A production method of high manganese steel thin wide plate for cryogenic tank

Abstract

The application discloses a production method of high manganese steel thin wide plate for low temperature tank, and the production process comprises the following steps: molten iron pretreatment, converter, LF and RH / VD refining, continuous casting, heating, rolling and MULPIC cooling, wherein the chemical composition of the steel is as follows: C=0.37-0.39%, Mn=23.0-24.0%, Si=0.2-0.4%, Cu=0.30-0.40%, Cr=3.1-3.5%, Ni=0.01-0.20%, Al<=0.07%, P<=0.01%, S<=0.005%, and the rest is Fe and inevitable impurity elements. The high temperature and long time heating mode is adopted to ensure that the temperature inside and outside the slab is uniform; the two-stage rolling mode is adopted to control the open and final rolling temperature and single pass reduction rate, so that the internal organization of the steel plate is refined and the good plate shape is ensured; and the slow roller speed and low water amount mode is adopted in the cooling process, so that the temperature difference between the upper and lower surfaces of the steel plate is reduced under the premise of avoiding the precipitation of carbide, and the high manganese austenitic steel thin wide plate with good plate shape and stable performance is produced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel material manufacturing, and relates to a production method of high-manganese steel thin wide plate for low-temperature tanks with good plate shape. BACKGROUND

[0002] Clean energy is the guarantee for the sustainable development of today's society, and in recent years, the production and trade of liquefied natural gas (LNG) are becoming increasingly active worldwide, and clean energy is becoming a new hotspot in the world oil and gas industry. Therefore, a large number of LNG storage tanks, LNG ships and LNG tank boxes and other equipment need to be built to store and transport LNG. High-manganese austenitic steel has excellent properties such as plasticity, low-temperature toughness, fatigue resistance and corrosion resistance, which is of great significance to improve the safety of LNG facilities. In addition, the price of manganese is only about 1 / 10 of the price of nickel, and the use of high-manganese austenitic steel as an LNG storage material can greatly reduce the material manufacturing cost.

[0003] The use of large-width steel plates can reduce the welding points and reduce the risk of tank cracking. For thin wide plates, the plate shape is difficult to control, and it is easy to appear wavy and difficult to straighten, which has great production difficulty. It has positive significance to develop high-manganese steel thin wide plates for low-temperature tanks with good plate shape and a production method thereof. SUMMARY

[0004] The application aims to provide a production method of high-manganese steel thin wide plate for low-temperature tanks with good plate shape, and solve the problems of poor plate shape of high-manganese steel thin wide plate and great production difficulty.

[0005] The application is implemented by the following technical scheme:

[0006] A production method of high-manganese steel thin wide plate for low-temperature tanks, the production process includes molten iron pretreatment-converter-LF and RH / VD refining-continuous casting-heating-rolling-MULPIC cooling. The chemical composition of the steel is C=0.37-0.39%, Mn=23.0-24.0%, Si=0.2-0.4%, Cu=0.30-0.40%, Cr=3.1-3.5%, Ni=0.01-0.20%, Al≤0.07%, P≤0.01%, S≤0.005%, and the rest is Fe and inevitable impurity elements; the key process steps include:

[0007] (1) the heating temperature range is 1150-1250℃, and the holding time is 220-300 minutes;

[0008] (2) the rolling mode is two-stage rolling, the rough rolling starting temperature is equal to or greater than 1100 DEG C, the single pass reduction rate of the spreading stage is 10% to 20%, the single pass reduction rate after spreading is 20% to 40%, the total reduction rate of the rough rolling stage is 54% to 69%, the fine rolling starting temperature is 930 to 1050 DEG C, and the final rolling temperature is 860 to 930 DEG C;

[0009] (3) after rolling, the MULPIC cooling is adopted, the re-red temperature is equal to or less than 400 DEG C, the upper water amount of the A zone is set to 0 to 40 L / s, the upper water amount of the A zone is set to 0 to 45 L / s, the upper water amount of the B / C / D zone is set to 0 to 100 L / s, the lower water amount of the B / C / D zone is set to 0 to 110 L / s, and the roller speed is controlled to be 0.5 to 1.0 m / s.

