CN113444971A

CN113444971A - Mo-V synergistic easy-to-weld steel plate with tensile strength of 1000MPa and production method thereof

Info

Publication number: CN113444971A
Application number: CN202110700254.4A
Authority: CN
Inventors: 麻衡; 王中学; 何康; 杜传治; 霍孝新; 王月香; 于全成; 李艳
Original assignee: Laiwu Steel Group Yinshan Section Steel Co Ltd
Current assignee: Laiwu Steel Group Yinshan Section Steel Co Ltd
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2021-09-28
Anticipated expiration: 2041-06-23
Also published as: CN113444971B

Abstract

The invention relates to a Mo-V synergistic easy-welding steel plate with tensile strength of 1000MPa and a production method thereof, wherein the steel plate comprises the following chemical components in percentage by weight: 0.09-0.11 percent of C, 0.20-0.29 percent of Si, 1.2-1.5 percent of Mn, 0.20-0.50 percent of Cr, 0.61-0.71 percent of Mo, 0.050-0.070 percent of V, 0.20-0.50 percent of Ni0.020-0.050 percent of Nb, 0.01-0.025 percent of Ti, less than or equal to 0.011 percent of P, less than or equal to 0.003 percent of S, 0.0008-0.002 percent of B, 0.01-0.035 percent of Al, less than or equal to 0.006 percent of As, and the balance of Fe and inevitable impurities; the high-efficiency welding of 31-40kJ/cm heat input can be realized, and the service safety performance is ensured.

Description

Mo-V synergistic easy-to-weld steel plate with tensile strength of 1000MPa and production method thereof

Technical Field

The invention belongs to the field of welding steel, relates to an easily-welded steel plate with a Mo-V synergistic effect and a production method thereof, and particularly relates to an easily-welded steel plate with a tensile strength of 1000MPa and a production method thereof.

Background

With the development of engineering machinery to high parameters, the strength grade of structural steel is higher and higher, and ultrahigh-strength steel with the tensile strength of 900MPa gradually becomes a reduction trend. Because the martensite ultrahigh-strength steel plate product with the tensile strength of more than 900MPa has the characteristic of martensite structure, the welding difficulty is increased in the application process, the technical requirement is higher and higher, and particularly, the joint performance of the ultrahigh-strength steel plate with the tensile strength of more than 1000MPa cannot be ensured under the condition of welding heat input of 31kJ/cm, so that the corresponding steel material and welding become one of the key technologies for improving the product development speed.

The tensile strength grade of the existing steel for high-heat input welding is not more than 830MPa, the structure of the steel is a ferrite plus pearlite or acicular ferrite structure, an oxide metallurgy process method is adopted to induce intragranular ferrite in a coarse crystal area of a heat affected zone, original austenite grains are divided, the final structure is further refined, and the toughness is improved. However, for the martensite ultrahigh-strength steel plate with the tensile strength of more than 1000MPa, the base metal and the structure of the welding heat affected zone must be martensite completely to meet the requirement of welding performance, so that the process method for improving the toughness of the steel by introducing intragranular ferrite through oxide metallurgy in the prior art is not suitable any more. This is because, once the steel material forms intragranular ferrite, the strength of the welded joint tends to be greatly reduced, and the extremely high toughness matching requirement of the steel material under the high heat input condition of welding cannot be satisfied.

The welding heat input quantity is improved, so that the welding pass can be reduced, the welding efficiency is improved, and the welding cost is reduced. When the joint heat affected zone is heated to a temperature exceeding the temper tempering temperature under the welding heat cycle, a softened zone having a lower strength and hardness than the base material may occur, and the softened zone may become a weak zone of the joint strength, that is, a problem of softening of the welded joint may occur. In general, as the welding heat input amount is larger, the joint softening becomes more remarkable, and it becomes difficult to satisfy the index requirements relating to high tensile strength equivalent to those of the base material in the joint performance.

Chinese patent CN111375926A discloses a method for welding an ultrahigh-strength steel plate Q1150 of a hydraulic support, the welding heat input of the method is less than or equal to 1.25kJ/cm, and the welding efficiency is far lower than 31-40kJ/cm of the method.

