TMCP structural steel plate for f-grade marine and production process therefor

Abstract

The present invention relates to the technical field of steel production. Disclosed are a TMCP structural steel plate for F-grade marine and a production process therefor. The structural steel plate comprises the following chemical components in percentage by mass: C: 0.03-0.08％, Si: 0.10-0.40％, Mn: 1.35-1.70％, P≤0.012％, S≤0.005％, Ni: 0.01-0.15％, Nb: 0.008-0.020％, Al: 0.020-0.040％, and the balance being Fe and other inevitable impurities. In the present invention, LF, VD, calcium treatment and soft blowing processes are used to reduce endogenous inclusions generated by molten steel, and at the same time, a continuous casting blank is used to increase the metal yield, thereby greatly reducing production costs. Additionally, by means of a reasonable controlled rolling process, the steel plate has good comprehensive performance, and involves greatly reduced production costs compared with normalized steel for an F-grade hull structure.

Description

TMCP type F-grade marine structure steel plate and production process thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of steel production, in particular to a TMCP type F-grade marine structure steel plate and production process thereof. BACKGROUND

[0002] With the rapid development of international trade in China, more and more large ships are needed, which has led to rapid development of domestic shipbuilding industry. High-strength ship structure steel has been in high demand. Currently, most of the F-grade ship structure steels in China are delivered in normalized state. The steel plate produced by rolling is further heat treated. Since the steel plate delivered in normalized state needs to be heat treated, an additional production process is required, thus increasing the production cost.

[0003] SUMMARY

[0004] The present application solves the technical problems of overcoming the shortcomings of the prior art and providing a TMCP type F-grade marine structure steel plate and production process thereof.

[0005] In order to solve the above technical problems, the technical scheme of the present application is as follows:

[0006] A TMCP type F-grade marine structure steel plate, the chemical composition and its mass percentage are as follows: C: 0.03-0.08%, Si: 0.10-0.40%, Mn: 1.35-1.70%, P≤0.012%, S≤0.005%, Ni: 0.01-0.15%, Nb: 0.008-0.020%, Al: 0.020-0.040%, and the rest is Fe and other unavoidable impurities.

[0007] As a preferred scheme of the TMCP type F-grade marine structure steel plate, the microstructure of the steel plate is ferrite and pearlite.

[0008] As a preferred scheme of the TMCP type F-grade marine structure steel plate, the yield strength of the steel plate is ≥390MPa, the tensile strength is 540-680MPa, and the V-type longitudinal impact energy at -60℃ is ≥80J.

[0009] As a preferred scheme of the TMCP type F-grade marine structure steel plate, the thickness of the steel plate is 20-40mm.

[0010] The present application also provides a production process of a TMCP type F-grade marine structure steel plate, which comprises the following steps in sequence: steelmaking, continuous casting, and rolling process.

[0011] As a preferred scheme of the production process of the TMCP type F-grade marine structure steel plate, in the steelmaking process, the molten steel after converter smelting is sent to the LF refining furnace for refining, argon blowing is good in the whole process, the total refining time is ≥35 min, the white slag retention time is ≥25 min, and the slag basicity at the end of refining is ≥3.5.

[0012] As a preferred scheme of the production process of the TMCP type F-grade marine structure steel plate, in the steelmaking process, after the LF furnace refining is completed, the molten steel is sent to the VD vacuum furnace for vacuum degassing treatment, the vacuum degree is ≤66.7 Pa, the vacuum holding time is ≥18 min, and after vacuum destruction, soft blowing is performed for 10-12 min, and 0.8-1.0 kg / t of steel calcium wire is fed for calcium treatment.

[0013] As a preferred scheme of the production process of the TMCP type F-grade marine structure steel plate, in the continuous casting process, electromagnetic stirring and light pressing down technology are used during casting, and the fluctuation range of the crystallizer liquid surface is ±3 mm, and the superheat degree is controlled to be 15-35℃.

[0014] As a preferred scheme of the production process of the TMCP type F-grade marine structure steel plate, in the rolling process, the casting blank is heated in the continuous furnace, when the furnace temperature T is ≤600℃, the heating speed is ≤200℃ / h; when the furnace temperature is 600℃

[0015] As a preferred scheme of the production process of the TMCP type F-grade marine structure steel plate, in the rolling process, the two-stage controlled rolling process is adopted, the one-stage opening rolling temperature is 1085-1160℃, the large reduction rolling process is adopted, and the air cooling thickness is h+70mm, the h is the thickness of the finished steel plate, the two-stage opening rolling temperature is 820-750℃, the final rolling temperature is 790-730℃, and the steel plate red temperature is 580-620℃.

[0016] The beneficial effects of the present application are:

[0017] (1) The TMCP type F-grade marine structure steel plate provided by the present application has reasonable chemical component design, uniform internal organization, less noble metal addition, low cost and strong market competitiveness.

