Abstract: A method for manufacturing a precipitation hardening cold-rolled steel sheet with an excellent yield ratio. The method may include the steps of hot rolling a steel slab with finish rolling at a temperature of Ar3 transformation point or more to form a hot-rolled steel sheet, coiling the hot-rolled steel sheet at a temperature of 550-600 ° C., cold rolling the hot-rolled steel sheet at a reduction ratio of 50% or more; and recovery-recrystallization annealing the cold-rolled steel sheet at a line speed of 150-200 mpm and at a temperature of 780-820° C. in a continuous annealing furnace. The recovery-recrystallization annealing may provide a recrystallization ratio of 65-75%. The steel slab includes, by weight %: C: 0.07-0.10%, Mn: 1.41-1.70%, P: 0.05-0.07%, S: 0.005% or less, N: 0.005% or less, acid-soluble Al: 0.10-0.15%, Nb: 0.06-0.09%, B: 0.0008-0.0012%, Sb: 0.02-0.06%, and the balance comprising Fe and other unavoidable impurities.

Abstract: The present invention provides spring use heat treated steel which is cold coiled, can achieve both sufficient atmospheric strength and coilability, has a tensile strength of 2000 MPa or more, and can improve the performance as a spring by heat treatment after spring fabrication, that is, high strength spring-use heat treated steel characterized by containing, by mass %, C: 0.45 to 0.9%, Si: 1.7 to 3.0%, and Mn: 0.1 to 2.0%, restricting N: to 0.007% or less, having a balance of Fe and unavoidable impurities, and satisfying, in terms of the analyzed value of the extracted residue after heat treatment, [amount of Fe in residue on 0.2 ?m filter/[steel electrolysis amount]×100?1.1.

Abstract: The present invention is steel for surface hardening for machine structural use which contains, by mass %, C: 0.3 to 0.6%, Si: 0.02 to 2.0%, Mn: 0.35 to less than 1.5%, and Al: 0.01 to 0.5%, is restricted to B: less than 0.0003%, S: 0.0001 to 0.021%, N: 0.003 to 0.0055%, P: 0.0001 to 0.03%, and O: 0.0001 to 0.0050%, has a ratio Mn/S of Mn and S satisfying 70 to 30,000, has a balance of Fe and unavoidable impurities, and, when nitrided, then induction hardened, has a surface hardenability of a Vicker's hardness when tempered at 300° C. of 650 or more.

Abstract: A low carbon resulfurized free cutting steel consisting of 0.04 to 0.15% of C, more than 0.10% and 0.70% or less of Si, 0.85 to 1.50% of Mn, 0.040 to 0.120% of P, 0.250% or more and less than 0.400% of S, less than 0.005% of Al, more than 0.0020% and 0.0120% or less of O, and more than 0.0070% and 0.0150% or less of N, all by mass percentage, and the balance of Fe and inevitable impurities, and satisfying a formula (1) and a formula (2), as follows: 0.15%?Si %+2×P %?(5×Al %+10×O %+3×N %)?0.75%??(1), and ([Mn %]5)/15<S %<([Mn %]5)/2??(2).

Abstract: A family of iron-based, phosphor-containing bulk metallic glasses having excellent processibility and toughness, methods for forming such alloys, and processes for manufacturing articles therefrom are provided. The inventive iron-based alloy is based on the observation that by very tightly controlling the composition of the metalloid moiety of the Fe-based, P-containing bulk metallic glass alloys it is possible to obtain highly processable alloys with surprisingly low shear modulus and high toughness.

Abstract: A low carbon resulfurized free-machining steel having a high machinability is provided. This steel comprises 0.02 to 0.15% by mass of C, up to 0.004% by mass (more than 0% by mass) of Si, 0.6 to 3% by mass of Mn, 0.02 to 0.2% by mass of P, 0.2 to 1% by mass of S, up to 0.005% by mass (more than 0%) of Al, 0.008 to 0.04% by mass of O, and 0.002 to 0.03% by mass of N; and the average oxygen concentration in the MnS in the steel is at least 0.4% by mass.

Abstract: The present invention provides steel superior in machinability comprised of, by wt %, C: 0.005 to 0.2%, Si: 0.001 to 0.5%, Mn: 0.2 to 3.0%, P: 0.001 to 0.2%, S: 0.03 to 1.0%, T.N: 0.002 to 0.02%, T.O: 0.0005 to 0.035%, and the balance of Fe and unavoidable impurities, said steel satisfying one or both of Mn/S in the steel being 1.2 to 2.8 or an area ratio of pearlite over a grain size of 1 ?m in a microstructure of the steel being not more than 5%.

Abstract: Maraging steel with improved machinability, good weldability, and high corrosion resistance, a process for the heat treatment of such a steel, as well as its use. According to the invention this steel contains (in % by weight) 0.02-0.075% carbon; 0.1-0.6% silicon; 0.5-0.9% manganese; 0.08-0.25% sulfur; maximum 0.04%; phosphorus; 12.4-15.2% chromium; 0.05-1.0% molybdenum; 0.2-1.8% nickel; maximum 0.15% vanadium; 0.1-0.45% copper; maximum 0.03% aluminum; 0.02-0.08% nitrogen; as well as optionally one or more additional alloying elements up to maximum 2.0%, residual iron, and impurities caused in manufacturing, and a ferrite percentage in the structure of less than 28% by volume.