Chinese patent CN111945077A discloses steel Q890D for ultra-high-strength engineering machinery and a production method thereof, wherein Mo of the related steel plate is 0.50-0.60% and is lower than 0.61-0.71% of the steel plate, V element is not contained, and meanwhile, the steel plate has no special requirement on As element influencing cold crack of steel plate welding, and the steel plate can not realize heat input 31-40kJ/cm linear energy welding in the continuous welding heat cycle process.

Chinese patents CN103589969A and CN103555911A respectively disclose a production method of a quenched and tempered high-strength Q890D super-thick steel plate and a production method of a quenched and tempered high-strength Q890E super-thick steel plate, wherein alloy elements such as Cu, Ni, Nb, V, Ti, Cr, Mo and the like are added in the design of alloy components, and the thickness specification of a final product is 100-120 mm. From the product thickness specification and the final product performance index, the product does not relate to a production method for welding a steel plate by heat input line energy of 31-40 kJ/cm.

Chinese patent CN106148822A discloses a method for producing a high-strength steel Q890 medium plate by on-line quenching, which focuses on parameters such as slab heating temperature, rolling process and the like, wherein the tempering temperature after quenching is 500 ℃, and the final steel plate structure is a dual-phase structure of lath martensite and lath bainite. Chinese patent CN105880834A discloses a welding method of Q890 high-strength steel, wherein the welding preheating temperature of a steel plate is 60-100 ℃, the interlayer temperature is controlled at 150-250 ℃, and the welded steel plate is tempered. Similarly, neither patent relates to a component design and a production process control method for welding the Q890 steel plate by heat input of 31-40kJ/cm linear energy.

Chinese patent CN111910127A discloses a Q890 steel plate for a hydraulic support meeting the welding heat input of 30kJ/cm and a production method thereof, wherein higher C element and Mn element greatly improve the welding cold crack sensitivity index Pcm value to deteriorate the performance of a welding joint, and meanwhile, no special requirement is provided for As element influencing the welding cold crack of the steel plate, and the welding heat input of the invention only reaches 30kJ/cm and is lower than the line energy of 31-40kJ/cm of the invention.

Chinese patent No. CN 109226941A discloses a GMAW welding method for a low-alloy ultrahigh-strength steel Q1100E sheet, wherein the content of C in the ultrahigh-strength steel Q1100E sheet is 0.15-0.20%, and meanwhile, no special requirements are imposed on As elements influencing steel plate welding cold cracks. In the continuous welding heat cycle process of the steel plate, the welding heat input is 7-13 kJ/cm, and the welding efficiency is low.

Therefore, how to obtain a high-strength steel sheet that combines a high heat input and good joint performance in welding becomes one of the key problems to be solved urgently.

Disclosure of Invention

Aiming at the technical requirements, the invention provides the super-strength steel plate with the tensile strength of more than 1000MPa and the production method thereof by adopting the component design under the Mo-V synergistic action, the steel plate can realize the high-welding heat input of 31-40kJ/cm linear energy welding, the tensile strength of a welding joint is not lower than 980MPa, and the impact energy of a heat affected zone at-20 ℃ is not lower than 60J.

In order to achieve the purpose, the invention adopts the following technical scheme:

the tensile strength of the easy-to-weld steel plate with the Mo-V synergistic effect is 1000MPa, and the easy-to-weld steel plate comprises the following chemical components in percentage by weight: 0.09-0.11 percent of C, 0.20-0.29 percent of Si, 1.2-1.5 percent of Mn, 0.20-0.50 percent of Cr, 0.61-0.71 percent of Mo, 0.050-0.070 percent of V, 0.20-0.50 percent of Ni, 0.020-0.050 percent of Nb0.020-0.025 percent of Ti, less than or equal to 0.011 percent of P, less than or equal to 0.003 percent of S, 0.0008-0.002 percent of B, 0.01-0.035 percent of Al, less than or equal to 0.006 percent of As, and the balance of Fe and inevitable impurities.

As a preferred embodiment, the easily-welded steel plate comprises the following chemical components in percentage by weight: 0.09-0.11 percent of C, 0.21-0.25 percent of Si, 1.21-1.5 percent of Mn, 0.31-0.50 percent of Cr0.31, 0.65-0.70 percent of Mo, 0.055-0.068 percent of V, 0.35-0.48 percent of Ni, 0.035-0.045 percent of Nb0.015-0.020 percent of Ti, less than or equal to 0.011 percent of P, less than or equal to 0.003 percent of S, 0.0009-0.0014 percent of B, 0.015-0.030 percent of Al, 0.0035-0.0055 percent of As, and the balance of Fe and inevitable impurities.

