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URN etd-0907106-123037 Statistics This thesis had been viewed 2826 times. Download 1509 times. Author En-Ja Hung Author's Email Address No Public. Department Materials Engineering Year 2005 Semester 2 Degree Master Type of Document Master's Thesis Language Chinese&English Page Count 37 Title Thermohydrogenation/dehydrogenation processing for grain refinement of Ti-6Al-4V alloy Keyword TCT thermochemical treatment As2O3 As2O3 thermochemical treatment TCT Abstract Cathodic hydrogenation of Ti-6Al-4V alloy was performed at 20∼100 mA．cm-2 current densities in 1N H2SO4(aq) for 6∼18 hrs with or without adding As2O3. The results showed that As2O3 is an excellent promoter for hydrogenation of Ti-6Al-4V alloy. Specimens having been hydrogenated were subjected in an air furnace at 300℃ for 1 and 3 hrs respectively to see the effects of heat treatment on the hydride dissolution and hydrogen redistribution at the near surface. Cyclic hydrogenation, specimens with cathodic hydrogenation combined post–heat treatment and then proceeded the same processing, can deepen the refined layer and enhance the effect of grain refinement of Ti-6Al-4V alloy. Coarse grain structure (2∼3 mm) of β-solution treated Ti-6Al-4V alloy can be refined to fine structure with grain size, 10∼20μm, within the refined layer (150∼200μm). The operating parameters were that processed two cycles with cathodic hydrogenation at 50 mA/cm2 in 1N H2SO4(aq) for 6 hrs, and then post–heat treatment at 300℃ for 3 hrs followed by water quench. Advisor Committee T.I Wu - advisor
J. K. Wu - co-chair
Yi Hu - co-chair
Files Date of Defense 2006-07-29 Date of Submission 2006-09-07