[0018] (2) The present application adopts LF, VD, calcium treatment and soft blowing process to reduce the endogenous inclusions generated by the molten steel, at the same time, utilizes the continuous casting blank to improve the metal yield, greatly reduces the production cost, in addition, through the reasonable controlled rolling process, the steel plate has good comprehensive performance, and the production cost of the normalized F-grade marine structure steel is greatly reduced.

[0019] (3)The steel plate produced by the application has uniform and compact internal structure, the structure is ferrite and pearlite, and the produced steel plate has good matching of strength and toughness, the yield strength is ≥ 390 MPa, the tensile strength is 540-680 MPa, the V-type longitudinal impact energy at-60℃ is ≥ 80 J, in addition, the produced steel plate is purer, the impurity content is low, P ≤ 0.012%, S ≤ 0.005%, the thickness specification of the steel plate is 20-40 mm, and the performance of the steel plate meets the requirements of users on the ship structure steel. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Fig. 1 is a metallographic structure schematic diagram of the TMCP type F-grade ship structure steel plate prepared in Example 1;

[0022] Fig. 2 is a metallographic structure schematic diagram of the TMCP type F-grade ship structure steel plate prepared in Example 2;

[0023] Fig. 3 is a metallographic structure schematic diagram of the TMCP type F-grade ship structure steel plate prepared in Example 3

[0024] Fig. 4 is a metallographic structure schematic diagram of the TMCP type F-grade ship structure steel plate prepared in Example 4. DETAILED DESCRIPTION

[0025] In order to make the content of the application more easily understood, the application will be further described in detail according to the specific embodiments.

[0026] Example 1: The present embodiment provides a TMCP type F-grade ship structure steel plate, the chemical composition and mass percentage content are as follows: C: 0.03%, Si: 0.10%, Mn: 1.35%, P: 0.010%, S: 0.004%, Ni: 0.02%, Nb: 0.008%, Al: 0.020%, and the rest is Fe and other unavoidable impurities.

[0027] The production method of the TMCP type F-grade ship structure steel plate in the present embodiment includes steelmaking, continuous casting and rolling process, and the specific process steps are as follows:

[0028] (1) Steelmaking process: the molten steel smelted by converter is sent to LF refining furnace for refining, argon is blown well in the whole process of LF refining, the total refining time is 45 min, the white slag maintaining time is 25 min, the slag basicity at the end of refining is 3.6; after the refining is completed, the molten steel is sent to VD furnace for vacuum degassing treatment, the vacuum degree is 60 Pa, the vacuum maintaining time is 19 min, after the vacuum is destroyed, soft blowing is performed for 10 min, so that the inclusions can fully float up, at the same time, 0.8 kg / t of calcium wire is fed for calcium treatment, so as to make the inclusions spheroidize and float up;

[0029] (2) Continuous casting process: a large-section continuous casting machine is used, the liquid level of the crystallizer is automatically controlled, the fluctuation range is ±3 mm, the overheat degree of the tundish is 16℃, electromagnetic stirring, light pressing and solidification end strong cooling technology are used, and large-section high-quality continuous casting billets are casted;

[0030] (3) Rolling process: the continuous casting billet is heated in a continuous furnace, the furnace temperature is 550℃, the heating speed is 160℃ / h; the highest heating temperature is 1270℃, the soaking segment temperature is 1230℃, and the total heating coefficient is 11 min / cm;

[0031] A two-stage controlled rolling process is used, the first-stage opening rolling temperature is 1085℃, large reduction rolling is used, and the air cooling thickness is 100 mm; the second-stage opening rolling temperature is 820℃, the finish rolling temperature is 790℃, and the red temperature is 590℃.

[0032] After cooling, the microstructure of the steel plate is ferrite and pearlite, the yield strength of the steel plate is 420 MPa, the tensile strength is 550 MPa, the V-type longitudinal-60℃ impact energy is 156 J, the thickness is 30 mm, the F-grade marine steel produced has excellent comprehensive performance, high strength, good impact toughness and high temperature tensile property, uniform microstructure and stable performance.

[0033] Embodiment 2: The embodiment provides an F-grade marine structure steel plate of TMCP type, the chemical composition and mass percentage content are as follows: C: 0.05%, Si: 0.25%, Mn: 1.45%, P: 0.010%, S: 0.005%, Ni: 0.12%, Nb: 0.012%, Al: 0.030%, and the rest is Fe and other unavoidable impurities.

