| The effects of microstructural change on the superplastic deformation of Ti-6Al-4V alloy were investigated. Three kinds of the specimens($quot;A$quot;, $quot;B$quot;, and $quot;C$quot;) were preparated and used for the present study : specimen $quot;A$quot; was heavily hot-rolled with 20% per pass draft percent at 800℃, specimen $quot;B$quot; was lightly hot-rolled with 3.5% per pass draft percent at 800℃, and specimen $quot;C$quot; was the annealed specimen $quot;A$quot; at 800℃ for 5hours. The maximum elongations were found in the persent work were 2470%, 1100%, and 970% for the specimen $quot;A$quot;, $quot;B$quot;, and $quot;C$quot; respectively. And so, we postulated that an unexampled elongation is, at 880℃ and 4 × 10^(-3)/s, due to very fine grain size that was recrystallized from the substructures created during hot-rolling process. The characteristics of superplastic deformation for Ti-6Al-4V alloy were also found to be strongly influenced by the testing condition. For the specimen tested in the open air, they were thermally oxidized and theirafter the elongation was decreased to the level of about 50% of that tested in the pure Ar gas atmosphere. |
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