Hot rolling production method of wide pure hydrogen conveying pipeline steel L415MH

Abstract

The invention discloses a hot rolling production method of wide pure hydrogen conveying pipeline steel L415MH, and discloses related process parameters of the wide pure hydrogen conveying pipeline steel L415MH, and the wide pure hydrogen conveying pipeline steel L415MH comprises the following components in percentage by weight: 0.04 to 0.06 percent of C, 0.10 to 0.20 percent of Si, 1.20 to 1.35 percent of Mn, 0.040 to 0.050 percent of Nb, 0.010 to 0.020 percent of Ti, 0.18 to 0.28 percent of Cr, 0.08 to 0.15 percent of Ni, 0.030 to 0.040 percent of V, 0.025 to 0.050 percent of Alt and the balance of Fe and other inevitable impurities. The invention aims to provide the hot rolling production method of the wide pure hydrogen conveying pipeline steel L415MH, and aims to improve the comprehensive performance of the finished strip steel and the pure hydrogen conveying service performance while meeting the hot rolling coil plate performance of customers.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgy, and particularly relates to a hot rolling production method of wide pure hydrogen conveying pipeline steel L415MH. BACKGROUND

[0002] In recent years, the state has introduced a series of policies related to the hydrogen energy industry. Under the guidance of the policy, the overall development of China's hydrogen energy industry is good, the industrial chain is gradually improving, and the gap with international advanced levels is gradually narrowing. China's hydrogen production and demand are the largest in the world and are showing an upward trend year by year. In 2022, the hydrogen production capacity exceeded 40 million tons / year, and the annual output reached 37.81 million tons. In 2023, the hydrogen production capacity was about 49 million tons / year, and the hydrogen output was 35 million tons. In terms of hydrogen transportation, at present, high-pressure gaseous vehicle transportation is mainly used, but the production and use of space distribution of hydrogen in China do not match, and the existing high-pressure gaseous vehicle transportation system cannot meet the future development needs. At the same time, the research on pipeline hydrogen transportation in China started relatively late, and the long-distance hydrogen transportation pipeline infrastructure needs to be improved. The existing hydrogen transportation pipeline is small in scale, with a total mileage of about 400 kilometers, and the in-service pipeline is only about 100 kilometers, which cannot support the large-scale development of the upstream and downstream of the green hydrogen industry chain, and large-scale, long-distance hydrogen transportation pipelines need to be built.

[0003] Foreign pipeline hydrogen transportation technology has developed earlier, and the total mileage of hydrogen transportation pipelines worldwide has exceeded 6,000 kilometers, of which the hydrogen transportation pipelines put into operation in the United States have reached 2,600 kilometers. According to the relevant plan approved by the European Commission in 2024, the European Union will build and modify about 2,700 kilometers of hydrogen transmission and distribution pipelines, build large-scale hydrogen storage facilities, etc., and the pipelines will be put into use between 2027 and 2029. The International Energy Agency predicts that global low-carbon hydrogen production will increase significantly by 2030, driving further development of hydrogen pipeline networks. As the core material of China's first large-scale pure hydrogen long-distance pipeline, hydrogen conveying pipeline steel L415M is used in the Kangbao (Zhangjiakou) to Caofeidian green hydrogen transportation project, which aims to connect the renewable energy hydrogen production base in Zhangjiakou with the demand for industrial hydrogen in Tangshan.

[0004] According to the search, the document with Chinese patent application number CN 119876785 A discloses a kind of high-grade hydrogen conveying pipeline steel and its preparation method, which is suitable for C:0.02~0.04%, Si:0.20~0.30%, Mn:1.20~1.30%, P≤0.010%, S≤0.0010%, Alt:0.015~0.055%, N:≤0.0020%, O:≤0.0010%, H:≤0.0001%, Cr:0.90~1.00%, Mo:0.40~0.50%, Ti:0.020~0.030%, Nb:0.05~0.07%, Ni≤0.40~0.50%, the rest is Fe and inevitable impurities; meet CSR=0, CLR=0, CTR=0 under A solution, slow stretching IRA, IEL≤20%, under 6.3MPa pure hydrogen environment, step type compact tensile specimen KIH≥100MPa.m 1 / 2 , fatigue life≥500,000 times. The document has the disadvantage that although the comprehensive performance is excellent and the hydrogen compatibility performance is good, the relative manufacturing cost increases, which is not conducive to long-term development.

