Abstract: The invention provides a steel material with satisfactory hydrogen embrittlement resistance, and particularly it relates to high-strength steel with satisfactory hydrogen embrittlement resistance and a strength of 1200 MPa or greater, as well as a process for production thereof. At least one simple or compound deposit of oxides, carbides or nitrides as hydrogen trap sites which trap hydrogen with a specific trap energy is added to steel, where the mean sizes, number densities, and length-to-thickness ratios (aspect ratio) are in specific ranges. By applying the specific steel components and production process it is possible to obtain high-strength steel with excellent hydrogen embrittlement resistance.

Abstract: A fine graphite uniform dispersion steel material excellent in cold workability, cuttability and hardenability, which has graphite finely and uniformly dispersed therein, and a production method for producing the same. The steel contains at least 0.30 to 1.0% of C, 0.4 to 1.3% of Si, 0.3 to 1.0% of Mn, 0.0003 to 0.006% of B, 0.002 to 0.010% of N and 0.05 to 0.20% of Mo as the basic components and contains graphite having a mean particle diameter of not more than 4.0 .mu.m and a number of particles per unit and of at least 3,000 per mm.sup.2. The production method includes at least the steps of cooling the steel having these components at a cooling start temperature of not less than an A.sub.rl point, a cooling end temperature of not more than an M.sub.s point and a mean cooling rate of 5.degree. to 100.degree. C./s.

Abstract: A high-strength, ultra-fine wire having an excellent workability in stranding, comprising a steel comprised of, in terms of % by weight, 0.85 to 1.10% of C, 0.10 to 0.70% of Si, 0.20 to 0.60% of Mn, 0.10 to 0.60% of Cr, 0.005% or less of Al and optionally at least one member selected from 0.10 to 2.00% of Ni and 0.10 to 3.00% of Co with the balance Fe and unavoidable impurities and, provided thereon, a brass plating, the steel wire having a diameter of 0.1 to 0.4 mm and a tensile strength of 400 kgf/mm.sup.2 or more, the surface of the brass plating being provided with indentations having a depth of 2 .mu.m or less at intervals of 50 .mu.

Abstract: A method of directly softening a rolled machine structural steel is provided. This method is characterized by the fact that it comprises the steps of:hot rolling a steel consisting essentially of 0.2-0.65% C, less than 0.1% Si, 0.2-0.5% Mn, 0.0003-0.01% B, more than 0.5-1.7% Cr, 0.01-0.1% Al, all of the percentages being on a weight basis, and the balance being Fe and incidental impurities, and may contain one or more other alloying elements selected from either one of or both of groups (A) and (B), group (A) consisting of not more than 1% Ni, 0.1-0.5% Mo and not more than 1% Cu, and the other group (B) consisting of 0.002-0.05% Ti, 0.005-0.05% Nb and 0.005-0.2% V,then subjecting said rolled steel to either one of the two softening treatments (1) or (2), the treatment (1) comprises slowly cooling the steel in a temperature range until transformation to pearlite is completed at a cooling rate of less than 15.degree. C.

Abstract: A method of softening a rolled medium carbon machine structural steel is provided. This method is characterized by:(1) hot rolling steel containing 0.32-0.65% C, less than 0.05% Si, 0.3-0.9% in total of Mn and Cr, with the Mn and Cr contents being 0.2-0.5% and 0.1-0.5%, respectively, 0.005-0.1% Al, less than 0.02% P and less than 0.02% S, all percents being on a weight basis, and the balance being Fe and incidental impurities; and(2) performing either one of the following softening treatments:(i) slowly cooling the as-rolled steel at a cooling rate of 3.degree.-30.degree. C./min over the temperature range of from 750.degree. C. to the point where transformation to pearlite is completed to thereby provide the rolled steel with a strength of not greater than 30+65.times.C % (kg/mm.sup.2), C % signifying the carbon content of the steel; oras-rolled quenching the hot rolled steel to a temperature within the range of 670.degree.-720.degree. C.