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

Zhenhua Dan,Lian Zhou,Jiafei Lu,Ying Wang,Aifeng Zhang,Yuecheng Dong,Hui Chang ,Peng Qu ,Zhigang Zak Fang

doi:10.1051/matecconf/202032111007

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.

Highlights

Titanium alloys have been widely applied in aerospace and ocean engineering due to their superior properties such as high specific strength, elastic modulus and corrosion resistance [1,2,3]
The main movements of the dislocations are controlled by c+a type Burgers vector sliding on the pyramidal planes and a-type sliding on the basal or prismatic planes
MPa on the compressive creep deformation behavior of Ti–6Al–4V ELI alloys had been investigated by using high-stress compressive creep tests at ambient temperature

Summary

Introduction

Titanium alloys have been widely applied in aerospace and ocean engineering due to their superior properties such as high specific strength, elastic modulus and corrosion resistance [1,2,3]. Ti-6Al-4V alloys has been the workhorse of the titanium industry due to their high specific strength, corrosion resistance, excellent high temperature properties and metallurgical stability[4]. At 375 and 470°C, the creep deformation of Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe alloys is controlled by dislocation creep mechanism within primary α phase and interface sliding within secondary α phases[12]. Creep curves exhibit creep saturation [15, 18], and primary creep is the dominant deformation during creep of titanium alloys[19, 20]. Several researches [21, 22] reported that ambient temperature creep is controlled by dislocation slip

Results

Discussion

Conclusion