A production method of a TMCP hydrogen-doped hydrogen-delivering pipeline steel

Abstract

A production method of TMCP hydrogen-doped hydrogen-delivering pipeline steel, characterized in that the chemical composition of the steel contains C=0.03%-0.05%, Si=0.12%-0.30%, Mn=0.95%-1.05%, P≤0.004%, S≤0.0010%, Alt=0.020%-0.045%, Nb=0.040%-0.050%, Ti=0.010%-0.020%, and the balance is Fe and inevitable impurities. The steel plate has good hydrogen environment compatibility performance in addition to the mechanical properties of conventional pipeline steel. In A solution environment, HIC: CSR≤2%, CLR≤15%, CTR≤5%; the tensile strength and the reduction of area of the smooth sample in a 6.3 MPa pure hydrogen environment are greater than 80% and 95% in the air environment; at the same time, in the 6.3 MPa pure hydrogen environment, the K1C of the step compact tension sample is ≥100 MPa·m1 / 2, and the fatigue life is ≥100,000 times.

Description

Technical Field

[0001] This invention belongs to the field of special purpose pipeline steel production technology, and relates to an X52MH hydrogen-doped hydrogen transportation pipeline steel and its production method. Background Technology

[0002] The uncontrolled generation of clean energy sources such as wind, solar, and tidal power results in a large amount of wasted electricity. Utilizing this wasted electricity to produce hydrogen, which is then stored and transported to users, represents a green energy development path. With the development of clean energy, the demand for hydrogen is gradually increasing, and traditional vehicle transportation methods cannot meet user needs. Pipeline hydrogen transportation, with its advantages of large capacity, low energy consumption, and low cost, is an economical way to achieve large-scale, long-distance hydrogen transport.

[0003] The key specifications for hydrogen-blended pipelines in the "Key Technologies for Long-Distance Pipeline Transportation and Application of Pure Hydrogen and Natural Gas" project are: gas transmission pressure ≥ 6.3 MPa; pipe diameter ≥ 500 mm. Currently, existing hydrogen transmission pipelines mainly use low-grade seamless pipes with transmission pressures ≤ 4.5 MPa and pipe diameters between 50 and 323.9 mm. The development of specialized hydrogen transmission pipeline steel with higher grades and larger diameters is urgently needed.

[0004] Chinese patent CN113862549A discloses "a production method of L360QS hydrogen pipeline steel". The steel plate of this invention uses heat treatment process, composition, rolling process and cooling method, and only performs HIC, SSCC and slow strain tensile tests in hydrogen environment, without mentioning hydrogen embrittlement sensitivity and fracture toughness test, and the test items under hydrogen environment conditions are insufficient. Summary of the Invention

[0005] This invention aims to provide a production method for TMCP hydrogen-doped pipeline steel, specifically a production method for X52MH hydrogen-doped pipeline steel, to solve the key technical challenges of steel plates for high-grade, large-diameter pure hydrogen and hydrogen-doped pipeline transportation. In addition to possessing the mechanical properties of conventional pipeline steel, the steel plate also exhibits excellent hydrogen environment compatibility. Requirements include: HIC in solution A: CSR≤2%, CLR≤15%, CTR≤5%; tensile strength and reduction of area of ​​smooth specimens in a 6.3MPa pure hydrogen environment greater than 80% and 95% of those in air; and K1C ≥100MPa·m for stepped compact tensile specimens in a 6.3MPa pure hydrogen environment. 1 / 2 Fatigue life ≥ 100,000 cycles.

[0006] The technical solution of the present invention:

[0007] A method for producing pipeline steel for TMCP hydrogen-doped hydrogen transportation, wherein the steel's chemical composition (mass percentage) is C=0.03%~0.05%, Si=0.12%~0.30%, Mn=0.95%~1.05%, P≤0.004%, S≤0.0010%, Alt=0.020%~0.045%, Nb=0.040%~0.050%, Ti=0.010%~0.020%, with the balance being Fe and unavoidable impurities. Key process steps include:

[0008] (1) Steelmaking: Converter tapping P≤0.012%; Refining adopts LF+VD combination. After entering LF, slag is removed and dephosphorized first, and then slag is re-formed and desulfurized. LF time in station ≥80min, calcium feeding line ≥150m, S out of station ≤0.001%; ​​VD vacuum time ≥12min, soft blowing ≥15min;

[0009] (2) Continuous casting: The cross-section thickness × width is 260 × (1700~2600) mm, and an integral nozzle is used to avoid secondary oxidation of molten steel;

[0010] (3) Heating: Heating temperature 1200~1220℃, heating time 200~240min;

[0011] (4) Rolling: The end temperature of the first stage rolling is 1000~1100℃, the end temperature of the second stage rolling is 810~900℃, and the rolling is carried out in 7~9 passes with a cumulative reduction of ≥60% in the finishing rolling;

[0012] (5) Cooling: Initial cooling temperature 760~820℃, cooling rate 6~15℃ / s, final cooling temperature 480~560℃.

