| 摘要 |
PROBLEM TO BE SOLVED: To provide a producing method which can obtain a blank (ordinarily, a flat blank or a bar wire rod) in which the crystal grain at the completing time of austenizing is made finer than heretofore and the growth of this fine austenitic crystal grain is slow and is hardly coarsened in the heat treatment step after hot-working in the case of producing the blank for manufacturing a finish-product from a tool steel and a plastic-molding die steel. SOLUTION: A steel having a structure consisting of martensite (M) or the martensite (M) and bainite (B) by cooling after hot-working is hot-worked in the austenite (γ) single phase (1), is successively hot-worked to hinder the re-crystallization ofγ-structure (2), is cooled at once to obtain the fine structure having≤30μm average crystal grain diameter (3), is subjected to re-quenching treatment or solution heat treatment and then cooled to obtain the structure mainly consisting of the martensite (M) or the bainite (B) (4), and is subjected to heat treatment (tempering or aging treatment) (5). COPYRIGHT: (C)2005,JPO&NCIPI
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