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Non hardened and tempered state hot-rolled steel strip with yield strength higher than 900MPa and preparation method thereof

A technology of yield strength and hot-rolled strip steel, applied in the field of metallurgy, can solve the problems of high alloy cost and high cost of quenching and tempering process, achieve high mechanical properties, improve work hardening ability, and reduce production costs

Inactive Publication Date: 2012-10-03
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In summary, through compositional design, 900MPa high-strength construction machinery steel with bainite or tempered martensite structure can be obtained, but there are problems such as high alloy cost and high cost of quenching and tempering process, so it is urgent to reduce production cost, new ways to simplify the production process, and increase the added value of products

Method used

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  • Non hardened and tempered state hot-rolled steel strip with yield strength higher than 900MPa and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Molten steel is smelted in a 150-ton converter according to the set composition, and continuously cast into a billet. The composition is C0.06%, Si 0.20%, Mn 1.20%, Nb 0.02%, V 0.04%, Ti0.04% by weight , Cr0.8%, Mo0.30%, B0.001%, P<0.012%, S<0.01%, the balance is iron Fe, and the thickness of the slab is 220mm.

[0025] The cast slab was heated to 1250°C for rough rolling, the rough rolling process was 5 passes, the rough rolling start temperature was 1170°C, and the rough rolling finish rolling temperature was 1070°C to obtain an intermediate slab with a thickness of 38mm.

[0026] The intermediate billet is finished rolling, the finishing rolling process is 7 passes, the starting temperature of the finishing rolling is 980°C, the temperature of the second rolling is 950°C, the temperature of the third rolling is 930°C, the temperature of the fourth rolling is 890°C, and the temperature of the fifth rolling is 850°C ℃, the sixth rolling temperature is 820 ℃, the finish...

Embodiment 2

[0029] The preparation method and composition of the slab are the same as in Example 1, and the thickness of the slab is 250 mm.

[0030] The rough rolling process was the same as in Example 1, and an intermediate billet with a thickness of 58 mm was obtained.

[0031]The intermediate billet is finished rolling, the finishing rolling process is 6 passes, the starting temperature of the finishing rolling is 960°C, the temperature of the second rolling is 940°C, the temperature of the third rolling is 920°C, the temperature of the fourth rolling is 900°C, and the temperature of the fifth rolling is 860°C ℃, the final rolling temperature is 840 ℃, the reduction of each pass of finishing rolling is controlled at 15~40%, and the strip thickness after finishing rolling is 12mm.

[0032] After finishing rolling, it is water-cooled to 450°C at a speed of 35°C / s, coiled by a coiler, and then tempered off-line. The performance test results are: yield strength 930MPa, tensile strength 9...

Embodiment 3

[0034] The preparation method and composition of the slab are the same as in Example 1, and the thickness of the slab is 240mm.

[0035] The rough rolling process was the same as in Example 1, and an intermediate billet with a thickness of 45 mm was obtained.

[0036] The intermediate billet is finished rolling, the finishing rolling process is 5 passes, the finishing rolling temperature is 1000°C, the second rolling temperature is 980°C, the third rolling temperature is 920°C, the fourth rolling temperature is 900°C, and the final rolling temperature is 880°C ℃, the reduction in each pass of finish rolling is controlled at 15~40%, and the strip thickness after finish rolling is 6mm.

[0037] After finishing rolling, it is water-cooled to 200°C at a speed of 15°C / s, coiled by a coiler, and then tempered offline. The offline tempering temperature is 600°C, and the tempering time is 2 hours. The mechanical performance test results are: yield strength 940MPa, tensile strength 98...

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Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to a non hardened and tempered state hot-rolled steel strip with yield strength higher than 900MPa and a preparation method of the hot-rolled steel strip. The non hardened and tempered state hot-rolled steel strip comprises the chemical components in percentage by weight: 0.06-0.12% of C, 0.10-0.30% of Si, 0.80-1.20% of Mn, 0.00-0.04% of Nb, 0.00-0.04% of V, 0.02-0.10% of Ti, 0.8-1.20% of Cr, 0.10-0.30% of Mo, 0.001-0.003% of B, less than 0.012% of P, less than 0.01% of S, and the balance of Fe, and has the yield strength not less than 900MPa, tensile strength not less than 940MPa, and elongation at break not less than 12%. The preparation method comprises the steps of: smelting molten steel according to the set components, casting into cast blank, heating the cast blank, carrying out rough rolling and finish rolling, cooling the steel strip to 200-450 DEG C after finish rolling, coiling, carrying out hot rolling, carrying out offline tempering at the tempering temperature of 400-600 DEG C, and delivering in the hot-rolled state or hot-rolled and offline tempered state. According to hot-rolled steel strip provided by the invention, the hardening and tempering heat treatment process is not needed, so that the production cost is greatly lowered.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a non-quenched and tempered hot-rolled steel strip with a yield strength higher than 900 MPa and a preparation method thereof. Background technique [0002] With the development of industries such as automobiles and construction machinery, the demand for high-strength steel with a strength level above 700MPa is becoming more and more urgent. At the same time, in order to save resources, save energy and protect the environment, it is urgent to develop high-quality steel with higher strength. . At present, the strength level of high-strength steel ranges from a yield strength of 600MPa to a yield strength of more than 1200MPa. On the whole, the comprehensive requirements for strength, toughness and welding performance are getting higher and higher. [0003] Steel products with a yield strength below 700MPa are mostly produced by controlled rolling and controlled coo...

Claims

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Application Information

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IPC IPC(8): C22C38/32C21D8/02
Inventor 衣海龙刘振宇徐洋吴迪王国栋
Owner NORTHEASTERN UNIV
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