The present invention provides a medium-carbon boron-containing steel. The chemical components of the medium-carbon boron-containing steel are as follows in mass percentage: 0.37-0.45% of C; 0.17-0.37% of Si; 0.60-0.90% of Mn; 0.020-0.060% of Al; 0.0008-0.0035% of B; 0.030-0.060% of Ti; P?0.025%; S?0.025%; Cr?0.25%; Ni?0.20%; Mo?0.10%; Cu?0.20%; and the remainder is Fe and inevitable impurities. The controlled rolling and controlled cooling method suitable for the on-line normalizing treatment of medium-carbon boron-containing steel sequentially comprises the following steps: heating, rough rolling, finishing rolling, cooling by passing through water, and cold bed slow cooling. The medium-carbon boron-containing steel can meet the requirements of having a hardness of 190-220 HBW, an actual grain size that is ?7 grade, and a banded structure that is ?2 grade.

A method of creating a ductile, work-hardened, nanotwinned, austenite/martensite nano-lamellar nanostructure in an austenite steel alloy. Briefly, raw materials with high-purity are smelted to obtain an as-cast steel alloy ingot, which will be subjected to homogenization and cold-roll treatment for reduction. The homogenized and cold-rolled steel alloy ingot is further recrystallized to eliminate any possible casting defects and form an as-recrystallized steel alloy having a single face-centered cubic structure with recrystallized grains. The as-recrystallized steel alloy is cold-rolled again for forming a nanotwinned austenite structure and for forming martensite lamellae along nanotwin boundaries such that an austenite/martensite nano-lamellar structure in the steel alloy.

Provided is an electric resistance welded steel pipe or tube that develops no quench cracks despite having carbon content of 0.40% or more and has excellent fatigue strength. An electric resistance welded steel pipe or tube comprises: a chemical composition containing, in mass %, C: 0.40% to 0.55%, Si: 0.10% to 1.0%, Mn: 0.10% to 2.0%, P: 0.10% or less, S: 0.010% or less, Al: 0.010% to 0.100%, Cr: 0.05% to 0.30%, Ti: 0.010% to 0.050%, B: 0.0005% to 0.0030%, Ca: 0.0001% to 0.0050%, and N: 0.0005% to 0.0050%, with a balance consisting of Fe and inevitable impurities; and a ferrite decarburized layer at each of an outer surface and an inner surface, the ferrite decarburized layer having a depth of 20 ?m to 50 ?m from the surface.

A method of producing a working area for a root canal instrument includes the steps of providing a strand made of a nickel-titanium alloy, cutting the strand to a blank size of the working area, forming a tip in the working area, heat-treating the working area at a temperature of 400 to 430? C. for 25 to 40 minutes, quenching the heat-treated working area to room temperature, and producing the final geometry of the working area, wherein the nickel-titanium alloy contains exclusively nickel and titanium as metal components.

The invention relates to a method for producing a hardened sheet steel component, wherein sheet steel sheet bars are cut from a coil made of a hardenable steel alloy or steel strip, formed into sheet steel component blanks in a cold forming process, and the blanks are heated in a continuous furnace to a temperature above the austenitization temperature required for the hardening and pressed and quench hardened in a form hardening tool. The blanks have point-shaped or linear beads, raised bumps, or flanges whose free ends or partial lengths are bent relative to the contact element so that the blanks rest on the contact element using only the point-shaped or linear beads, raised bumps, or free ends or partial lengths of the flanges. During form hardening, the beads, bumps or bends are pressed or deformed into the desired geometry of the finished component.

A hot-stamp formed body has a predetermined chemical composition and has a microstructure including, by area ratio, martensite: 90% to 100% and a remainder in the microstructure: 0% to 10%. The percentage of martensite having a GAIQ value of 40000 or less in all of the martensite is less than 5.0%, an average grain size of prior austenite grains is 6.0 ?m or less, and a standard deviation of grain sizes of the prior austenite grains is 2.6 ?m or less.

Provided is a railway wheel which has excellent toughness even if the C content is as high as 0.80% or more. The chemical composition of the railway wheel of the present embodiment consists of: in mass %, C: 0.80 to 1.60%, Si: 1.00% or less, Mn: 0.10 to 1.25%, P: 0.050% or less, S: 0.030% or less, Al: 0.010 to 0.650%, and N: 0.0030 to 0.0200%, with the balance being Fe and impurities, and wherein, in a microstructure of the web part of the railway wheel, an area fraction of pearlite is 85.0% or more, an area fraction of pro-eutectoid cementite is 0.90 to 15.00%, and an average value of a width W of the pro-eutectoid cementite defined by Formula (3) is less than 0.70 ?m:
W=??(P/2?((P/2).sup.2?4A).sup.1/2)(3) where, in Formula (3), A is an area (?m.sup.2) of the pro-eutectoid cementite, and P is a circumference length (?m) of the pro-eutectoid cementite.

The method for rolling a high-toughness high-strength low-alloy steel, sequentially comprising the following steps: heating, descaling, rough rolling, continuous rolling, first water cooling, finish rolling, second water cooling, and cold hearth cooling; and using a converter continuous casting billet as a raw material, the continuous casting billet comprising the following chemical components in percentage by mass: C?0.20, Si?0.60, Mn: 1.00-1.70, Cr?0.30, P?0.020, S?0.020, V: 0.05-0.10, Al?0.03, and N?0.025, with the balance being Fe and inevitable impurities. By using the rolling method, the actual grain size of the high-strength low-alloy steel can be refined; the comprehensive performance of the high-strength low-alloy steel is excellent; the metallographic structure is fine ferrite and pearlite; the grain size reaches 9.0 or above; the impact energy at ?20? C. is greater than 100 J, and the impact energy at ?40? C. is greater than 80 J.

A high-strength hot-dip galvanized steel sheet with improved bending workability and reduced strength difference between a center part and end parts in the sheet width direction is provided. A method for manufacturing the high-strength hot-dip galvanized steel sheet is also provided. The hot-dip galvanized steel sheet has a hot-dip galvanizing layer on a surface of a base steel sheet containing: C, Mn, P, S, and Al; Ti and B in amounts satisfying expression (1): 0.005[Mn]+0.02[B].sup.1/2+0.025[Ti]0.15; N; and Si as needed; the remainder being iron and unavoidable impurities. The base steel sheet has 50 area % or more of the martensite, 15-50 area % of the bainite, and 5 area % or less of the ferrite, with respect to the overall metallographic structure.

A high-strength hot-dip galvanized steel sheet with improved bending workability and reduced strength difference between a center part and end parts in the sheet width direction is provided. A method for manufacturing the high-strength hot-dip galvanized steel sheet is also provided. The hot-dip galvanized steel sheet has a hot-dip galvanizing layer on a surface of a base steel sheet containing: C, Mn, P, S, and Al; Ti and B in amounts satisfying expression (1): 0.005[Mn]+0.02[B].sup.1/2+0.025[Ti]0.15; N; and Si as needed; the remainder being iron and unavoidable impurities. The base steel sheet has 50 area % or more of the martensite, 15-50 area % of the bainite, and 5 area % or less of the ferrite, with respect to the overall metallographic structure.