The objective of this work is to investigate the influence of hot rolling process on the
mechanical properties of AA 5052 aluminum alloy. Hot-rolled band fabricated by tandem
mill (hot-band A) will be compared with that fabricated by reverse mill hot-band C).
Optical microscopic observations revealed that hot-band A has a uniform microstructure
throughout the thickness, while hot-band C exhibits non-uniform microstructure, fine
grains near the surface and coarser grains in the center. Both hot-bands were subjected to
cold-rolling and annealing to O-temper. Two annealing processes were used: (a) annealing
in 500oC salt bath, which may simulate the high heating rate of continuous annealing line
(CAL), and (b) annealing in 320oC conventional air furnace with heating rate of 30oC/h,
which may simulate the slow heating rate of batch-type annealing. In general, both
materials annealed in 320oC air furnace exhibit higher yield strength than those annealed in
500oC salt bath do, however, both materials exhibit better tensile ductility after annealed in
500oC salt bath as compared with those annealed in 320oC air furnace.TEM examinations
indicated that the cold-rolled sheet after annealing in 320oC air furnace contains larger
number of precipitates comparing with its 500oC salt bath annealed counterpart. This
observation may account for the higher yield strength of cold-rolled sheet annealed in
320oC air furnace. After cold-rolling and annealing in 320oC air furnace, the material C
shows higher yield strength than the material A does. However, after annealing in 500oC
salt bath, both materials have similar yield strength. XRD pole-figure analysis indicated
that hot-band A exhibited stronger texture than hot-band C did. The texture intensity for
both materials decreased considerably after cold-rolling and annealing. Orientation image
mapping (OIM) obtained by EBSD (electron backscattered diffraction) analysis indicated
that the grain boundaries in both materials after cold-rolling and annealing were mainly
high angle boundaries, and the 500oC salt bath annealed specimens have more equiaxed
grain shape as compared with the 320oC air furnace annealed specimens.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0724112-165735 |
| Date | 24 July 2012 |
| Creators | Hung, Liang-Jie |
| Contributors | Dr. Chih-Pu Chang, Dr. Po-We Kao, Chung-Yi Yu |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0724112-165735 |
| Rights | user_define, Copyright information available at source archive |
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