| Summary: | 碩士 === 國立中央大學 === 機械工程研究所 === 100 === Effect of annealing temperature and sensitization treatment on mechanical behavior, intergranular - corrosion property and stress – corrosion cracking susceptibility of AA5083-H15 alloys were estimated in this research. Optical microscopy(OM), Transmission Electron Microscopy(TEM) and scanning electron microscope(SEM) are used to observe the microstructure variation, corrosion surface and fracture surface of alloys.
β phase will precipitate continuously on grain boundary in alloys annealed below 200℃. The continuous precipitation on grain boundary offered a continuous path for corrosion and lead to the severe intergranular corrosion. β phase was prone to precipitate continuously along grain boundary during the sensitization treatment and made the alloys sensitive to intergranular corrosion. Precipitation on grain boundary was discontinuous in alloy annealed at 250℃. The discontinuous precipitation on grain boundary could hindered the spread of corrosion and lead to the good resistance to corrosion.
After the sensitization treatment, H15 and alloys annealed below 200℃ were sensitive to stress corrosion due to the poor resistance to corrosion. The sensitized, 250℃ -annealed alloy exhibited a great resistance to stress corrosion due to the great resistance to corrosion.
Alloys annealed above 300℃ exhibited a poor resistance to intergranular corrosion after the sensitization, but great resistance to stress corrosion due to the low strength which made the propagation of stress corrosion cracking harder.
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