| 摘要 |
PURPOSE:To enlarge the range of application of superplastic working and to improve and stabilize working quality by refining a material into fine-grained structure by performing the first-stage working at a temp. lower than that in superplastic working conditions or at a strain rate higher than that in superplastic working conditions. CONSTITUTION:In superplastic working for high strength Al alloy, etc., working is applied, as the first-stage working, at about 20% draft at a temp. lower than the temp. in superplastic working or at a strain rate higher than the prescribed strain rate, by which the structure of a material to be worked is regulated to a fine-grained structure suitable for superplastic working, followed by the second-stage superplastic working. By this method, critical draft free from the occurrence of cavity can be improved. |