[0005] According to the search, the document with Chinese patent application number CN 118756036 A discloses a kind of 360MPa grade pipeline steel for low proportion hydrogen-doped conveying pipeline and its preparation method, which is suitable for C:0.03~0.06%, Si:0.10~0.30%, Mn:0.90~1.15%, Nb:0.020~0.050%, Ti:0.010~0.030%, Als:0.020~0.040%, P≤0.010%, S≤0.0015%, H≤2ppm, O≤30ppm, N≤50ppm, the rest is Fe and inevitable impurities, mechanical properties meet: yield strength: 400~500MPa, tensile strength: 500~600MPa, elongation A 50 : 35~45%. The document only proposes the conventional mechanical properties and hydrogen compatibility of low proportion hydrogen-doped L360M grade pipeline steel.

[0006] According to the search, the document with Chinese patent application number CN 117987615 A, "A method for improving the hydrogen compatibility of pure hydrogen transmission pipeline steel", this method is applicable to C: 0.02%-0.07%, Si: 0.10%-0.60%, Mn: 0.9%-1.40%, Al: 0.020%-0.050%, Cr: 0.10%-0.50%, Ni: 0.10%-0.20%, Nb: 0.030%-0.055%, P≤0.0080%, S≤0.002%, H≤0.0002%, the rest is Fe and inevitable impurities. The yield strength of pure hydrogen transmission pipeline steel is ≥360MPa, the tensile strength is ≥520MPa, the elongation A is ≥25%, the DWTT shear area at-20℃ is ≥90%; hydrogen compatibility test: (1) hydrogen pressure and nitrogen pressure are 6.3MPa, pure hydrogen and pure nitrogen test box volume is ≥4000mL, slow tensile rate is ≤1.8×10 -5 / s, the test result is that the area reduction loss value under hydrogen environment is ≤25% compared with that under nitrogen environment, the elongation loss value is ≤15%, the strength loss rate is ≤1%, (2) the fracture toughness K IC ≥55MPa·m 1 / 2 under hydrogen environment is 55MPa·m, (3) 6.3MPa hydrogen embrittlement sensitivity is ≤1.5. This document is also aimed at low-grade L360M pipeline steel, strengthening steelmaking process, improving the high strength, high toughness and excellent hydrogen compatibility of pure hydrogen transmission pipeline steel. SUMMARY

[0007] The purpose of the present application is to provide a hot rolling production method of wide pure hydrogen transmission pipeline steel L415MH, aiming to meet the performance of customer hot rolled coil while improving the comprehensive performance of finished strip steel and pure hydrogen transmission service performance.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0009] The present application is a hot rolling production method of wide pure hydrogen transmission pipeline steel L415MH, comprising the following steps:

[0010] 1) Hot metal conditions: the phosphorus content of hot metal is required to be ≤0.130%, the sulfur content is ≤0.050%, the silicon content is between 0.20%-0.60%, and the hot metal temperature is ≥1350℃;

[0011] 2) Steelmaking process: the molten iron needs to be treated by KR desulfurization, the sulfur content of the molten iron entering the converter is required to be ≤0.002%, and the desulfurization slag cleaning area is greater than 95%; the vacuum degree of the RH process is required to be ≤2.6 mbar, and the vacuum holding time is ≥15 min. During the RH vacuum treatment, the circulating pure degassing time is guaranteed to be ≥7 min; titanium-iron alloy is added during the RH vacuum treatment to adjust the composition to the target range; calcium treatment is carried out after the RH vacuum treatment is completed, and the soft blowing time after calcium treatment is guaranteed to be ≥8 min;

[0012] 3) Continuous casting process: constant speed, full-range argon gas protection and light pressing down control are adopted;

[0013] 4) After smelting and pouring, the slab is formed, and the hot rolling heating system is shown in the following table:

[0014]

[0015] 6) The rolling key process parameters and rolling passes are shown in the following tables:

[0016] Rolling key process parameters:

[0017]

[0018]

[0019] Rolling passes:

[0020]

[0021] 6) After the finishing rolling, the slab is cooled to the set temperature of the layer cooling for cooling, and the layer cooling temperature is 600±15℃.

