Steel bar for ecological electric furnace petroleum pipeline and production and preparation method of steel bar

Abstract

The invention discloses a steel bar for an ecological electric furnace petroleum pipeline and a production and preparation method of the steel bar, and belongs to the field of steelmaking. The steel for the petroleum pipeline is prepared from, by mass, 0.36%-0.41% of C, 1.00%-1.20% of Si, 0.35%-0.50% of Mn, smaller than or equal to 0.016% of P, smaller than or equal to 0.010% of S, 1.35%-1.50% of Cr, smaller than or equal to 0.20% of Ni, smaller than or equal to 0.05% of Mo, smaller than or equal to 0.15% of Cu and the balance iron and inevitable impurities. According to the method, the ecological electric furnace, LF, RH and continuous casting smelting processes are adopted for smelting, the steel bar for the petroleum pipeline is produced and manufactured, the indexes such as the mechanical property and the high steel purity of finished steel of the steel bar for the petroleum pipeline are guaranteed, and the surface quality level of the steel bar for the petroleum pipeline is also guaranteed.

Description

Technical Field

[0001] The invention relates to a steel bar for an ecological electric furnace petroleum pipeline and a production method thereof, belonging to the field of steelmaking. Background Art

[0002] An oil pipeline is a pipeline system used to transport oil and oil products. It is usually composed of a series of interconnected pipelines, used to transport crude oil, natural gas liquids, refined oil products, etc. from production sites to processing plants, storage facilities or end users. The quality of steel used in oil pipelines is related to the safety of oil transportation. Therefore, the high temperature resistance, wear resistance, mechanical properties, fatigue life, and steel purity of oil pipeline steel are very high, in order to ensure the normal and safe operation of the oil transportation process.

[0003] This patent develops steel for oil pipelines with excellent mechanical properties and high steel purity, meeting the requirements of high-end products.

[0004] The ecological electric furnace + LF + RH + continuous casting smelting process and rolling process are used to produce steel bars for oil pipelines, which meets high-end usage requirements and achieves a breakthrough in the mass production of steel bars for oil pipelines using the ecological electric furnace continuous casting process. Summary of the invention

[0005] The purpose of the present invention is to provide a production process preparation method for steel bars for oil pipelines. The method adopts ecological electric furnace + LF + RH + continuous casting smelting process to produce steel bars for oil pipelines, which not only ensures the mechanical properties of the finished steel bars for oil pipelines and high steel purity, but also ensures the surface quality level of the steel bars for oil pipelines.

[0006] In order to achieve the above invention purpose, the present invention provides a composition design and process design of steel bars for oil pipelines, with specific steps: ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting billet → annealing, heating furnace heating → rolling → insulation. It meets the quality requirements of steel bars for oil pipelines, and the indicators such as mechanical properties and high steel purity can also meet the standard requirements.

[0007] The invention provides a steel bar for an ecological electric furnace petroleum pipeline, which comprises, by mass percentage, C: 0.36%-0.41%, Si: 1.00%-1.20%, Mn: 0.35%-0.50%, P: ≤0.016%, S: ≤0.010%, Cr: 1.35%-1.50%, Ni: ≤0.20%, Mo: ≤0.05%, Cu: ≤0.15%, and the remainder is iron and inevitable impurities.

[0008] The present invention provides a method for producing the above-mentioned steel bar for ecological electric furnace petroleum pipeline, comprising the following steps:

[0009] The process route is ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting → annealing + heating process → rolling → insulation process. Furthermore, after insulation, the process of → finishing → inspection → packaging and storage → delivery is carried out.

[0010] The ecological electric furnace smelting is:

[0011] 100% scrap steel smelting, of which heavy scrap steel accounts for 85-95%, lump scrap steel accounts for 5-15%, tapping temperature is 1610-1620℃, C is 0.10-0.15wt% when tapping, P≤0.010wt%, auxiliary materials and alloys are added when 1 / 4-1 / 3 of the steel is tapped, and the smelting cycle is 45-55min; the LF furnace refining is:

[0012] The LF station temperature is 1495-1505℃, and a high current of 35000-36000A is used to heat and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime and silicon carbide are added. After 5-6 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke particles are added for carbon increase to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1600-1610℃, 1.5-1.6kg / t of alumina balls, a diffusion deoxidizer, is added for diffusion deoxidation. The furnace door is closed for 10-13 minutes. When the temperature of the molten steel reaches 1580-1600℃, the chemical composition is analyzed for the second time to confirm the deviation of the content of each chemical element from the target value. After the second sample is taken, the station is left when the temperature of the molten steel reaches 1600-1610℃. The LF smelting cycle is 35min-45min.

[0013] The RH is refined as follows:

[0014] The inlet temperature is 1580-1590℃, the operation time is 30min-40min, and the argon pressure is controlled at 0.1-0.3MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 100-110Pa, the timing starts and the time is maintained for 10-15min. At the same time, the argon pressure is adjusted to 0.3-0.5MPa. After the static argon blowing is completed, 0.6-0.7kg / t of carbonized rice husk as a covering agent is added, and the outlet temperature is 1550-1560℃.

[0015] Furthermore, in the above technical scheme, in the ecological electric furnace smelting, the amount of alloy added per ton of steel is: 12-12.2 Kg / t of ferrosilicon, 4.1-4.2 Kg / t of silicon manganese, 25-25.5 Kg / t of high carbon ferrochrome, 1.0-1.2 Kg / t of aluminum wire segments (diameter of 10-16 mm); the amount of auxiliary materials added per ton of steel is: 40-41 Kg / t of active lime (particle size of 10-70 mm), 20-21 Kg / t of dolomite (particle size of 20-70 mm), and 6-6.2 Kg / t of ladle ash.