[0034] The production method of the F-grade marine structure steel plate of TMCP type in the embodiment includes steelmaking, continuous casting and rolling process, and the specific process steps are as follows:

[0035] (1) Steelmaking process: The molten steel smelted in the primary refining furnace is sent to the LF refining furnace for refining. During the LF refining process, argon blowing is good throughout the process. The total refining time is 40 minutes, the white slag holding time is 30 minutes, and the slag basicity is 3.5 after refining. After refining, the molten steel is sent to the VD furnace for vacuum degassing treatment. The vacuum degree is 66.7 Pa, the vacuum holding time is 18 minutes, and after the vacuum is broken, soft blowing is performed for 12 minutes to allow the inclusions to float fully. At the same time, calcium wire of 0.9 kg / t molten steel is fed in for calcium treatment to promote the spheroidization and floating of the inclusions.

[0036] (2) Continuous casting process: Using a large-section continuous casting machine, the liquid level in the crystallizer is automatically controlled with a fluctuation range of ±3mm. The superheat of the tundish is 35℃. Electromagnetic stirring, light pressing and strong cooling technology at the end of solidification are used to cast high-quality continuous casting billets with large sections.

[0037] (3) Rolling process: The continuously cast billet is heated in a continuous furnace at a temperature of 600℃ and a heating rate of 200℃ / h; the maximum heating temperature is 1270℃, the soaking zone temperature is 1240℃, and the total heating coefficient is 10min / cm.

[0038] The two-stage controlled rolling process is adopted. The first stage starts rolling at 1090℃, using high reduction rolling, and the steel thickness is 110mm. The second stage starts rolling at 800℃, finishes rolling at 780℃, and the red-hot temperature is 580℃.

[0039] The steel plate obtained after cooling has a microstructure of ferrite and pearlite, a yield strength of 450 MPa, a tensile strength of 636 MPa, a V-shaped longitudinal impact energy of -60℃ of 207 J, and a thickness of 40 mm. The produced F-grade marine steel has excellent comprehensive performance, high strength, good impact toughness and high-temperature tensile properties, uniform microstructure, and stable performance.

[0040] Example 3: This example provides TMCP type F grade marine structural steel plate, whose chemical composition and mass percentage are as follows: C: 0.07%, Si: 0.38%, Mn: 1.62%, P: 0.007%, S: 0.001%, Ni: 0.15%, Nb: 0.020%, Al: 0.040%, with the remainder being Fe and other unavoidable impurities.

[0041] The production method of TMCP type F-grade marine structural steel plate in this embodiment includes steelmaking, continuous casting, and rolling processes. The specific process steps are as follows:

[0042] (1) Steelmaking process: the molten steel from converter smelting is sent to LF refining furnace for refining, argon is blown well in the whole process of LF refining, the total refining time is 50 min, the white slag maintaining time is 35 min, the slag basicity at the end of refining is 4.0; after the refining is completed, the molten steel is sent to the VD furnace for vacuum degassing treatment, the vacuum degree is 50 Pa, the vacuum maintaining time is 20 min, after the vacuum is destroyed, soft blowing is carried out for 11 min, so that the inclusions can fully float up, at the same time, 1.0 kg / t of calcium wire is fed for calcium treatment to promote the spheroidization and floating of inclusions;

[0043] (2) Continuous casting process: using a large section continuous casting machine, the liquid level of the crystallizer is automatically controlled, the fluctuation range is ±3 mm, the superheat degree of the tundish is 30℃, electromagnetic stirring, light pressing and solidification end strong cooling technology are adopted, and large section high quality continuous casting billets are casted;

[0044] (3) Rolling process: the continuous casting billet is heated in a continuous furnace, the furnace temperature is 1200℃, the heating speed is 300℃ / h; the highest heating temperature is 1270℃, the soaking segment temperature is 1240℃, and the total heating coefficient is 12 min / cm;

[0045] The second-order controlled rolling process is adopted, the first stage opening rolling temperature is 1160℃, large reduction rolling is adopted, and the air cooling thickness is 108 mm; the second stage opening rolling temperature is 780℃, the finish rolling temperature is 730℃, and the red temperature is 610℃.

[0046] After cooling, the microstructure of the steel plate is ferrite and pearlite, the yield strength of the steel plate is 470 MPa, the tensile strength is 680 MPa, the V-type longitudinal-60℃ impact energy is 190 J, the thickness is 35 mm, the F-grade marine steel produced has excellent comprehensive performance, high strength, good impact toughness and high temperature tensile property, uniform structure and stable performance.

[0047] Example 4: The example provides a TMCP type F-grade marine structure steel plate, the chemical composition and mass percentage content are as follows: C: 0.08%, Si: 0.40%, Mn: 1.70%, P: 0.005%, S: 0.001%, Ni: 0.15%, Nb: 0.020%, Al: 0.035%, and the rest is Fe and other unavoidable impurities.

