Effect Of Heat Treatment And Equal Channel Angular Pressing On The Microstructures, Hardness And Wear Resistance Of A356 Aluminium Alloy With Tib2
Equal Channel Angular Pressing (ECAP) is a relatively simple procedure to produce ultra-fine grains and there is a potential for use in commercial metal processing. However processing difficulties may arise during ECAP because of the occurrence of cracking. In the present work, A356 aluminium all...
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| Format: | Thesis |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | http://eprints.usm.my/45782/1/Effect%20Of%20Heat%20Treatment%20And%20Equal%20Channel%20Angular%20Pressing%20On%20The%20Microstructures%2C%20Hardness%20And%20Wear%20Resistance%20Of%20A356%20Aluminium%20Alloy%20With%20Tib2.pdf |
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| Summary: | Equal Channel Angular Pressing (ECAP) is a relatively simple procedure to
produce ultra-fine grains and there is a potential for use in commercial metal
processing. However processing difficulties may arise during ECAP because of the
occurrence of cracking. In the present work, A356 aluminium alloy and A356
aluminium alloy with varying addition of TiB2 grain refiner (0.75, 1.5, 2.63 wt.%)
were prepared via gravity die casting. The as-cast A356 aluminium alloy specimens
with TiB2 addition contains hard phase of eutectic Si, hard particles of TiB2 and
TiAl3 which potentially cause cracking during ECAP processing therefore heat
treatments were carried out prior to ECAP. The heat treatments were annealing at
540°C for 8 hours followed by furnace cooling, solution treatment at 540°C for 4
hours followed by water quenching, and aging treatment at 110°C, 155°C, 200°C,
245°C and 290°C for 3 hours. The heat treated specimens were processed through 4-
pass ECAP via BA route (rotation 90°). The combinations between heat treatment
and (ECAP) were done to analyze the effect of both processes on microstructures,
hardness and wear resistance of the specimens. The specimens were characterized
with optical microscope, SEM, EBSD, TEM, hardness and wear test. The 4-pass
ECAP processing increased significantly the hardness of the specimens which have
relatively soft matrix. The relatively soft matrix in combination with TiB2 and Si
particles gave benefit in accelerating multiplication of dislocation density leading to
grain refinement during ECAP processing. From the overall considerations of hardness,
average grain size and wear rate, pre-ECAP solution treatment specimen has the best
value in general, then followed by post-ECAP aging 155°C specimen in the second rank. |
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