A production method of SA387Gr22CL2 steel plate for pressure-bearing equipment

Abstract

The present invention relates to a production method of a large-size SA387Gr22CL2 steel plate for pressure-bearing equipment, including steel ingot forging: taking a steel ingot and forging it into an intermediate billet, the ingot shape of the steel ingot is 70t-90t, the thickness of the intermediate billet is 850mm-1000mm, the width is 1800mm-2200mm, and the length is 3500-3600mm; intermediate billet rolling: the thickness of the rolled steel plate is 150-200mm, air cooling after rolling or air cooling to nearly 500°C and then slow cooling with a hood, slow cooling to room temperature and exiting the slow cooling hood; quenching heat treatment; tempering heat treatment. In order to meet the needs of large-scale and thick-walled development of petrochemical equipment such as hydrogenation reactors, the present application provides a low-cost and short-cycle production method for producing steel plates for hydrogenation reactors with a thickness of 50-200mm, a unit weight of more than 45 tons, and high strength and high toughness requirements.

Description

Technical Field

[0001] The invention relates to the field of production methods of iron-based alloys, and in particular to a production method of a SA387Gr22CL2 steel plate for pressure-bearing equipment. Background Art

[0002] At present, pressure-bearing equipment such as hydrogenation reactors are developing in the direction of large-scale and large-wall thickness, and the requirements for SA387Gr22CL2 steel plates for hydrogenation reactors are becoming higher and higher. Not only are the steel plates required to have high strength and high toughness, but the weight / specification of a single steel plate is also required to be as large as possible, so as to reduce longitudinal welds and reduce manufacturing costs. Usually, for hydrogenation reactor steel plates with a thickness of ≤150mm are produced by continuous casting billets, which have the advantages of low cost and short production cycle, but the disadvantage is that the thickness of the continuous casting billets is limited. Under the premise of meeting the compression ratio ≥3, the production thickness of the steel plates is difficult to exceed 150mm, and the unit weight of the continuous casting billet rolling extra-thick steel plates is difficult to exceed 45 tons; therefore, for hydrogenation reactor steel with a thickness of >150mm-200mm generally uses forgings. Although forgings can meet the requirements of large compression ratio and large unit weight, the production cost is extremely high and the production cycle is long, which cannot meet the needs of mass production of enterprises.

[0003] In order to meet the needs of large-scale and thick-walled development of petrochemical equipment such as hydrogenation reactors, it is very necessary to develop a low-cost, short-cycle production method for hydrogenation reactor steel plates that can produce thicknesses greater than 150-200 mm, a unit weight of more than 45 tons, and high strength and toughness requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a production method of large-size SA387Gr22CL2 steel plates for pressure equipment, which can be used to replace the high-cost forging production method. It breaks through the bottleneck of the unit weight of less than 45t of 150-200mm thick SA387Gr22CL2 steel plates for pressure equipment rolled from flat steel ingots, and solves the industry problem.

[0005] The technical solution adopted by the present invention to solve the above problems is: a production method of large-size SA387Gr22CL2 steel plate for pressure-bearing equipment, comprising:

[0006] Step 1, steel ingot forging: take the steel ingot and forge it into an intermediate billet, the ingot shape of the steel ingot is 70t~90t, the thickness of the intermediate billet is 850mm~1000mm, the width is 1800mm~2200mm, and the length is 3500~3600mm;

[0007] Step 2, intermediate billet rolling: starting rolling temperature 1000-1150°C, final rolling temperature 750-900°C, thickness of rolled steel plate 150-200mm, air cooling after rolling or air cooling to nearly 500°C and then slow cooling with a hood, slow cooling to room temperature and exiting the slow cooling hood;

[0008] Step 3: Quenching heat treatment: Heat the steel plate to 900-950℃, keep warm for 300-400min, and cool it in the quenching machine after it comes out of the furnace. The quenching water temperature is ≤29℃, the roller speed is 1.4-2.5m / min, and the cooling water volume in the high-pressure zone is 4000-5100m 3 / h, water pressure in high pressure zone ≥520kPa, steel plate in high pressure zone does not swing, cooling rate of steel plate surface in high pressure zone ≥2℃ / s, cooling rate of steel plate core ≥0.5℃ / s; when steel plate surface cools to below 400℃, it enters low pressure zone, cooling water volume in low pressure zone 1000-3000m 3 / h, water pressure in low pressure zone ≥210kPa, swing time of steel plate in low pressure zone ≥6min, when the measured temperature of steel plate surface ≤100℃ and the calculated temperature of steel plate core ≤200℃, the steel plate leaves the quenching machine;

[0009] Step 4: Tempering heat treatment: tempering is used to eliminate quenching stress, reduce hardness and strength, improve plasticity and toughness, and obtain a structure dominated by tempered troostite.

