Abstract: The present invention provides a spring steel that has superior hardenability, undergoes less pitting in a corrosive environment, and can achieve higher stress and toughness. More specifically, the present invention provides a high-strength and high-toughness spring steel with improved hardenability and pitting resistance, containing, in mass percent, 0.40 to 0.70% carbon, 0.05 to 0.50% silicon, 0.60 to 1.00% manganese, 1.00 to 2.00% chromium, 0.010 to 0.050% niobium, 0.005 to 0.050% aluminum, 0.0045 to 0.0100% nitrogen, 0.005 to 0.050% titanium, 0.0005 to 0.0060% boron, no more than 0.015% phosphorus and no more than 0.010% sulfur, the remainder being composed of iron and unavoidable impurities, the steel having a tensile strength of at least 1700 MPa in 400° C. tempering after quenching and a Charpy impact value of at least 40 J/cm2 for a 2 mm U-notched test piece of JIS Z 2202 and the parameter Fce being at least 1.70.

Abstract: The present invention provides a spring steel that has superior hardenability, undergoes less pitting in a corrosive environment, and can achieve higher stress and toughness. More specifically, the present invention provides a high-strength and high-toughness spring steel with improved hardenability and pitting resistance, containing, in mass percent, 0.40 to 0.70% carbon, 0.05 to 0.50% silicon, 0.60 to 1.00% manganese, 1.00 to 2.00% chromium, 0.010 to 0.050% niobium, 0.005 to 0.050% aluminum, 0.0045 to 0.0100% nitrogen, 0.005 to 0.050% titanium, 0.0005 to 0.0060% boron, no more than 0.015% phosphorus and no more than 0.010% sulfur, the remainder being composed of iron and unavoidable impurities, the steel having a tensile strength of at least 1700 MPa in 400° C. tempering after quenching and a Charpy impact value of at least 40 J/cm2 for a 2 mm U-notched test piece of JIS Z 2202 and the parameter Fce being at least 1.70.

Abstract: The present invention provides a spring steel that has superior hardenability, undergoes less pitting in a corrosive environment, and can achieve higher stress and toughness. More specifically, the present invention provides a high-strength and high-toughness spring steel with improved hardenability and pitting resistance, containing, in mass percent, 0.40 to 0.70% carbon, 0.05 to 0.50% silicon, 0.60 to 1.00% manganese, 1.00 to 2.00% chromium, 0.010 to 0.050% niobium, 0.005 to 0.050% aluminum, 0.0045 to 0.0100% nitrogen, 0.005 to 0.050% titanium, 0.0005 to 0.0060% boron, no more than 0.015% phosphorus and no more than 0.010% sulfur, the remainder being composed of iron and unavoidable impurities, the steel having a tensile strength of at least 1700 MPa in 400° C. tempering after quenching and a Charpy impact value of at least 40 J/cm2 for a 2 mm U-notched test piece of JIS Z 2202 and the parameter Fce being at least 1.70.

Abstract: The present invention provides a spring steel that has superior hardenability, undergoes less pitting in a corrosive environment, and can achieve higher stress and toughness. More specifically, the present invention provides a high-strength and high-toughness spring steel with improved hardenability and pitting resistance, containing, in mass percent, 0.40 to 0.70% carbon, 0.05 to 0.50% silicon, 0.60 to 1.00% manganese, 1.00 to 2.00% chromium, 0.010 to 0.050% niobium, 0.005 to 0.050% aluminum, 0.0045 to 0.0100% nitrogen, 0.005 to 0.050% titanium, 0.0005 to 0.0060% boron, no more than 0.015% phosphorus and no more than 0.010% sulfur, the remainder being composed of iron and unavoidable impurities, the steel having a tensile strength of at least 1700 MPa in 400° C. tempering after quenching and a Charpy impact value of at least 40 J/cm2 for a 2 mm U-notched test piece of JIS Z 2202 and the parameter Fce being at least 1.70.

Abstract: The present invention provides a spring steel that has superior hardenability, undergoes less pitting in a corrosive environment, and can achieve higher stress and toughness. More specifically, the present invention provides a high-strength and high-toughness spring steel with improved hardenability and pitting resistance, containing, in mass percent, 0.40 to 0.70% carbon, 0.05 to 0.50% silicon, 0.60 to 1.00% manganese, 1.00 to 2.00% chromium, 0.010 to 0.050% niobium, 0.005 to 0.050% aluminum, 0.0045 to 0.0100% nitrogen, 0.005 to 0.050% titanium, 0.0005 to 0.0060% boron, no more than 0.015% phosphorus and no more than 0.010% sulfur, the remainder being composed of iron and unavoidable impurities, the steel having a tensile strength of at least 1700 MPa in 400° C. tempering after quenching and a Charpy impact value of at least 40 J/cm2 for a 2 mm U-notched test piece of JIS 2202 and the parameter Fce being at least 1.70.

