Abstract: The invention provides a maraging steel production method in which an oxide is added during an Mg oxide formation step, the production method including: the Mg oxide formation step in which Mg is added to molten steel and MgO is formed in the molten steel, during primary melting; a consumable electrode production step in which, after the Mg oxide formation step, the molten steel is solidified and a consumable electrode having residual MgO is obtained; and a vacuum arc re-melting step in which the consumable electrode is used and vacuum arc re-melting is performed.

Abstract: The invention provides a maraging steel production method in which an oxide is added during an Mg oxide formation step, the production method including: the Mg oxide formation step in which Mg is added to molten steel and MgO is formed in the molten steel, during primary melting; a consumable electrode production step in which, after the Mg oxide formation step, the molten steel is solidified and a consumable electrode having residual MgO is obtained; and a vacuum arc re-melting step in which the consumable electrode is used and vacuum arc re-melting is performed.

Abstract: Provided is maraging steel with which maraging steel that has been subjected to nitriding treatment has excellent fatigue strength and stable high strength. Maraging steel that has been subjected to nitriding treatment to a thickness of 0.5 mm or less and comprises, by mass %, 0.008% or less of C, 0.5% or less of Si, 0.5% or less of Mn, 0.5 to 1.5% of Cr, 16.0 to 22.0% of Ni, 3.0 to 7.0% of Co, and 3.0 to 7.0% of Mo is maraging steel further comprising, by mass %, 0.6 to 1.3% of Al and Fe and impurities as the balance, wherein the impurities are maintained at 0.01% or less of Ti, 0.01% or less of Nb, 0.01% or less of Ta, and 0.01% or less of W, the ratio of Al and Ti is Al/Ti>250, and by Vickers hardness, the surface hardness of the maraging steel is 800 to 1,050 HV and internal hardness of the maraging steel is 570 HV or less.

Abstract: Provided is a maraging steel strip which has such a composition that can reduce the content of TiN acting as the starting point of fatigue fracture in a high-cycle region, and the bending fatigue strength of which has been improved by the precipitation hardening effect yielded by precipitating coherent nitrides in the nitrided structure. A maraging steel strip produced by nitriding a managing steel which contains by mass, C: 0.01% or less, Si: 0.1% or less, Mn: 0.1% or less, P: 0.01% or less, S: 0.005% or less, Ni: 8.0 to 22.0%, Cr: 0.1 to 8.0%, Mo: 2.0 to 10.0%, Co: 2.0 to 20.0%, Ti: 0.1% or less, Al: 2.5% or less, N: 0.03% or less, and O: 0.005% or less, with the balance being Fe and unavoidable impurities, wherein Baker-Nutting orientation relationship with an orientation difference within 10° exists between the Cr nitride precipitated in the nitrided layer and the matrix martensite.

Abstract: To provide an inexpensive heat-resisting steel for engine valves by causing Fe-based heat-resisting steel to exhibit high temperature strength not inferior to that of Ni-based heat-resisting steel. A heat-resisting steel for engine valves excellent in high temperature strength containing, in % by mass, C: 0.20 to 0.50%, Si: 1.0% or less, Mn: 5.0% or less, P: 0.1 to 0.5%, Ni: 8.0 to 15.0%, Cr: 16.0 to 25.0%, Mo: 2.0 to 5.0%, Cu: 0.5% or less, Nb: 1.0% or less (including 0%), W: 8.0% or less (including 0%), N: 0.02 to 0.2%, B: 0.01% or less, and remnants of Fe and impurities, wherein the heat-resisting steel for engine valves satisfies formulae below: 442P(%)+12Mo(%)+5W(%)+7Nb(%)+328N(%)+171?300??Formula (1) ?38.13P(%)+1.06Mo(%)+0.13W(%)+9.64Nb(%)+13.52N(%)+4.83?0.12??Formula (2).

