摘要
针对热等静压态TC4钛合金,采用Gleeble-1500D热模拟试验机在温度为950~850℃、应变速率为0.01~1.00 s^(-1)下对其进行多道次热压缩实验,研究了多道次热变形对TC4钛合金组织演变的影响。结果表明:由于加工硬化,变形初期流变应力迅速上升,随着动态软化作用出现了不连续屈服现象。随后应力值趋于稳定,表明变形行为符合稳态流变特征。1道次变形后,试样中存在大量粗大的β晶粒。提高应变速率在一定程度上可以细化晶粒,在高应变速率下软化机制以动态回复为主,而在低应变速率下软化机制以动态再结晶为主。2道次变形后,在低应变速率(0.10和0.01 s^(-1))下,发生了α相的几何动态再结晶,并且片层状α相断裂,球化为等轴α相。3道次变形后,大量条状α相形核长大并最终与等轴α相和β转变相共同表现为三态组织。
Multi-pass hot compression experiments of hot isostatic pressed TC4 titanium alloy were carried out at 950-850 ℃ and strain rate of 0.01-1 s^(-1) on Gleeble-1500 D thermal simulator.The effect of multi-pass hot deformation on microstructure evolution of TC4 titanium alloy was investigated.The results show that the flow stress rises rapidly at the initial stage of deformation due to the work hardening,and discontinuous yield phenomenon occurs with the dynamic softening effect.Then the stress value tends to stabilize,which indicates that the deformation behavior is consistent with the steady-state flow characteristics.After one pass deformation,there are plenty of coarse βgrains existing in the samples.Increasing strain rate can refine the grains to some extent.At high strain rates,dynamic recovery is the main softening mechanism,while at low strain rates,dynamic recrystallization is the main softening mechanism.After two passes deformation,at low strain rates(0.10 and 0.01 s^(-1)),geometric dynamic recrystallization of α phase occurs,and the lamellar α phase fractures and spheroidizes into equiaxed α phase.After three passes deformation,a large number of strip-shaped α phases nucleate and grow,and finally appear as a tri-modal structure which contain equiaxed α phase,lamellar α phase and β transformed phase.
作者
徐凯华
刘海军
闫江鹏
杨亚琴
徐健
薛勇
XU Kai-hua;LIU Hai-jun;YAN Jiang-peng;YANG Ya-qin;XU Jian;XUE Yong(School of Materials Science and Engineering,North University of China,Taiyuan 030051,China)
出处
《塑性工程学报》
CAS
CSCD
北大核心
2021年第7期150-156,共7页
Journal of Plasticity Engineering
基金
国家自然科学基金资助项目(51675492)。
关键词
热等静压
TC4钛合金
热压缩
微观组织演变
hot isostatic pressing
TC4 titanium alloy
hot compression
microstructure evolution