[0016] Furthermore, in the above technical scheme, in the LF furnace refining, the amount of alloy added is: 1.15-1.25 kg / t of ferrosilicon, 0.6-0.7 kg / t of high carbon ferromanganese, and 0.5-0.6 kg / t of high carbon ferrochrome; the amount of other auxiliary materials added is: 1.4-1.6 kg / t of diffusion deoxidizer alumina balls, 6-6.5 kg / t of active lime (particle size is 10-70 mm), 2.1-2.2 kg / t of silicon carbide (particle size is less than or equal to 5 mm), and 0.7-0.9 kg / t of coke particles.

[0017] Furthermore, in the above technical scheme, the continuous casting is as follows: the ladle arrival temperature is 1545-1555°C, the molten steel volume is 110-115t, the H in the middle ladle is controlled to be ≤2ppm, the casting time is 40min-45min, the whole process is protected casting, and the crystallizer protective slag uses medium carbon steel protective slag.

[0018] Furthermore, in the above technical scheme, the heating process is: the heating process in chronological order is: heating process: the temperature entering the heating furnace is 480℃~550℃, the temperature of the preheating section is required to be 680℃~700℃, and the time is 1.3~1.5h; the temperature of the heating section 2 is required to be 850℃~870℃, and the time is 1.3~1.5h; the temperature of the heating section 1 is required to be 1200℃~1220℃, and the time is 1.3~1.5h; the temperature of the soaking section is required to be 1190℃~1210℃, and the time is 1.3~1.5h; the steel tapping temperature is 1185℃~1195℃.

[0019] Furthermore, in the above technical solution, the rolling includes a primary rolling process and a continuous rolling process;

[0020] The initial rolling process is as follows: rolling 9 times, turning the steel → the first time is 408-408.02 mm wide, 421-421.02 mm high, and 65-65.02 mm in reduction → the second time is 426-426.02 mm wide, 351-351.02 mm high, and 70-70.02 mm in reduction → turning the steel → the third time is 370-370.02 mm wide, 362-362.02 mm high, and 64-64.02 mm in reduction → the fourth time is 397-397.02 mm wide, 272-272.02 mm high, and 90-90.02 mm in reduction → turning the steel → the fifth time is 285-285.02 mm wide, 355-355.02 mm high mm, reduction 42~42.02mm→the 6th pass width 297~297.02mm, height 315~315.02mm, reduction 40~40.02mm→the 7th pass width 307~307.02mm, height 280~280.02mm, reduction 35~35.02mm→the 8th pass width 317~317.02mm, height 246~246.02mm, reduction 34~34.02mm→steel turning→the 9th pass width 271~271.02mm, height 235~235.02mm, reduction 82~82.02mm, passes through 3 850mm rolling mills and 1 735mm rolling mill, and then enters the continuous rolling mill group for rolling.

[0021] Further, in the above technical solution, the continuous rolling product rolling process is: rolling 11 times, the first pass is 229-229.02mm high and 245-245.02mm wide; the second pass is 192-192.02mm high and 235-235.02mm wide; the third pass is 200-200.02mm high and 195-195.02mm wide; the fourth pass is 160-160.02mm high and 214.7-214.72mm wide; the fifth pass is 165-165.02mm high and 174.6-174.62mm wide; the The 6th pass is 118~118.02mm high and 187~187.02mm wide; the 7th pass is 135~135.02mm high and 132~132.02mm wide; the 8th pass is 92~92.02mm high and 148~148.02mm wide; the 9th pass is 110~110.02mm high and 115~115.02mm wide; the 10th pass is 78~78.02mm high and 118.7~118.72mm wide; the 11th pass is 91~91.02mm high and 91~91.02mm wide; the finished product is produced after 11 passes.

[0022] Furthermore, in the above technical solution, the insulation process is: steel insulation, lower insulation pit temperature ≥ 580°C, insulation 52 to 55 hours, pit exit temperature ≤ 150°C.

[0023] Furthermore, in the above technical solution, the steel sample after the heat preservation process is taken for heat treatment, and the heat treatment includes the following steps:

[0024] 1) Quenching: 880-920℃, keeping warm for 0.8-1.2h, oil cooling;

[0025] 2) Tempering: 580-620℃, keep warm for 1.8-2.2h, water cooling.

[0026] Furthermore, in the above technical solution, the steel sample is a Φ25±0.1mm blank.

[0027] Advantageous Effects of the Invention

[0028] (1) The ecological electric furnace + LF + RH + continuous casting smelting process and rolling process are used to produce steel bars for oil pipelines, which meets the mechanical properties requirements and ensures the purity of the steel.

[0029] (2) Reasonable component design and production process ensure surface quality and mechanical properties.

[0030] (3) The macrostructure and non-metallic inclusions of the finished steel meet the requirements of high-end products. DETAILED DESCRIPTION

[0031] Embodiment 1:

[0032] 1Chemical composition of steel bars for ecological electric furnace oil pipeline

[0033] The metal compositions are as follows by mass percentage: C: 0.39%, Si: 1.08%, Mn: 0.42%, P: 0.012%, S: 0.005%, Cr: 1.38%, Ni: 0.05%, Mo: 0.02%, Cu: 0.02%, and the balance is iron and unavoidable impurities.

