L485Q seamless steel pipe for compressed air energy storage and manufacturing method of L485Q seamless steel pipe

Abstract

The invention relates to an L485Q seamless steel pipe for compressed air energy storage and a manufacturing method of the L485Q seamless steel pipe. The invention provides a high-fatigue-resistance L485Q seamless steel pipe which can meet the service life of 30 years (cumulative 40,000 times of pressurizing-decompressing circulation) under the design pressure of 15-18 MPa. The corrosion resistance of the steel pipe in the salt cavern environment is improved, and the annual corrosion rate is controlled to be 0.005 mm / a or below. Strength-toughness matching is optimized, the yield strength reaches 550-635 MPa, and transverse impact energy at-10 DEG C is larger than or equal to 140 J.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of L485Q seamless steel pipes for compressed air energy storage and manufacturing method thereof, belong to energy storage equipment technical field, specifically related to a kind of high-strength, corrosion-resistant seamless steel pipe suitable for compressed air energy storage system and manufacturing method thereof. BACKGROUND

[0002] With the rapid development of compressed air energy storage (CAES) technology, higher requirements are put forward for the delivery pipeline. The conventional L485Q pipeline steel pipe has the following problems when applied to compressed air energy storage environment: 1. The conventional L485Q pipeline steel pipe is prone to fatigue cracks under high pressure cyclic loading; 2. The corrosion rate of traditional steel pipe exceeds the standard (>0.01 mm / a) due to the underground salt cavern environment; 3. The existing L485Q steel pipe has insufficient low temperature impact toughness at -10℃; 4. Stainless steel pipe and composite pipe can meet the requirements, but the cost is high.

[0003] The reference CN102235554A patent solves the problem of low temperature acid environment, but does not consider the high pressure cyclic loading condition specific to compressed air energy storage; CN104313470A uses rare earth elements to improve performance, but the process is complex and the cost is high; The reference patent CN107419168A discloses a large diameter X70 grade pipeline seamless steel pipe, which has high dimensional accuracy, but does not optimize its corrosion resistance for compressed air energy storage environment; Patent CN103215517A improves the H2S corrosion resistance, but is not suitable for compressed air salt cavern environment. SUMMARY

[0004] The present application aims to solve the problems in the prior art and provide a L485Q seamless steel pipe for compressed air energy storage system with excellent performance and manufacturing method thereof.

[0005] To this end, the technical solution adopted by the present application is as follows: a L485Q seamless steel pipe for compressed air energy storage, by weight percentage, comprising the following components: C 0.10-0.15%; Si 0.20-0.35%; Mn 1.40-1.60%; Cr 0.40-0.50%; V 0.04-0.08%; Al 0.02-0.05%; RE 0.005-0.010%; P ≤0.015%; S ≤0.003% ; Balance is Fe.

[0006] Further, the RE element is in proportion by weight: Ce 67%, La 33%.

[0007] Further, the V is 0.06%, and the Al is 0.03%.

[0008] Further, the C is 0.12%, the Mn is 1.5%, and the Cr is 0.45%.

[0009] A manufacturing method of L485Q seamless steel pipe for compressed air energy storage is manufactured in the following steps: 1) Forming molten iron according to component proportioning and performing pretreatment: adopting metal magnesium powder to desulfurize, so that the S of the molten iron is less than or equal to 0.010%; 2) Converter / electric arc furnace smelting: end point temperature is 1650-1680 DEG C, adopting silicon manganese+aluminum iron composite deoxidation; 3) LF refining: white slag operation, feeding rare earth wire; 4) RH / VD vacuum degassing: vacuum time is greater than or equal to 15 min; 5) Continuous casting: electromagnetic stirring+low superheat degree ΔT is less than or equal to 30 DEG C control; 6) Hot rolling: adopting "two piercing+equalizing+rotary sizing" process, once piercing temperature is 1240-1260 DEG C, twice piercing temperature is 1180-1220 DEG C, equalizing temperature is 1050-1150 DEG C, and rotary sizing temperature is 850-950 DEG C; 7) Heat treatment: 910±10 DEG C water quenching, and 630±20 DEG C tempering; 8) Straightening: temperature straightening, temperature is greater than or equal to 500 DEG C; 9) Anti-corrosion treatment: spraying FBE anti-corrosion coating 0.2-0.5 mm on the inner wall of the pipe, and adopting three-layer PE for the outer wall anti-corrosion of the pipe.

[0010] The advantages of the present application are: 1. providing a high fatigue resistance L485Q seamless steel pipe which meets 30 years of service life (cumulative 40000 times of pressure charging-discharge cycles) under the design pressure of 15-18 MPa.

[0011] 2. improving the corrosion resistance of the steel pipe in the salt cave environment, and controlling the annual corrosion rate to be less than or equal to 0.005 mm / a.

