期刊：
International Journal of Mechanical Sciences,2002年44(12):2415-2425 ISSN：0020-7403
通讯作者：
Rao, KP
作者机构：
City Univ Hong Kong, Dept Mfg Engn & Engn Management, Kowloon, Hong Kong, Peoples R China.;Cent S Univ, Dept Mat Sci & Engn, Changsha 410083, Peoples R China.;Nehua Univ, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Rao, KP] City Univ Hong Kong, Dept Mfg Engn & Engn Management, 83 Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
通讯机构：
[Rao, KP] C;City Univ Hong Kong, Dept Mfg Engn & Engn Management, 83 Tat Chee Ave, Kowloon, Hong Kong, Peoples R China.
摘要：
Hot extrusion of Ti–6Al–4V alloy has been studied using finite element simulation and the results are compared with those obtained experimentally. First, the constitutive behavior of the material and friction at the extrusion temperatures are established based on the results obtained through cylindrical and ring compression tests, respectively. While the flow stress below β transus temperature is expressed as a strain-dependent function, it is taken as strain-independent one at higher temperatures. The distribution of strain, temperature and effective stress has been simulated under different design and processing conditions. Simulation results show that heat generation due to deformation is significant (as much as 160°C) in the hot extrusion of Ti alloys, and it mainly occurs at the beginning of the extrusion process. This leads to reduction in flow stress which, in turn, leads to enlarged deformation zone. A fair agreement has been found between the experimental results and those obtained through simulations.
作者机构：
Cent S Univ, Dept Mat Sci & Engn, Changsha 410083, Peoples R China.;Nanhua Univ, Dept Mech Engn, Hengyang 421001, Peoples R China.;City Univ Hong Kong, Dept Mfg Engn & Engn Management, Hong Kong, Hong Kong, Peoples R China.;[Li, LX; Yang, LB; Peng, DS] Department of Materials Science and Engineering, Central South University, Changsha 410083, PR China;[Lou, Y] Department of Mechanical Engineering, Nanhua University, Hengyang 421001, PR China
摘要：
Samples of Ti-3Al-5V-5Mo alloy were compressed in both beta and alpha + beta phase region on a Gleeble 1500 Simulator. Compression tests were carried out in the temperature range of 700-1000 degreesC and strain rate range of 0.05-15 s(-1). Experimental results show that the flow stress of Ti-3Al-5V-5Mo alloy decreases with the increase of temperature and the decrease of strain rate. At high strain rate, typically 5 and 15 s(-1), discontinuous yielding followed by flow oscillations was observed in both beta phase region and alpha+beta phase region; at low strain rate, the flows display single peak stress. The flow stress at a strain of 0.2 was analyzed with a stand constitutive equation. Activation energy parameters were obtained, and they are 133.46 kJ/mol for the beta phase region and 661.90 kJ/mol for the alpha + beta phase region. Microstructures of the compressed specimens in water-quenched conditions were critically observed. High temperature deformation mechanisms have been elucidated. In the beta phase region, the operative deformation mechanisms are dynamic recovery at high strain rates and grain boundary sliding at low strain rates. In alpha + beta phase region, the alpha phase undergoes dynamically recrystallization at both high and low stain rates. (C) 2002 Elsevier Science Ltd. All rights reserved.