[0010] Preferably, in step 1, the initial forging temperature of the steel ingot is 1000-1100°C, and the final forging temperature is 820-920°C.

[0011] Preferably, in step one, the steel ingot is a cylindrical steel ingot, and the ingot shape is 70t to 90t, so as to break through the bottleneck of the single plate weight being less than 45t.

[0012] Preferably, in step 4, the tempering heating temperature is 700-750° C., the temperature is kept for 450-600 min, and the steel is air-cooled or blown-cooled to room temperature after being taken out of the furnace.

[0013] The SA387Gr22CL2 pressure-bearing equipment steel plate with a thickness of 150 to 200 mm and a weight of more than 45 tons obtained according to the above method has a structure of tempered bainite on the surface and near-surface thickness of the steel plate, and tempered bainite and a very small amount of ferrite at 1 / 2 thickness of the steel plate, wherein the proportion of tempered bainite in the metallographic diagram is more than 90%; the -30°C impact energy at 1 / 2 thickness of the steel plate is ≥100J, the yield strength is ≥450MPa, and the tensile strength is ≥600MPa. The -30°C impact energy at 1 / 2 thickness of the steel plate is ≥100J, the yield strength is ≥450MPa, and the tensile strength is ≥600MPa.

[0014] Compared with the prior art, the advantages of the present invention are:

[0015] 1. The production method of SA387Gr22CL2 steel plate for pressure-bearing equipment designed in the present invention adopts cylindrical steel ingots as blanks, significantly improves the forging ratio, and improves the structural uniformity and density of the full-thickness section of the blank.

[0016] 2. The 70-90t cylindrical steel ingot forging + intermediate billet rolling process can significantly increase the weight of a single steel plate, and the maximum weight of the product can reach more than 45 tons, breaking through the bottleneck of the small unit weight of such steel plates and meeting the manufacturing needs of pressure-bearing equipment such as large hydrogenation reactors. Compared with the simple forging process, the forging + rolling process of the present invention has an obvious low-cost advantage.

[0017] 3. After quenching and tempering, the steel plate surface, 1 / 4 thickness and 3 / 4 thickness are tempered troostite, and 1 / 2 thickness is tempered troostite and a very small amount of ferrite. This structure can well ensure that the steel plate has both high strength and excellent low-temperature toughness. The technical requirements of the steel plate 1 / 2 thickness (core) -30℃ impact energy ≥100J, yield strength ≥450MPa, tensile strength ≥600MPa, etc., compared with the ultra-thick steel plates produced by continuous casting billet + rolling and traditional flat steel ingot + rolling methods, the core performance margin and stability are significantly improved.

[0018] The tensile strength, yield strength and -30°C impact properties of the 200 mm thick steel plate obtained by the method of the present invention and the steel plate of the same thickness produced by the conventional flat ingot forging process at 1 / 2 of the plate thickness are shown in Table 1.

[0019] Table 1

[0020] DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with examples. The examples are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0022] Example 1

[0023] The weight of a single SA387Gr22CL2 steel plate in this embodiment is 45.2 tons and the thickness is 152 mm (Note: Because a large cap opening and tail casting opening are generated at the head of the steel ingot during casting, they need to be completely removed after forging. The removed portion accounts for about 20-30% of the steel ingot. The larger the ingot, the lower the proportion. Therefore, the weight of the final product is quite different from the weight of the steel ingot. The production method includes steel ingot forging, intermediate billet rolling, quenching process, and tempering process. The specific implementation steps are:

[0024] Ingot forging process: cylindrical ingots are used, the ingot shape is 70t, the initial forging temperature is 1080℃, and the final forging temperature is 850℃.

[0025] Intermediate billet rolling process: The steel ingot is forged into an intermediate billet with a thickness of 900mm, a width of 1900mm, a length of 3600mm and a weight of 48 tons. The starting rolling temperature is 1120℃, the final rolling temperature is 770℃, the steel plate after rolling is 152mm thick, 2400mm wide and 15800mm long, and air cooling is performed after rolling.

