JP2023505172A - Hot-rolled H-shaped steel based on beam blank rolling forming and its preparation method - Google Patents

Abstract

The present invention discloses a method for making hot-rolled H-shaped steel based on beam blank rolling forming, and its chemical composition, in weight percent, is C: 0.04-0.08, Si: ≤ 0.25, Mn : 1.25 to 1.45, V: 0.04 to 0.10, Ni: 0.2 to 1.0, P: ≤ 0.02, S: ≤ 0.01, Nb: 0.02 to 0 .06, Al: 0.02 to 0.06, N: ≤ 0.015, O: ≤ 0.005, the balance being iron (Fe) and unavoidable impurities, yielding the upper and lower flanges of the H-shaped steel The strength is ≧420 MPa, the transverse impact energy is ≧34 J at −40° C., and the longitudinal impact energy is ≧120 J at −60° C. The method for producing the H-shaped steel includes step 1) of performing smelting and continuous casting steps of smelting in a converter and casting into a deformed continuous casting billet using LF refining, a heating step, a rolling step, and a rolling step 1). a step 2) of performing a rolling process including a post-cooling process; The low-temperature resistant H-shaped steel product for marine engineering according to the present invention has good mechanical properties, is easy to manufacture industrially, reduces the demands on rolling mills, and is suitable for use in areas with extreme temperature conditions. [Selection drawing] Fig. 1

Description

[Cross reference to related applications]
This application claims priority from Chinese Patent Application No. 2019112501386 filed on Dec. 9, 2019, the entire content of which is incorporated herein by reference.
[Field of Invention]
The present invention belongs to the field of metallurgical technology, and specifically relates to hot-rolled H-shaped steel based on beam blank rolling forming and its preparation method. The present invention is based on fabrication processes and molding methods.

With the increasing demand for oil and natural gas resources, offshore oil platforms are gradually expanding into complex climate regions, and the construction quality and requirements of platforms are becoming more and more stringent. Therefore, hot-rolled H-beam steels used in platform construction are not only in increasing demand, but are also placing higher requirements on their toughness in low-temperature environments. Currently, the hot-rolled H-shaped steels used at home and abroad are for longitudinal impacts, with the requirements for impact toughness mainly found along the rolling direction. The H-shaped steel has a complicated shape, a complicated structure change, and a relatively large difference in structure along the lateral direction of the flange. don't ask for However, with the development of engineering, the structure of the platform has become more complex, and in consideration of the changing local conditions of use, higher requirements are also being demanded for the index of lateral impact toughness. and projects with high lateral impact toughness profiles are prevalent.

In the case of medium and large standard H-shaped steel, beam blank rolling is often used, and in the case of microalloy application in the field of manufacturing H-shaped steel, it is more difficult to secure the structure. , a combination of many factors ultimately affect the lateral impact toughness. In particular, when produced industrially, there is a certain problem of stability. Various patents propose different technical concepts to ensure lateral impact differentials.

WO 2005/030300 discloses a hot rolled H-shaped steel for use in offshore natural gas mining platform construction and a method for producing the same, and in one aspect of the invention, a hot rolled H-section steel for use in offshore natural gas mining platform construction. Provide shape steel. Said hot rolled H-beam steel has the following chemical composition in weight percent: Its chemical composition is C: 0.10 to 0.17, Si: 0.10 to 0.40, Mn: 1.00 to 1.60, P ≤ 0.025, S ≤ 0.015, Nb: 0 .02-0.05, Ti≤0.025, the rest being iron and unavoidable impurities. Regarding the mechanical properties of the hot-rolled H-shaped steel of the offshore natural gas mining platform structure according to the invention, the lateral and longitudinal impact energies and surface quality at -20° C. It can fully meet the technical requirements of shape steel. However, in the present invention, the design of medium carbon and Nb, Ti composite microalloy components is mainly used, and due to the influence of the Nb, Ti composite microalloy mechanism, the rolling force in the actual rolling process is large, and the rolling equipment is affected. Relatively high demand.

