| 摘要 |
PURPOSE:To manufacture an alpha+beta-type Ti-alloy sheet suitable for superplastic working, by subjecting an alpha+beta-type Ti alloy to rolling twice and then to heat treatment under respectively specified conditions, further applying a repetition of rolling and heat treatment under respectively specified conditions to the rolled plate and then carrying out recrystallization annealing. CONSTITUTION:An alpha+beta-type Ti alloy is hot-rolled at a temp. of beta-transformation point or above at >=50% draft and then rolled in an alpha+beta temp. region of the beta-transformation point or below at >=20% draft. Subsequently, the rolled plate is heated, held in a temp. region between the beta-transformation point and (beta-transformation point +70 deg.C) for 30sec-30min, cooled down to <=500 deg.C at >=5 deg.C/sec cooling rate, and further rolled in a temp. region between (beta-transformation point -200 deg.C) and (beta-transformation point -400 deg.C) at >=50% draft. Then, the plate is held at a temp. between (beta-transformation point -20 deg.C) and (beta-transformation point -100 deg.C) for 30-120min, cooled down to room temp. at 0.1-5 deg.C/sec cooling rate, cold-rolled at >=70% draft, and finally subjected to recrystallization annealing at 700-800 deg.C for 30-120min. In this way, the (alpha+beta)-type Ti alloy sheet with superfine isometric alpha+beta two-phase structure suitable for superplastic working can be manufactured at a low cost. |
