M. Amuei, M. Emamy, R. Khorshidi, A. Akrami,
Volume 12, Issue 3 (9-2015)
Abstract
In this study, Al2014 alloy refined with Al-5%Ti-1%B master alloy was prepared by strain-induced melt
activated (SIMA) process. The main variables of the SIMA process were cold working, holding time and temperature in
semi-solid state. Cold working was applied on specimens by upsetting technique to achieve 10%, 20% and 30% height
reduction. Cold worked specimens were heat treated in semi-solid state at 585 °C, 595 °C, 605 °C, 615 °C, 625 °C and
635 °C and were kept in these temperatures for different times (20 and 30 min). Observations through optical and
scanning electron microscopy were used to study the microstructural evaluation. The results revealed that fine and
globular microstructures are obtained by applying 30 % height reduction percentage and heat treating in 625 °C for
30 min. Comparison between refined and unrefined Al2014 alloy after applying SIMA process showed that Al-5%Ti-1%B master alloy has no significant effect on average globule size but makes the final structure more globular.
M. Alipour, M. Emami, R. Eslami Farsania, M. H. Siadati, H. Khorsand,
Volume 12, Issue 4 (12-2015)
Abstract
A modified strain-induced melt activation (SIMA) process was applied and its effect on the structural characteristics and hardness of the aluminum alloy Al–12Zn–3Mg–2.5Cu was investigated. Specimens subjected to a deformation of 40% at 300 °C were heat treated at various times (10-40 min) and temperatures (550-600 °C). Microstructural studies were carried out using optical and scanning electron microscopies (SEM). Results showed that the best microstructure was obtained at the temperature and time of 575 °C and 20 min, respectively. The hardness test results revealed superior hardness in comparison with the samples prepared without the application of the modified SIMA process.
T6 heat treatment including quenching to 25 °C and aging at 120 °C for 24 h was employed to reach to the maximum strength. After the T6 heat treatment, the average tensile strength increased from 231 MPa to 487 and 215 MPa to 462 for samples before and after strain-induced melt activation process, respectively. Ultimate strength of globular microstructure specimens after SIMA process has a lower value than as-cast specimens without SIMA process