[0034] 2. The production process of electric furnace continuous casting of steel bars for petroleum pipelines in ecological electric furnaces includes the following steps:

[0035] Process route: ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting → annealing + heating process → rolling → insulation process → finishing → inspection → packaging and storage → delivery.

[0036] (1) Ecological electric furnace smelting

[0037] 100% scrap steel smelting, heavy scrap steel 90%, lump scrap steel 10%; tapping temperature 1615℃, C is 0.12wt%, P is 0.008wt%, auxiliary materials and alloys are added when 1 / 4 of the steel is tapped, and the smelting cycle is 49min. Alloy addition per ton of steel: 12Kg / t of ferrosilicon, 4.1Kg / t of silicon manganese, 25.3Kg / t of high carbon ferrochrome, 1.0Kg / t of aluminum wire segment (diameter 12mm). Auxiliary material addition per ton of steel: 40Kg / t of active lime (particle size 35mm), 20Kg / t of dolomite (particle size 40mm), 6Kg / t of ladle ash.

[0038] (2) LF furnace refining

[0039] The LF station temperature is 1502℃, and the 35500A high current is used to heat up and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime and silicon carbide are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke particles are added for carbon increase to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1604℃, 1.5kg / t of alumina balls, a diffusion deoxidizer, is added for diffusion deoxidation. The furnace door is closed for 10 minutes. When the temperature of the molten steel reaches 1590℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the station is left when the temperature of the molten steel reaches 1604℃. The LF smelting cycle is 40 minutes. Alloys are added: 1.12kg / t of ferrosilicon, 0.6kg / t of high carbon ferromanganese, and 0.5kg / t of high carbon ferrochromium. Supplementary materials: alumina balls 1.5kg / t, active lime (particle size 35mm) 6.2Kg / t, silicon carbide (particle size 3mm) 2.1kg / t, coke particles 0.7kg / t.

[0040] (3) RH refining

[0041] The inlet temperature is 1585℃, the operation time is 35min, and the argon pressure is controlled at 0.1MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 104Pa, the timing starts and the maintenance time is 12min. At the same time, the argon pressure is adjusted to 0.3MPa. After the static argon blowing is completed, 0.6kg / t of carbonized rice husk as a covering agent is added, and the outlet temperature is 1555℃.

[0042] (4) Continuous casting

[0043] The temperature of the ladle arriving at the station is 1551℃, the amount of molten steel is 112t, the H content of the tundish is controlled at 1.4ppm, the casting time is 42min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0044] (5) Heating process

[0045] Heating process: the temperature entering the heating furnace is 520℃, the temperature of the preheating section is required to be 685℃, and the time is 1.4h; the temperature of the heating section 2 is required to be 860℃, and the time is 1.4h; the temperature of the heating section 1 is required to be 1208℃, and the time is 1.3h; the temperature of the soaking section is required to be 1198℃, and the time is 1.5h; the steel tapping temperature is 1190℃.

[0046] (6) Rolling process

[0047] Primary rolling process: 9 passes, steel turning → 1st pass width 408mm, height 421mm, reduction 65mm → 2nd pass width 426mm, height 351mm, reduction 70mm → steel turning → 3rd pass width 370mm, height 362mm, reduction 64mm → 4th pass width 397mm, height 272mm, reduction 90mm → steel turning → 5th pass width 285mm, height 355mm, reduction 42mm→The 6th pass is 297mm wide, 315mm high, and 40mm reduction→The 7th pass is 307mm wide, 280mm high, and 35mm reduction→The 8th pass is 317mm wide, 246mm high, and 34mm reduction→Steel turning→The 9th pass is 271mm wide, 235mm high, and 82mm reduction, passes through 3 850mm rolling mills and 1 735mm rolling mill, and then enters the continuous rolling mill for rolling.

[0048] Continuous rolling product rolling process: 11 passes, the 1st pass is 229mm high and 245mm wide; the 2nd pass is 192mm high and 235mm wide; the 3rd pass is 200mm high and 195mm wide; the 4th pass is 160mm high and 214.7mm wide; the 5th pass is 165mm high and 174.6mm wide; the 6th pass is 118mm high and 187mm wide; the 7th pass is 135mm high and 132mm wide; the 8th pass is 92mm high and 148mm wide; the 9th pass is 110mm high and 115mm wide; the 10th pass is 78mm high and 118.7mm wide; the 11th pass is 91mm high and 91mm wide; the finished product is produced after 11 passes.

[0049] (7) Insulation process

[0050] Insulation process: Steel insulation, lower insulation pit temperature 600℃, insulation 52h, exit pit temperature 120℃.

[0051] (8) Heat treatment process

[0052] Take the Φ25 mm blank for heat treatment, the heat treatment includes the following steps:

[0053] 1) Quenching: 900℃, holding time 1.0h, oil cooling;

[0054] 2) Tempering: 600℃, keep warm for 2.0h, water cooling.

[0055] Embodiment 2:

[0056] 1Chemical composition of steel bars for ecological electric furnace oil pipeline

[0057] The internal control chemical composition was determined to be C: 0.39%, Si: 1.05%, Mn: 0.42%, P: 0.010%, S: 0.005%, Cr: 1.42%, Ni: 0.05%, Mo: 0.02%, Cu: 0.02%, and the balance was iron and unavoidable impurities.

[0058] 2. The production process of electric furnace continuous casting of steel bars for petroleum pipelines in ecological electric furnaces includes the following steps:

[0059] Process route: ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting → annealing + heating process → rolling → insulation process → finishing → inspection → packaging and storage → delivery.

