5V-1Cr Alloy Containing (γ + α2 + B2) Phases

Metals

Yanguo Liu¹  Qingfeng Wang²  Rong Rong²  Hongwu Liu²  Zhenxi Li³  Fan Gao³ 

[1] School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China;State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China;Titanium Alloys Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095, China;

关键词: TiAl alloy;    hot deformation behavior;    microstructure;    dynamic recrystallization;    hot extrusion;   

DOI  :  10.3390/met6120305

来源: DOAJ

【 摘 要 】

The hot deformation behavior and microstructural evolution of Ti-44Al-5V-1Cr alloy were investigated by hot compression tests at temperatures of 1000–1250 °C and strain rates of 0.001–1 s−1. It was indicated that the dependence of peak stress on deformation temperature and strain rate could be accurately described by a hyperbolic sine type equation. The activation energy, Q, was estimated to be 632 kJ/mol. The hot processing map was developed at different strains on the basis of dynamic materials modeling and the Murty criteria. As a result, the instability zones occurred in the regions of low temperature (<1050 °C) and a high strain rate (>0.1 s−1). The flow soft mechanism of the instability regions is stress relaxation caused by localization deformation at lamellar boundaries. Dynamic recrystallization is the mainly refining and spheroidizing mechanism of lamellar microstructures. The optimum hot working condition of as-cast TiAl alloy occurs in the temperature range of 1175–1225 °C and the strain rate range 0.05–0.1 s−1. The large-size TiAl alloy rectangular bars with crack-free appearance were successfully prepared by hot extrusion. After annealing, the fine and uniform microstructure with excellent deformation ability was obtained.

【 授权许可】

Unknown