Low-yield-ratio high-intensity hardened and tempered steel for coal mine hydraulic support frame and manufacturing method of low-yield-ratio high-intensity hardened and tempered steel

Abstract

The invention provides low-yield-ratio high-intensity hardened and tempered steel for a coal mine hydraulic support frame. The hardened and tempered steel is prepared from the following raw materialsin percentage by weight: 0.10 to 0.14 percent of C, 1.35 to 1.50 percent of Mn, 0.10 to 0.40 percent of Si, less than or equal to 0.015 percent of S, less than or equal to 0.020 percent of P, 0.015 to0.030 percent of Nb, 0.20 to 0.30 percent of Mo, 0.30 to 0.40 percent of Cr, 0.020 to 0.040 percent of Al, less than or equal to 0.0050 percent of N, 0.0010 to 0.0020 percent of B and the balance ofFe and unavoidable impurities. Meanwhile, the invention also discloses a manufacturing method of the low-yield-ratio high-intensity hardened and tempered steel for the coal mine hydraulic support frame. The method comprises the steps of top and bottom combined blown converter treatment, LF refining, VD degassing, wide plate blank continuous casting, furnace roll mill rolling, two-phase interval quenching, and tempering. The hardened and tempered steel has a low yield ratio and can be applied to the coal mine hydraulic support frame industry.

Description

technical field [0001] The invention relates to the technical field of iron and steel materials, in particular to a low-yield ratio high-strength quenched and tempered steel quenched in a two-phase region and a manufacturing method thereof. The method is suitable for producing low yield ratio quenched and tempered steel with a yield strength of 550 MPa. In coal mine hydraulic support manufacturing industry. Background technique [0002] At present, high-strength quenched and tempered steel with a yield strength of 550MPa is widely used in the coal mine hydraulic support industry. In engineering practice, the yield ratio of steel is usually used as an important index to measure the safety of the structure. A high yield ratio indicates that the material is not easy to undergo plastic deformation, and will soon break and fail after plastic deformation; a low yield ratio The material is easy to produce plastic deformation under the action of external tension, because the materi...

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Problems solved by technology

[0003] After quenching and high-temperature tempering, structural steel can obtain better matching of strength, plasticity and toughness, but high-strength quenched and tempered steel usually obtains tempered sorbite after quenching and tempering, and tempered sorbite is iron An organic mixture of ferrite and cementite, and the lamellar structure of tempered sorbite is dense, but it increases the yield strength while increasing the tensile strength, resulting in a higher yield ratio

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