CN114182172B

CN114182172B - Production method of super-thick steel plate with strength greater than 550MPa

Info

Publication number: CN114182172B
Application number: CN202111420452.1A
Authority: CN
Inventors: 李中平; 周文浩; 罗登; 杨小军; 张勇伟; 熊祥江; 史术华; 范明; 陈奇明
Original assignee: Hunan Valin Xiangtan Iron and Steel Co Ltd
Current assignee: Hunan Valin Xiangtan Iron and Steel Co Ltd
Priority date: 2021-11-26
Filing date: 2021-11-26
Publication date: 2022-06-28
Anticipated expiration: 2041-11-26
Also published as: CN114182172A

Abstract

The production method of the super-thick steel plate with the strength of more than 550MPa comprises the following chemical components, by weight, 0.14% -0.16% of C, 0.10% -0.30% of Si, 1.10% -1.20% of Mn, 0.015% or less of P, 0.003% or less of S, 0.020% to 0.030% of Nb, 0.60-0.80% of Cr, 0.40-0.50% of Ni, 0.40-0.60% of Mo, 0.0015-0.0020% of B, 0.07-0.09% of ALT, and the balance of Fe and inevitable impurities. The method overcomes the problems of center segregation, shrinkage cavity and looseness of the extra-thick plate rolled by the large single continuous casting billet, solves the problems of penetration of rolling force along the thickness direction and insufficient core deformation in the thick plate rolling process, can manufacture the steel plate with the thickness of 100-150 mm and the strength of more than 550MPa by adopting the continuous casting billet, has short production period and low manufacturing cost, and is suitable for large-scale production of the thick plate.

Description

Production method of super-thick steel plate with strength greater than 550MPa

Technical Field

The invention belongs to the technical field of metallurgy, and relates to a production method of an ultra-thick steel plate with the strength of more than 550 MPa.

Background

The extra-thick plate becomes an indispensable material in modern social economic development, national defense construction and national major engineering construction, and is widely applied to industries such as coal mining machines, shipbuilding, boiler containers, wind power generation, bridges, high-rise construction and the like. With the implementation of the policy of 'carbon peak reaching and carbon neutralization' in China, the development of wind energy and hydrogen energy is accelerated, and the high-quality extra-thick plate has wide market space as an important wind power base in northwest regions. At present, the annual demand of the super-thick plates with the thickness of more than 100mm in the domestic steel market is about 200 ten thousand tons, and the super-thick plates tend to rise year by year, for example, in the last few years, the wind power industry rapidly grows up in the northwest region, and the super-thick plates have a certain proportion of demand during the tower cylinder manufacturing.

However, in the smelting process of the extra-thick plate, the size of a continuous casting billet of the rolled extra-thick plate is correspondingly increased along with the increase of the thickness of the steel plate, so that the element segregation in the solidification process seriously deteriorates the quality of the casting billet, and the flaw detection qualification rate of the steel plate is easily influenced by the occurrence of center segregation, shrinkage cavity and porosity; meanwhile, in the rolling process of the extra-thick plate, the rolling force is difficult to permeate along the thickness direction, the core deformation is insufficient, and the performance difference in the thickness direction is large. At present, steel enterprises capable of producing casting blanks with the thickness of more than 400mm commonly encounter the problems of small rolling compression ratio of super-extra-thick steel plates and unstable steel plate performance, particularly the central performance of the thick steel plates, such as the Z-direction performance of the thick plates.

At present, the relatively mature process for producing the extra-thick plate mainly adopts an electroslag ingot and a die-cast steel ingot, the production efficiency of the spindles is low, the manufacturing cost is high, the large-scale production is difficult, the production of the extra-thick plate by adopting an ultra-thick continuous casting billet is rare in the industry, and the key technology for producing the high-strength extra-thick plate by utilizing a large-tonnage continuous casting billet is in urgent need of breakthrough.

