Preparation method for 800 MPa low-temperature resistant high strength steel

A low-temperature-resistant, high-strength steel technology, applied in the field of steel rolling, can solve problems such as poor shape of low-temperature-resistant high-strength steel plates, improve head and tail warpage and waves, and achieve the effect of efficient energy utilization

Active Publication Date: 2020-09-25

SHOUGANG CORPORATION

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AI-Extracted Technical Summary

Problems solved by technology

[0003] Aiming at the deficiencies of the above-mentioned prior art, the present invention provides a preparation method of 800MPa low-temperature-resistant high-str...

Method used

The cooling pattern that described online water cooling adopts UFC+ACC, wherein, UFC is ultrafast cooling, and ACC is laminar flow cooling, and online water cooling is carried out in cooler, and straightening speed is 1~1.2m/s in cooler , This online water cooling can make full use of the waste heat of the steel plate, saving heating time and heat. After the online water cooling, the dislocations after the rolling of the steel plate can be preserved. Compared with the offline quenching process, the strength of the online quenched steel plate will be improved. If the water entry temperature of the steel plate is too low, pro-eutectoid ferrite will be precipitated and the strength of the steel plate will be reduced. If the water entry temperature is too high, relatively large thermal stress will be generated due to the excessive temperature drop in the cooler, which will affect the water cooling. After the shape of the plate. If the cooling rate and final cooling temperature in the cooling process do not reach the above range, the water-cooled steel plate cannot obtain the predetermined bainite and martensite structure, and the bainite and martensite are relatively hard, such as bainite and martensite. If the volume fraction of martensite is low, the strength of low temperature resistance will decrease.

The main effect of Cr in quenched and tempered structural steel is to improve hardenability, improve the intensity of steel, make steel have better comprehensive mechanical properties after quenching and tempering; Mo can improve hardenability and thermal conductivity in steel Strong, preventing temper brittleness; Ti can improve plasticity and toughness in low-alloy steel; trace Nb can increase the strength of steel without affecting the plasticity or toughness of steel, and can improve the The impact toughness of steel and reduce its brittle transition temperature; Mn strongly increases the hardenability of steel and forms MnS with a higher melting point with S, which can prev...

Abstract

The invention discloses a preparation method for 800 MPa low-temperature resistant high strength steel. The method comprises the steps of heating, descaling, rough rolling, finish rolling and pre-straightening of a plate blank obtained through continuous casting; the plate blank comprises the following chemical components, by mass: 0.08%-0.12% of C, 1.1%-1.4% of Mn, 0.02%-0.04% of Nb, 0.01%-0.03%of Ti, 0.2%-0.5% of Cr, 0.1%-0.3% of Mo and 0.0015%-0.003% of B; in the pre-straightening process, the bite speed is 0.5-0.8 m/s; and a steel plate is water-cooled, air-cooled and tempered on line toobtain the low-temperature resistant high strength steel. According to the preparation method, the hot rolled steel plate is directly subjected to quenching treatment, and reheating after cooling is not required; the waste heat utilization of the steel plate is achieved, and energy sources are saved; and the production cost is reduced.

Technology Topic

Steel platesHot rolled +5

Image

Examples

Comparison scheme(1)
Effect test(1)

Comparison Example

[0060] Comparative Example 1

[0061] Comparative example 1 provides a preparation method of 800MPa grade low temperature resistant high strength steel, the method includes,

[0062] S1, heating, descaling, rough rolling, and finish rolling are performed on the slab obtained by continuous casting to obtain a steel sheet.

[0063] S2, after the steel plate is air-cooled off-line, heating, water-cooling, air-cooling and tempering are performed in sequence to obtain a low-temperature resistant high-strength steel.

[0064] Among them, the heating temperature is 900°C, the water cooling temperature is 100°C, the water cooling rate is 30°C/s, the tempering temperature is 650°C, and the tempering time is 60min.

PUM

Description & Claims & Application Information

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