Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior
The non-dendritic microstructure plays a crucial role in determining the rheological properties of semi-solid alloys, which are of the utmost importance for the successful industrial application of the thixoforging process. To further understand the impact of the reheating process on the evolution o...
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2023-09-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/18/6145 |
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| author | Guochao Gu Ruifen Li Lixin Xiang Guiyong Xiao Yupeng Lu |
| author_facet | Guochao Gu Ruifen Li Lixin Xiang Guiyong Xiao Yupeng Lu |
| author_sort | Guochao Gu |
| collection | DOAJ |
| description | The non-dendritic microstructure plays a crucial role in determining the rheological properties of semi-solid alloys, which are of the utmost importance for the successful industrial application of the thixoforging process. To further understand the impact of the reheating process on the evolution of microstructure and thixotropic deformation behavior in the semi-solid state, a hot extruded and T6 treated 7075 aluminum alloy was reheated to the selected temperature ranges using varying heating rates. Subsequently, thixo-compression tests were performed. The study found that during reheating and isothermal holding, the elongated microstructure of the as-supplied alloy can transform into equiaxed or spherical grains. The presence of recrystallized grains was found to be closely linked to the penetration of the liquid phase into the recrystallized grain boundaries. Furthermore, it was observed that higher heating rates resulted in smaller grain sizes. The thixotropic flow behavior of the alloy with various microstructures was analyzed using the true stress–strain curves obtained by thixo-compression experiments, which exhibited three stages: a rapid increase in true stress to a peak value, followed by a decrease in true stress and a steady stress until the end of compression. The stress fluctuated with strain during the formation of the slurry at a strain rate of 10 s<sup>−1</sup>, indicating the significant role of strain rate in material flow during semisolid formation. |
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| id | doaj.art-449b14706f4e4413a19c327a68bdfc9a |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T22:30:55Z |
| publishDate | 2023-09-01 |
| publisher | MDPI AG |
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| series | Materials |
| spelling | doaj.art-449b14706f4e4413a19c327a68bdfc9a2023-11-19T11:43:31ZengMDPI AGMaterials1996-19442023-09-011618614510.3390/ma16186145Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation BehaviorGuochao Gu0Ruifen Li1Lixin Xiang2Guiyong Xiao3Yupeng Lu4Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, ChinaShandong Institute for Product Quality Inspection, Jinan 250102, ChinaKey Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, ChinaKey Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, ChinaKey Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, ChinaThe non-dendritic microstructure plays a crucial role in determining the rheological properties of semi-solid alloys, which are of the utmost importance for the successful industrial application of the thixoforging process. To further understand the impact of the reheating process on the evolution of microstructure and thixotropic deformation behavior in the semi-solid state, a hot extruded and T6 treated 7075 aluminum alloy was reheated to the selected temperature ranges using varying heating rates. Subsequently, thixo-compression tests were performed. The study found that during reheating and isothermal holding, the elongated microstructure of the as-supplied alloy can transform into equiaxed or spherical grains. The presence of recrystallized grains was found to be closely linked to the penetration of the liquid phase into the recrystallized grain boundaries. Furthermore, it was observed that higher heating rates resulted in smaller grain sizes. The thixotropic flow behavior of the alloy with various microstructures was analyzed using the true stress–strain curves obtained by thixo-compression experiments, which exhibited three stages: a rapid increase in true stress to a peak value, followed by a decrease in true stress and a steady stress until the end of compression. The stress fluctuated with strain during the formation of the slurry at a strain rate of 10 s<sup>−1</sup>, indicating the significant role of strain rate in material flow during semisolid formation.https://www.mdpi.com/1996-1944/16/18/61457075 aluminum alloygrain coarseningthixo-compressionheating rate |
| spellingShingle | Guochao Gu Ruifen Li Lixin Xiang Guiyong Xiao Yupeng Lu Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior Materials 7075 aluminum alloy grain coarsening thixo-compression heating rate |
| title | Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior |
| title_full | Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior |
| title_fullStr | Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior |
| title_full_unstemmed | Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior |
| title_short | Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior |
| title_sort | effects of heating rates on microstructural evolution of hot extruded 7075 aluminum alloy in the semi solid state and thixotropic deformation behavior |
| topic | 7075 aluminum alloy grain coarsening thixo-compression heating rate |
| url | https://www.mdpi.com/1996-1944/16/18/6145 |
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