Disclosure of Invention

The invention aims to provide a production method of an extra-thick steel plate with strength greater than 550MPa, which aims to solve the bottleneck of producing an extra-thick plate with the thickness of 100-150 mm by using a large single continuous casting billet, adopts the continuous casting billet with the thickness of 450mm to produce the steel plate with the thickness of 100-150 mm, and obtains the high-strength extra-thick steel plate with excellent obdurability through off-line quenching and high-temperature tempering. The steel plate is required to have the yield strength of more than or equal to 550MPa, the tensile strength of more than or equal to 720MPa, the impact toughness of more than or equal to 160J at minus 20 ℃, particularly the thickness tension of more than 35 percent, and good lamellar tearing resistance.

The technical scheme of the invention is as follows:

a production method of a super-thick plate with the strength of more than 550MPa comprises the following chemical components, by weight, 0.14% -0.16% of C, 0.10% -0.30% of Si, 1.10% -1.20% of Mn, 0.015% or less of P, 0.003% or less of S, 0.020% to 0.030% of Nb, 0.60-0.80% of Cr, 0.40-0.50% of Ni, 0.40-0.60% of Mo, 0.0015-0.0020% of B, 0.07-0.09% of ALT, and the balance Fe and inevitable impurities; the key process steps comprise:

(1) continuous casting: the whole process is protected and cast, the superheat degree is controlled to be 8-20 ℃, the pulling speed is controlled to be 0.3-0.55 m/min, dynamic soft reduction is adopted, heavy reduction is adopted at the solidification tail end, the two-stage reduction amount at the solidification end point of the continuous casting billet is respectively 5-7 mm and 1-3 mm, and the secondary cooling specific water amount is 0.5-0.8L/kg;

(2) and (3) cooling in a stacking manner: stacking and cooling the casting blank in a stacking and cooling pit for 36-72 h;

(3) rolling: heating at 1100-1290 ℃, heating for 300-400 min, and keeping the thickness of the warm blank to be more than 1.5T, wherein T is the thickness of a finished steel plate; the initial rolling temperature is less than 860 ℃, the final rolling temperature is less than 800 ℃, the rolled steel is stacked and cooled after finish rolling, and the stacking and cooling time is more than 36 hours;

(4) tempering: the quenching process is 930 ℃, the heat preservation time is 2min/mm multiplied by T +20min, the tempering process is 650 ℃, and the heat preservation time is 3min/mm multiplied by T +20 min.

The method overcomes the bottleneck of producing the 100-150 mm extra-thick plate by using a large single continuous casting billet, adopts the continuous casting billet with the thickness of 450mm to produce the steel plate with the wall thickness of 100-150 mm, and obtains the high-strength extra-thick steel plate with excellent obdurability through off-line quenching and high-temperature tempering; the yield strength of the steel plate is more than or equal to 550MPa, the tensile strength is more than or equal to 720MPa, the impact toughness at minus 20 ℃ is more than or equal to 160J, and particularly, the thickness stretch is more than 35 percent, so that the steel plate has good lamellar tearing resistance; the steel plate has short production period and low manufacturing cost, and is suitable for large-scale production of thick plates.

Drawings

FIG. 1 is a metallographic structure drawing of a steel plate.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1: production of 140mm steel plate

The steel has the chemical composition percentage of C =0.14%, Si =0.16%, Mn =1.15%, P =0.012%, S =0.002%, Nb =0.023%, Cr =0.65%, Ni =0.43%, Mo =0.48%, B =0.0018%, ALT =0.078%, and the balance of Fe and inevitable impurities. The key technology is as follows:

(1) continuous casting: the whole process is protected and cast, the superheat degree is controlled at 12 ℃, the pulling speed is controlled at 0.48m/min, dynamic light reduction is adopted, heavy reduction is adopted at the solidification tail end, the reduction force effectively penetrates into the center of the continuous casting billet, the reduction amounts of two sections at the solidification end point position of the continuous casting billet are respectively 5.6mm and 1.8mm, and the secondary cooling specific water amount is 0.64L/kg;