Abstract: To provide an inexpensive heat-resisting steel for engine valves by causing Fe-based heat-resisting steel to exhibit high temperature strength not inferior to that of Ni-based heat-resisting steel. A heat-resisting steel for engine valves excellent in high temperature strength containing, in % by mass, C: 0.20 to 0.50%, Si: 1.0% or less, Mn: 5.0% or less, P: 0.1 to 0.5%, Ni: 8.0 to 15.0%, Cr: 16.0 to 25.0%, Mo: 2.0% or less (including 0%), Cu: 0.5% or less, Nb: 1.0% or less (including 0%), W: 2.0% or less (including 0%), N: 0.02 to 0.30%, B: 0.01% or less, and remnants of Fe and impurities, wherein the heat-resisting steel for engine valves satisfies formulae below: 156.42P(%)+0.91Mo(%)+0.73W(%)?12.27Nb(%)+220.96N(%)+120.59?170??Formula (1) 13.70P(%)?6.97Mo(%)?4.32W(%)?3.29Nb(%)+119.10N(%)+27.75?25??Formula (2).

Abstract: A piston ring material is provided which retains excellent mechanical properties and processability, which are required of piston ring materials, and has wearing resistance and scuffing resistance, which are sliding properties required of piston rings. The piston ring material, which is for use in internal combustion engines, contains, in terms of mass %, 0.3-0.8% carbon, 0.1-3.0% silicon, 0.1-3.0% manganese, 0.01-0.3% sulfur, 0.1-2.0% chromium, and 0.05-2.0% the sum of titanium and/or zirconium, with the remainder being iron and incidental impurities. The titanium and/or zirconium contained in the piston ring material and the sulfur contained therein satisfy the following relationship. [Ti (%)+½Zr (%)]/S (%)?5.0 Preferably, the material may contain one or more members selected from up to 1.0% copper, less than 3.0% molybdenum, up to 1.0% aluminum, and less than 2.0% nickel, in terms of mass %.

Abstract: An alloy to be surface-coated, which can keep excellent hardness of 58HRC or above even when the amount of an alloying element added is reduced or even when the alloy is heated to a temperature of as high as 400 to 500° C.; and sliding members produced by forming a hard film on the surface of the alloy. An alloy to be surface-coated, the surface of which is to be covered with a hard film, which alloy contains by mass C: 0.5 to 1.2%, Si: 2.0% or below, Mn: 1.0% or below, Cr: 5.0 to 14.0%, Mo+1/2 W: 0.5 to 5.0%, and N: more than 0.015 to 0.1% with the balance being Fe and impurities, preferably such an alloy which contains by mass C: 0.6 to 0.85%, Si: 0.1 to 1.5%, Mn: 0.2 to 0.8%, Cr: 7.0 to 11.0%, Mo+1/2 W: 1.0 to 4.0%, and N: 0.04 to 0.08%.

Abstract: A piston ring material that when formed into a piston ring product, maintains excellent properties, and that at the production of piston ring rod, realizes excellent processability and shape stability. There is provided a piston ring material for internal combustion engine comprising, by mass, 0.5 to less than 0.7% C, 1.0% or less Si, 1.0% or less Mn, 12.0 to 16.0% Cr, 3.0% or less Mo and/or W (Mo+½W), 0.02 to 0.14% N and the balance Fe and unavoidable impurities, wherein the relationship of contained C, N and Cr satisfies the formulae: 25?43.22C (%)+42.45N (%)?0.02Cr (%)?40, and 0.15?0.92C (%)+0.67N (%)?0.03Cr (%)?0.30.

Abstract: Provided is a coated-surface sliding part having excellent adhesion of a hard coating, and a method for producing the same part. The coated-surface sliding part is a sliding part wherein a hard coating is formed by physical deposition on the surface of a base material formed from, by mass percent, C 0.5 to 0.8%, Si 0.1 to 1.5%, Mn 0.2 to 1.0%, Cr 8.0 to 13.5%, Mo and/or W 0.5 to 4.0% in terms of (Mo+ 1/2 W), and N 0.01 to 0.1%, with the remainder being Fe and impurities. The physically deposited coating is a titanium metal coating further covered by a diamond-like carbon coating. The method for producing a coated-surface part involves sputtering in order to apply the physically deposited coating, which consists of the titanium metal coating and then the diamond-like carbon coating which forms the surface layer, to the surface of the base material having the aforementioned composition. The base material is preferably subjected to argon gas bombardment prior to application of the physically deposited coating.