[0060] (1) Ecological electric furnace smelting

[0061] 100% scrap steel smelting, heavy scrap steel 90%, lump scrap steel 10%; tapping temperature 1616℃, C is 0.11wt%, P is 0.009wt%, auxiliary materials and alloys are added when 1 / 4 of the steel is tapped, and the smelting cycle is 48min. Alloy addition per ton of steel: 12Kg / t of ferrosilicon, 4.1Kg / t of silicon manganese, 25Kg / t of high carbon ferrochrome, 1.0Kg / t of aluminum wire segment (diameter 12mm). Auxiliary material addition per ton of steel: 40Kg / t of active lime (particle size 35mm), 20Kg / t of dolomite (particle size 40mm), 6Kg / t of ladle ash.

[0062] (2) LF furnace refining

[0063] The LF station temperature is 1499℃, and the 35600A high current is used to heat up and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime and silicon carbide are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke particles are added for carbon increase to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1606℃, 1.5kg / t of alumina balls, a diffusion deoxidizer, is added for diffusion deoxidation. The furnace door is closed for 10 minutes. When the temperature of the molten steel reaches 1592℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the station is left when the temperature of the molten steel reaches 1606℃. The LF smelting cycle is 40 minutes. Alloys are added: 1.19kg / t of ferrosilicon, 0.6kg / t of high carbon ferromanganese, and 0.5kg / t of high carbon ferrochromium. Supplementary materials: alumina balls 1.5kg / t, active lime (particle size 35mm) 6.2Kg / t, silicon carbide (particle size 3mm) 2.1kg / t, coke particles 0.8kg / t.

[0064] (3) RH refining

[0065] The inlet temperature is 1586℃, the operation time is 36min, and the argon pressure is controlled at 0.1MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 104Pa, the timing starts and the maintenance time is 12min. At the same time, the argon pressure is adjusted to 0.3MPa. After the static argon blowing is completed, 0.6kg / t of carbonized rice husk as a covering agent is added, and the outlet temperature is 1556℃.

[0066] (4) Continuous casting

[0067] The temperature of the ladle at the station is 1551℃, the amount of molten steel is 112t, the H content of the tundish is controlled at 1.7ppm, the casting time is 42min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0068] (5) Heating process

[0069] Heating process: the temperature entering the heating furnace is 510℃, the temperature of the preheating section is required to be 690℃, and the time is 1.4h; the temperature of the heating section 2 is required to be 858℃, and the time is 1.4h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.4h; the temperature of the soaking section is required to be 1198℃, and the time is 1.3h; the steel tapping temperature is 1190℃.

[0070] (6) Rolling process

[0071] Primary rolling process: 9 passes, steel turning → 1st pass width 408mm, height 421mm, reduction 65mm → 2nd pass width 426mm, height 351mm, reduction 70mm → steel turning → 3rd pass width 370mm, height 362mm, reduction 64mm → 4th pass width 397mm, height 272mm, reduction 90mm → steel turning → 5th pass width 285mm, height 355mm, reduction 42mm→The 6th pass is 297mm wide, 315mm high, and 40mm reduction→The 7th pass is 307mm wide, 280mm high, and 35mm reduction→The 8th pass is 317mm wide, 246mm high, and 34mm reduction→Steel turning→The 9th pass is 271mm wide, 235mm high, and 82mm reduction, passes through 3 850mm rolling mills and 1 735mm rolling mill, and then enters the continuous rolling mill for rolling.

[0072] Continuous rolling product rolling process: 11 passes, the 1st pass is 229mm high and 245mm wide; the 2nd pass is 192mm high and 235mm wide; the 3rd pass is 200mm high and 195mm wide; the 4th pass is 160mm high and 214.7mm wide; the 5th pass is 165mm high and 174.6mm wide; the 6th pass is 118mm high and 187mm wide; the 7th pass is 135mm high and 132mm wide; the 8th pass is 92mm high and 148mm wide; the 9th pass is 110mm high and 115mm wide; the 10th pass is 78mm high and 118.7mm wide; the 11th pass is 91mm high and 91mm wide; the finished product is produced after 11 passes.

[0073] (7) Insulation process

[0074] Insulation process: Steel insulation, lower insulation pit temperature 590℃, insulation 53h, exit pit temperature 130℃.

[0075] (8) Heat treatment process

[0076] Take the Φ25 mm blank for heat treatment, the heat treatment includes the following steps:

[0077] 1) Quenching: 900℃, holding time 1.0h, oil cooling;

[0078] 2) Tempering: 600℃, keep warm for 2.0h, water cooling.

[0079] Embodiment 3:

[0080] 1Chemical composition of steel bars for ecological electric furnace oil pipeline

[0081] The internal control chemical composition was determined to be C: 0.39%, Si: 1.08%, Mn: 0.42%, P: 0.010%, S: 0.006%, Cr: 1.39%, Ni: 0.06%, Mo: 0.02%, Cu: 0.02%, and the balance was iron and unavoidable impurities.

[0082] 2. The production process of electric furnace continuous casting of steel bars for petroleum pipelines in ecological electric furnaces includes the following steps:

[0083] Process route: ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting → annealing + heating process → rolling → insulation process → finishing → inspection → packaging and storage → delivery.