[0022] Further, the cold charging soaking time in step 4) is 30-60 min, the hot charging is 25-55 min, and the first pass descaling treatment is carried out.

[0023] Further, the method of encrypted laminar cooling is adopted for cooling to the cooling bed temperature.

[0024] Further, the wide pure hydrogen delivery pipeline steel L415MH has the following components by weight percentage: C: 0.04-0.06%, Si: 0.10-0.20%, Mn: 1.20-1.35%, Nb: 0.040-0.050%, Ti: 0.010-0.020%, Cr: 0.18-0.28%, Ni: 0.08-0.15%, V: 0.030-0.040%, Alt: 0.025-0.050%, the balance being Fe and other unavoidable impurities, wherein P≤0.012%, S≤0.0015%, O≤0.0030%, N≤0.0055%, H≤0.0001%.

[0025] Further, the wide pure hydrogen delivery pipeline steel L415MH component is C: 0.05%, Si: 0.12%, Mn: 1.23%, Nb: 0.042%, Ti: 0.017%, Cr: 0.21%, Ni: 0.11%, V: 0.032%, Alt: 0.048%, the balance is Fe and other inevitable impurities, wherein P: 0.010%, S: 0.0004%, O: 27ppm, N: 36ppm, H: 0.8ppm.

[0026] Further, the range of drawing speed is 1.0-1.5 m / min.

[0027] Further, the rough rolling final rolling temperature in the rolling process is ≤1050℃.

[0028] Compared with the prior art, the beneficial technical effects of the present application are:

[0029] The wide pure hydrogen delivery pipeline steel L415MH hot rolling production method of the present application adopts low carbon equivalent design (Ceq≤0.15%), which significantly improves the weldability and hydrogen embrittlement resistance. By adding trace Cr and Mo to enhance the hydrogen corrosion resistance of the matrix, and using Ti / Nb composite micro-alloying to refine the grains and form high-density nanoscale carbonitride precipitates, which effectively act as "hydrogen traps" to inhibit hydrogen diffusion. At the same time, the content of P (≤0.012%) and S (≤0.0015%) is strictly controlled to reduce impurity segregation and reduce hydrogen induced cracking (HIC) sensitivity. Through the TMCP process, a fine and uniform ferrite + a small amount of pearlite structure (ferrite grain size ≥10 grade) is obtained. High proportion of small angle grain boundaries and uniform precipitates hinder crack propagation, giving the steel excellent low temperature toughness (-20℃ impact energy ≥160J, -20℃ DWTT ≥85%) and high hydrogen embrittlement resistance. The uniformity of the structure also ensures the stability of the strength (yield strength ≥415MPa), and the hydrogen compatibility test: (1) the hydrogen pressure and nitrogen pressure are 7.1MPa, the pure hydrogen and pure nitrogen test box volume is ≥4000mL, the slow tensile rate is <2×10 -5 / s, and the test result is that the area reduction loss value under hydrogen environment is ≤28% compared with that under nitrogen environment. (2) the fracture toughness K IC ≥353MPa·m 1 / 2 under hydrogen environment, (3) the air fatigue life of the notched sample is >32,000 times, and the hydrogen fatigue life of the notched sample is >14,000 times. It meets the standard requirements of high-pressure pure hydrogen delivery.

[0030] Through the alloy-structure collaborative design, the unification of high strength, high hydrogen embrittlement resistance and excellent processability is realized, which provides a reliable material solution for long-distance high-pressure pure hydrogen delivery pipelines. BRIEF DESCRIPTION OF DRAWINGS

[0031] The application will be further described in connection with the accompanying drawings.