Abstract: To provide an inexpensive heat-resisting steel for engine valves by causing Fe-based heat-resisting steel to exhibit high temperature strength not inferior to that of Ni-based heat-resisting steel. A heat-resisting steel for engine valves excellent in high temperature strength containing, in % by mass, C: 0.20 to 0.50%, Si: 1.0% or less, Mn: 5.0% or less, P: 0.1 to 0.5%, Ni: 8.0 to 15.0%, Cr: 16.0 to 25.0%, Mo: 2.0 to 5.0%, Cu: 0.5% or less, Nb: 1.0% or less (including 0%), W: 8.0% or less (including 0%), N: 0.02 to 0.2%, B: 0.01% or less, and remnants of Fe and impurities, wherein the heat-resisting steel for engine valves satisfies formulae below: 442P(%)+12Mo(%)+5W(%)+7Nb(%)+328N(%)+171?300??Formula (1) ?38.13P(%)+1.06Mo(%)+0.13W(%)+9.64Nb(%)+13.52N(%)+4.83?0.

Abstract: Provided is a maraging steel strip which has such a composition that can reduce the content of TiN acting as the starting point of fatigue fracture in a high-cycle region, and the bending fatigue strength of which has been improved by the precipitation hardening effect yielded by precipitating coherent nitrides in the nitrided structure. A maraging steel strip produced by nitriding a managing steel which contains by mass, C: 0.01% or less, Si: 0.1% or less, Mn: 0.1% or less, P: 0.01% or less, S: 0.005% or less, Ni: 8.0 to 22.0%, Cr: 0.1 to 8.0%, Mo: 2.0 to 10.0%, Co: 2.0 to 20.0%, Ti: 0.1% or less, Al: 2.5% or less, N: 0.03% or less, and O: 0.005% or less, with the balance being Fe and unavoidable impurities, wherein Baker-Nutting orientation relationship with an orientation difference within 10° exists between the Cr nitride precipitated in the nitrided layer and the matrix martensite.

Abstract: To provide an inexpensive heat-resisting steel for engine valves by causing Fe-based heat-resisting steel to exhibit high temperature strength not inferior to that of Ni-based heat-resisting steel. A heat-resisting steel for engine valves excellent in high temperature strength containing, in % by mass, C: 0.20 to 0.50%, Si: 1.0% or less, Mn: 5.0% or less, P: 0.1 to 0.5%, Ni: 8.0 to 15.0%, Cr: 16.0 to 25.0%, Mo: 2.0% or less (including 0%), Cu: 0.5% or less, Nb: 1.0% or less (including 0%), W: 2.0% or less (including 0%), N: 0.02 to 0.30%, B: 0.01% or less, and remnants of Fe and impurities, wherein the heat-resisting steel for engine valves satisfies formulae below: 156.42P(%)+0.91Mo(%)+0.73W(%)?12.27Nb(%)+220.96N(%)+120.59?170??Formula (1) 13.70P(%)?6.97Mo(%)?4.32W(%)?3.29Nb(%)+119.10N(%)+27.

Abstract: A piston ring material is provided which retains excellent mechanical properties and processability, which are required of piston ring materials, and has wearing resistance and scuffing resistance, which are sliding properties required of piston rings. The piston ring material, which is for use in internal combustion engines, contains, in terms of mass %, 0.3-0.8% carbon, 0.1-3.0% silicon, 0.1-3.0% manganese, 0.01-0.3% sulfur, 0.1-2.0% chromium, and 0.05-2.0% the sum of titanium and/or zirconium, with the remainder being iron and incidental impurities. The titanium and/or zirconium contained in the piston ring material and the sulfur contained therein satisfy the following relationship. [Ti (%)+½Zr (%)]/S (%)?5.0 Preferably, the material may contain one or more members selected from up to 1.0% copper, less than 3.0% molybdenum, up to 1.0% aluminum, and less than 2.0% nickel, in terms of mass %.