[0084] (1) Ecological electric furnace smelting

[0085] 100% scrap steel smelting, heavy scrap steel 90%, lump scrap steel 10%; tapping temperature 1615℃, C is 0.12wt% when tapping, P is 0.008wt%, auxiliary materials and alloys are added when 1 / 4 of the steel is tapped, and the smelting cycle is 49min. Alloy addition per ton of steel: 12Kg / t of ferrosilicon, 4.1Kg / t of silicon manganese, 25.2Kg / t of high carbon ferrochrome, 1.0Kg / t of aluminum wire segment (diameter 12mm). Auxiliary material addition per ton of steel: 40Kg / t of active lime (particle size 35mm), 20Kg / t of dolomite (particle size 40mm), 6Kg / t of ladle ash.

[0086] (2) LF furnace refining

[0087] The LF station temperature is 501℃, and the 35600A high current is used to heat up and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime and silicon carbide are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke particles are added for carbon increase to promote the rapid melting and homogenization of the alloy and carbon powder. When the molten steel temperature reaches 1602℃, 1.5kg / t of alumina balls, a diffusion deoxidizer, is added for diffusion deoxidation. The furnace door is closed for 11 minutes. When the molten steel temperature reaches 1590℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the station is left when the molten steel temperature reaches 1605℃. The LF smelting cycle is 42 minutes. Alloys are added: 1.19kg / t of ferrosilicon, 0.6kg / t of high carbon ferromanganese, and 0.5kg / t of high carbon ferrochromium. Supplementary materials: alumina balls 1.5kg / t, active lime (particle size 35mm) 6.2g / t, silicon carbide (particle size 3mm) 2.1kg / t, coke particles 0.8kg / t.

[0088] (3) RH refining

[0089] The inlet temperature is 1585℃, the operation time is 35min, and the argon pressure is controlled at 0.1MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 106Pa, the timing starts and the maintenance time is 12min. At the same time, the argon pressure is adjusted to 0.4MPa. After the static argon blowing is completed, 0.6kg / t of carbonized rice husk is added as a covering agent, and the outlet temperature is 1557℃.

[0090] (4) Continuous casting

[0091] The temperature of the ladle at the station is 1550℃, the amount of molten steel is 112t, the H content of the tundish is controlled at 1.5ppm, the casting time is 42min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0092] (5) Heating process

[0093] Heating process: the temperature entering the heating furnace is 520℃, the temperature of the preheating section is required to be 690℃, and the time is 1.4h; the temperature of the heating section 2 is required to be 860℃, and the time is 1.3h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.3h; the temperature of the soaking section is required to be 1198℃, and the time is 1.4h; the steel tapping temperature is 1190℃.

[0094] (6) Rolling process

[0095] Primary rolling process: 9 passes, steel turning → 1st pass width 408mm, height 421mm, reduction 65mm → 2nd pass width 426mm, height 351mm, reduction 70mm → steel turning → 3rd pass width 370mm, height 362mm, reduction 64mm → 4th pass width 397mm, height 272mm, reduction 90mm → steel turning → 5th pass width 285mm, height 355mm, reduction 42mm→The 6th pass is 297mm wide, 315mm high, and 40mm reduction→The 7th pass is 307mm wide, 280mm high, and 35mm reduction→The 8th pass is 317mm wide, 246mm high, and 34mm reduction→Steel turning→The 9th pass is 271mm wide, 235mm high, and 82mm reduction, passes through 3 850mm rolling mills and 1 735mm rolling mill, and then enters the continuous rolling mill for rolling.

[0096] Continuous rolling product rolling process: 11 passes, the 1st pass is 229mm high and 245mm wide; the 2nd pass is 192mm high and 235mm wide; the 3rd pass is 200mm high and 195mm wide; the 4th pass is 160mm high and 214.7mm wide; the 5th pass is 165mm high and 174.6mm wide; the 6th pass is 118mm high and 187mm wide; the 7th pass is 135mm high and 132mm wide; the 8th pass is 92mm high and 148mm wide; the 9th pass is 110mm high and 115mm wide; the 10th pass is 78mm high and 118.7mm wide; the 11th pass is 91mm high and 91mm wide; the finished product is produced after 11 passes.

[0097] (7) Insulation process

[0098] Insulation process: Steel insulation, lower insulation pit temperature 590℃, insulation 53h, exit pit temperature 140℃.

[0099] (8) Heat treatment process

[0100] Take the Φ25 mm blank for heat treatment, the heat treatment includes the following steps:

[0101] 1) Quenching: 900℃, holding time 1.0h, oil cooling;

[0102] 2) Tempering: 600℃, keep warm for 2.0h, water cooling.

[0103] Embodiment 4:

[0104] 1Chemical composition of steel bars for ecological electric furnace oil pipeline

[0105] The internal control chemical composition was determined to be C: 0.38%, Si: 1.07%, Mn: 0.41%, P: 0.010%, S: 0.005%, Cr: 1.42%, Ni: 0.05%, Mo: 0.02%, Cu: 0.02%, and the balance was iron and unavoidable impurities.

[0106] 2. The production process of electric furnace continuous casting of steel bars for petroleum pipelines in ecological electric furnaces includes the following steps:

[0107] Process route: ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting → annealing + heating process → rolling → insulation process → finishing → inspection → packaging and storage → delivery.

[0108] (1) Ecological electric furnace smelting

[0109] 100% scrap steel smelting, heavy scrap steel 90%, lump scrap steel 10%; tapping temperature 1615℃, C is 0.12wt%, P is 0.008wt%, auxiliary materials and alloys are added when 1 / 4 of the steel is tapped, and the smelting cycle is 49 minutes. Alloy addition per ton of steel: ferrosilicon 12Kg / t, silicon manganese 4.1Kg / t, high carbon ferrochrome 25Kg / t, aluminum wire segment (diameter 12mm) 1.0Kg / t. Auxiliary material addition per ton of steel: active lime (particle size 35mm) 40Kg / t, dolomite (particle size 40mm) 20Kg / t, ladle ash 6Kg / t.

