High-Stress Compressive Creep Behavior of Ti-6Al-4V ELI Alloys with Different Microstructures

¹ College of Materials Science and Engineering and Tech Institute for Advanced Materials, Nanjing Tech University, Nanjing 210009, China
² State Key Laboratory of Metal Materials for Marine Equipment and Applications, Anshan Iron and Steel Company, Anshan, 114021, China
³ Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composite, Nanjing Tech University, Nanjing 210009, China
⁴ Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 210009, China
⁵ China Ship Scientific Research Center, Wuxi 214082, China
⁶ Naval Academy of Armament, Beijing 100161, China

Abstract

Influence of initial microstructure of Ti-6Al-4V ELI alloys on their compressive creep behavior at ambient temperature was investigated with applying compression stresses from 695 to 1092 MPa The experimental results show that the basketweave alloys have better compressive creep resistances than those duplex ones. The constitutive equations in steady-state compressive creeps of duplex or basketweave structure are calculated to be =2.77×10-15(σ-710)2.1 and =2.36×10-14(σ-740)1.7 by fitting the linear regression creep curves after uniaxial compression tests. The noticeable compressive creep strains occur when the applied compression stresses are higher than the threshold stresses, i.e. 710 MPa for duplex Ti-6Al-4V ELI alloys and 740 MPa for basketweave alloys. Microstructural analysis indicates that the creep deformation of Ti-6Al-4V ELI alloys at ambient temperature is mainly controlled by dislocation slip. The creep behavior of Ti-6Al-4V ELI alloy with duplex microstructure is controlled by dislocation slip, like slip dislocations with a-type Burgers vector sliding on the basal or prismatic planes and a few c+a type dislocation sliding on the pyramidal planes. While creep mechanism for basketweave ones is dislocation glide controlled by c+a type Burgers vector sliding on the pyramidal planes and a-type sliding on the basal or prismatic planes.