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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 53072 (07)
- University: Sharif University of Technology
- Department: Materials Science and Engineering
- Advisor(s): Serajzadeh, Siamak
- Abstract:
- In this study, the high temperature deformation behavior of Al-Cu aluminum alloy and the results of single-stage and multi-stage creep tests have been investigated. To investigate the behavior of alloy fluidity in temperature range 150 ° C to 500 ° C and strain rate 0.0005 s-1 – 0.05 s-1 were subjected to tensile test. The results show that in the temperature range of 200 ° C to 225 ° C, the sensitivity coefficient to the strain rate is negative, which indicates the occurrence of dynamic precipitation during deformation. In the meantime, the reverse processes in the mentioned temperature range were investigated and it was found that 250 ° C was the starting temperature of the dynamic recovery phenomenon, and also dynamic recrystallization from 400 ° C was observed at low strain rates. Using microscopic images and graphs, the relationship between fluidity stress and strain rate is described using the hyperbolic sine equation and the stress power is 6.85 and the activation energy is 234 is obtained according to the optimal value of alpha 0.007 in the temperature range of 350 ° C to 500 ° C. The effect of soaking time on the deformation behavior of the alloy at 350 ° C was also investigated. The alloy deformation process map is performed by structural equations in two ways and in order to obtain more experimental data, the fluidity stress is modeled using a neural network. Also, by examining the results of the creep test in the temperature range of 150 ° C to 225 ° C and the applied stress of 150 MPa to 270 MPa, the dominant creep mechanism with regard to the stress strength greater than 5.5 and the activation energy of 169, the dislocation climb is considered. Examination of light and scanning electron microscopy images showed the suitable places for germination of cavities, which are three points around the second phase particles and dual grain boundaries. Finally, the cavitation rate of the alloy was simulated using the cellular automata method and in order to validate, the creep samples at 190 ° C and the applied stress of 200 MPa were tested
- Keywords:
- Neural Network ; Processing Map ; Cellular Automata ; Dynamic Recrystallization ; Dynamic Recovery ; Cavitation Rate Simulation ; Dynamic Precipitation ; Soak Time
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