Abstract: A projection forming method forming a projection on the surface of a work and includes: forming a first bank by LMD such that the first bank surrounds a projection forming region on the surface of the work; forming a first layer on the projection forming region by the LMD such that the first layer covers the first bank; laminating at least one first height raising layer on the first layer by the LMD; forming a second bank by the LMD along a peripheral edge of the at least one first height raising layer; forming an intermediate base layer on the at least one first height raising layer by the LMD such that the intermediate base layer covers the second bank; and laminating at least one second height raising layer on the intermediate base layer by the LMD.

Abstract: A projection forming method forming a projection on the surface of a work and includes: forming a first bank by LMD such that the first bank surrounds a projection forming region on the surface of the work; forming a first layer on the projection forming region by the LMD such that the first layer covers the first bank; laminating at least one first height raising layer on the first layer by the LMD; forming a second bank by the LMD along a peripheral edge of the at least one first height raising layer; forming an intermediate base layer on the at least one first height raising layer by the LMD such that the intermediate base layer covers the second bank; and laminating at least one second height raising layer on the intermediate base layer by the LMD.

Abstract: A nitrided component has a chemical composition consisting of, by mass percent, C: 0.07-0.14%, Si: 0.10-0.30%, Mn: 0.4-1.0%, S: 0.005-0.030%, Cr: 1.0-1.5%, Mo: ?0.05% (including 0%), Al: 0.010% or more to less than 0.10%, V: 0.10-0.25%, optionally at least one element selected from Cu: ?0.30% and Ni: ?0.25%, [0.61Mn+1.11Cr+0.35Mo+0.47V?2.30], and the balance of Fe and impurities. P, N, Ti and O among the impurities are P: ?0.030%, N: ?0.008%, Ti: ?0.005%, and O: ?0.0030%. The nitrided composition is suitable for use as an automobile ring gear. The nitrided component has a surface hardness of 650-900 HV, core hardness being ?150 HV, effective case depth of ?0.15 mm, has excellent bending fatigue strength and surface fatigue strength although the content of Mo is as low as ?0.05% and has a small amount of expansion caused by nitriding.

Abstract: A steel for cold forging/nitriding has, by mass percent, C: 0.01 to 0.15%, Si?0.35%, Mn: 0.10 to 0.90%, P?0.030%, S?0.030%, Cr: 0.50 to 2.0%, V: 0.10 to 0.50%, Al: 0.01 to 0.10%, N?0.0080%, and O?0.0030%, further according to need a specific amount of one or more elements selected from Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, with the balance being Fe and impurities, and further satisfying the conditions of [399×C+26×Si+123×Mn+30×Cr+32×Mo+19×V?160], [20?(669.3×logeC?1959.6×logeN?6983.3)×(0.067×Mo+0.147×V)?80], [140×Cr+125×Al+235×V?160] and [90?511×C+33×Mn+56×Cu+15×Ni+36×Cr+5×Mo+134×V?170] are excellent in cold forgeability and machinability after cold forging.

Abstract: A nitrided steel member including an iron nitride compound layer formed on a surface of a steel member having predetermined components, wherein: in X-ray diffraction peak intensity IFe4N (111) of a (111) crystal plane of Fe4N and X-ray diffraction peak intensity IFe3N (111) of a (111) crystal plane of Fe3N, which are measured on a surface of the nitrided steel member by X-ray diffraction, an intensity ratio expressed by IFe4N (111)/{IFe4N (111)+IFe3N (111)} is 0.5 or more; Vickers hardness of the iron nitride compound layer is 900 or less, Vickers hardness of a base metal immediately under the iron nitride compound layer is 700 or more, and a difference between the Vickers hardness of the iron nitride compound layer and the Vickers hardness of the base metal is 150 or less; and a thickness of the iron nitride compound layer is 2 to 17 ?m.

Abstract: A nitrided component has a chemical composition consisting of, by mass percent, C: 0.07-0.14%, Si: 0.10-0.30%, Mn: 0.4-1.0%, S: 0.005-0.030%, Cr: 1.0-1.5%, Mo: ?0.05% (including 0%), Al: 0.010% or more to less than 0.10%, V: 0.10-0.25%, optionally at least one element selected from Cu: ?0.30% and Ni: ?0.25%, [0.61Mn+1.11Cr+0.35Mo+0.47V?2.30], and the balance of Fe and impurities. P, N, Ti and O among the impurities are P: ?0.030%, N: ?0.008%, Ti: ?0.005%, and O: ?0.0030%. The nitrided composition is suitable for use as an automobile ring gear. The nitrided component has a surface hardness of 650-900 HV, core hardness being ?150 HV, effective case depth of ?0.15 mm, has excellent bending fatigue strength and surface fatigue strength although the content of Mo is as low as ?0.05% and has a small amount of expansion caused by nitriding.

Abstract: A steel material for nitriding has a composition comprising, by mass percent, C: more than 0.15% and not more than 0.35%, Si?0.20%, Mn: 0.10 to 2.0%, P?0.030%, S?0.050%, Cr: 0.80 to 2.0%, V: 0.10 to 0.50%, Al: 0.01 to 0.06%, N?0.0080%, O?0.0030%, and optionally one or more elements of Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, the balance being Fe and impurities. The composition satisfies the conditions of [20?(669.3×logeC?1959.6×logeN?6983.3)×(0.067×Mo+0.147×V)?80] and [140×Cr+125×Al+235×V?160]. The microstructure is a ferritic-pearlitic structure, a ferritic-bainitic structure, or a ferritic-pearlitic-bainitic structure. The area fraction of ferrite is 20% or more and the precipitate content of V is 0.10% or less.

