Showing 2 results for Dynamic Recrystallization.
S. Emami, T. Saeid,
Volume 6, Issue 1 (8-2020)
Abstract
Single phase brass strips with 2 mm thickness were severely deformed through 1 and 3 cycles of accumulative roll bonding process (ARB). ARB process effectively increased the hardness, yield strength, and the ultimate strength of the processed materials. The hardness of processed material increased from 95 HV in annealed material to 225 HV in 3 cycle ARBed material, and the yielding and ultimate strengths increased more than 5 and 2 times of the annealed sample, respectively. Friction stir welding (FSW) process was successfully conducted on the annealed and ARBed samples to investigate and compare the microstructure and the mechanical properties of the joints obtained in bead on plate configuration. Microstructural observations showed that very fine dynamically recrystallized grains developed in the stir zones (SZs) of all welded samples. Mechanical properties were evaluated by hardness and tensile testing. Hardness test for the ARBed and FS welded samples showed that the hardness value decreased by 110 Hv in the resultant SZs. Results of tensile testing revealed that yield and ultimate strength of the FS welded ARBed samples 1.3 and 1.8 times are greater than that of the annealed FS welded sample .
S. Sajjadi Nikoo, F. Qods, M. Yousefieh,
Volume 11, Issue 1 (7-2025)
Abstract
In this research, the ultrafine-grained (UFG) composite of AA2024 and AA5083 aluminum alloys was made by accumulative roll bonding (ARB) process and butt-welded by friction stir welding. Friction stir welding (FSW) is the best method for the joining of UFG strips. Microstructural investigations were performed by optical microscope and transmission electron microscope in the stir zone (SZ), thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ). The fine recrystallized structure with a grain size of about 900 nm was determined in the weldment. Due to the strengthening mechanisms of grain boundaries, nano-meter size precipitates and solid solution strengthening, the high strength of about 403 MPa was achieved. The presence of precipitates with homogeneous distribution in FSWed strips caused a high ductility of about 14% compared to the fabricated composite strips (6.9%). The high hardness of the SZ was caused by the formation of new equiaxed grains and fine precipitates, and also the decrease in the hardness of the HAZ was due to the dissolution and coarsening of T-phase precipitates.
