Strain rate sensitivity in commercial pure titanium: The competition between slip and deformation twinning

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:734

Article

Luan, Qinmeng^1,2  Britton, T. Benjamin²  Jun, Tea-Sung^2,3 

[1] Imperial Coll London, Dept Mech Engn, London SW7 2AZ, England

[2] Imperial Coll London, Royal Sch Mines, Dept Mat, London SW7 2AZ, England

[3] Incheon Natl Univ, Dept Mech Engn, Incheon 22012, South Korea

关键词: Strain rate sensitivity;    Pure titanium;    Macroscopic uniaxial compression;    Twin;    Dislocation;   

DOI  :  10.1016/j.msea.2018.08.010

来源: Elsevier

【 摘 要 】

Titanium alloys are widely used in light weight applications such as jet engine fans, where their mechanical performance under a range of loading regimes is important. Titanium alloys are mechanically anisotropic with respect to crystallographic orientation, and remarkably titanium creeps at room temperature. This means that the strain rate sensitivity (SRS) and stress relaxation performance are critical in predicting component life. In this work, we focus on systematically exploring the macroscopic SRS of Grade 1 commercially pure titanium (CP Ti) with varying grain sizes and texture using uniaxial compression. Briefly, we find that Ti samples had positive SRS and samples compressed along the sheet rolling direction (RD) (i.e. soft grains dominant) were less rate sensitive than bars compressed along the sheet normal direction (ND) (i.e. hard grains dominant). We attribute this rate sensitivity to the relative activity of slip and twinning. Within the grain size range of similar to 317 +/- 7 mu m, we observe an increase in the rate sensitivity, where volume fraction of {10 (1) over bar2}<10<(1)over bar>1> T1 tensile twins was low, and the twin width at different strain rates were similar. These observations imply that the macroscopic rate sensitivity is controlled by the ensemble behaviour of local deformation processes: the amount of slips accumulated at grain boundaries affects the SRS, which is grain size and texture dependent. We hope that this experimental study motivates mechanistic modelling studies using crystal plasticity, including strain rate sensitivity and twinning, to predict the performance of titanium alloys.

【 授权许可】

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