| 摘要 |
PROBLEM TO BE SOLVED: To provide a deep drawing method in hot forming which excels in post-forming strength. SOLUTION: In the deep drawing method in hot forming, a steel sheet is heated to a temperature not lower than Ac3 but not higher than the melting point, forming is started at a temperature higher than the one at which any of the ferrite, pearlite, bainite and martensite transformation is caused, and then a clearance between a wrinkle holding face and a die face is made not more than the clearance at which a wrinkle is caused in a manner that it is in excess of the thickness of the steel sheet and that the same surface of the steel sheet is brought into contact. Desirably, the steel sheet is held inside the die after forming and cooled to the martensitic transformation starting temperature faster than the cooling rate causing the martensitic transformation. COPYRIGHT: (C)2006,JPO&NCIPI
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