scholarly journals Hot-Deformation Behavior and Microstructure Evolution of the Dual-Scale SiCp/A356 Composites Based on Optimal Hot-Processing Parameters

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2825 ◽  
Author(s):  
Yahu Song ◽  
Aiqin Wang ◽  
Douqin Ma ◽  
Jingpei Xie ◽  
Zhen Wang ◽  
...  

Hot deformation at elevated temperature is essential to densify particle-reinforced aluminum matrix composites (AMCs) and improve their performance. However, hot deformation behavior of the AMCs is sensitive to the variation of hot-processing parameters. In this paper, optimal processing parameters of dual-scale SiCp/A356 composites were determined to explore the control strategy of the microstructure. Hot-compression tests were conducted at temperatures ranging from 460 to 520 °C under strain rates from 0.01 to 5 s−1. Constitutive equation and processing maps were presented to determine the hot-processing parameters. Microstructure evolution of the dual-scale SiCp/A356 composites was analyzed. The strain rate of 0.62–5 s−1 and deformation temperature of 495–518 °C is suitable for the hot processing. The number of dynamic recrystallization (DRX) grains in the “safe” domains is larger and the dislocation density is lower compared to those of instability domains. DRX grains mainly occurred around SiC particles. The presence of SiC particles can promote effectively the DRX nucleation, which results in the dynamic softening mechanism of the dual-scale SiCp/A356 composites being dominated by DRX.

2011 ◽  
Vol 189-193 ◽  
pp. 1456-1464
Author(s):  
Jiao Yan Dai ◽  
Si Guo Mu ◽  
Yong Ru Wang

The hot deformation behavior of Cu-0.35Cr-0.15Zr (wt.%) alloy was investigated by hot compression tests using a Gleeble-1500D thermal simulator system. The tests were performed under the conditions of 700°С- 820°С temperature and 0.01-10s-1strain rate. The results show that the flow behavior of the studied alloy could be described by the hyperbolic sine constitutive equation, and an active energy of 597.53 kJ/mol was calculated. The processing maps were obtained and analyzed according to the dynamic materials model. The optimum processing parameters of hot deformation of this alloy in the range of this experiment can be attained by the maps. The hot deformation temperature was 800-820°C and the strain rate was 0.01-0.1s-1.The instability zones of flow behavior can also be recognized by the maps.


Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 481 ◽  
Author(s):  
Zhang ◽  
Lian ◽  
Chen ◽  
Sun ◽  
Zhang ◽  
...  

The hot deformation behavior and microstructure evolution of a 7.5 vol% TiBw/near α-Ti composite with fine matrix microstructure were investigated under the deformation conditions in a temperature range of 800–950 °C and strain rate range of 0.001–1 s−1 using plane strain compression tests. The flow stress curves show different characteristics according to the various deformation conditions. At a higher strain rate (1 s−1), the flow stress of the composite continuously increases until a peak value is reached. The activation energy is 410.40 kJ/mol, much lower than the activation energy of as-sintered or as-forged composites. The decreased activation energy is ascribed to the breaking of the TiBw reinforcement during the multi-directional forging and the resultant fine matrix microstructure. Refined reinforcement and refined matrix microstructure significantly improve the hot deformation ability of the composite. The deformation conditions determine the morphology and fraction of α and β phases. At 800–900 °C and 0.01 s−1 the matrix α grains are much refined due to the continuous dynamic recrystallization (CDRX). The processing map is constructed based on the hot deformation behavior and microstructure evolution. The optimal hot processing window is determined to be 800–950 °C/0.001–0.01 s−1, which lead to CDRX of primary α grains or dynamic recovery (DRV) and dynamic recrystallization (DRX) of β phase.


2011 ◽  
Vol 291-294 ◽  
pp. 640-644
Author(s):  
Qing Miao Guo ◽  
De Fu Li ◽  
Sheng Li Guo ◽  
Guo Ling Xie

Flow behavior and microstructures of GH625 superalloy were investigated by hot compression tests. Then the GH625 superalloy tube was hot extruded according to the hot deformation behavior, and the microstructures of different position of extruded tube was also analyzed. The results show that the actual deformation temperature of the specimen deformed at a strain rate of 10.0s-1 is higher than the preset temperature, resulting in a deformation thermal effect. Thus, the microstructure evolution of GH625 superalloy is controlled both by the strain rate and deformation temperature. It is also found that the GH625 superalloy tube can be successfully fabricated with a stable extrusion speed of 40 mm·s-1, extrusion ratio of 4.1 and preheating temperature of 1200°C. The microstructure of extruded tube was obviously fined due to the occurrence of dynamic recrystallization(DRX). Different degrees of DRX were observed in outer wall, center and inner wall of the tube, which is similar to that in the head, middle and tail of the tube. An extruded tube containing fully DRX grains can be obtained by cutting the head and tail of the tube, and machining a small amount of the inner wall.


2021 ◽  
Vol 31 (6) ◽  
pp. 1700-1716
Author(s):  
Yong MAO ◽  
Dan-li ZHU ◽  
Jun-jie HE ◽  
Chao DENG ◽  
Ying-jie SUN ◽  
...  

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1743 ◽  
Author(s):  
Lei Luo ◽  
Zhiyi Liu ◽  
Song Bai ◽  
Juangang Zhao ◽  
Diping Zeng ◽  
...  

The hot deformation behavior of an Al-Zn-Mg-Cu alloy was investigated by hot compression test at deformation temperatures varying from 320 to 440 °C with strain rates ranging from 0.01 to 10 s−1. The results show that the Mg(Zn, Cu)2 particles as a result of the sufficient static precipitation prior to hot compression have an influence on flow softening. A constitutive model compensated with strain was developed from the experimental results, and it proved to be accurate for predicting the hot deformation behavior. Processing maps at various strains were established. The microstructural evolution demonstrates that the dominant dynamic softening mechanism stems from dynamic recovery (DRV) and partial dynamic recrystallization (DRX). The recrystallization mechanism is continuous dynamic recrystallization (CDRX). The microstructure observations are in good agreement with the results of processing maps. On account of the processing map and microstructural observation, the optimal hot processing parameters at a strain of 0.6 are at deformation temperature range of 390–440 °C and strain rate range of 0.010–0.316 s−1 with a peak efficiency of 0.390.


2013 ◽  
Vol 709 ◽  
pp. 143-147 ◽  
Author(s):  
Tao Wang ◽  
Zhao Li ◽  
Shu Hong Fu ◽  
Yong Zhang ◽  
Yu Xin Zhao ◽  
...  

The hot deformation behavior of U720Li was investigated by isothermal compression tests at temperature ranging from 1060-1180°C and strain rate from 0.001s-1 to 20s-1. The flow stress-strain curves and microstructures were investigated and a constitutive equation was established. It is found that flow stress is sensitive to stain rate and deformation temperature greatly. The higher stain rate resultes in a larger fluctuation in flow stress. The hot deformation activation energy is determined to be 552.8kJ/mol. Grain size increases with increasing temperature and decreases firstly and then increases with increasing strain rate. U720Li alloy should be deformed below the solve temperature of γ primary phase with lower strain rate in order to obtain the even and fine grain size.


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