[0110] (2) LF furnace refining

[0111] The LF station temperature is 1501℃, and the 35600A high current is used to heat and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime and silicon carbide are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke particles are added for carbon increase to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1602℃, 1.5kg / t of alumina balls, a diffusion deoxidizer, is added for diffusion deoxidation. The furnace door is closed for 10 minutes. When the temperature of the molten steel reaches 1590℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the station is left when the temperature of the molten steel reaches 1604℃. The LF smelting cycle is 40 minutes. Alloys are added: 1.18kg / t of ferrosilicon, 0.6kg / t of high carbon ferromanganese, and 0.5kg / t of high carbon ferrochromium. Supplementary materials: alumina balls 1.4kg / t, active lime (particle size 35mm) 6.2Kg / t, silicon carbide (particle size 3mm) 2.1kg / t, coke particles 0.7kg / t.

[0112] (3) RH refining

[0113] The inlet temperature is 1585℃, the operation time is 35min, and the argon pressure is controlled at 0.1MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 103Pa, the timing starts and the maintenance time is 11min. At the same time, the argon pressure is adjusted to 0.3MPa. After the static argon blowing is completed, 0.6kg / t of carbonized rice husk is added as a covering agent, and the outlet temperature is 1555℃.

[0114] (4) Continuous casting

[0115] The temperature of the ladle at the station is 1550℃, the amount of molten steel is 112t, the H content of the tundish is controlled at 1.5ppm, the casting time is 42min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0116] (5) Heating process

[0117] Heating process: the temperature entering the heating furnace is 520℃, the temperature of the preheating section is required to be 690℃, and the time is 1.3h; the temperature of the heating section 2 is required to be 860℃, and the time is 1.3h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.3h; the temperature of the soaking section is required to be 1200℃, and the time is 1.5h; the steel tapping temperature is 1190℃.

[0118] (6) Rolling process

[0119] Primary rolling process: 9 passes, steel turning → 1st pass width 408mm, height 421mm, reduction 65mm → 2nd pass width 426mm, height 351mm, reduction 70mm → steel turning → 3rd pass width 370mm, height 362mm, reduction 64mm → 4th pass width 397mm, height 272mm, reduction 90mm → steel turning → 5th pass width 285mm, height 355mm, reduction 42mm→The 6th pass is 297mm wide, 315mm high, and 40mm reduction→The 7th pass is 307mm wide, 280mm high, and 35mm reduction→The 8th pass is 317mm wide, 246mm high, and 34mm reduction→Steel turning→The 9th pass is 271mm wide, 235mm high, and 82mm reduction, passes through 3 850mm rolling mills and 1 735mm rolling mill, and then enters the continuous rolling mill for rolling.

[0120] Continuous rolling product rolling process: 11 passes, the 1st pass is 229mm high and 245mm wide; the 2nd pass is 192mm high and 235mm wide; the 3rd pass is 200mm high and 195mm wide; the 4th pass is 160mm high and 214.7mm wide; the 5th pass is 165mm high and 174.6mm wide; the 6th pass is 118mm high and 187mm wide; the 7th pass is 135mm high and 132mm wide; the 8th pass is 92mm high and 148mm wide; the 9th pass is 110mm high and 115mm wide; the 10th pass is 78mm high and 118.7mm wide; the 11th pass is 91mm high and 91mm wide; the finished product is produced after 11 passes.

[0121] (7) Insulation process

[0122] Insulation process: Steel insulation, lower insulation pit temperature 600℃, insulation 53h, exit pit temperature 140℃.

[0123] (8) Heat treatment process

[0124] Take the Φ25 mm blank for heat treatment, the heat treatment includes the following steps:

[0125] 1) Quenching: 900℃, holding time 1.0h, oil cooling;

[0126] 2) Tempering: 600℃, keep warm for 2.0h, water cooling.

[0127] Embodiment 5:

[0128] 1Chemical composition of steel bars for ecological electric furnace oil pipeline

[0129] The internal control chemical composition was determined to be C: 0.38%, Si: 1.09%, Mn: 0.41%, P: 0.010%, S: 0.005%, Cr: 1.42%, Ni: 0.05%, Mo: 0.02%, Cu: 0.02%, and the balance was iron and unavoidable impurities.

[0130] 2. The production process of electric furnace continuous casting of steel bars for petroleum pipelines in ecological electric furnaces includes the following steps:

[0131] Process route: ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting → annealing + heating process → rolling → insulation process → finishing → inspection → packaging and storage → delivery.

[0132] (1) Ecological electric furnace smelting

[0133] 100% scrap steel smelting, heavy scrap steel 90%, lump scrap steel 10%; tapping temperature 1614℃, C is 0.11wt%, P is 0.008wt%, auxiliary materials and alloys are added when 1 / 4 of the steel is tapped, and the smelting cycle is 50min. Alloy addition per ton of steel: 12Kg / t of ferrosilicon, 4.1Kg / t of silicon manganese, 25Kg / t of high carbon ferrochrome, 1.0Kg / t of aluminum wire segment (diameter 12mm). Auxiliary material addition per ton of steel: 40Kg / t of active lime (particle size 35mm), 20Kg / t of dolomite (particle size 40mm), 6Kg / t of ladle ash.