[0012] 3. optimizing the strength-toughness matching, the yield strength reaches 550-635 MPa, and the transverse impact energy at-10 DEG C is greater than or equal to 140 J. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a schematic diagram of the steel pipe structure of the present application.

[0014] Figure 2 A heat treatment process curve diagram for the present application.

[0015] Figure 3 A ductile-brittle transition temperature curve diagram for the present application.

[0016] In the figure, 1-base steel pipe; 2-inner wall FBE anti-corrosion coating; 3-outer anti-corrosion PE layer. DETAILED DESCRIPTION

[0017] RE element ratio (Ce 67%+La 33%), making inclusions spheroidized, reducing corrosion rate.

[0018] V+Al: refine grain, improve impact performance.

[0019] C+Mn+Cr: ensure that more than 75% of bainite structure is obtained after heat treatment, and improve fatigue life.

[0020] Components wt% Action C 0.10-0.15% Guarantee strength while reducing the sensitivity of welding cold cracks Si 0.20-0.35% Deoxidizing strengthening element Mn 1.40-1.60% Improve hardenability, synergistic effect with Cr Cr 0.40-0.50% Improve corrosion resistance and strength V 0.04-0.08% Refine grains, improve toughness Al 0.02-0.05% Deoxidize and fix nitrogen, refine grains RE 0.005-0.010% Mixed rare earth (Ce 67% + La 33%), improve inclusion morphology P ≤0.015% Control impurity content S ≤0.003% Control impurity content A kind of L485Q seamless steel pipe for compressed air energy storage, by weight percentage, including the following components: C 0.10-0.15%; Si 0.20-0.35%; Mn 1.40-1.60%; Cr 0.40-0.50%; V 0.04-0.08%; Al 0.02-0.05%; RE 0.005-0.010%; P ≤0.015%; S ≤0.003% ; balance is Fe.

[0021] Further, the RE element is matched by weight: Ce 67%, La 33%.

[0022] Further, the V is 0.06%, and Al is 0.03%.

[0023] Further, the C is 0.12%, Mn is 1.5%, and Cr is 0.45%.

[0024] A manufacturing method of L485Q seamless steel pipe for compressed air energy storage is manufactured by the following steps: 1) match component ratio to form molten iron and carry out pretreatment: adopt metal magnesium powder to desulfurize, so that the S of molten iron is less than or equal to 0.010%; 2) converter / arc furnace smelting: end point temperature is 1650-1680 DEG C, adopt silicon manganese+aluminum iron composite deoxidation; 3) LF refining: white slag operation, feeding of rare earth wire; 4) RH / VD vacuum degassing: vacuum time ≥ 15 min; 5) Continuous casting: electromagnetic stirring + low superheat ΔT ≤ 30℃ control; 6) Hot rolling: adopting "two piercing + equalizing + rotary sizing" process, one-time piercing temperature 1240-1260℃, two-time piercing temperature 1180-1220℃, equalizing temperature 1050-1150℃, rotary sizing temperature 850-950℃; 7) Heat treatment: 910±10℃ water quenching, 630±20℃ tempering; 8) Straightening: strip temperature straightening, temperature ≥ 500℃; 9) Anti-corrosion treatment: pipe inner wall spraying FBE anti-corrosion coating 0.2-0.5mm, pipe outer wall anti-corrosion adopting three-layer PE.

[0025] Through the above technical scheme, the following technical effects can be obtained: Tensile: ASTM E8 / E8M-24; Impact: ASTM E23-24; Salt spray test: ASTM B117; Fatigue test: ASTM E466.

[0026] Table 1 steel pipe performance data Performance indicators The invention Yield strength 580-635 MPa Tensile strength 690-760 MPa -10℃ impact energy ≥140J Corrosion rate (salt water environment) ≤0.005 mm / a Fatigue life (16.5 MPa cycle) ≥ 10 6 secondary Table 2 series impact data The cost is reduced by about 20% compared with conventional compressed air L485Q steel pipe, and the yield is increased by more than 15%. Example 1:

[0027] The production specification of the L485Q seamless steel pipe for compressed air energy storage is Φ406mm×23mm: 1. Raw material: 90% blast furnace molten iron (pretreated S ≤ 0.008%) + 10% high-quality scrap steel; 2. Composition: C 0.12%, Si 0.28%, Mn 1.50%, Cr 0.50%, V 0.06%, Al 0.03%, RE 0.002%, P 0.012%, S 0.004%, and the balance is Fe.

[0028] 3. Smelting: converter end point temperature 1665℃, LF refining feeding 1.5kg / t rare earth wire (67%Ce+33%La), vacuum degassing time ≥ 15min.

[0029] 4. Continuous casting: electromagnetic stirring, superheat 25℃, slow cooling of the casting blank.

