Quenching process of 1000MPa-level low-carbon high-strength steel plates

A high-strength steel plate and process technology, applied in the field of quenching technology, can solve the problems of steel plate toughness, reduced carbon diffusion rate, high content of alloy elements, etc., and achieve the effect of uneven structure, fine grain and uniform structure

Inactive Publication Date: 2019-02-15
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the traditional quenching process of 1000MPa low-carbon high-strength steel is prone to the following problems: (1) Due to the low-carbon composition design and high content of alloying elements, the diffusion rate of carbon is reduced. The traditional quenching process is likely to cause coarse grains in the steel plate. Mixed crystals, poor hardenability, uneven structure, etc., the general grain size is 25-30μm
(2) Due to the low-carbon composition design, the hardenability of the steel plate is poor, and the impact energy of the steel plate at -40°C is often less than 50J
Therefore, the traditional quenching process cannot meet the requirements of steel plate strength and toughness, which is a common problem in 1000MPa low-carbon high-strength steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Embodiment 1: The quenching process of the 1000 MPa grade low-carbon high-strength steel plate is specifically as follows.

[0017] The chemical composition of this low-carbon high-strength steel plate is (wt): C 0.11%, Si 0.35%, Mn 1.4%, P 0.0010%, S0.05%, Ni 1.2%, Cr 0.5%, Nb 0.03%, Al 0.05%, Mo 0.48%, V 0.04%, Ti 0.02%, B 0.0015%, the balance is Fe and unavoidable impurities. The steel plate thickness is 20mm, AC1 is 710°C, and AC3 is 880°C.

[0018] The quenching process is as follows: (1) The first step quenching: heat the steel plate to 950°C, soak for 10 minutes; then cool down to 900°C, soak for 20 minutes; then quickly water-cooled and quenched.

[0019] (2) The second step quenching: reheat the steel plate after the first step quenching to 680°C at a heating rate of 200°C / h; then raise the temperature to 930°C at a heating rate of 300°C / h, and hold for 6 minutes ; Then lower the temperature to 900°C and keep it warm for 20 minutes; then quickly water-cooled ...

Embodiment 2

[0021] Embodiment 2: The quenching process of the 1000 MPa grade low-carbon high-strength steel plate is specifically as follows.

[0022] The chemical composition of this low-carbon high-strength steel plate is (wt): C 0.10%, Si 0.20%, Mn 1.1%, P 0.008%, S0.003%, Ni 1.0%, Cr 0.4%, Nb 0.02%, Al 0.03%, Mo 0.36%, V 0.01%, Ti 0.01%, B 0.0011%, the balance is Fe and unavoidable impurities. The steel plate thickness is 20mm, AC1 is 719°C, and AC3 is 890°C.

[0023] The quenching process is as follows: (1) The first step quenching: heat the steel plate to 940°C, soak for 20 minutes; then cool down to 900°C, soak for 30 minutes; then quickly water-cooled and quenched.

[0024] (2) The second step quenching: reheat the steel plate after the first step quenching to 709°C at a heating rate of 200°C / h; then raise the temperature to 930°C at a heating rate of 350°C / h, and hold for 10 minutes for a short time ; Then lower the temperature to 900°C and keep it warm for 30 minutes; then qui...

Embodiment 3

[0026] Embodiment 3: The quenching process of the 1000 MPa grade low-carbon high-strength steel plate is specifically as follows.

[0027] The chemical composition of this low-carbon high-strength steel plate is (wt): C 0.10%, Si 0.25%, Mn 1.3%, P 0.008%, S0.003%, Ni 1.0%, Cr 0.4%, Nb 0.02%, Al 0.03%, Mo 0.40%, V 0.04%, Ti 0.02%, B 0.0011%, the balance is Fe and unavoidable impurities. The steel plate thickness is 20mm, AC1 is 712°C, and AC3 is 883°C.

[0028] The quenching process is as follows: (1) The first step quenching: heat the steel plate to 943°C, soak for 0.8min / mm; then cool down to 901°C, soak for 1.3min / mm; then quench with rapid water cooling.

[0029] (2) The second step quenching: reheat the steel plate after the first step quenching to 697°C at a heating rate of 160°C / h; min / mm; then cool down to 898°C, keep warm for 1.3min / mm; then quickly water-cooled and quenched.

[0030] Using the above quenching process, the thickness of the steel plate is uniform, th...

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Abstract

The invention discloses a quenching process of 1000MPa-level low-carbon high-strength steel plates. Two times of stepped quenching are adopted by the quenching process, specifically, the first time ofstepped quenching is that the steel plates are subjected to soaking and heat preservation for 0.5-1.0 min/mm at the heating temperature of AC3+(50-70) DEG C, then the temperature is reduced to AC3+(10-20) DEG C and preserved for 1-1.5 min/mm, and finally the steel plates are quickly cooled and quenched; and the second time of stepping quenching is that the steel plates are heated to AC3-(10-30) DEG C at the heating speed of 150-200 DEG C/h, heated to AC3+(40-50) DEG C at the heating speed of 300 DEG C/h or above, and subjected to heat preservation for 0.3-0.5 min/mm, then the steel plates arecooled to AC3+(10-20) DEG C and subjected to heat preservation for 1.0-1.5 min/mm, and finally the steel plates are quickly cooled and quenched. As for the finished steel plates prepared according tothe process, the thickness section texture is uniform, grains are fine, the average dimension of the grains is 15 microns or below, the low-temperature toughness is greatly improved, the martensite proportion of the one fourth position in the thickness direction of the plates is up to 94-98%, the strength of the one fourth position in the thickness direction of the plates is improved, the averageimpact energy at minus 40 DEG C is improved by 50 J or above, and the steel plates obtain an excellent match between strength and toughness.

Description

technical field [0001] The invention relates to a heat treatment process, in particular to a quenching process for a 1000MPa grade low-carbon high-strength steel plate. Background technique [0002] 1000MPa high-strength steel has special requirements and broad application prospects in the fields of pressure vessels, mining machinery, transmission pipelines, and hydropower stations. The use of high-strength steel can effectively reduce the weight of equipment, improve work efficiency and reduce manufacturing costs. With the rapid development of the economy, engineering construction has higher and higher requirements for the welding quality of high-strength steel. The development trend of high-strength steel has gradually evolved into the use of low-carbon composition design. There are more and more applications in engineering. For high-strength steel with a strength level of 1000MPa, it is often produced by quenching and tempering heat treatment. However, as the strength ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/00C21D1/18
CPCC21D1/18C21D9/0081C21D2211/008
Inventor 赵燕青孙力王九清车金峰刘宏强陈振业姚纪坛潘进田志强罗应明杨浩
Owner HEBEI IRON AND STEEL
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