[0032] Figure 1 Microstructure metallographic chart at 1 / 2 of slab 1.

[0033] Figure 2 Microstructure metallographic chart at 1 / 4 of slab 1. DETAILED DESCRIPTION

[0034] The application will be further described in connection with the accompanying drawings.

[0035] The following examples are used to describe the application in more detail, which are only the description of the best mode of the application, and do not have any limitation on the scope of the application. Figure 1 The microstructure metallographic chart at 1 / 2 of slab 1 is shown in Fig. 1, and the microstructure metallographic chart at 1 / 4 of slab 1 is shown in Fig. 2. Figure 2 The microstructure metallographic chart at 1 / 2 of slab 1 is shown in Fig. 1, and the microstructure metallographic chart at 1 / 4 of slab 1 is shown in Fig. 2.

[0036] Example 1

[0037] The composition of L415MH used in the example of the application is as follows in terms of percentage by weight: C: 0.04-0.06%, Si: 0.10-0.20%, Mn: 1.20-1.35%, Nb: 0.040-0.050%, Ti 0.010-0.020%, Cr 0.18-0.28%, Ni 0.08-0.15%, V 0.030-0.040%, Alt 0.025-0.050%, and the balance of Fe and other inevitable impurities, wherein P≤0.012%, S≤0.0015%, O≤0.0030%, N≤0.0055%, and H≤0.0001%.

[0038] In the example of the application, the converter adopts a strong dephosphorization smelting operation method, and the composition and temperature of the converter tapping are shown in Table 3. The dephosphorization rate of the converter is 95%-96%.

[0039] In the example of the application, the LF adopts a strong desulfurization and alloying smelting operation method, and the composition and temperature of the LF tapping are shown in Table 4.

[0040] In the example of the application, the RH adopts a strong desulfurization and alloying smelting operation method, and the composition and temperature of the RH tapping are shown in Table 5.

[0041] The heating temperature in the embodiment of the application is 1190-1220 DEG C, the cold charging time in the furnace is 180-300 min, the soaking temperature is 1170-1210 DEG C, and the cold charging and soaking time is 30-60 min.

[0042] The rough rolling final rolling temperature in the embodiment of the application is ≤1050 DEG C, and the cumulative reduction of rough rolling is 80-85%.

[0043] The rough rolling final rolling temperature in the embodiment of the application is ≤1050 DEG C, and the cumulative reduction of rough rolling is 80-85%.

[0044] The layer cooling temperature in the embodiment of the application is 500-560 DEG C.

[0045] The intermediate blank thickness in the embodiment of the application is 55-65 mm, and the finished product thickness is 14.3 mm.

[0046] The layer cooling temperature in the embodiment of the application is 500-560 DEG C.

[0047] The non-metallic inclusion, banded structure and grain size indicators in the embodiment of the application all meet the technical standard requirements, and see table 13.

[0048] The performance results in the embodiment of the application completely meet the standard requirements, and the-20 DEG C impact and drop hammer performance are stable, and see tables 11 and 12.

[0049] The hydrogen compatibility performance results in the embodiment of the application completely meet the standard requirements, and see table 14.

[0050] Table 1 incoming molten iron composition and temperature

[0051] Steel grade Furnace number Si (%) Mn (%) P(％) S(％) Temperature (°C) L415M 24306174 0.40 0.45 0.125 0.038 1397

[0052] Table 2 molten iron composition and temperature after KR treatment

[0053] Steel grade Furnace number Si (%) Mn (%) P(％) S(％) Temperature (°C) L415M 24306174 0.37 0.51 0.116 0.001 1371

[0054] Table 3 molten steel composition and temperature after converter tapping

[0055]

[0056] Table 4 molten steel composition and temperature after LF treatment

[0057]

[0058] Table 5 molten steel composition and temperature after RH treatment

[0059]

[0060] Table 6 tundish liquid steel composition

[0061]

[0062]

[0063] Table 7 Continuous casting parameters and slab quality

[0064]

[0065] Table 8 Reheating furnace process parameters

[0066]

[0067] Table 9 Rolling key process parameters

[0068]

[0069] Table 10 Rolling pass schedule

[0070]

[0071] Table 11 Mechanical properties of trial products

[0072]

[0073] Table 12 Impact and DWTT properties of trial products

[0074]

[0075] Table 13 Non-metallic inclusions, banded structure and grain size

[0076]

[0077] Table 14 Hydrogen compatibility test

[0078]

[0079] The above-described embodiments are merely preferred modes of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art without departing from the design spirit of the present application shall fall within the scope of protection of the present application as defined by the claims.