As a preferable embodiment, the easy-welding steel plate has the tensile strength of more than or equal to 1000MPa, the elongation of more than or equal to 13 percent and the impact energy of more than or equal to 160J at the temperature of minus 20 ℃.

According to a preferable embodiment, after the easily-welded steel plate is welded by heat input with 31-40kJ/cm linear energy, the tensile strength of a welding joint is more than or equal to 980MPa, and the impact energy of a heat affected zone at 20 ℃ below zero is more than or equal to 60J.

In order to improve the strength of a welding joint of a steel plate under the condition of high heat input, the Mo-V synergistic effect is innovatively utilized, a nano phase is formed in the tempering process, the precipitation strengthening effect of V is enhanced, the dislocation recovery is hindered, and the tempering resistance is further improved. The easily welded steel plate comprises the following elements:

(1) mo: the Mo element can obviously hinder the recovery of dislocation in martensite and improve the tempering resistance of steel, so that the hardness of tempered martensite phases in a tempering area and an incomplete quenching area is reduced slowly; meanwhile, Mo and microalloy elements can form a nano composite precipitated phase to slow down the coarsening rate of the precipitated phase, so that higher precipitation strengthening is provided to make up for the strength loss caused by dislocation recovery.

(2) V: v is added to obtain a nanoscale VC precipitated phase in a tempered martensite matrix, and not only does V generate a precipitation strengthening effect, but also can block dislocation recovery, thereby further improving the tempering resistance; when V is added in combination with Mo, the above effect is more remarkable.

Compared with Nb and Ti, V has higher solid solubility in austenite, can be completely dissolved at normal quenching temperature (about 900 ℃), is precipitated to form a nano phase in the subsequent tempering process, and generates larger precipitation strengthening effect; however, Nb and Ti can only be partially dissolved in a solid solution, so that a few nano precipitated phases are formed in the tempering process, and the size of an undissolved precipitated phase is large, so that the total precipitation strengthening effect of Nb and Ti is not as good as that of V microalloying.

(3) C: carbon has an obvious effect on improving the hardenability of steel, but the higher carbon content can improve the carbon equivalent of the steel and the welding cold crack sensitivity index Pcm value, so that the welding performance is poor, therefore, on the basis of giving consideration to the obdurability and the welding performance, the carbon content of the ultrahigh-strength steel plate with the tensile strength of 1000MPa is reasonably designed to be within the range of 0.09-0.11%, and the hardenability and the strength of the steel are provided through the synergistic effect of C, Mn, Ni, Cr, Nb, V, Alt, Ti, Mo and B.

(4) As: as can reduce impact toughness in steel, increase the brittleness of steel, and has great influence on welding performance and cold brittleness increase, so that high-heat input welding is realized for the ultrahigh-strength steel plate, and the content of As is controlled to be less than or equal to 0.0006 percent.

The easily-welded steel plate provided by the invention has high welding efficiency and service safety performance, namely, the welding heat input of the easily-welded steel plate is 31-40kJ/cm, so that high-efficiency welding is realized; the strength of the welding joint is more than or equal to 980MPa, and the service safety performance is ensured.

The invention also provides a production method of the easy-welding steel plate, which adopts the following technical scheme:

the production method of the easy-welding steel plate sequentially comprises the following steps: smelting, casting, heating a plate blank, rolling and carrying out heat treatment; wherein the content of the first and second substances,

in the rolling process, the heated plate blank is rolled, the rolling comprises rough rolling and finish rolling, the initial rolling temperature of the finish rolling stage is 890-930 ℃ (for example, 895 ℃, 900 ℃, 910 ℃ and 920 ℃), and the accumulated reduction of the finish rolling stage is ensured to be more than or equal to 40%.

In the above production method, as a preferred embodiment, in the smelting process, the smelting includes molten iron desulphurization, primary smelting, refining and vacuum degassing treatment; the vacuum degassing treatment is performed in an RH furnace.