Abstract: A steel comprises, by mass percent, C: 0.10 to 0.15%, Si: not less than 0.02% and less than 0.10%, Mn: more than 0.90% and not more than 2.50%, P?0.030%, S?0.050%, Cr: 0.80 to 2.0%, V: 0.05 to 0.50%, Al: 0.01 to 0.07%, N?0.0080%, O?0.0030%, and one or more selected from Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, the balance being Fe and impurities. The composition satisfies [35?Mn/S?200], [20?(669.3×loge C?1959.6×loge N?6983.3)×(0.067×Mo+0.147×V)?80], [140×Cr+125×Al+235×V?160] and [150?511×C+33×Mn+56×Cu+15×Ni+36×Cr+5×Mo+134×V?200].

Abstract: A steel comprises, by mass percent, C: 0.10 to 0.15%, Si: not less than 0.02% and less than 0.10%, Mn: more than 0.90% and not more than 2.50%, P?0.030%, S?0.050%, Cr: 0.80 to 2.0%, V: 0.05 to 0.50%, Al: 0.01 to 0.07%, N?0.0080%, O?0.0030%, and one or more selected from Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, the balance being Fe and impurities. The composition satisfies [35?Mn/S?200], [20?(669.3×logeC?1959.6×logeN?6983.3)×(0.067×Mo+0.147×V)?80], [140×Cr+125×Al+235×V?160] and [150?511×C+33×Mn+56×Cu+15×Ni+36×Cr+5×Mo+134×V?200].

Abstract: A nitrided steel member including an iron nitride compound layer formed on a surface of a steel member having predetermined components, wherein: in X-ray diffraction peak intensity IFe4N (111) of a (111) crystal plane of Fe4N and X-ray diffraction peak intensity IFe3N (111) of a (111) crystal plane of Fe3N, which are measured on a surface of the nitrided steel member by X-ray diffraction, an intensity ratio expressed by IFe4N (111)/{IFe4N (111)+IFe3N (111)} is 0.5 or more; Vickers hardness of the iron nitride compound layer is 900 or less, Vickers hardness of a base metal immediately under the iron nitride compound layer is 700 or more, and a difference between the Vickers hardness of the iron nitride compound layer and the Vickers hardness of the base metal is 150 or less; and a thickness of the iron nitride compound layer is 2 to 17 ?m.

Abstract: A steel material for nitriding has a composition comprising, by mass percent, C: more than 0.15% and not more than 0.35%, Si?0.20%, Mn: 0.10 to 2.0%, P?0.030%, S?0.050%, Cr: 0.80 to 2.0%, V: 0.10 to 0.50%, Al: 0.01 to 0.06%, N?0.0080%, O?0.0030%, and optionally one or more elements of Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, the balance being Fe and impurities. The composition satisfies the conditions of [20?(669.3×logeC?1959.6×logeN?6983.3)×(0.067×Mo+0.147×V)?80] and [140×Cr+125×Al+235×V?160]. The microstructure is a ferritic-pearlitic structure, a ferritic-bainitic structure, or a ferritic-pearlitic-bainitic structure. The area fraction of ferrite is 20% or more and the precipitate content of V is 0.10% or less.

Abstract: A steel for nitriding having a chemical composition consisting of, by mass percent, C: 0.07-0.14%, Si: 0.10-0.30%, Mn: 0.4-1.0%, S: 0.005-0.030%, Cr: 1.0-1.5%, Mo: ?0.05% (including 0%), Al: 0.010% or more to less than 0.10%, V: 0.10-0.25%, optionally at least one element selected from Cu: ?0.30% and Ni: ?0.25% [0.61Mn+1.11Cr+0.35Mo+0.47?2.30], and the balance of Fe and impurities. P, N, Ti and O among the impurities are P: ?0.030%, N: ?0.008%, Ti: ?0.005%, and O: ?0.0030%. The steel is easily subjected to cutting before nitriding and suitable for use as an automobile ring gear. The nitrided component having a surface hardness of 650-900 HV, core hardness being ?150 HV, and effective case depth of ?0.15 mm has excellent bending fatigue strength and surface fatigue strength although the content of Mo is as low as ?0.05% and has a small amount of expansion caused by nitriding.

Abstract: A steel for cold forging/nitriding has, by mass percent, C: 0.01 to 0.15%, Si?0.35%, Mn: 0.10 to 0.90%, P?0.030%, S?0.030%, Cr: 0.50 to 2.0%, V: 0.10 to 0.50%, Al: 0.01 to 0.10%, N?0.0080%, and O?0.0030%, further according to need a specific amount of one or more elements selected from Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, with the balance being Fe and impurities, and further satisfying the conditions of [399×C+26×Si+123×Mn+30×Cr+32×Mo+19×V?160], [20?(669.3×logeC?1959.6×logeN?6983.3)×(0.067×Mo+0.147×V)?80], [140×Cr+125×Al+235×V?160] and [90?511×C+33×Mn+56×Cu+15×Ni+36×Cr+5×Mo+134×V?170] are excellent in cold forgeability and machinability after cold forging.