Disclosed herein is a method of using a water-based coolant for quenching or cutting a metal material. The water-based coolant is formed of: water; at least one inorganic acid salt selected from the group consisting of a carbonate, a hydrogen carbonate, a sesquicarbonate, a phosphate, a borate, a molybdate and a tungstate; a metal corrosion inhibitor; and optionally at least one of a bactericide, a water-soluble rust inhibitor, an antioxidant and a detergent dispersant.

The present invention relates to a rack steel plate with a thickness up to 177.8 mm by a continuous casting slab, the constituents and mass percentages including C0.11˜0.15%, Si0.15˜0.35%, Mn0.95˜1.25%, P≤0.010%, S≤0.002%, Cr0.45˜0.75%, Mo0.4˜0.6%, Ni1.3˜2.6%, Cu0.2˜0.4%, Al0.06˜0.09%, V0.03˜0.06%, Nb≤0.04%, N≤0.006%, B0.001˜0.002%, the balance is Fe and unavoidable impurity elements. The manufacture method includes, in sequence, KR molten steel pretreatment, converter smelting, LF refining, RH refining, continuous casting through a straight-arc continuous casting machine, shielding the continuous casting slab a cover and slowly cooling, cleaning the continuous casting slab, heating, high-pressure water descaling, control rolling, straightening, slowly cooling, quenching and tempering treatment. The rack steel plate of large thickness in present invention has advantages of high strength, good plasticity and excellent toughness at a low temperature, the process method has advantages of simple process, low cost and efficiently quick etc.

High productivity plant for the continuous quenching of steel bars which comprises a loading station suitable to dispose a plurality of bars separated and distanced from each other. Such plant also comprises a first treatment line, a quenching machine, a transfer station disposed downstream of the quenching machine, and a second treatment line.

Cooling device (1) for cooling a wire (100), comprising a first chamber (2) and a second cooling chamber (4) through which the wire (100) passes. The device also comprises cooling liquid driving means (16) for driving the cooling liquid from the first chamber (2) to the second chamber (4) through at least one coding liquid inlet (12). Through the driving means (16) and the cooling liquid inlet (12), a jet of coding liquid is projected on the wire path at a mean speed of at least 0.6 m/s, and at a distance between 6 and 13 times the diameter of the wire (100). Cooling is performed in an inert gas atmosphere inside the second chamber (4). The invention also relates to a corresponding installation and a corresponding wire cooling method.

Cooling device (1) for cooling a wire (100), comprising a first chamber (2) and a second cooling chamber (4) through which the wire (100) passes. The device also comprises cooling liquid driving means (16) for driving the cooling liquid from the first chamber (2) to the second chamber (4) through at least one coding liquid inlet (12). Through the driving means (16) and the cooling liquid inlet (12), a jet of coding liquid is projected on the wire path at a mean speed of at least 0.6 m/s, and at a distance between 6 and 13 times the diameter of the wire (100). Cooling is performed in an inert gas atmosphere inside the second chamber (4). The invention also relates to a corresponding installation and a corresponding wire cooling method.

The present cooling device includes: when cooling regions obtained by dividing an entire cooling region into a plurality of portions in a steel sheet conveyance direction and three or more portions in a width direction are set as divided cooling surfaces, a cooling water nozzle 23 and a switching device that switches between collision and non-collision of cooling water jetted from the cooling water nozzle 23 with the divided cooling surface, the cooling water nozzle 23 and the switching device provided for each of the divided cooling surfaces; and a control device that controls operation of the switching device based on a width-direction temperature distribution. The cooling water nozzle 23 has a jet axis P inclined with respect to a vertical line to the entire cooling region when viewed in the steel sheet conveyance direction, and the cooling water goes to the side opposite to the cooling water nozzle 23 in the width direction after colliding with the divided cooling surface.

Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, the retained austenite has a mean free path of 1.2 μm or less, and the tempered martensite has a mean free path of 1.2 μm or less.

Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, the retained austenite has a mean free path of 1.2 μm or less, and the tempered martensite has a mean free path of 1.2 μm or less.

The invention provides a wear-resistant steel plate, which has the following chemical composition (wt. %): C: 0.22-0.35%, Si: 0.10-0.40%, Mn: 0.60-1.35%, P: ≤0.015%, S: ≤0.010%, Nb: 0.010-0.040%, Al: 0.010-0.080%, B: 0.0006-0.0014%, Ti: 0.005-0.050%, Ca: 0.0010-0.0080%, V≤0.080%, Cr≤0.60%, W≤1.00 wt. %, N≤0.0080%, O≤0.0060%, H≤0.0004%, wherein 0.025%≤Nb+Ti≤0.080%, 0.030%≤Al+Ti≤0.12%, and the balance of Fe and unavoidable impurities. The method of manufacturing the wear-resistant steel plate comprises the steps of smelting, casting, rolling, post-rolling direct cooling and the like. The wear-resistant steel plate obtained from the above composition and process has high strength, high hardness, good low-temperature toughness, and excellent machinability, and is suitable for quick-wear devices in engineering and mining machinery, such as bucket and scraper transporter, etc.

The invention provides a wear-resistant steel plate, which has the following chemical composition (wt. %): C: 0.22-0.35%, Si: 0.10-0.40%, Mn: 0.60-1.35%, P: ≤0.015%, S: ≤0.010%, Nb: 0.010-0.040%, Al: 0.010-0.080%, B: 0.0006-0.0014%, Ti: 0.005-0.050%, Ca: 0.0010-0.0080%, V≤0.080%, Cr≤0.60%, W≤1.00 wt. %, N≤0.0080%, O≤0.0060%, H≤0.0004%, wherein 0.025%≤Nb+Ti≤0.080%, 0.030%≤Al+Ti≤0.12%, and the balance of Fe and unavoidable impurities. The method of manufacturing the wear-resistant steel plate comprises the steps of smelting, casting, rolling, post-rolling direct cooling and the like. The wear-resistant steel plate obtained from the above composition and process has high strength, high hardness, good low-temperature toughness, and excellent machinability, and is suitable for quick-wear devices in engineering and mining machinery, such as bucket and scraper transporter, etc.