[0134] (2) LF furnace refining

[0135] The LF station temperature is 1501℃, and the 35600A high current is used to heat up and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime and silicon carbide are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke particles are added for carbon increase to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1604℃, 1.5kg / t of alumina balls, a diffusion deoxidizer, is added for diffusion deoxidation. The furnace door is closed for 10 minutes. When the temperature of the molten steel reaches 1585℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the station is left when the temperature of the molten steel reaches 1604℃. The LF smelting cycle is 40 minutes. Alloys are added: 1.20kg / t of ferrosilicon, 0.6kg / t of high carbon ferromanganese, and 0.5kg / t of high carbon ferrochromium. Supplementary materials: alumina balls 1.5kg / t, active lime (particle size 35mm) 6.2Kg / t, silicon carbide (particle size 3mm) 2.1kg / t, coke particles 0.8kg / t.

[0136] (3) RH refining

[0137] The inlet temperature is 1585℃, the operation time is 35min, and the argon pressure is controlled at 0.1MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 105Pa, the timing starts and the maintenance time is 12min. At the same time, the argon pressure is adjusted to 0.3MPa. After the static argon blowing is completed, 0.6kg / t of carbonized rice husk as a covering agent is added, and the outlet temperature is 1555℃.

[0138] (4) Continuous casting

[0139] The temperature of the ladle at the station is 1550℃, the amount of molten steel is 112t, the H content of the tundish is controlled at 1.5ppm, the casting time is 42min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0140] (5) Heating process

[0141] Heating process: the temperature entering the heating furnace is 510℃, the temperature of the preheating section is required to be 690℃, and the time is 1.3h; the temperature of the heating section 2 is required to be 860℃, and the time is 1.4h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.4h; the temperature of the soaking section is required to be 1200℃, and the time is 1.3h; the steel tapping temperature is 1190℃.

[0142] (6) Rolling process

[0143] Primary rolling process: 9 passes, steel turning → 1st pass width 408mm, height 421mm, reduction 65mm → 2nd pass width 426mm, height 351mm, reduction 70mm → steel turning → 3rd pass width 370mm, height 362mm, reduction 64mm → 4th pass width 397mm, height 272mm, reduction 90mm → steel turning → 5th pass width 285mm, height 355mm, reduction 42mm→The 6th pass is 297mm wide, 315mm high, and 40mm reduction→The 7th pass is 307mm wide, 280mm high, and 35mm reduction→The 8th pass is 317mm wide, 246mm high, and 34mm reduction→Steel turning→The 9th pass is 271mm wide, 235mm high, and 82mm reduction, passes through 3 850mm rolling mills and 1 735mm rolling mill, and then enters the continuous rolling mill for rolling.

[0144] Continuous rolling product rolling process: 11 passes, the 1st pass is 229mm high and 245mm wide; the 2nd pass is 192mm high and 235mm wide; the 3rd pass is 200mm high and 195mm wide; the 4th pass is 160mm high and 214.7mm wide; the 5th pass is 165mm high and 174.6mm wide; the 6th pass is 118mm high and 187mm wide; the 7th pass is 135mm high and 132mm wide; the 8th pass is 92mm high and 148mm wide; the 9th pass is 110mm high and 115mm wide; the 10th pass is 78mm high and 118.7mm wide; the 11th pass is 91mm high and 91mm wide; the finished product is produced after 11 passes.

[0145] (7) Insulation process

[0146] Insulation process: Steel insulation, lower insulation pit temperature 590℃, insulation 53h, exit pit temperature 130℃.

[0147] (8) Heat treatment process

[0148] Take the Φ25 mm blank for heat treatment, the heat treatment includes the following steps:

[0149] 1) Quenching: 900℃, holding time 1.0h, oil cooling;

[0150] 2) Tempering: 600℃, keep warm for 2.0h, water cooling.

[0151] 2. Test results of finished products of Examples 1 to 5, 2 samples were tested for each heat of steel

[0152] (1) Φ90mm specification macrostructure (finished steel obtained by heat preservation process)

[0153]

[0154] (2) Φ90mm non-metallic inclusions (finished steel obtained by thermal insulation process)

[0155]

[0156]

[0157] (3) Mechanical properties of Φ90mm specification (the test was conducted on Φ25mm specimens obtained after heat treatment)

[0158]

Claims

1. A steel bar for ecological electric furnace petroleum pipeline, characterized in that : Calculated by mass percentage: C: 0.36% ~ 0.41%, Si: 1.00% ~ 1.20%, Mn: 0.35% ~ 0.50%, P: ≤ 0.016%, S: ≤ 0.010%, Cr: 1.35% ~ 1.50%, Ni: ≤ 0.20%, Mo: ≤ 0.05%, Cu: ≤ 0.15%, the balance is iron and unavoidable impurities.