In Patent Document 2, a method for rolling a niobium-containing H-shaped steel is disclosed. The method utilizes the principles of physical metallurgy of metals to adjust and optimize the normal process conditions, using controlled rolling of the recrystallized region and controlled rolling of the unrecrystallized region to control the amount of deformation in a single pass. Then, ferrite is nucleated in the deformation zone to obtain fine ferrite grains, thereby uniformly refining the metal structure to obtain H-shaped steel with high strength, high toughness and high weldability. The resulting H-shaped steel has a tensile strength of 490-610 MPa and a lateral impact energy of 34-98 J at -20°C, which meets the requirements of American Petroleum Institute platform design standard II steel. However, this invention has strict control conditions for deformation temperature and deformation amount, and similarly increases the load on the rolling mill, making it difficult to adjust the reduction amount in real time. large, volatile, and significantly lower product acceptance rates.

In short, it is necessary to carry out a targeted design for the smelting and rolling process of H-shaped steel made by rolling beam blanks, not only to meet the smelting demand and reduce the rolling load, but also to reduce the post-rolling The texture should also have relatively high lateral impact toughness at constant low temperature conditions.

China Patent No. 103556055 Chinese Patent Application Publication No. 1421286

In order to meet the construction demands of offshore oil platforms in different regions and harsh and complex environments, the present invention provides a hot-rolled H-section steel and its fabrication method based on beam blank rolling forming. The technical solution of the present invention is as follows.

A method of making a hot rolled H-shaped steel based on beam blank roll forming, said H-shaped steel having the following chemical composition in weight percent: Its chemical composition is C: 0.04-0.08, Si: ≤0.25, Mn: 1.25-1.45, V: 0.04-0.10, Ni: 0.2-1. 0, P: ≤0.02, S: ≤0.01, Nb: 0.02 to 0.06, Al: 0.02 to 0.06, N: ≤0.015, O: ≤0.005 and the balance is iron (Fe) and unavoidable impurities.

Preferably, the chemical components (wt%) of the molten steel are C: 0.05 to 0.07, Si: ≤0.25, Mn: 1.25 to 1.45, V: 0.04 to 0.06, Ni: 0.2 to 0.7, P: ≤0.02, S: ≤0.01, Nb: 0.02 to 0.04, Al: 0.02 to 0.05, N: ≤0.015 , O: ≤ 0.005.
The production making process mainly includes the steps of converter smelting, LF refining, continuous casting and hot rolling forming, the steps of which are as follows:

Step 1) Smelting and continuous casting process:
Cast into deformed continuous casting billet using converter smelting and LF refining, the rest is iron and inevitable impurities, the liquid level of the tundish in the continuous casting process is 900mm ~ 950mm, and the full protection casting process is used. , the drawing speed is controlled to 0.7-1.3 m/min.

Step 2) Rolling process:
In the heating process, the deformed continuous casting billet is heated by a digitally controlled heating furnace, removed from the furnace, and then descaled using high-pressure water,
In the rolling process, rough rolling uses water cooling to control cooling, precision rolling uses temperature waiting rolling and water cooling controlled rolling, and the rolling reduction of the non-recrystallized region is greater than 30%, preferably 30 to 45. %, activating the cooling devices before and after the rolling mill to forcefully cool the lower leg of the H-shaped steel, and control the final rolling temperature at 750° C.-820° C.;
In the cooling process, according to the difference in standards, after rolling, the shaped steel is divided into standards and air-cooled or water-cooled. After the temperature of the shaped steel drops below 100°C, it is straightened by a straightening machine. Finally, the shaped steel is cut into standard lengths and stacked into bands to ring

Preferably, the heating temperature in step 2) is controlled to 1220° C. to 1260° C., and the heating time is 90 to 180 minutes.

Preferably, the rolling start temperature of the rough rolling in step 2) is controlled to 1030° C. to 1130° C., and the number of rolling passes is 5 to 7.

Preferably, the rolling start temperature of precision rolling in step 2) is controlled to 900° C. to 1000° C., and the number of rolling passes for precision rolling is set to 3 to 5 passes.

