Medium plate Q345B and production method of same

A production method and thick steel plate technology, which is applied in the field of steel rolling technology, can solve problems such as the difficulty of refining the structure, the high price of Nb alloys, and the increase in smelting costs, and achieve the effects of increasing unit output, improving internal organizational structure, and improving toughness

Inactive Publication Date: 2012-12-19
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] For low-alloy, high-strength, thick-gauge hot-rolled structural steel plates of Q345B steel, due to the limitation of production process and equipment conditions, the amount of deformation is generally small, and it is very difficult to achieve the purpose of refining the structure by traditional methods
In particular, Nb alloy elements are added to the Q345B steel grades. Nb alloys are expensive, and the smelting cost per ton of steel will increase by more than 120 yuan. In addition, this steel grade must be equipped with a low-temperature controlled rolling process, resulting in slow rolling rhythm. Disadvantages of low output and high production cost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] The chemical composition and weight percentage of Q345B medium and thick steel plates are:

[0018] C 0.130%, Si 0.35%, Mn 1.50%, P0.020%, S0.020%, Ti 0.007%, V 0.06%, the N content in the steel is controlled at 100ppm, and the rest is iron and trace impurities.

[0019] Its main production methods are:

[0020] 1. The steel billet is heated at a low temperature, and the temperature of the billet out of the furnace is controlled at 1180°C.

[0021] 2. High-temperature rolling process is adopted, and the finishing rolling temperature is controlled at 1070°C.

[0022] 3. Adopt ultra-fast cooling process, the cooling speed is 18°C / s, and the final cooling temperature is controlled at 650°C.

Embodiment 2

[0024] The chemical composition and weight percentage of Q345B medium and thick steel plates are:

[0025] C 0.150%, Si 0.30%, Mn 1.35%, P0.025%, S0.018%, Ti 0.01%, V 0.05%, the N content in the steel is controlled at 150ppm, and the rest is iron and trace impurities.

[0026] Its main production methods are:

[0027] 1. The steel billet is heated at a low temperature, and the temperature of the billet out of the furnace is controlled at 1190°C.

[0028] 2. High-temperature rolling process is adopted, and the finishing rolling temperature is controlled at 1085°C.

[0029] 3. Adopt ultra-fast cooling process, the cooling rate is 20°C / s, and the final cooling temperature is controlled at 680°C.

Embodiment 3

[0031] The chemical composition and weight percentage of Q345B medium and thick steel plates are:

[0032] C 0.140%, Si 0.40%, Mn 1.40%, P0.015%, S0.020%, Ti 0.005%, V 0.07%, the N content in the steel is controlled at 170ppm, and the rest is iron and trace impurities.

[0033] Its main production methods are:

[0034] 1. The steel billet is heated at a low temperature, and the temperature of the billet out of the furnace is controlled at 1200°C.

[0035] 2. High-temperature rolling process is adopted, and the finishing rolling temperature is controlled at 1100°C.

[0036] 3. Adopt ultra-fast cooling process, the cooling speed is 22°C / s, and the final cooling temperature is controlled at 750°C.

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Abstract

The invention provides a medium steel plate Q345B and a production method of the same. The medium plate Q345B comprises the following chemical components in percentage by mass: 0.130-0.150% of carbon, 0.30-0.40% of silicon, 1.35-1.50% of manganese, less than or equal to 0.025 of phosphorus, less than or equal to 0.020 of sulfur, 0.005-0.01% of titanium, 0.05-0.07% of vanadium, and the content of the nitrogen is controlled to be 80-180 ppm. The tapping temperature of billet is 1180-1200 DEG C, the finish-rolling finishing temperature is controlled to be 1070-1100 DEG C, the cooling rate is 18-22 DEG C per second, and the final cooling temperature is controlled to be 650-750 DEG C. The method provided by the invention can effectively improve the internal structure of the steel and reach higher combination of toughness and strength under lower carbon equivalent. The steel has a yield strength of 401 MPa, a strength of extension of 536 MPa, the coefficient of elongation of 31%, and the cold bending index thereof are all qualified. Moreover, the material costs of the steel can be reduced by over 20 RMB / ton.

Description

technical field [0001] The invention belongs to the field of steel rolling technology, and in particular relates to a Q345B low-alloy high-strength medium-thick structural steel plate and a production method thereof. Background technique [0002] For low-alloy, high-strength, thick-gauge hot-rolled structural steel plates of Q345B steel, due to the limitation of production process and equipment conditions, the amount of deformation is generally small, and it is very difficult to achieve the purpose of refining the structure by traditional methods . In particular, Nb alloy elements are added to the Q345B steel grades. Nb alloys are expensive, and the smelting cost per ton of steel will increase by more than 120 yuan. In addition, this steel grade must be equipped with a low-temperature controlled rolling process, resulting in slow rolling rhythm. The disadvantages of low output and high production cost. Contents of the invention [0003] The purpose of the present inventi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/14C21D8/02
Inventor 李新玲王若钢杨军赵坦丛津功张健刘源王明林乔馨苏小利
Owner ANGANG STEEL CO LTD
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