[0013] This invention has the following advantages: the composition design uses low carbon, low manganese, and ultra-low phosphorus and sulfur to ensure controllable central segregation; in addition, only niobium is added for microalloying, reducing the formation of hard structures such as bainite and improving the material's compatibility in a hydrogen environment; steelmaking adopts slag removal and secondary slag-making processes to ensure ultra-low phosphorus and sulfur and inclusion control; continuous casting uses an integral nozzle to avoid secondary oxidation and contamination of molten steel; the TMCP process is used, resulting in low production costs and short delivery cycles, giving it a competitive advantage in both cost and delivery; the X52MH steel plate produced according to this invention has a banded structure of 0.5 grade or below, fewer inclusions, less obvious hard bainite structure, and uniform and stable steel plate properties. In addition to meeting the mechanical properties required for conventional pipelines, the following parameters were observed in hydrogen-induced cracking tests under solution A: CSR ≤ 2%, CLR ≤ 15%, CTR ≤ 5%; the tensile strength and reduction of area of ​​smooth specimens in a pure hydrogen environment at 6.3 MPa were greater than 80% and 95% of those in an air environment, respectively; and the K1C of the stepped compact tensile specimens in a pure hydrogen environment at 6.3 MPa was ≥ 100 MPa·m. 1 / 2 Fatigue life ≥ 100,000 cycles. Attached Figure Description

[0014] Figure 1 This is a metallographic diagram of the steel plate. Detailed Implementation

[0015] The present invention will be further described below with reference to the embodiments.

[0016] Example 1: Production of 12.7mm x 52MH pipeline steel

[0017] A method for producing pipeline steel for TMCP hydrogen-doped hydrogen transportation, wherein the chemical composition of the steel is C=0.04%, Si=0.16%, Mn=0.98%, P=0.003%, S=0.0008%, Alt=0.035%, Nb=0.042%, Ti=0.012%, with the balance being Fe and unavoidable impurities. The properties of the steel are shown in Table 1. The process steps are as follows:

[0018] (1) Steelmaking: Converter tapping P=0.010%; Refining adopts LF+VD combination. After entering LF, slag is removed and dephosphorized first, and then slag is re-formed and desulfurized. LF time in station is 112min, calcium feed line is 200m, and S out of station is 0.001%; ​​VD vacuum time is 15min, soft blowing is 25min.

[0019] (2) Continuous casting: The cross-section thickness × width is 260 × 1750 mm, and an integral nozzle is used to avoid secondary oxidation of molten steel;

[0020] (3) Heating: Heating temperature 1205℃, heating time 220min;

[0021] (4) Rolling: The first stage rolling end temperature is 1080℃, the second stage rolling end temperature is 865℃, and the rolling is carried out in 7 passes, with a cumulative reduction of 67% in the finishing rolling;

[0022] (5) Cooling: Initial cooling temperature 780℃, cooling rate 9℃ / s, final cooling temperature 530℃.

[0023] Example 2: Production of 17.5mm x 52MH pipeline steel

[0024] A type of TMCP hydrogen-doped pipeline steel X52MH and its production method are disclosed. The chemical composition of the steel is as follows: C=0.04%, Si=0.18%, Mn=0.99%, P=0.003%, S=0.0009%, Alt=0.032%, Nb=0.044%, Ti=0.014%, with the balance being Fe and unavoidable impurities. The properties of the steel are shown in Table 1. The process steps are as follows:

[0025] (1) Steelmaking: Converter tapping control P=0.009%; Refining adopts LF+VD combination. After entering LF, slag is removed and dephosphorized first, and then slag is re-formed and desulfurized. LF time in station is 105min, calcium feed line is 200m, and S out of station is 0.001%; ​​VD vacuum time is 15min, soft blowing is 23min.

[0026] (2) Continuous casting: cross-section thickness × width: 260 × 1750 mm, using an integral nozzle to avoid secondary oxidation of molten steel;

[0027] (3) Heating: Heating temperature 1206℃, heating time 220min;

[0028] (4) Rolling: The first stage rolling end temperature is 1068℃, the second stage rolling end temperature is 870℃, and the rolling is carried out in 7 passes, with a cumulative reduction of 65% in the finishing rolling;

[0029] (5) Cooling: Initial cooling temperature 790℃, cooling rate 9℃ / s, final cooling temperature 490℃.

[0030] Table 1 Performance test results of X52MH steel in Example 1

[0031] .

Claims

1. A method for producing pipeline steel for hydrogen transportation using TMCP (Transmission Timing Capacity Concentration Technology), characterized in that: The steel's chemical composition (mass percentage) is: C = 0.03%–0.05%, Si = 0.12%–0.30%, Mn = 0.95%–1.05%, P ≤ 0.004%, S ≤ 0.0010%, Alt = 0.020%–0.045%, Nb = 0.040%–0.050%, Ti = 0.010%–0.020%, with the balance being Fe and unavoidable impurities. In solution A, the HIC values ​​are: CSR ≤ 2%, CLR ≤ 15%, CTR ≤ 5%. The tensile strength and reduction of area of ​​the smooth specimen in a pure hydrogen environment at 6.3 MPa are 80% and 95% greater than those in air, respectively. The K1C of the stepped compact tensile specimen in a pure hydrogen environment at 6.3 MPa is ≥ 100 MPa·m. 1 / 2 Fatigue life ≥ 100,000 cycles; Key process steps include: (1) Steelmaking: Converter tapping P≤0.012%; Refining adopts LF+VD combination. After entering LF, slag is removed and dephosphorized first, and then slag is re-formed and desulfurized. LF time in station ≥80min, calcium feeding line ≥150m, S out of station ≤0.001%; ​​VD vacuum time ≥12min, soft blowing ≥15min; (2) Continuous casting: The cross-section thickness × width is 260 × (1700~2600) mm, and an integral nozzle is used to avoid secondary oxidation of molten steel; (3) Heating: Heating temperature 1200~1220℃, heating time 200~240min; (4) Rolling: The end temperature of the first stage rolling is 1000-1100℃, the end temperature of the second stage rolling is 810-900℃, and the rolling is carried out in 7-9 passes with a cumulative reduction of ≥60% in the finishing rolling; (5) Cooling: Initial cooling temperature 760~820℃, cooling rate 6~15℃ / s, final cooling temperature 480~560℃.

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