[0048] The production method of the TMCP type F-grade marine structure steel plate of the example includes steelmaking, continuous casting and rolling process, and the specific process steps are as follows:

[0049] (1) Steelmaking process: the molten steel smelted by converter is sent into LF refining furnace for refining, argon is blown well in the whole process of LF refining, the total refining time is 35 min, the white slag maintaining time is 31 min, the slag basicity after refining is 3.9; after refining, the molten steel is sent into VD furnace for vacuum degassing treatment, the vacuum degree is 62 Pa, the vacuum maintaining time is 20 min, after vacuum destruction, soft blowing is carried out for 12 min, so that the inclusions can be fully floated, at the same time, 1.0 kg / t molten steel of calcium line is fed for calcium treatment, so as to accelerate the spheroidization and floating of inclusions;

[0050] (2) Continuous casting process: the large-section continuous casting machine is used, the liquid level of crystallizer is automatically controlled, the fluctuation range is ±3 mm, the overheat degree of tundish is 15℃, the electromagnetic stirring, light press-down and solidification end strong cooling technology are adopted, and the large-section high-quality continuous casting billet is casted;

[0051] (3) Rolling process: the continuous casting billet is heated in continuous furnace, the furnace temperature is 900℃, the heating speed is 350℃ / h; the highest heating temperature is 1270℃, the soaking section temperature is 1250℃, and the total heating coefficient is 12 min / cm;

[0052] The second-order controlled rolling process is adopted, the first-stage opening rolling temperature is 1150℃, the large press-down rolling is adopted, the air cooling thickness is 90 mm, the second-stage opening rolling temperature is 750℃, the finish rolling temperature is 730℃, and the red temperature is 620℃.

[0053] After cooling, the microstructure of the steel plate is ferrite and pearlite, the yield strength of the steel plate is 440 MPa, the tensile strength is 650 MPa, the V-type longitudinal-60℃ impact energy is 155 J, the F-grade marine steel with a thickness of 20 mm produced has excellent comprehensive performance, high strength, good impact toughness and high temperature tensile property, uniform microstructure and stable performance.

[0054] In addition to the above-mentioned embodiments, the present application can also have other implementation manners; any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present application.

Claims

1. A TMCP type F-grade marine structural steel plate characterized by: The chemical composition and mass percentage thereof are: C: 0.03-0.08%, Si: 0.10-0.40%, Mn: 1.35-1.70%, P≤0.012%, S≤0.005%, Ni: 0.01-0.15%, Nb: 0.008-0.020%, Al: 0.020-0.040%, and the rest is Fe and other inevitable impurities.

2. The TMCP type F-grade steel plate for ship structure according to claim 1, characterized in that: The microstructure of the steel plate is ferrite and pearlite.

3. The TMCP type F-grade steel plate for ship structure according to claim 1, characterized in that: The yield strength of the steel plate is ≥390 MPa, the tensile strength is 540-680 MPa, and the V-type longitudinal impact energy at -60°C is ≥80 J.

4. The TMCP type F-grade steel plate for ship structure according to claim 1, characterized in that: The thickness of the steel plate is 20-40 mm.

5. A production process of a TMCP type F-grade marine structural steel plate according to any one of claims 1 to 4, characterized in that: The steel plate is prepared by sequentially including a steelmaking process, a continuous casting process and a rolling process.

6. The process for producing a TMCP grade F steel plate for ship structure according to claim 5, characterized in that: In the steelmaking process, the molten steel smelted by a converter is sent to a LF refining furnace for refining, and argon is blown well in the whole process of LF refining, the total refining time is ≥35 min, the white slag maintaining time is ≥25 min, and the slag basicity at the end of refining is ≥3.

5.

7. The process for producing a TMCP grade F steel plate for ship structure according to claim 5, characterized in that: In the steelmaking process, after the LF furnace refining is completed, the molten steel is sent to a VD vacuum furnace for vacuum degassing treatment, the vacuum degree is ≤66.7 Pa, the vacuum maintaining time is ≥18 min, and after the vacuum is destroyed, soft blowing is performed for 10-12 min, and calcium wire with a feeding amount of 0.8-1.0 kg / t of steel is fed for calcium treatment.

8. The process for producing a TMCP grade F steel plate for ship structure according to claim 5, characterized in that: In the continuous casting process, electromagnetic stirring and light pressing down technology are used during casting, and the liquid surface fluctuation range of the crystallizer is ±3 mm, and the superheat degree is controlled to be 15-35℃.

9. The process for producing a TMCP grade F steel plate for ship structure according to claim 5, characterized in that: In the rolling process, the cast blank is heated in a continuous furnace, when the furnace temperature T is ≤600℃, the heating speed is ≤200℃ / h; when the furnace temperature is 600℃ 10. The process for producing a TMCP grade F-class shipbuilding structural steel plate according to claim 5, characterized in that: In the rolling process, the cast blank is heated in a continuous furnace, when the furnace temperature T is ≤600℃, the heating speed is ≤200℃ / h; when the furnace temperature is 600℃

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