Hitachi Metals, Ltd.

Yousuke Nakano

Kousuke Kuwabara

Shiho Fukumoto

Koichi Sakamaki

Kazuya Saito

Norihide Fukuzawa

Ryuuichiroh Sugano

Kouta Kataoka

Hidemitsu Horie

Provided are a laminate shaped article made of a maraging steel and having excellent toughness, a method for manufacturing the same, and a metal powder for laminate shaping. The laminate shaped article is made of a maraging steel comprising 0.1-5.0 mass % of Ti. When sis is performed on concentration distribution of Ti in a cross section parallel to a lamination direction of the above laminate shaped article, a length of a linear Ti-rich portion having a Ti concentration B of (1.5&#xd7;A) or more with respect to an average Ti concentration A in the cross section is 15 &#x3bc;m or less. In addition, the method for manufacturing the laminate shaped article uses a metal powder made of a maraging steel comprising 0.1-5.0 mass % of Ti, and a heat source output is set to 50-330 W and a scanning speed is set to 480-3000 mm/sec during the laminate shaping.

Laminate shaped article, method for manufacturing the same, and metal powder for laminate shaping

Provided is a hot-working tool capable of maintaining adequate toughness even if the permissible amount of P contained in the hot-working tool is increased. The present invention is a hot-working tool, which has a component composition that can be adjusted to a martensitic structure by quenching and has a post-quenching and tempering martensitic structure, wherein: the component composition comprises greater than 0.020 mass % to 0.050 mass % of P; prior austenite grain diameter in said post-quenching and tempering martensitic structure is at least No. 9.5 in grain size number according to JIS-G-0551; and the P concentration of the grain boundary of said prior austenite particles is not more than 1.5 mass %. A hot-working tool wherein said component composition also comprises not more than 0.0250 mass % of Zn is preferable. The present invention also is a method for manufacturing a hot-working tool in which quenching and tempering are performed on a hot-working tool material with said component composition.

Hot-working tool and manufacturing method therefor

Provided are a hot work tool material having an annealed structure effective for producing a finer quenched and tempered structure when made into a hot work tool, and a method for manufacturing a hot work tool. A hot work tool material which has an annealed structure and which is used upon being quenched and tempered, wherein the hot work tool material has a composition that can be adjusted to a martensite structure by the aforementioned quenching, and ferrite grains in a cross-section of the annealed structure of the hot work tool material have, in an oversize cumulative distribution based on the cross-sectional area of the ferrite grains, a grain diameter distribution such that the grain diameter is 25 &#x3bc;m or less as a circle equivalent diameter when the cumulative cross-sectional area is 90% of the total cross-sectional area. In addition, a method for manufacturing a hot work tool in which quenching and tempering is performed on the aforementioned hot work tool material.

Hot work tool material and method for manufacturing hot work tool

A method for evaluating the corrosion-fatigue life of a steel material includes: bringing a corrosive medium into contact with a predetermined portion of the steel material; measuring strain on the steel material while applying cyclic loads to the steel material; measuring an N-th strain index from strain amplitude at the number of initial load applications and strain amplitude at the N-th load application (N is a natural number larger than the number of initial load applications); and estimating the corrosion-fatigue life of the steel material by comparing the N-th strain index with a previously certified life strain index.

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Yasugi, Japan

Yousuke Nakano