Abstract: The present invention is a steel, excellent in machinability, wherein forging workability is improved by suppressing the deterioration of mechanical properties in the direction in which the mechanical properties are the lowest, and more specifically, is a steel excellent in forgeability and machinability, characterized in that: the steel contains, in mass, C: 0.1 to 0.85%, Si: 0.01 to 1.5%, Mn: 0.05 to 2.0%, P: 0.003 to 0.2%, S: 0.003 to 0.5%, and Zr: 0.0003 to 0.01%; the following steel components are controlled in the following ranges respectively, in mass, Al: 0.01% or less, total O: 0.02% or less, and total N: 0.02% or less; the average aspect ratio of MnS grains is 10 or less and the maximum aspect ratio of those is 30 or less; and the balance of the steel components consists of Fe and unavoidable impurities.

Abstract: A microalloyed steel easy to separate by fracture splitting at low temperatures, which comprises from 0.15 to 0.35 wt % carbon, from 0.5 to 2.0 wt % silicon, from 0.5 to 1.5 wt % manganese, from 0.03 to 0.15 wt % phosphorus, from 0.01 to 0.15 wt % sulfur, from 0.01 to 0.5 wt % copper, from 0.01 to 0.5 wt % nickel, from 0.01 to 1.0 wt % chromium, from 0.001 to 0.01 wt % soluble aluminium, from 0.005 to 0.035 wt % nitrogen, from 0.001 to 0.01 wt % calcium, and from 0.001 to 0.01 wt % oxyge ough separation by fracture splitting at a low temperature, e.g., a connecting rod for engines.

Abstract: Disclosed is a free-cutting steel which exhibits good machinability in turning and small roughness of the turned surfaces, and in which substantially no macro-streak-flaw occurs. The free-cutting steel contains, by weight %, C: 0.03-0.20%, Mn: 0.5-3.0%, P: 0.02-0.40%, S: more than 0.2% up to 1.0%, one or both of Ti and Zr (in case of both, the total amount): 0.01-3.0%, O: 0.0005-0.0050% and Pb: less than 0.01%, the balance being Fe and inevitable impurities. The steel is characterized in that it contains, as the inclusion therein, Ti-based and/or Zr-based carbosulfide compound or compounds. The steel may further contain at least one from the group of Bi: up to 0.4%, Se: up to 0.5% and Te: up to 0.1%.

Abstract: The present invention provides a cold-rolled steel sheet and a hot-dip galvanized steel sheet having good bake hardenability, non-aging properties at room temperature and good formability and a process for producing the same. An extra low carbon steel or an extra low carbon steel containing at least one element selected from Ti and Nb is annealed at a temperature of not lower than the AC.sub.3 transformation point to bring the structure after annealing to a structure of low-temperature transformation products. This makes it possible to provide a steel sheet that has a combination of high paint-bake hardenability and non-aging properties at room temperature and is excellent also in formability in respect of average r value (deep drawability) and elongation (punch stretchability). In particular, with respect to paint-bake hardenability, a BH property on a high level up to about 10 kgf/mm.sup.

Abstract: The ferrophosphorus refining method entails forming a ferrophosphorus melt and adding an oxidizing agent to the melt to oxidize the impurities in the melt. The oxidized impurities then rise to the top of the melt and either go into the slag or escape in a gaseous forte. The slag is removed and a refined ferrophosphorus is recovered. Suitable oxidizing agents include solids such as ferrous oxide (Fe.sub.2 O.sub.3), ferric oxide (Fe.sub.3 O.sub.4), ferrous-ferric oxide (FeO), mill scale, limestone, dolomitic limestone, lime and any alkalide carbonate; and gaseous oxidizing agents such as oxygen, air and mixtures thereof.

Abstract: A soft steel for machine cutting with high machinability performances having a content of C.ltoreq.0.25%, a content of Mn of 0.8 to 1.5%, a content of P of .ltoreq.0.1%, a content of S of 0.15 to 0.40%, and a content of Si of 0.05 to 0.40%, expressed in percentages by weight. After finishing of the metal, the inclusions of manganese sulfide are surrounded by a plastic oxide layer of an average composition SiO.sub.2 : 35 to 45%; Al.sub.2 O.sub.3 : 10 to 20%; CaO: 15 to 25%; MnO: 10 to 20%. In producing this grade, after the addition of silicon and manganese, the liquid metal is agitated in the presence of a slag of a composition CaO: 20 to 55%; SiO.sub.2 : 35 to 65%; Al.sub.2 O.sub.3 : 15 to 40%; with a CaO %/SiO.sub.2 % ratio of about 1.

Abstract: Sulfur-containing free-cutting steel may have an improved machinability and fewer defects by adding certain amounts of Te, Pb and Bi to prevent elongation of sulfide inclusion particles, and by lowering Al-content to decrease Al.sub.2 O.sub.3 of oxide inclusions or by lowering O-content to decrease large Al.sub.2 O.sub.3 inclusion particles. The free-cutting steel may be produced by continuous casting.

Abstract: A cold-rolled, annealed and coated steel sheet or strip characterized by (1) a high degree of creep resistance, as measured by excellent performance in a sag deflection test when subjected to temperatures up to 1500.degree. F. for times in excess of 100 hours, and (2) a composition consisting essentially of, by weight %:______________________________________ Carbon 0.05-0.15 Manganese 0.50 max. Phosphorus 0.04-0.15 Sulfur 0.03 max. Silicon 0.10 max. Aluminum 0.08 max. Titanium 0.20-0.