Revealing the influence of pre-precipitation microstructure on hot workability in an Al-Cu-Mg-Zr alloy
Autor: | Zhaoyu Dong, Fulin Jiang, Guan Wang, Hui Zhang, Guowei Bo |
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Rok vydání: | 2019 |
Předmět: |
Materials science
020502 materials Mechanical Engineering Alloy 02 engineering and technology Flow stress engineering.material 021001 nanoscience & nanotechnology Condensed Matter Physics Microstructure Condensed Matter::Materials Science 0205 materials engineering Mechanics of Materials Dynamic recrystallization engineering General Materials Science Deformation (engineering) Composite material 0210 nano-technology Ductility Softening Electron backscatter diffraction |
Zdroj: | Materials Science and Engineering: A. 755:147-157 |
ISSN: | 0921-5093 |
Popis: | Hot workability, which indicates the ability of metallic materials to be deformed at elevated temperatures, is generally governed by the microstructure-dependent strength and ductility. In this work, the influence of three types of pre-precipitation microstructure, tailored through different cooling conditions (i.e., air cooling, water quenching and furnace cooling) after heat treatment, on hot workability in an Al-Cu-Mg-Zr alloy was studied by means of constitutive analysis, processing maps and microstructure characterizations using scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. The results showed that pre-precipitation microstructure had a considerable influence on flow stress, hot deformation activation energy, dynamic softening and hot workability. The highest flow stress accompanied by a more notable dynamic softening was shown in the water-quenched alloy, whereas the flow stress in the furnace-cooled alloy was the lowest. The flow stresses of air-cooled, water-quenched and furnace-cooled alloys could be described well by the hyperbolic sine equation with hot deformation activation energies of 180.5, 298.9 and 161.5 kJ/mol, respectively. Dynamic softening mechanisms were found to be associated with different contributions of dynamic recovery, dynamic precipitation and/or dynamic recrystallization in various tempers of the present alloy. Further, the air-cooled alloy showed minimal instability regimes and an optimal pre-precipitation microstructure for hot forming. The deteriorated hot workability in the water-quenched alloy was attributed to dynamic precipitation effects. However, coarse constituent phases in the furnace-cooled alloy were easily broken during deformation under a higher strain rate, which led to deformation instability. |
Databáze: | OpenAIRE |
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