2. A method for producing steel bars for ecological electric furnace petroleum pipelines according to claim 1, characterized in that: The steps include: The process route is: ecological electric furnace smelting + LF furnace refining + RH refining + continuous casting → annealing + heating process → rolling → insulation process; The ecological electric furnace smelting is: 100% scrap steel smelting, of which heavy scrap steel accounts for 85-95%, lump scrap steel accounts for 5-15%, tapping temperature is 1610-1620℃, C is 0.10-0.15wt% when tapping, P≤0.010wt%, auxiliary materials and alloys are added when 1 / 4-1 / 3 of the steel is tapped, and the smelting cycle is 45-55min; the LF furnace refining is: The LF station temperature is 1495-1505℃, and a high current of 35000-36000A is used to heat and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime and silicon carbide are added. After 5-6 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke particles are added for carbon increase to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1600-1610℃, 1.5-1.6kg / t of alumina balls as a diffusion deoxidizer are added for diffusion deoxidation. The furnace door is closed for 10-13 minutes. When the temperature of the molten steel reaches 1580-1600℃, the chemical composition is analyzed for the second time to confirm the deviation of the content of each chemical element from the target value. After the second sample is taken, the station is left when the temperature of the molten steel reaches 1600-1610℃. The LF smelting cycle is 35min-45min. The RH is refined as follows: The inlet temperature is 1580-1590℃, the operation time is 30min-40min, and the argon pressure is controlled at 0.1-0.3MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 100-110Pa, the timing starts and the time is maintained for 10-15min. At the same time, the argon pressure is adjusted to 0.3-0.5MPa. After the static argon blowing is completed, 0.6-0.7kg / t of carbonized rice husk as a covering agent is added, and the outlet temperature is 1550-1560℃.

3. The method according to claim 2, characterized in that In the ecological electric furnace smelting, the amount of alloy added per ton of steel is: 12-12.2 Kg / t of ferrosilicon, 4.1-4.2 Kg / t of silicon manganese, 25-25.5 Kg / t of high carbon ferrochrome, and 1.0-1.2 Kg / t of aluminum wire segments; the amount of auxiliary materials added per ton of steel is: 40-41 Kg / t of active lime, 20-21 Kg / t of dolomite, and 6-6.2 Kg / t of ladle ash.

4. The method according to claim 2, characterized in that: During the LF furnace refining, the amount of alloy added is: 1.15-1.25 kg / t of ferrosilicon, 0.6-0.7 kg / t of high carbon ferromanganese, and 0.5-0.6 kg / t of high carbon ferrochrome; the amount of diffusion deoxidizer alumina balls added is 1.4-1.6 kg / t, active lime is 6-6.5 kg / t, silicon carbide is 2.1-2.2 kg / t, and coke particles are 0.7-0.9 kg / t.

5. The method according to claim 2, characterized in that: The continuous casting is: The temperature of the ladle arriving at the station is 1545~1555℃, the amount of molten steel is 110~115t, the H content of the tundish is controlled to be ≤2ppm, the casting time is 40min~45min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

6. The method according to claim 2, characterized in that The heating process in chronological order is: the temperature entering the heating furnace is 480℃~550℃, the temperature of the preheating section is required to be 680℃~700℃, and the time is 1.3~1.5h; the temperature of the heating section 2 is required to be 850℃~870℃, and the time is 1.3~1.5h; the temperature of the heating section 1 is required to be 1200℃~1220℃, and the time is 1.3~1.5h; the temperature of the soaking section is required to be 1190℃~1210℃, and the time is 1.3~1.5h; the steel tapping temperature is 1185℃~1195℃.

7. The method according to claim 2, characterized in that: The rolling process includes a preliminary rolling process and a continuous rolling process; The initial rolling process is as follows: rolling 9 times, turning the steel → the first time is 408-408.02 mm wide, 421-421.02 mm high, and 65-65.02 mm in reduction → the second time is 426-426.02 mm wide, 351-351.02 mm high, and 70-70.02 mm in reduction → turning the steel → the third time is 370-370.02 mm wide, 362-362.02 mm high, and 64-64.02 mm in reduction → the fourth time is 397-397.02 mm wide, 272-272.02 mm high, and 90-90.02 mm in reduction → turning the steel → the fifth time is 285-285.02 mm wide, 355-355.02 mm high mm, reduction 42~42.02mm→the 6th pass width 297~297.02mm, height 315~315.02mm, reduction 40~40.02mm→the 7th pass width 307~307.02mm, height 280~280.02mm, reduction 35~35.02mm→the 8th pass width 317~317.02mm, height 246~246.02mm, reduction 34~34.02mm→steel turning→the 9th pass width 271~271.02mm, height 235~235.02mm, reduction 82~82.02mm, passes through 3 850mm rolling mills and 1 735mm rolling mill, and then enters the continuous rolling mill group for rolling.

8. The method according to claim 7, characterized in that Continuous rolling process: 11 passes, the first pass is 229-229.02mm high and 245-245.02mm wide; the second pass is 192-192.02mm high and 235-235.02mm wide; the third pass is 200-200.02mm high and 195-195.02mm wide; the fourth pass is 160-160.02mm high and 214.7-214.72mm wide; the fifth pass is 165-165.02mm high and 174.6-174.62mm wide; the sixth pass is 118- 118.02mm, width 187~187.02mm; the 7th pass is 135~135.02mm high, 132~132.02mm wide; the 8th pass is 92~92.02mm high, 148~148.02mm wide; the 9th pass is 110~110.02mm high, 115~115.02mm wide; the 10th pass is 78~78.02mm high, 118.7~118.72mm wide; the 11th pass is 91~91.02mm high, 91~91.02mm wide; the finished product is produced after 11 passes.

9. The method according to claim 2, characterized in that: The insulation process is as follows: steel insulation, lower insulation pit temperature ≥ 580°C, insulation 52 to 55 hours, pit exit temperature ≤ 150°C.

10. The method according to claim 2, characterized in that The steel sample after the heat preservation process is taken for heat treatment, and the heat treatment includes the following steps: 1) Quenching: 880-920℃, keeping warm for 0.8-1.2h, oil cooling; 2) Tempering: 580-620℃, keep warm for 1.8-2.2h, water cooling.

Images