Preferably, in step 2), the lower leg of the H-shaped steel is forcibly cooled using a water tap, the temperature difference between the upper and lower legs is controlled within the range of ≤ 10 ° C, and the final rolling temperature is 780 ° C ~ Control at 810°C. The present invention provides a low-temperature resistant H-shaped steel product with high lateral impact toughness based on beam blank rolling in combination with hole-type controlled rolling of shaped steel by design of low carbon and V and Nb, Al microalloy process. Realize and industrially produce and manufacture H-shaped steel products with a flange thickness of 18 mm to 24 mm. According to an embodiment of the present invention, the method for producing low-temperature resistant H-shaped steel for marine engineering with high lateral impact toughness includes converter smelting, LF refining, full protection continuous casting, rough rolling and precision rolling. Including rolling processes such as rolling and online water cooling control processes.

The present invention uses a low carbon and V, Nb microalloy controlled rolling process to industrially produce H-shaped steel products with a standard flange thickness of 18 mm to 24 mm, and controls recrystallization rolling with Nb to perform precision rolling. In combination with temperature control, the matrix structure is refined to obtain a fine and uniform ferrite structure. Ensure that the hot-rolled H-shaped steel of the standard has high lateral impact toughness.

Any other processes that do not refer to the present invention can use conventional techniques.

Compared with the conventional low-temperature resistant H-shaped steel and production method required for lateral impact toughness, the advantages of the technical solution of the present invention are as follows.

1. A hot-rolled H-shaped steel for marine engineering with a tensile strength of 510 MPa or more is obtained by using a fine grain strengthening and precipitation strengthening mechanism and having a composite microalloy component design that is more suitable for producing a fine grain structure. .

2. In all processes, the cooling process is controlled online, combined with the rolling of recrystallized and non-recrystallized regions, adapted to the design of Nb, V, Al, Ni microalloy components, low temperature resistant hot rolling H-shaped It is suitable for making section steel and ensures high lateral impact toughness.

3. Average rolling force is reduced by 10% to 30% compared to chemical composition designs in other patents, making it easier to manufacture industrially and reducing the demands on rolling equipment.

4. The low temperature resistant H-shaped steel product for marine engineering according to the present invention has good mechanical properties, a tensile strength greater than 510 MPa, especially a lateral impact energy greater than 34 J at -40 ° C. Longitudinal impact energy greater than 120 J at 60°C, suitable for use in areas with extreme temperature conditions.

Fig. 2 shows the microstructure of a flange thickness of 24 mm according to the present invention;

The present invention will now be described with reference to specific examples. It should be noted that the examples are for further explanation of the present invention and do not limit the protection scope of the present invention. belongs to the protection scope of the invention.

The continuously cast billets of the following examples use chemical components C, Si, Mn, S, P and Fe as raw materials based on the set chemical component range (Table 1), and are smelted by a converter, refined, It was made according to a process flow of continuous casting and direct or uniform heating of the cast billet. The fabrication steps of Examples 1-4 are as follows.

Step 1. The content of hot metal As and Sn in the smelting furnace should be less than 80 ppm, and the slag material should be added 3 minutes before the end. The alkalinity of the final slag is controlled within the range of 2.9-3.9. A double slag drop type tapping process is used to control the slag carryover of the converter at 55 mm. The whole process of refining implements argon gas bottom blow stirring and argon gas blowing system to ensure that the impurities are sufficiently lifted, and the refining argon gas soft blow is more than 20 minutes. To ensure smooth production, 100m of calcium wire is supplied before it is taken out from the smelting station.

Step 2. Continuous Casting A full protection casting process is used and the drawing speed is controlled between 0.7 and 1.3 m/min.

Step 3. Rolling in the hot rolling process and controlled cooling Rolling in the hot rolling process and controlled cooling after rolling are the main means of temperature control, the final rolling temperature is detected outside the flange, and the rolled material is concentrated on the cooling bed after rolling. It is gradually cooled, and the carbonitride of V is sufficiently precipitated. FIG. 1 is a diagram showing the microstructure of a flange thickness of 24 mm according to the present invention. The chemical components and specific processes of Examples 1-4 are shown in the table below.