[0030] 5. Hot rolling: a) heating in a ring furnace: preheating section 800-900°C, heating section 1100-1200°C, soaking section 1220-1250°C b) piercing: first piercing temperature 1250°C, second piercing temperature 1200°C, two piercing process makes the steel pipe obtain greater (>1.5) elongation, promotes recrystallization, and refines grains; c) sizing: temperature 1100°C, wall thickness uniformity 4.5%; d) rotary sizing: temperature 900°C, outer diameter 406.4±1.5mm, sizing→rotary sizing" improves wall thickness deviation to within ±5%.

[0031] 6. Heat treatment: a) quenching: 910°C for 50 minutes, water cooling to below 100°C; b) tempering: 630°C for 100 minutes, air cooling.

[0032] 7. Straightening: 520°C with temperature straightening.

[0033] 8. Corrosion protection treatment: inner wall of the pipe is sprayed with FBE corrosion resistant coating 0.30mm, and outer wall corrosion resistant coating is three-layer PE.

[0034] Performance test results: 1) yield strength 610MPa, tensile strength 725MPa, elongation 22%; 2) impact energy at -10°C: 140J, 142J, 143J (transverse direction); 3) corrosion rate: 0.004mm / a (salt water environment, 720h). Example 2:

[0035] Production of L485Q seamless steel pipe for compressed air energy storage with specification Φ711mm×40mm: 1. The pipe blank manufacturing process is the same as that of Example 1.

[0036] 2. Hot rolling: a) using Φ700mm pipe blank, heating in a ring furnace: preheating section 800-900°C, heating section 1260-1280°C, soaking section 1250-1260°C; b) piercing: first piercing temperature 1260°C, second piercing temperature 1220°C, two piercing process makes the steel pipe obtain greater (>1.5) elongation, promotes recrystallization, and refines grains; c) sizing: temperature 1120°C, wall thickness uniformity 4.8%; d) rotary sizing: temperature 920°C, outer diameter 711±3mm, sizing→rotary sizing" improves wall thickness deviation to within ±5%.

[0037] 3. Heat treatment: a) quenching: 910°C for 90 minutes, water cooling to below 100°C; b) tempering: 630 °C for 160 minutes, air cooling 4. straightening: 520 °C with temperature straightening 5. corrosion protection: FBE coating 0.30 mm on the inner wall of the pipe, three-layer PE on the outer wall Performance test results: 1) yield strength 595 MPa, tensile strength 705 MPa, elongation 22%; 2) impact energy at -10 °C: 145 J, 142 J, 142 J (transverse); 3) corrosion rate: 0.0035 mm / a (salt water environment, 720 h).

Claims

1. A seamless L485Q steel pipe for compressed air energy storage, characterized in that, By weight percentage, it includes the following components: C 0.10-0.15%； Si 0.20-0.35%; Mn 1.40-1.60%; Cr 0.40-0.50%； V 0.04-0.08%； Al 0.02-0.05%; RE 0.005-0.010%; P ≤0.015%； S ≤0.003% ； The balance is Fe.

2. The L485Q seamless steel pipe for compressed air energy storage according to claim 1, characterized in that, The RE elements are in the following weight ratios: Ce 67%, La 33%.

3. The L485Q seamless steel pipe for compressed air energy storage according to claim 1, characterized in that, The V is 0.06% and Al is 0.03%.

4. The L485Q seamless steel pipe for compressed air energy storage according to claim 1, characterized in that, The C content is 0.12%, Mn content is 1.5%, and Cr content is 0.45%.

5. A method for manufacturing an L485Q seamless steel pipe for compressed air energy storage, characterized in that, To manufacture, follow these steps: 1) Molten iron is formed according to the batching ratio and pretreated: magnesium powder is used for desulfurization to ensure that the sulfur content of the molten iron is ≤0.010%; 2) Converter / electric arc furnace smelting: final temperature 1650-1680℃, using silicon-manganese + aluminum-iron composite deoxidation; 3) LF refining: white slag production operation, feeding in rare earth wire; 4) RH / VD vacuum degassing: vacuum time ≥ 15 min; 5) Continuous casting: Electromagnetic stirring + low superheat ΔT≤30℃ control; 6) Hot rolling: The process of "two-stage piercing + leveling + rotary sizing" is adopted. The first piercing temperature is 1240-1260℃, the second piercing temperature is 1180-1220℃, the leveling temperature is 1050-1150℃, and the rotary sizing temperature is 850-950℃. 7) Heat treatment: water quenching at 910±10℃, tempering at 630±20℃; 8) Straightening: Heated straightening, temperature ≥ 500℃; 9) Corrosion protection: The inner wall of the pipe is sprayed with an FBE anti-corrosion coating of 0.2-0.5mm, and the outer wall of the pipe is protected with three layers of PE.

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