Claims

1. A hot-rolling production method for wide-width pure hydrogen transmission pipeline steel L415MH, characterized in that: Includes the following steps: 1) Molten iron conditions: The molten iron should have a phosphorus content ≤0.130%, a sulfur content ≤0.050%, a silicon content between 0.20% and 0.60%, and a molten iron temperature ≥1350℃; 2) Steelmaking process: Molten iron needs to undergo KR desulfurization treatment, requiring the sulfur content of the molten iron entering the converter to be ≤0.002%, and the desulfurization slag removal area to be greater than 95%; the vacuum degree of the RH process needs to be ≤2.6mbar, and the vacuum time must be ≥15min. During the RH vacuum treatment, the pure degassing time must be ≥7min; during the RH vacuum treatment, titanium-iron alloy is added to adjust the composition to the target range; after the RH vacuum treatment, calcium treatment is carried out, and the soft blowing time after calcium treatment must be ≥8min. 3) Continuous casting process: constant casting speed, argon gas protection throughout the process, and gentle pressure control are adopted; 4) After smelting and casting, the slabs are produced. The hot rolling heating process is shown in the table below: 5) The key rolling process parameters and rolling passes are shown in the table below: Key rolling process parameters: Rolling passes: 6) After finishing rolling, the slab is cooled to the set temperature of the layer cooling, which is 600±15℃.

2. The hot-rolling production method of wide-width pure hydrogen transmission pipeline steel L415MH according to claim 1, characterized in that: In step 4), the heating time for cold loading is 30-60 minutes, and for hot loading it is 25-55 minutes, during which the first descaling process is carried out.

3. The hot-rolling production method of wide-width pure hydrogen transmission pipeline steel L415MH according to claim 1, characterized in that: The temperature is reduced to the cooling bed temperature using a dense laminar flow cooling method.

4. The hot-rolling production method of wide-width pure hydrogen transmission pipeline steel L415MH according to claim 1, characterized in that: The L415MH steel used in the wide-width pure hydrogen transmission pipeline has the following composition by weight percentage: C: 0.04-0.06%, Si: 0.10-0.20%, Mn: 1.20-1.35%, Nb: 0.040-0.050%, Ti: 0.010-0.020%, Cr: 0.18-0.28%, Ni: 0.08-0.15%, V: 0.030-0.040%, Alt: 0.025-0.050%, with the balance being Fe and other unavoidable impurities, wherein P≤0.012%, S≤0.0015%, O≤0.0030%, N≤0.0055%, and H≤0.0001%.

5. The hot-rolling production method of wide-width pure hydrogen transmission pipeline steel L415MH according to claim 4, characterized in that: The L415MH steel for wide-width pure hydrogen transmission pipelines has the following composition by weight percentage: C: 0.05%, Si: 0.12%, Mn: 1.23%, Nb: 0.042%, Ti: 0.017%, Cr: 0.21%, Ni: 0.11%, V: 0.032%, Alt: 0.048%, with the balance being Fe and other unavoidable impurities, including P: 0.010%, S: 0.0004%, O: 27ppm, N: 36ppm, and H: 0.8ppm.

6. The hot-rolling production method of wide-width pure hydrogen transmission pipeline steel L415MH according to claim 1, characterized in that: Pulling speed range: 1.0~1.5m / min.

7. The hot-rolling production method of wide-width pure hydrogen transmission pipeline steel L415MH according to claim 1, characterized in that: The roughing and finishing rolling temperatures during the rolling process are ≤1050℃.

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