Abstract: A sulfur-containing free-cutting steel for machine structural use, containing, in weight percent, 0.10 to 0.55% of C, 0.05 to 1.00% of Si, 0.30 to 2.50% of Mn, not more than 0.15% of P, 0.050 to 0.350% of S, more than 0.010% but not more than 0.020% of Al, 0.015 to 0.200% of Nb, 0.0015 to 0.0150% of O, and not more than 0.02% of N, and further containing, in weight percent, at least one selected from the group consisting of 0.03 to 0.50% of V, 0.02 to 0.20% of Ti and 0.01 to 0.20% of Zr, wherein the ratio S/O of the S content to the O content is 15 to 120, and at least one selected from the group consisting of an oxide, a carbide, a nitride and a carbonitride of Nb(see FIG. 1) acts as nuclei for precipitation of MnS type inclusions.

Abstract: The present invention provides a spring steel that has superior hardenability, undergoes less pitting in a corrosive environment, and can achieve higher stress and toughness. More specifically, the present invention provides a high-strength and high-toughness spring steel with improved hardenability and pitting resistance, comprising, in mass percent, 0.40 to 0.70% carbon, 0.05 to 0.50% silicon, 0.60 to 1.00% manganese, 1.00 to 2.00% chromium, 0.010 to 0.050% niobium, 0.005 to 0.050% aluminum, 0.0045 to 0.0100% nitrogen, 0.005 to 0.050% titanium, 0.0005 to 0.0060% boron, no more than 0.015% phosphorus and no more than 0.010% sulfur, the remainder being composed of iron and unavoidable impurities, the steel having a tensile strength of at least 1700 MPa in 400° C. tempering after quenching and a Charpy impact value of at least 40 J/cm2 for a 2 mm U-notched test piece of JIS No. 3 and the parameter Fce being at least 1.70.

Abstract: A magnesium alloy with formability at room temperature and excellent corrosion resistance is provided. Specifically, a magnesium alloy is provided which comprises, in mass %, 8.0 to 11.0% Li, 0.1 to 4.0% Zn, and 0.1 to 4.5% Ba, with the balance being Mg and unavoidable impurities, the alloy which further comprises 0.1 to 0.5% Al, and the alloy which further comprises 0.1 to 2.5% Ln (a total amount of one or more lanthanoids) and 0.1 to 1.2% Ca.

Abstract: A magnesium alloy with formability at room temperature and excellent corrosion resistance is provided. Specifically, a magnesium alloy is provided which comprises, in mass %, 8.0 to 11.0% Li, 0.1 to 4.0% Zn, and 0.1 to 4.5% Ba, with the balance being Mg and unavoidable impurities, the alloy which further comprises 0.1 to 0.5% Al, and the alloy which further comprises 0.1 to 2.5% Ln (a total amount of one or more lanthanoids) and 0.1 to 1.2% Ca.

Abstract: A high-sulfur free-cutting steel which has a chemical composition containing, in mass %, 0.03 to 0.20% C, 0.35% or less Si (including 0%), 0.30 to 2.00% Mn, 0.01 to 0.15% P, 0.35 to 0.65% S 0.0100 to 0.0250% O, 0.020% or less N, 0.005% or less Al (including 0%), 0.02 to 0.20% Nb, and further containing 0.05 to 0.50% V or 0.02 to 0.20% Ti, or both, with the remainder consisting of Fe and unavoidable impurities, wherein sulfide type inclusions, as the principal nonmetallic inclusions contained in the steel, have a mean size of 50 &mgr;m2 or less and are present at the rate of 500 to 1000 inclusions per mm2 in the cross section of the steel. The sulfur-containing free-cutting steel has a good machinability comparable or superior to that of free-cutting steels containing heavy metals which have a deleterious effect on the environment, without requiring the addition of such undesirable heavy metals.