Abstract: An alloy to be surface-coated, which can keep excellent hardness of 58HRC or above even when the amount of an alloying element added is reduced or even when the alloy is heated to a temperature of as high as 400 to 500° C.; and sliding members produced by forming a hard film on the surface of the alloy. An alloy to be surface-coated, the surface of which is to be covered with a hard film, which alloy contains by mass C: 0.5 to 1.2%, Si: 2.0% or below, Mn: 1.0% or below, Cr: 5.0 to 14.0%, Mo+1/2 W: 0.5 to 5.0%, and N: more than 0.015 to 0.1% with the balance being Fe and impurities, preferably such an alloy which contains by mass C: 0.6 to 0.85%, Si: 0.1 to 1.5%, Mn: 0.2 to 0.8%, Cr: 7.0 to 11.0%, Mo+1/2 W: 1.0 to 4.0%, and N: 0.04 to 0.08%.

Abstract: A maraging steel for metallic belts which has a composition capable of being reduced in the content of TiN serving as a starting point for fatigue fracture in a high-cycle-rate region. The composition facilitates nitriding to heighten the surface hardness. The steel has a nitrided surface layer having increased compressive residual stress and hence improved flexural fatigue strength. In the steel, former austenite crystal grains have been reduced in size in order to secure higher strength and higher ductility. The maraging steel consists of, by mass %, up to 0.01% C, up to 0.1% Si, up to 0.1% Mn, up to 0.01% P, up to 0.005% S, 17.0-22.0% Ni, 0.1-4.0% Cr, 3.0-7.0% Mo, from more than 7.0 to 20.0% Co, up to 0.1% Ti, up to 2.5% Al, up to 0.03% N, up to 0.005% 0, up to 0.01% B (exclusive zero), and the balance of Fe and unavoidable impurities, wherein Co/3+Mo+4Al is 8.0-15.0%.

Abstract: A piston ring material that when formed into a piston ring product, maintains excellent properties, and that at the production of piston ring rod, realizes excellent processability and shape stability. There is provided a piston ring material for internal combustion engine comprising, by mass, 0.5 to less than 0.7% C, 1.0% or less Si, 1.0% or less Mn, 12.0 to 16.0% Cr, 3.0% or less Mo and/or W (Mo+1/2W), 0.02 to 0.14% N and the balance Fe and unavoidable impurities, wherein the relationship of contained C, N and Cr satisfies the formulae: 25?43.22C (%)+42.45N (%)?0.02Cr (%)<40, and 0.15 <0.92C (%)+0.67N (%)?0.03Cr (%)<0.30.

Abstract: An object of the present invention is to provide a porous liquid absorbing-and-holding member having a high absorbing capacity for a liquid owing to capillarity and having in itself a structure capable of holding a large amount of the liquid, a process for producing this member, and a member for absorbing and holding an alcohol used as a fuel for a fuel cell. The porous liquid absorbing-and-holding member provided by the present invention is that including a porous sintered product having a skeleton formed by sintering of metal powder around voids and subjected to hydrophilicity-imparting treatment. The hydrophilicity-imparting treatment is preferably the formation of one or more substances selected from the group consisting of silicon oxides, titanium oxides, chromium oxides and aluminum oxide on the skeleton.

Abstract: An object of the present invention is to provide a porous liquid absorbing-and-holding member having a high absorbing capacity for a liquid owing to capillarity and having in itself a structure capable of holding a large amount of the liquid, a process for producing this member, and a member for absorbing and holding an alcohol used as a fuel for a fuel cell. The porous liquid absorbing-and-holding member provided by the present invention is that including a porous sintered product having a skeleton formed by sintering of metal powder around voids and subjected to hydrophilicity-imparting treatment. The hydrophilicity-imparting treatment is preferably the formation of one or more substances selected from the group consisting of silicon oxides, titanium oxides, chromium oxides and aluminum oxide on the skeleton.