In the above production method, as a preferred embodiment, in the casting step, the molten steel obtained in the smelting step is continuously cast, and the continuous casting is performed under the protection of argon in the whole process to obtain a slab; preferably, the casting adopts a light reduction technology to ensure the internal quality of the casting blank, and the superheat degree of the casting is controlled to be 10-20 ℃ (for example, 12 ℃, 15 ℃, 16 ℃ and 18 ℃), preferably 13-18 ℃ (for example, 14 ℃, 15 ℃, 16 ℃ and 17 ℃).

In the above production method, as a preferable embodiment, the reduction in the casting step is 5 to 6 mm.

In the above production method, as a preferred embodiment, in the slab heating step, the slab obtained in the casting step is heated and then rolled; the heating temperature is 1180 to 1240 ℃ (e.g., 1190 ℃, 1200 ℃, 1210 ℃, 1220 ℃, 1230 ℃).

In the above production method, as a preferred embodiment, in the slab heating step, the heating time is calculated according to 9-10 min/cm to ensure that the steel slab is uniformly and thoroughly burnt, and the soaking time is 70-85 min (for example, 72min, 75min, 78min, 80min, 82min, 84 min).

In the above production method, as a preferred embodiment, in the slab heating step, the temperature of the slab before charging is controlled to 240 ℃ to 270 ℃ (for example, 245 ℃, 250 ℃, 260 ℃, 265 ℃).

According to the invention, the temperature of the slab before entering the furnace is controlled so as to reduce the heating rate and prevent the slab from being broken due to the excessively high temperature rise speed.

In the above production method, as a preferred embodiment, in the rolling step, the rough rolling stage is subjected to complete recrystallization rolling at 1000 ℃ or higher, that is, the initial rolling temperature in the rough rolling stage is 1000 ℃ or higher, and is preferably 1000 to 1080 ℃ (for example, 1010 ℃, 1020 ℃, 1050 ℃, 1060 ℃, 1070 ℃).

In the above production method, as a preferable embodiment, in the rolling step, the cumulative rolling reduction at the finish rolling stage is secured at 40% to 70% (for example, 45%, 50%, 55%, 60%, 65%).

In the above production method, as a preferred embodiment, in the rolling step, the rolling temperature at the finish rolling stage is controlled to 890 to 930 ℃ (e.g., 895 ℃, 900 ℃, 910 ℃, 920 ℃).

In the above production method, as a preferred embodiment, in the rolling step, two-stage rolling is performed by a wide and thick plate rolling mill, and the rolled plate is air-cooled to room temperature.

In the above production method, as a preferred embodiment, in the heat treatment step, the rolled steel sheet is quenched at 900 to 920 ℃ (for example, 905 ℃, 910 ℃ and 915 ℃), preferably 910 ℃, and the holding time is 2.2H ± 5min, wherein H is the thickness of the steel sheet, and good strength and structure of the easily weldable steel sheet base material are ensured; and then tempering at 600-650 ℃ (for example, 610 ℃, 620 ℃, 630 ℃ and 640 ℃), and keeping the temperature for 1.8H +/-5 min, wherein H is the thickness of the steel plate, so that good toughness matching of the easily welded steel plate base material is ensured.

In the above production method, as a preferable embodiment, the steel sheet has a thickness of 10mm to 40mm (for example, 15mm, 20mm, 25mm, 30mm, 35 mm).

In the above production method, as a preferred embodiment, the tensile strength of the steel sheet after the heat treatment in the heat treatment step is not less than 1000 MPa.

In the above production method, as a preferred embodiment, the production method further includes a welding step of joining at least two heat-treated steel sheets by the welding step; the form of the steel plate welding groove is V-shaped or X-shaped.

In the above production method, as a preferred embodiment, in the welding step, after welding with a heat input of 31 to 40kJ/cm, the inter-pass temperature is 100 to 150 ℃ (e.g., 110 ℃, 120 ℃, 130 ℃, 140 ℃), the tensile strength of the welded joint is not less than 980MPa, and the heat affected zone-20 ℃ impact energy is not less than 60J.

In the invention, the temperature between the selected channels is 100-150 ℃ when the steel plate is welded, thereby preventing the inter-channel temperature from being too high and easily heating a welding heat affected zone continuously and performing high-temperature thermal cycle, causing the growth of crystal grains and the reduction of strength; meanwhile, the low welding efficiency caused by the excessively low inter-lane temperature is avoided.

