| 摘要 |
PROBLEM TO BE SOLVED: To work the subject hardly workable alloy to a stock having a desired shape such as a sheet material or a wire rod by covering a lump of a shape memory alloy having a specified compsn. with a sheath of a soft steel and repeating hot working under the conditions of a specified temp. and draft. SOLUTION: A lump of a shape memory alloy contg., by atom, 45 to 50% Ni, one or more kinds of Zr and Hf by 9 to 16%, and te balance Ti is covered with a seath made of a soft steel, hot working is executed under the conditions of 850 to 950 deg.C working starting temp., >=770 deg.C working finishing temp. and <=10% draft per time, and this is repeated for required times. The reason that the lump of the alloy is covered with the sheath is that the generation of partial oxidation cracking caused by oxidation in the case Ti and Zr are exposed to the air is prevented and cracking is prevented by utilizing compressive restraint. In the case the working starting temp. is lower than 850 deg.C or the working finishing temp. is lower than 770 deg.C, the generation of cracking in the material can not be evaded, in the case the working starting temp. is higher than 950 deg.C, the sheath is oxidized and thinned, and the draft of 10% per time is the limit in the hot working. |