Abstract: A sulfur-containing free-cutting steel for machine structural use, comprising, in weight percent, 0.10 to 0.55% of C, 0.05 to 1.00% of Si, 0.30 to 2.50% of Mn, not more than 0.15% of P, 0.050 to 0.350% of S, more than 0.010% but not more than 0.020% of Al, 0.015 to 0.200% of Nb, 0.0015 to 0.0150% of O, and not more than 0.02% of N, and further containing, in weight percent, at least one selected from the group consisting of 0.03 to 0.50% of V, 0.02 to 0.20% of Ti and 0.01 to 0.20% of Zr, wherein the ratio S/O of the S content to the O content is 15 to 120, and at least one selected from the group consisting of an oxide, a carbide, a nitride and a carbonitride of Nb (see FIG. 1) acts as nuclei for precipitation of an MnS type inclusions.

Abstract: A high-sulfur free-cutting steel which has a chemical composition comprising, in mass %, 0.03 to 0.20% C, 0.35% or less Si (including 0%), 0.30 to 2.00% Mn, 0.01 to 0.15% P, 0.35 to 0.65% S, 0.0100 to 0.0250% O, 0.020% or less N, 0.005% or less Al (including 0%), 0.02 to 0.20% Nb, and further containing 0.05 to 0.50% V or 0.02 to 0.20% Ti, or both, with the remainder consisting of Fe and unavoidable impurities, wherein sulfide type inclusions as principal nonmetallic inclusions contained in the steel have a mean size of 50 &mgr;m2 or less and are present at the rate of 500 to 1000 inclusions per mm2 in the cross section of the steel. The sulfur-containing free-cutting steel has a good machinability well comparable to or superior that of free-cutting steels containing heavy metals which have a deleterious effect on the environment, without requiring the addition of such undesirable heavy metals.

Abstract: A high-strength spring steel having an Hv of at least 600 and an impact value of at least 40 J/cm2, comprising 0.40 to 0.70 wt. % carbon, 1.00 to 2.50 wt. % silicon, 0.30 to 0.90 wt. % manganese, 0.50 to 1.50 wt. % nickel, 1.00 to 2.00 wt. % chromium, 0.30 to 0.60 wt. % molybdenum, 0.25 to 0.50 wt. % copper, 0.01 to 0.50 wt. % vanadium, 0.010 to 0.050 wt. % niobium, 0.005 to 0.050 wt. % aluminum, 0.0045 to 0.0100 wt. % nitrogen, 0.005 to 0.050 wt. % titanium, and 0.0005 to 0.0060 wt. % boron, with phosphorus limited to 0.010 wt. % or less, sulfur to 0.010 wt. % or less, and OT to 0.0015 wt. % or less, and the remainder being composed of iron and unavoidable impurities. The spring steel has better hardness and toughness than those of existing spring steel.

Abstract: A steel for darburized gear having softening resistance, consisting essentially of, in weight percentages, 0.18 to 0.25% C, 0.45 to 1.00% Si, 0.40 to 0.70% Mn, 0.30 to 0.70% Ni, 1.00 to 1.50% Cr, 0.30 to 0.70% Mo, up to 0.50% Cu, 0.015 to 0.030% A1, 0.03 to 0.30% V, 0.010 to 0.030% Nb, up to 0.0015% O, 0.0100 to 0.0200% N and the balance consisting of Fe and inevitable impurity elements, wherein quenching at 820.degree. C. or higher after carburization does not cause any ferrite to be formed in a hardened structure of the core part of the carburized steel, and wherein, while tempering is generally performed at 160.degree. to 180.degree. C. after the quenching, reheating at any of temperatures inclusive of the tempering temperature and up to 300.degree. C. does not cause the hardness of a carburized case of the carburized steel to decrease by HV 50 or more from the one after the carburization, quenching and tempering.

Abstract: Disclosed is a high strength spring steel consisting of, in weight percentage, 0.50 to 0.70% C, 1.00 to 2.50% Si, 0.30 to 1.20% Mn, 0.80 to less than 1.20% Cr, 0.05 to 0.3% Mo, 0.05 to 0.30% V, 0.01 to 0.30% Nb, 0.005 to 0.100% Al and the balance being Fe and unavoidable impurities. The steel of the present invention has a high hardness coupled with high toughness and is very useful, especially for springs used in suspension devices or other various industrial machines.

Abstract: Disclosed is a high strength spring steel consisting of, in weight percentage, 0.40 to 0.70% C, 0.50 to 2.00% Si, more than 0.50 to 1.50% Mn, 0.50 to 2.50% Ni, 0.20 to 1.50% Cr, more than 0.60 to 1.50% Mo, 0.01 to 0.50% V, 0.01 to 0.50% Nb, 0.005 to 0.100% Al and the balance being Fe and unavoidable impurities. The steel of the present invention has a high hardness coupled with high toughness and is very useful especially for springs used in suspension devices or other various industrial machines.