The chemical components of the easily welded steel plate are innovatively designed, so that the stability of the welded structure is ensured, and the high-toughness requirement of the easily welded steel plate finished product is met under the condition of large heat input.

In the invention, the technical characteristics can be freely combined to form a new technical scheme under the condition of not conflicting with each other.

Techniques not described in the present invention employ conventional techniques in the art.

Compared with the prior art, the invention has the following beneficial effects:

(1) the easily-welded steel plate provided by the invention belongs to an ultrahigh-strength steel plate, has excellent tempering softening energy resistance, has the tensile strength not lower than 1000MPa after being tempered within the range of 600-650 ℃, and provides a foundation for the tensile strength of a heat affected zone not lower than 980MPa in the welding heat cycle process.

(2) The easily-welded steel plate provided by the invention realizes efficient welding of 31-40kJ/cm heat input, the strength of a welding joint is more than or equal to 980MPa, and the service safety performance is ensured.

Drawings

FIG. 1 is a metallographic structure diagram of a steel sheet obtained after heat treatment in example 1 of the present invention.

FIG. 2 is a metallographic structure diagram of a steel sheet after welding in example 1 of the present invention, wherein (a) to (d) are metallographic structure diagrams of a weld metal region, a weld line region, a HAZ superheated region, and a HAZ fine grain region, respectively.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are only for the purpose of the present invention and are not intended to limit the scope of the present invention. It should be understood that various changes and modifications can be made by those skilled in the art after reading the disclosure of the present invention, and equivalents fall within the scope of the appended claims.

Example 1

The embodiment provides a Q890D easily welded steel plate with a Mo-V synergistic effect and a tensile strength of 1000MPa, wherein the steel comprises the following chemical components in percentage by mass: 0.09% of C, 0.22% of Si, 1.30% of Mn, 0.35% of Cr, 0.66% of Mo, 0.065% of V, 0.40% of Ni, 0.35% of Nb, 0.02% of Ti, 0.008% of P, 0.001% of S, 0.0009% of B, 0.015% of Al, 0.0035% of As, and the balance of Fe and inevitable impurities. The thickness of the easy-welding steel plate is 16 mm.

The production method of the Mo-V synergistic easy-welding steel plate with the tensile strength of 1000MPa comprises the following steps: smelting, casting, slab heating, rolling (including rough rolling and finish rolling), heat treatment (including quenching and tempering), and welding, specifically,

the smelting comprises the following steps: molten iron desulfurization, primary smelting, refining and vacuum degassing treatment; firstly, carrying out molten iron desulphurization treatment on molten iron containing various elements, then conveying the molten iron to a converter for primary refining, then conveying the molten iron to an LF refining furnace for refining, and carrying out vacuum treatment on the molten iron in a vacuum degassing furnace (RH furnace) after refining is finished;

casting: the continuous casting adopts the whole-process argon protection casting, the internal quality of a casting blank is ensured by adopting a soft reduction technology, the casting superheat degree is controlled at 18 ℃, and a plate blank with the thickness of 250mm is obtained. Wherein the reduction in the casting process is 5-6 mm.

Heating the plate blank: the temperature of the plate blank before entering the furnace is controlled at 260 ℃, the heating temperature of the plate blank is 1220 ℃, the heating reference time is 9min/cm to ensure that the steel blank is evenly and completely burnt, the soaking time is 80min, and the plate blank is rolled after being heated.

Rolling: the two-stage rolling is completed by using a 4300mm wide and thick plate rolling mill. And performing complete recrystallization rolling in the rough rolling stage, wherein the rough rolling temperature is 1000 ℃. The initial rolling temperature of the finish rolling stage is controlled to be 930 ℃, the final rolling temperature is controlled to be 890 ℃, and the accumulated reduction of the finish rolling stage is not lower than 60%. And air-cooling to room temperature after rolling.

And (3) heat treatment: and quenching and tempering the steel plate obtained after rolling. Wherein in the quenching treatment, the steel plate is heated to the quenching temperature of 910 ℃, the heat preservation time in the furnace is 40.2min, and then the steel plate is water-quenched to the room temperature. In the tempering treatment, the tempering temperature is 650 ℃, the heat preservation time is 33.8min, and the air cooling is carried out to the room temperature after the heat preservation; a steel sheet having a thickness of 16mm was obtained and had a tensile strength of 1060MPa, an elongation of 14%, and an impact energy of 214J at 20 ℃. The structure of the heat-treated steel sheet (i.e., the base material Q890D) is a martensite structure, as shown in fig. 1.