The hot rolling process conditions for Examples 1-4 are shown in Table 2. BS EN ISO 377-1997 "Sampling position and preparation of samples in mechanical property tests" is used as the standard, and the test methods for yield strength, tensile strength and elongation are ISO 6892-1-2009 "For metallic materials at room temperature Tensile test method” as standard, impact energy test method refers to ISO 148-1 “Charpy pendulum impact test for metallic materials” as standard, and the results are shown in Table 2.

As can be seen from the above table, the yield strength of the upper and lower flanges in Examples 1 to 4 of the present invention are all maintained at 420 MPa or more, and the impact toughness is good. Satisfies the conditions for use in the environment.

Finally, it should be noted that the above examples are for illustration of the technical solution of the present invention, not for limitation. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent substitution of the technical solution of the present invention does not affect the spirit or scope of the technical solution of the present invention. should be included within the scope of the claims of the present invention without departing from

Claims (7)

A hot-rolled H-shaped steel based on beam blank rolling forming, comprising:
The chemical composition of the H-shaped steel is, in weight percent, C: 0.04 to 0.08, Si: ≤ 0.25, Mn: 1.25 to 1.45, V: 0.04 to 0.10. , Ni: 0.2 to 1.0, P: ≤0.02, S: ≤0.01, Nb: 0.02 to 0.06, Al: 0.02 to 0.06, N: ≤0. 015, O: ≤ 0.005, the balance being iron Fe and unavoidable impurities,
The thickness standard of the H-shaped steel flange is 18-24mm, the yield strength of the upper and lower flanges is ≧420MPa, the lateral impact energy at −40° C. is ≧34J, and the vertical direction at −60° C. A hot-rolled H-shaped steel based on beam blank rolling forming, characterized in that the impact energy of is ≧120J. The chemical component composition is, in weight percent, C: 0.05 to 0.07, Si: ≤ 0.25, Mn: 1.25 to 1.45, V: 0.04 to 0.06, Ni: 0 .2 to 0.7, P: ≤0.02, S: ≤0.01, Nb: 0.02 to 0.04, Al: 0.02 to 0.05, N: ≤0.015, O: H-shaped steel according to claim 1, characterized in that ≤ 0.005, the remainder being iron and unavoidable impurities. A method for making hot rolled H-section steel based on beam blank rolling forming, comprising step 1), a smelting and continuous casting process, and step 2), a rolling process,
The step 1) is
Smelted by a converter, cast into a deformed continuous casting billet using LF refining, the liquid level of the tundish in the continuous casting process is ≥ 900mm, a full protection casting process is used, and the withdrawal speed is 0.7-1.3m. /min,
The step 2) is
A heating step of heating the deformed continuous casting billet and descaling it after removing it from the furnace;
Rough rolling uses water cooling to cool, precision rolling uses temperature waiting rolling and water cooling rolling, the rolling reduction of the non-recrystallized region is greater than 30%, and cooling devices before and after the rolling mill are used. a rolling process that operates to force the lower leg of the H-shaped steel to cool and control the final rolling temperature between 750°C and 820°C;
and a post-rolling cooling step in which the shaped steel after rolling is air-cooled or water-cooled, is then intensively cooled in a cooling bed, and after the temperature is lowered to 100° C. or less, it is straightened by a straightening machine. A method for making hot-rolled H-shaped steel based on beam blank rolling forming. 4. The manufacturing method according to claim 3, wherein the heating temperature in step 2) is controlled to 1220° C. to 1260° C., and the heating time is 90 to 180 minutes. 4. The manufacturing method according to claim 3, wherein the rolling start temperature of the rough rolling in step 2) is controlled to 1030° C. to 1130° C., and the number of rolling passes is 5 to 7. 4. The manufacturing method according to claim 3, wherein the rolling start temperature of the precision rolling in step 2) is controlled to 900° C. to 1000° C., and the rolling passes of the precision rolling are 3 to 5 passes. 4. The method according to claim 3, wherein in step 2), a water tap is used to forcibly cool the lower leg of the H-shaped steel, and the temperature difference between the upper and lower legs is controlled within ≤10°C. How to make.

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