Study on the Hot-deformation Behavior and Microstructure Evolution of Ti150 Alloy

Author of the article:JING Chunhong1, 2,LI Jiang1, 3,DENG Hao2,YANG Jingyun2,FU Qiang2,PENG Wenya4,LI Gang4

Author's Workplace：1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072,China; 2. China National Erzhong Group Deyang Wanhang Die Forging Co., Ltd., Deyang 618000,China; 3. Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment, Northwestern Polytechnical University, Xi'an 710072, China; 4. AECC Hunan Aviation Powerplant Research Institute, Zhuzhou 412000,China

Key Words：Ti150; hot compression test; constitutive equation; hot processing map; hot deformation behavior

Abstract：The hot deformation behavior and microstructure evolution of a Ti150 near-α titanium alloy were investigated at deformation temperatures ranging from 970~1 040 ℃,strain rates ranging from 10-3~1 s-1,and a deformation amount of 60%. The influences of the true strain, deformation temperature, and strain rate on the flow stress were analysed. On the basis of the stress-strain curve data, an Arrhenius constitutive equation considering strain compensation was established, and ahot working map based on the Prasad criterion and criterion was constructed. The results show that the response of the flow stress to the strain rate of the Ti150 alloy varies significantly across different temperature ranges. The higher the deformation temperature is, the more sensitive the peak stress drop is to the deformation rate at higher strains. Discontinuous yielding is observed at high strain rates. The calculated activation energy for deformation is 919 kJ·mol-1. The prediction error of the established Arrhenius constitutive model considering strain compensation is AARE=6.53%, and the correlation coefficient R is 0.985 6, indicating high prediction accuracy. The hot working map indicates that the optimal process parameter range is a temperature range of 970 to 1 010 ℃ and a strain rate of 10-2 to 1 s-1.The microstructure characteristics of the samples were analysed via optical microscopy (OM) and electron backscatter diffraction (EBSD). The results show that the strain rate plays a decisive role in the microstructure evolution path. At high strain rates, intense plastic deformation leads to rapid dislocation proliferation, and deformation energy storage becomes the core factor driving phase transformation. However, owing to insufficient thermal activation time, microstructure reconstruction is limited. At low strain rates, sufficient thermal activation conditions promote the diffusion mechanism to dominate the phase transformation process, and dislocations gradually release distortion energy through dynamic recovery/recrystallization, ultimately achieving microstructure stabilization.