Welding: connecting at least two heat-treated steel plates through a welding process; after the steel plate is subjected to groove V-shaped welding at the preheating temperature of 120 ℃, the maximum welding heat input is 32kJ/cm, the inter-channel temperature is 130 ℃, the tensile strength of a welding joint reaches 995MPa, and the heat affected zone has the impact energy of 75J at the temperature of-20 ℃.

FIG. 2 shows a sectional structure diagram of a welded steel plate, in which (a) is a weld metal region, (b) is a weld line region, (c) is a HAZ superheated zone region, and (d) is a HAZ fine grain zone region. As can be seen from figure 2, the welded steel plate has no cold cracks, and the tensile strength of the welded joint is high, so that the softening resistance effect of the welded joint under the condition of thermal cycle is realized, and the use expectation of a user is better met.

Example 2

A Q890D easily welded steel plate with a Mo-V synergistic action tensile strength of 1000MPa is disclosed, wherein the steel comprises the following chemical components in percentage by mass: 0.10% of C, 0.25% of Si, 1.5% of Mn, 0.40% of Cr, 0.70% of Mo, 0.059% of V, 0.35% of Ni, 0.40% of Nb, 0.020% of Ti, 0.006% of P, 0.002% of S, 0.0012% of B, 0.025% of Al, 0.004% of As, and the balance of Fe and inevitable impurities. The thickness of the easy-welding steel plate is 30 mm.

casting: and continuously casting the molten steel obtained by smelting, wherein the whole-process argon protection casting is adopted for continuous casting, the internal quality of a casting blank is ensured by adopting a soft reduction technology, the casting superheat degree is controlled at 15 ℃, and a plate blank with the thickness of 250mm is obtained. . Wherein the reduction in the casting process is 5-6 mm.

Heating the plate blank: the temperature of the plate blank before the plate blank is put into the furnace is controlled at 240 ℃, the heating temperature of the plate blank is 1230 ℃, the heating reference time is 9.5min/cm to ensure that the steel blank is uniformly and completely burnt, the soaking time is 70min, and the plate blank is rolled after being heated.

Rolling: the two-stage rolling is completed by using a 4300mm wide and thick plate rolling mill. And in the rough rolling stage, complete recrystallization rolling at the temperature of more than or equal to 1000 ℃ is carried out. The initial rolling temperature of the finish rolling stage is controlled at 900 ℃, and the accumulated reduction of the stage is ensured to be not less than 50%. And air-cooling to room temperature after rolling.

And (3) heat treatment: and quenching and tempering the steel plate obtained after rolling. Wherein in the quenching treatment, the steel plate is heated to the quenching temperature of 920 ℃, the heat preservation time in the furnace is 66min, and then the steel plate is water-quenched to the room temperature. In the tempering treatment, the tempering temperature is 620 ℃, the heat preservation time is 59min, the steel plate with the thickness of 30mm is obtained after the heat preservation and the air cooling to the room temperature, and the tensile strength of the steel plate is 1100MPa, the elongation is 13.5 percent, and the impact energy is 184J at 20 ℃. The structure of the heat-treated steel sheet (i.e., the base material Q890D) is a martensite structure.

Welding: connecting at least two heat-treated steel plates through a welding process; the steel plate is welded in a groove X shape, the preheating temperature is 130 ℃, the maximum welding heat input is 39.6kJ/cm, and the inter-channel temperature is 145 ℃; after welding, the tensile strength of a welding joint reaches 986MPa, and the impact energy of a heat affected zone is 80J at minus 20 ℃.

Cold cracks do not appear in a welding seam metal area, a fusion line area, an HAZ overheating area and an HAZ fine grain area of the welded steel plate, the tensile strength of the welded joint is high, the softening resistance effect of the welded joint under the thermal cycle condition is achieved, and the use expectation of a user is better met.