[0010] Compared with the prior art, the application has the beneficial effects that: the inner and outer temperatures of the slab are uniform in the heating process, the upper and lower surfaces are uniformly deformed during rolling, the thin plate rolling process will not fail due to low steel plate temperature or buckling head, the rough rolling process can fully dynamic recrystallize, the grain is refined, the fine rolling process can effectively control the grain size, and a good structure with good strength and toughness matching is obtained; the post-rolling water cooling adopts a low water amount cooling rate control mode, the water amount and cooling rate are reduced under the premise of avoiding carbide precipitation, the temperature difference between the upper and lower surfaces of the steel plate during the temperature reduction process is reduced, and the steel plate will not occur buckling, buckling head, edge wave, middle wave and other plate shape problems during the cooling process. The low-temperature tank high manganese steel thin wide plate with good plate shape is obtained, and the mechanical properties are: yield strength equal to or greater than 420 MPa, tensile strength equal to or greater than 800 MPa, total elongation equal to or greater than 35%, and transverse and longitudinal -196 DEG C impact energy equal to or greater than 50 J. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is the overall appearance of the thin wide plate in the embodiment 2 of the application.

[0012] Figure 2 It is the microstructure diagram of the thin wide plate in the embodiment 2 of the application. DETAILED DESCRIPTION

[0013] The following will be further illustrated by combining with the embodiments.

[0014] The embodiment one group: the smelting method of high manganese austenitic steel, including the embodiment 1 and the embodiment 2.

[0015] The chemical composition of the steel is as follows in percentage by weight: C=0.38%, Mn=23.2%, Si=0.28%, Cu=0.32%, Cr=3.3%, Ni=0.1%, Al=0.05%, P=0.008%, S=0.003%, and the rest is Fe and inevitable impurity elements; the smelting process is as follows: hot metal pretreatment, converter stirring P removal, LF furnace refining, RH furnace vacuum treatment, 220 mm section continuous casting, and stack cooling.

[0016] The heating mode of the examples 1 and 2 is shown in Table 1, the rolling mode is shown in Table 2, the rolling reduction is shown in Table 3, the MULPIC water amount parameter setting and the water outlet plate shape are shown in Table 4, and the mechanical property detection results are shown in Table 5.

[0017] From the mechanical property detection results, it can be seen that the mechanical properties of the steel plates of the examples are: yield strength ≥ 440 MPa, tensile strength ≥ 870 MPa, total elongation ≥ 50%, and transverse and longitudinal impact energy at -196℃ ≥ 50J.

[0018] From the attached Figure 2 It can be seen that the austenite grains in the microstructure are fine and uniform, the grain size is 8, and no precipitates are found.

[0019] Table 1 Heating mode of examples

[0020]

[0021] Table 2 Rolling mode

[0022]

[0023] Table 3 Rolling reduction

[0024]

[0025] Table 4 MULPIC water amount parameter and water outlet plate shape

[0026]

[0027] Table 5 Mechanical properties

[0028]

Claims

1. A production method of high manganese steel thin wide plate for a cryogenic tank, the production process including molten iron pretreatment - converter - LF and RH / VD refining - continuous casting - heating - rolling - MULPIC cooling, characterized in that: The steel has the following chemical composition by weight: C=0.37-0.39%, Mn=23.0-24.0%, Si=0.2-0.4%, Cu=0.30-0.40%, Cr=3.1-3.5%, Ni=0.01-0.20%, Al≤0.07%, P≤0.01%, S≤0.005%, and the balance being Fe and inevitable impurities; The key process steps include: (1) the heating temperature is 1150-1250℃, and the holding time is 220-300 minutes; (2) the rolling mode is two-stage rolling, the rough rolling open rolling temperature is ≥1100℃, the single pass reduction rate in the spreading stage is 10-20%, the single pass reduction rate after spreading is 20-40%, the total reduction rate in the rough rolling stage is 54-69%, the finish rolling open rolling temperature is 930-1050℃, and the final rolling temperature is 860-930℃; (3) after rolling, the MULPIC cooling is performed, the re-red temperature is ≤400℃, the A zone upper water amount is set to 0-40L / s, the A zone lower water amount is set to 0-45L / s, the B / C / D zone upper water amount is set to 0-100L / s, the B / C / D zone lower water amount is set to 0-110L / s, the roller speed is controlled to be 0.5-1.0m / s, the low-temperature tank high manganese steel thin wide plate with good plate shape is obtained, and the mechanical properties are: yield strength ≥420MPa, tensile strength ≥800MPa, total elongation ≥35%, and transverse and longitudinal -196℃ impact energy ≥50J.

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