Abstract: A hot work tool steel or hot work tool contains, in mass %, 0.25 to 0.45% of C, 0.1 to 0.4% of Si, 0.5 to 0.9% of Mn, 0.2 to 0.6% of Ni, 4.9 to 5.5% of Cr, 1.9 to 2.3% of Mo or 1/2W by itself or 1.9 to 2.3% of (Mo+1/2W) in combination, 0.6 to 0.9% of V, and a balance of Fe and impurities, and value A and value B calculated by the following Formula 1 and Formula 2 satisfy that value A is 6.00 or more and value B is 1.00 or less. Value A=?0.7(% Si)+1.5(% Mn)+1.3(% Ni)+0.9(% Cr)+0.6(%(Mo+1/2W))+0.3(% V)??Formula 1: Value B=1.9(% C)+0.043(% Si)+0.12(% Mn)+0.09(% Ni)+0.042(% Cr)+0.03(%(Mo+1/2W))?0.

Abstract: 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×A) or more with respect to an average Ti concentration A in the cross section is 15 ?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.

Abstract: The hot work tool steel or hot work tool contains, in mass %, 0.25 to 0.45% of C, 0.1 to 0.4% of Si, 0.5 to 0.9% of Mn, 0 to 0.6% of Ni, 4.9 to 5.5% of Cr, 1.3 to 2.3% of Mo or 1/2W by itself or 1.3 to 2.3% of (Mo+1/2W) in combination, 0.6 to 0.9% of V, and a balance of Fe and impurities, and value A and value B calculated by the following Formula 1 and Formula 2 satisfy that value A is 6.00 or more and value B is 1.00 or less. Value A=?0.7(% Si)+1.5(% Mn)+1.3(% Ni)+0.9(% Cr)+0.6(%(Mo+1/2W))+0.3(% V) ??Formula 1 Value B=1.9(% C)+0.043(% Si)+0.12(% Mn)+0.09(% Ni)+0.042(% Cr)+0.03(%(Mo+1/2W))?0.

Abstract: An additive layer manufactured hot work tool according to the present disclosure includes a component composition of by mass %, C: 0.3-0.5% to Si: 2.0% or less, Mn: 1.5% or less, P: 0.05% or less, S: 0.05% or less, Cr: 3.0 to 6.0%, 1 or 2 kinds of compounds of Mo and W, a relation between Mo and W being represented by a relational expression of (Mo+1/2W): 0.5 to 3.5%, V: 0.1 to 1.5%, Ni: 0 to 1.0%, Co: 0 to 1.0%, and Nb: 0 to 0.3%, and with Fe and an unavoidable impurity as a remainder, and an area ratio of defects having an area of 1 ?m2 or more is 0.6% or less in a cross section parallel to the amination direction.

Abstract: 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×A) or more with respect to an average Ti concentration A in the cross section is 15 ?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.

Abstract: 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.

Abstract: 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 ?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.

Abstract: 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.

Abstract: 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 ?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.

Abstract: 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.

Abstract: 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.

Abstract: A line generator according to the present invention includes a light source, a first lens group, and a second lens group. An optical axis is set to a position of a light beam which travels orthogonal to incidence surfaces of both the first and second lens groups and the first lens group is configured such that light beams from the light source are not collimated in a first direction in a plane orthogonal to the optical axis and are collimated or focused only in a second direction orthogonal to the first direction in the plane orthogonal to the optical axis and the second lens group is configured such that the light beams which have passed through the first group form a line.

Abstract: A line generator according to the present invention includes a light source, a first lens group, and a second lens group. An optical axis is set to a position of a light beam which travels orthogonal to incidence surfaces of both the first and second lens groups and the first lens group is configured such that light beams from the light source are not collimated in a first direction in a plane orthogonal to the optical axis and are collimated or focused only in a second direction orthogonal to the first direction in the plane orthogonal to the optical axis and the second lens group is configured such that the light beams which have passed through the first group form a line.