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AssigneeProterial, Ltd.
InventorsYousuke Nakano, Yuya Koga, Kouta Kataoka
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Provided is a method for producing hot work tool steel that has a fine annealed structure even if a cross-sectional size is large. This method for producing hot work tool steel having a cross-sectional area of at least 200,000 mm2 includes: a cogging step for heating a steel ingot to 1100 to 1250° C. and then performing hot forging to obtain a semi-finished product; a first finishing forging step for heating the semi-finished product to 850 to 1020° C., and performing upset forging with an upset forging forming ratio of 1.6 or more to obtain an intermediate forged material; and a second finishing forging step for subjecting the intermediate forged material to solid forging with a solid forging forming ratio of 2.0 to 4.0 to obtain a forged material.
A method for producing hot work tool steel having a cross-sectional area of 200000 mm2 or more, comprising:
Hot work tool steel, having an area of a cross-section perpendicular to a longitudinal direction of 200000 mm2 or more, and ferrite grains in the cross-section having a grain size distribution in which a grain size at a cumulative cross-sectional area of 90% of a total cross-sectional area in an oversize cumulative distribution based on a cross-sectional area of the ferrite grains is 25 μm or less in an equivalent circular diameter.
Dependencies are inferred from the claim text.