| 摘要 |
PROBLEM TO BE SOLVED: To provide a press forging method which can impart the tensile strength, ductility, impact resistance and toughness at a certain or higher level to a steel product by eliminating porosities when a steel ingot is used as a raw material in press forging. SOLUTION: In the invented press forging method, the cylindrical steel ingot (a so-called "round billet" 1) as the raw material is placed in a mold (drag 22) and is forged so as not to cause buckling during forging and to make the reduction ratio and the forging ratio the reference values or more respectively. For example, press forging in the transverse direction is performed at the forging ratio of 1.2 or more, and thereafter press forging in the axial direction is performed at the reduction ratio of 1.7 or more. COPYRIGHT: (C)2008,JPO&INPIT
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