Superplastic deformation mechanical behavior and constitutive modelling of a near-α titanium alloy TNW700 sheet
| Autor: | Xuepiao Bai, Wei Li, Jichun Zhang, Jie Shao, Min Wan, Lixia Ma |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
010302 applied physics
Materials science Mechanical Engineering Superplasticity 02 engineering and technology Work hardening Strain hardening exponent Strain rate 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Deformation mechanism Mechanics of Materials 0103 physical sciences Hardening (metallurgy) General Materials Science Composite material Deformation (engineering) 0210 nano-technology Grain Boundary Sliding |
| Zdroj: | Materials Science and Engineering: A. 817:141419 |
| ISSN: | 0921-5093 |
| Popis: | TNW700 is a newly developed near-α high temperature titanium alloy and has great application potential in the aerospace industry owing to excellent creep strength and short-term service temperature up to 700 °C. The superplastic tensile deformation behavior and constitutive model of TNW700 alloy in the temperature range of 900–975 °C and strain rate range of 0.0005–0.01s−1 were investigated. Results indicated that TNW700 alloy exhibits significant work hardening behavior, which may be related to dynamic growth of β grains, dislocation evolution, and silicide precipitates. In addition, work hardening coefficient (n) as well as the critical strain between flow hardening and softening increases with decreasing strain rate, and first increases and then decreases with increasing deformation temperature. TNW700 alloy exhibits excellent superplasticity at 900 °C–950 °C corresponding to strain rate sensitivity exponent (m) greater than 0.3, and expresses poor superplasticity at 975 °C with lower m value. The m value decreases monotonously with strain owing to decrease of grain boundary sliding contribution caused by dynamic grain growth of β grains. The deformation activation energy increases with decreasing strain rate due to the change of deformation mechanism. A phenomenological constitutive model considering strain hardening, strain rate hardening and temperature softening was proposed and material constants were calibrated by true stress-strain data. The constitutive model was implemented into Abaqus code by UHARD subroutine to simulate the superplastic forming of cone parts, and thickness distribution and bulging heights under different forming time were used to verify the validity of constitutive model. |
| Databáze: | OpenAIRE |
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