Example 3

A Q890D easily welded steel plate with a Mo-V synergistic action tensile strength of 1000MPa is disclosed, wherein the steel comprises the following chemical components in percentage by mass: 0.11% of C, 0.21% of Si, 1.22% of Mn, 0.41% of Cr, 0.70% of Mo, 0.068% of V, 0.45% of Ni, 0.38% of Nb, 0.018% of Ti, 0.010% of P, 0.003% of S, 0.0009% of B, 0.030% of Al, 0.0052% of As, and the balance of Fe and inevitable impurities. The thickness of the easy-welding steel plate is 40 mm.

casting: the continuous casting adopts the whole-process argon protection casting, the internal quality of a casting blank is ensured by adopting a soft reduction technology, the casting superheat degree is controlled at 13 ℃, and a plate blank with the thickness of 250mm is obtained. . Wherein the reduction in the casting process is 5-6 mm.

Heating the plate blank: the temperature of the slab before entering the furnace is controlled at 270 ℃, the heating temperature of the slab is 1210 ℃, the heating reference time is 10min/cm to ensure that the steel slab is evenly and completely burnt, the soaking time is 85min, and the rolling is carried out after heating.

Rolling: the two-stage rolling is completed by using a 4300mm wide and thick plate rolling mill. And in the rough rolling stage, complete recrystallization rolling at the temperature of more than or equal to 1000 ℃ is carried out. The initial rolling temperature of the finish rolling stage is controlled at 890 ℃, and the accumulated reduction of the stage is ensured to be not lower than 40%. And air-cooling to room temperature after rolling.

And (3) heat treatment: and quenching and tempering the steel plate obtained after rolling. Wherein in the quenching treatment, the steel plate is heated to the quenching temperature of 910 ℃, the heat preservation time in the furnace is 93min, and then the steel plate is water-quenched to the room temperature. In the tempering treatment, the tempering temperature is 640 ℃, the heat preservation time is 72min, the steel plate with the thickness of 30mm is obtained after heat preservation and air cooling to the room temperature, and the tensile strength of the steel plate is 1150MPa, the elongation is 15.5 percent, and the impact energy of the steel plate is 166J at 20 ℃. The structure of the heat-treated steel sheet (i.e., the base material Q890D) is a martensite structure.

Welding: connecting at least two heat-treated steel plates through a welding process; the steel plate is welded in a groove form V shape, the preheating temperature is 140 ℃, the maximum welding heat input is 33.5kJ/cm, and the inter-channel temperature is 150 ℃; after welding, the tensile strength of a welding joint reaches 1060MPa, and the impact energy of a heat affected zone is 88J at minus 20 ℃.

As can be seen from the examples 1-3, the ultrahigh-strength steel plate produced according to the requirements of the component design, the rolling process and the heat treatment process meets the requirements that the thickness is 10-40 mm, the tensile strength is not lower than 1000MPa, and the impact energy at-20 ℃ is not lower than 150J; after the welding is carried out at the preheating temperature of 100-160 ℃, the maximum welding heat input is 31-40kJ/cm, the groove is V-shaped or X-shaped, the inter-channel temperature is 100-150 ℃, the welding joint is not lower than 980MPa, and the impact energy of a heat affected zone at-20 ℃ is not lower than 60J. The steel plate has the advantages of high strength and good toughness, can realize high-efficiency construction with the maximum heat input of welding of 31-40kJ/cm, realizes the softening resistance effect of a welding joint under a thermal cycle condition, better meets the use expectation of a user, and fills the domestic blank in the specification of products manufactured by adopting the production technology.

The method can be realized by upper and lower limit values and interval values of intervals of process parameters (such as temperature, time and the like), and embodiments are not listed.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Variations and modifications to these embodiments may occur to those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. An easy-to-weld steel plate with tensile strength of 1000MPa and Mo-V synergistic effect is characterized in that,

the easy-welding steel plate comprises the following chemical components in percentage by weight: 0.09 to 0.11 percent of C, 0.20 to 0.29 percent of Si, 1.2 to 1.5 percent of Mn, 0.20 to 0.50 percent of Cr, 0.61 to 0.71 percent of Mo, 0.050 to 0.070 percent of V, 0.20 to 0.50 percent of Ni, 0.020 to 0.050 percent of Nb, 0.01 to 0.025 percent of Ti, less than or equal to 0.011 percent of P, less than or equal to 0.003 percent of S, 0.0008 to 0.002 percent of B, 0.01 to 0.035 percent of Al, less than or equal to 0.006 percent of As, and the balance of Fe and inevitable impurities.

