SUPER PLASTICITY FORMING METHOD OF TITANIUM ALLOY SHEET

摘要

PURPOSE: To provide a formed product of uniform thickness by changing the structure of the required part of a plate from the equiaxed crystal to the acicular crystal in achieving the superplastic forming, and suppressing the superplastic behavior to prevent the reduction in the thickness by the forming of the part. ;CONSTITUTION: A plate cut to the prescribed shape and dimensions is superplastically formed to a product shape 10, the part 13 where the thickness of the product is reduced is detected, and the thickness t₁ of the part is measured. The position and depth where the structure of the plate is changed from the equiaxed crystal to the acicular crystal are set based on this result. The preset part of a new plate cut to the prescribed shape and dimensions is irradiated with the electron beam of the quantity corresponding to the reduction in thickness, and after the position to irradiate the electron beam on the plate and the conditions of irradiation are determined by repeating the trial process for the superplastic forming, the production is started. The formed product 10 through this process is not superplastically formed at the part 13 whose structure is changed to the acicular crystal, but only the equiaxed crystal is superplastically formed, and the thickness t₁, t₂ of the bottom corner part 10a and the bottom part 10b can be approximately equal to each other.;COPYRIGHT: (C)1996,JPO