Hot deformation mechanism and microstructure evolution in Ti-6.5AI-1.5Zr-3.5Mo-0.3Si with lamellar structure
Hot deformation behavior and microstructure evOLufion of Ti-6.5Al-1.5Zr-3.5Mo-0.3Si with a lameLLar starting microstructure have been investigated in the α-β region.Constant strain rate hot compression tests were conducted on cylindrical specimens in the tem perature range 980-800 ℃ and strain rate range 1x10-3-1 x 10-1 s-1. The stress-strain curves exhibit a sharp continuous flowing soften ing due to globularization and kinking of lamellar structure.Microstructurul observations suggested that deformation temperature and strain rate have a great influence on globularization process and globularized α grain size. The variation of primary α grain size with Zener-Hol lomon parameter (Z) in the globuiarization region exhibited a linear relationship on a log-log scale. The fine-structure analysis shows that the process of globularization should be divided into three stages. The first includes forming of sub-structures with low-angle boundaries by deformation and recovery in α plates.Different types of defects such as dislocation sub-structure,slipping bands and twins were found. The second consists of segmentation of α plates via boundary diffusion and slipping.Globularizing of α grains and homogenizing of struc ture by diffusing and slipping along grain boundaries characterize the last stage. An investigation of typical boundary misorientation spec tra in the α-and β-phases deformed to strain of 0.7 at 950 ℃ and 10~-3 s~-1 was carried out. The results show that the mechanism of glob ularizafion of the lamellar structure during hot deformation is continuous dynamic recrystallization occurred in α plates,and dynamic re covery or discontinuous dynamic recrystallization occurred in β phase.
Ti-6.5Al-1.5Zr-3.5Mo-0.3Si lamellar structure hot deformation microstructure evolution globularization
CAO Chunxiao CHEN Huiqin
Beijing Institute of Aeronautical Materials,AVIC,Beijing 100095,China Taiyuan University of Science and Technology,Taiyuan 030024,China
国际会议
The 10th China-Russia System on Advanced Materials and Technologies(第十届中俄新材料新工艺研讨会)
浙江嘉兴
英文
18-25
2009-10-20（万方平台首次上网日期，不代表论文的发表时间）