2. The easy-to-weld steel sheet according to claim 1,

the easy-welding steel plate comprises the following chemical components in percentage by weight: 0.09-0.11 percent of C, 0.21-0.25 percent of Si, 1.21-1.5 percent of Mn, 0.31-0.50 percent of Cr, 0.65-0.70 percent of Mo, 0.055-0.068 percent of V, 0.35-0.48 percent of Ni, 0.035-0.045 percent of Nb, 0.015-0.020 percent of Ti, less than or equal to 0.011 percent of P, less than or equal to 0.003 percent of S, 0.0009-0.0014 percent of B, 0.015-0.030 percent of Al, 0.0035-0.0055 percent of As, and the balance of Fe and inevitable impurities;

preferably, the tensile strength of the easily welded steel plate is more than or equal to 1000MPa, the elongation is more than or equal to 13%, and the impact energy at the temperature of minus 20 ℃ is more than or equal to 160J;

preferably, after the easily welded steel plate is welded through heat input with the linear energy of 31-40kJ/cm, the tensile strength of a welding joint is more than or equal to 980MPa, and the impact energy of a heat affected zone at the temperature of-20 ℃ is more than or equal to 60J.

3. A method for producing an easily weldable steel sheet according to any one of claims 1 to 2,

the production method sequentially comprises the following steps: smelting, casting, heating a plate blank, rolling and heat treating,

in the rolling procedure, the heated plate blank is rolled, the rolling comprises rough rolling and finish rolling, the initial rolling temperature in the finish rolling stage is 890-930 ℃, and the accumulated reduction of the finish rolling stage is ensured to be more than or equal to 40%.

4. The method for producing easily weldable steel sheet according to claim 3,

in the smelting process, the smelting comprises molten iron desulphurization, primary smelting, refining and vacuum degassing treatment; the vacuum degassing treatment is performed in an RH furnace.

5. The method for producing easily weldable steel sheet according to claim 3 or 4,

in the casting process, the molten steel obtained in the smelting process is continuously cast, and the continuous casting adopts the whole-process argon protection casting to obtain a plate blank;

preferably, the casting adopts a light reduction technology to ensure the internal quality of a casting blank, and the casting superheat degree is controlled at 10-20 ℃, preferably 13-18 ℃;

preferably, the reduction in the casting step is 5 to 6 mm.

6. The method for producing easily weldable steel sheet according to any one of claims 3 to 5,

in the slab heating procedure, a slab obtained in the casting procedure is heated and then rolled, and the heating temperature is 1180-1240 ℃;

preferably, in the slab heating procedure, the heating time is calculated according to 9-10 min/cm, and the soaking time is 70-85 min;

preferably, in the slab heating step, the temperature of the slab before charging is controlled to 240 to 270 ℃.

7. The method for producing easily weldable steel sheet according to any one of claims 3 to 6,

in the rolling procedure, the initial rolling temperature in the rough rolling stage is more than or equal to 1000 ℃, and preferably 1000-1080 ℃;

preferably, in the rolling procedure, the accumulated reduction in the finish rolling stage is ensured to be 40-70%;

preferably, in the rolling step, the two-stage rolling is performed by a wide and thick plate rolling mill, and the rolled plate is air-cooled to room temperature.

8. The method for producing an easily weldable steel sheet according to any one of claims 3 to 7, wherein in the heat treatment step, the rolled steel sheet is quenched at 900 to 920 ℃, preferably 910 ℃, for 2.2H ± 5min, where H is the thickness of the steel sheet; then tempering at 600-650 ℃, and keeping the temperature for 1.8H +/-5 min, wherein H is the thickness of the steel plate;

preferably, the thickness of the steel plate is 10mm to 40 mm.

9. The method for producing easily weldable steel sheet according to any one of claims 3 to 8, further comprising a welding step of joining at least two heat-treated steel sheets by the welding step; the form of the steel plate welding groove is V-shaped or X-shaped.

10. The method for producing an easily weldable steel sheet according to any one of claims 3 to 9, wherein, in the welding step, after the heat-treated steel sheet is welded by heat input at a heat input of 31 to 40kJ/cm, the inter-track temperature is 100 to 150 ℃, the tensile strength of the welded joint is not less than 980MPa, and the heat-affected zone-20 ℃ impact energy is not less than 60J.