CN102828115A

CN102828115A - Medium plate Q345B and production method of same

Info

Publication number: CN102828115A
Application number: CN2012103577666A
Authority: CN
Inventors: 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
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2012-09-25
Filing date: 2012-09-25
Publication date: 2012-12-19

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

A kind of Q345B steel plate and working method thereof

Technical field

The invention belongs to the steel rolling process field, relate in particular to thick structure steel plate and working method thereof in a kind of Q345B low-alloy high-strength.

Background technology

For the hot rolled steel plate of the Q345B steel grade of the thick specification of low-alloy high-strength, owing to receive the restriction of conditions such as production technique and equipment, deflection is less generally speaking, and the purpose that reaches thinning microstructure through traditional method is difficulty very.Especially all add in the Q345B steel grade Nb alloying element is arranged; The Nb alloy costs an arm and a leg; The smelting cost of steel per ton will improve more than 120 yuan, and this steel grade must be combined with low temperature rolling technology in addition, therefore cause rolling rhythm slow, yield poorly and drawback that production cost is high.

Summary of the invention

The object of the invention aims to provide a kind of through v n micro alloying and controlled rolling, cooling control technology, thereby reduces the alloy usage quantity, reduces production costs, and the raising rolling rhythm improves the Q345B steel plate and the working method thereof of steel plate structure property.

For this reason, the solution that the present invention taked is:

A kind of Q345B steel plate, its chemical component weight degree is:

C 0.130-0.150%, Si 0.30-0.40%, Mn 1.35-1.50%, P≤0.025%, S≤0.020%, Ti 0.005-0.01%, V 0.05-0.07%, N content is controlled at 80-180ppm in the steel, and all the other are iron and trace impurity.

A kind of working method of Q345B steel plate is characterized in that:

1, steel billet adopts low-temperature heat, and the steel billet tapping temperature is controlled at 1180-1200 ℃;

2, adopt high temperature rolling technology, the finish rolling finishing temperature is controlled at 1070-1100 ℃;

3, adopt supper-fast process for cooling, speed of cooling is 18-22 ℃/s, and final cooling temperature is controlled at 650-750 ℃.

Beneficial effect of the present invention is:

1, the present invention takes alloy minimizing technology, has cancelled expensive Nb alloy in the chemical ingredients, and therefore steel per ton can reduce material cost more than 20 yuan;

2, the present invention adopts the V-N micro-alloying technology, utilizes the VN particle of separating out in the high temperature rolling process to bring out the tiny intracrystalline ferritic of formation and comes thinning microstructure, makes more refinement of grain structure, and thickness direction is more even, has effectively improved the inherent weave construction of steel;

3, technology of the present invention is simple, is convenient to control and operation, helps accelerating rolling rhythm, improves unit output.

4, adopt high temperature controlled rolling and the cold bonded rolling technology of control, when improving intensity, the toughness that makes steel also be improved significantly, make it under lower carbon equivalent condition, to have obtained higher obdurability coupling.Its each item performance index all reach fully and surpassed the requirement in the 345MPa level steel: ys reaches 401MPa, and tensile strength is 536MPa, and unit elongation is 31%, and the clod wash index is all qualified.

Embodiment

Embodiment 1:

Q345B steel plate chemical ingredients and weight percent content are:

C 0.130%, Si 0.35%, Mn 1.50%, P0.020%, S0.020%, Ti 0.007%, V 0.06%, N content is controlled at 100ppm in the steel, and all the other are iron and trace impurity.

Its main working method is:

1, steel billet adopts low-temperature heat, and the steel billet tapping temperature is controlled at 1180 ℃.

2, adopt high temperature rolling technology, the finish rolling finishing temperature is controlled at 1070 ℃.

3, adopt supper-fast process for cooling, speed of cooling is 18 ℃/s, and final cooling temperature is controlled at 650 ℃.

Embodiment 2:

Q345B steel plate chemical ingredients and weight percent content are:

C 0.150%, Si 0.30%, Mn 1.35%, P0.025%, S0.018%, Ti 0.01%, V 0.05%, N content is controlled at 150ppm in the steel, and all the other are iron and trace impurity.

Its main working method is:

1, steel billet adopts low-temperature heat, and the steel billet tapping temperature is controlled at 1190 ℃.

2, adopt high temperature rolling technology, the finish rolling finishing temperature is controlled at 1085 ℃.

3, adopt supper-fast process for cooling, speed of cooling is 20 ℃/s, and final cooling temperature is controlled at 680 ℃.

Embodiment 3:

Q345B steel plate chemical ingredients and weight percent content are:

C 0.140%, Si 0.40%, Mn 1.40%, P0.015%, S0.020%, Ti 0.005%, V 0.07%, N content is controlled at 170ppm in the steel, and all the other are iron and trace impurity.

Its main working method is:

1, steel billet adopts low-temperature heat, and the steel billet tapping temperature is controlled at 1200 ℃.

2, adopt high temperature rolling technology, the finish rolling finishing temperature is controlled at 1100 ℃.

3, adopt supper-fast process for cooling, speed of cooling is 22 ℃/s, and final cooling temperature is controlled at 750 ℃.

Claims

1. Q345B steel plate is characterized in that:

Its chemical component weight degree is:

2. working method of Q345B steel plate according to claim 1 is characterized in that:

(1), steel billet adopts low-temperature heat, the steel billet tapping temperature is controlled at 1180-1200 ℃;

(2), adopt high temperature rolling technology, the finish rolling finishing temperature is controlled at 1070-1100 ℃;

(3), to adopt supper-fast process for cooling, speed of cooling be 18-22 ℃/s, final cooling temperature is controlled at 650-750 ℃.