(2) and (3) cooling in a stacking manner: stacking and cooling the casting blank in a stacking and cooling pit for 42 h;

(3) rolling: heating at 1120-1250 ℃, heating for 362min, keeping the thickness of the blank to be heated 235mm, the initial rolling temperature at 850 ℃, and the final rolling temperature at 792 ℃, stacking for cooling after finish rolling, and stacking for 42 h;

(4) tempering: the quenching process is 930 ℃, the heat preservation time is 300min, the tempering process is 650 ℃, and the heat preservation time is 440 min.

The results of the property test of the produced steel are shown in table 1.

Example 2: production of 150mm steel plate

The steel has a chemical composition percentage of C =0.15%, Si =0.26%, Mn =1.16%, P =0.008%, S =0.002%, Nb =0.025%, Cr =0.68%, Ni =0.44%, Mo =0.45%, B =0.0017%, ALT =0.081%, and the balance of Fe and unavoidable impurities.

The key technology is as follows:

(1) continuous casting: the whole process of protective casting is carried out, the superheat degree is controlled to be 15 ℃, the pulling speed is controlled to be 0.52m/min, dynamic soft reduction is adopted, heavy reduction is adopted at the solidification tail end, the reduction force effectively penetrates into the center of the continuous casting billet, the reduction amounts of two sections at the solidification end point of the continuous casting billet are respectively 6.1mm and 2.2mm, and the secondary cooling specific water amount is 0.71L/kg.

(2) And (3) cooling in a stacking manner: and (5) stacking and cooling the casting blank in a stacking and cooling pit for 40 h.

(3) Rolling: heating temperature is 1150-1240 ℃, heating time is 388min, the thickness of the blank to be heated is 240mm, the initial rolling temperature is 840 ℃, the final rolling temperature is 790 ℃, stacking and stacking for cooling after finish rolling, and the stacking and cooling time is 45 h.

(4) Tempering: the quenching process is 930 ℃, the heat preservation time is 320min, the tempering process is 650 ℃, and the heat preservation time is 470 min.

The results of the property test of the produced steel are shown in table 1.

Table 1 results of property measurements of steels of examples

。

Claims

1. A production method of an ultra-thick steel plate with the strength of more than 550MPa is characterized by comprising the following steps: the steel comprises the following chemical components, by weight, 0.14-0.16% of C, 0.10-0.30% of Si, 1.10-1.20% of Mn, 0.015% or less of P, 0.003% or less of S, 0.020% to 0.030% of Nb, 0.60-0.80% of Cr, 0.40-0.50% of Ni, 0.40-0.60% of Mo, 0.0015-0.0020% of B, 0.07-0.09% of ALT, and the balance of Fe and inevitable impurities; the key process steps comprise:

(1) Continuous casting: the whole process is protected for casting, the superheat degree is controlled to be 8-20 ℃, the drawing speed is controlled to be 0.3-0.55 m/min, dynamic soft reduction is adopted, heavy reduction is adopted at the solidification tail end, the two-stage reduction amount at the solidification end point of the continuous casting billet is 5-7 mm and 1-3 mm respectively, and the secondary cooling specific water amount is 0.5-0.8L/kg;

(2) and (3) cooling in a heaped mode: stacking and cooling the casting blank in a stacking and cooling pit for 36-72 h;

(3) rolling: heating at 1100-1290 ℃, heating for 300-400 min, and keeping the blank thickness to be greater than 1.5T, wherein T is the thickness of a finished steel plate, and T = 100-150 mm; the initial rolling temperature is more than or equal to 840 ℃ and less than 860 ℃, the final rolling temperature is more than or equal to 790 ℃ and less than 800 ℃, the stacking and the cooling are carried out after the finish rolling, and the stacking and cooling time is more than 36 hours;