[0026] Quenching process: The steel plate is heated to 920℃, kept warm for 300min, and then quickly cooled in the quenching machine after being taken out of the furnace. The water temperature of the quenching machine is 28℃, the roller speed is 2.5m / min, and the water volume in the high-pressure zone is 4000m 3 / h, water pressure in high pressure zone is 520kPa, steel plate in high pressure zone does not swing, cooling rate of steel plate surface in high pressure zone is 3℃ / s, cooling rate of steel plate core is 0.65℃ / s; steel plate surface cools to below 350℃ and enters low pressure zone, water volume in low pressure zone is 1500m 3 / h, the water pressure in the low-pressure zone is 220kPa, the swing time of the steel plate in the low-pressure zone is 8min, when the measured temperature of the steel plate surface is 90℃ and the calculated temperature of the steel plate core is 120℃, the steel plate leaves the quenching machine to complete the quenching.

[0027] Tempering process: heat the steel plate to 750℃, keep it warm for 450min, and cool it to room temperature with a fan after it comes out of the furnace.

[0028] Example 2

[0029] The weight of a single SA387Gr22CL2 steel plate in this embodiment is 47.6 tons and the thickness is 160 mm. The production method includes steel ingot forging, intermediate billet rolling, quenching process, and tempering process. The specific implementation steps are as follows:

[0030] Ingot forging process: cylindrical ingots are used, the ingot shape is 75t, the initial forging temperature is 1085℃, and the final forging temperature is 860℃.

[0031] Intermediate billet rolling process: The steel ingot is forged into an intermediate billet with a thickness of 900mm, a width of 2000mm, a length of 3600mm and a weight of 50.9 tons. The starting rolling temperature is 1125℃, the final rolling temperature is 790℃, the steel plate after rolling is 160mm thick, 2400mm wide and 15800mm long, and air cooling is performed after rolling.

[0032] Quenching process: The steel plate is heated to 920℃, kept warm for 320min, and then quickly cooled in the quenching machine after being taken out of the furnace. The water temperature of the quenching machine is 28℃, the roller speed is 2.4m / min, and the water volume in the high-pressure zone is 4100m 3 / h, water pressure in high pressure zone is 530kPa, steel plate in high pressure zone does not swing, cooling rate of steel plate surface in high pressure zone is 3℃ / s, cooling rate of steel plate core is 0.64℃ / s; steel plate surface cools to below 340℃ and enters low pressure zone, water volume in low pressure zone is 1550m 3 / h, the water pressure in the low-pressure zone is 225kPa, the swing time of the steel plate in the low-pressure zone is 9min, when the measured temperature of the steel plate surface is 95℃ and the calculated temperature of the steel plate core is 130℃, the steel plate leaves the quenching machine to complete the quenching.

[0033] Tempering process: Heat the steel plate to 745℃, keep it warm for 480min, and cool it to room temperature with a fan after it comes out of the furnace.

[0034] Example 3

[0035] The weight of a single SA387Gr22CL2 steel plate in this embodiment is 45.6 tons and the thickness is 175 mm. The production method includes steel ingot forging, intermediate billet rolling, quenching process, and tempering process. The specific implementation steps are as follows:

[0036] Ingot forging process: cylindrical ingots are used, the ingot shape is 75t, the initial forging temperature is 1090℃, and the final forging temperature is 880℃.

[0037] Intermediate billet rolling process: The steel ingot is forged into an intermediate billet with a thickness of 920mm, a width of 2000mm, a length of 3600mm and a weight of 52.0 tons. The starting rolling temperature is 1130℃, the final rolling temperature is 810℃, the steel plate after rolling is 175mm thick, 2100mm wide and 15800mm long, and air-cooled after rolling.

[0038] Quenching process: The steel plate is heated to 930℃, kept warm for 350min, and then quickly cooled in the quenching machine after being taken out of the furnace. The water temperature of the quenching machine is 28℃, the roller speed is 2.1m / min, and the water volume in the high-pressure zone is 4500m 3 / h, water pressure in high pressure zone is 550kPa, steel plate in high pressure zone does not swing, cooling rate of steel plate surface in high pressure zone is 2.9℃ / s, cooling rate of steel plate core is 0.60℃ / s; steel plate surface cools to below 335℃ and enters low pressure zone, water volume in low pressure zone is 1600m 3 / h, the water pressure in the low-pressure zone is 230kPa, the swing time of the steel plate in the low-pressure zone is 10min, when the measured temperature of the steel plate surface is 100℃ and the calculated temperature of the steel plate core is 145℃, the steel plate leaves the quenching machine to complete the quenching.

[0039] Tempering process: Heat the steel plate to 740℃, keep it warm for 525min, and cool it to room temperature with a fan after it comes out of the furnace.

[0040] Example 4

[0041] The weight of a single SA387Gr22CL2 steel plate in this embodiment is 46.6 tons and the thickness is 190 mm. The production method includes steel ingot forging, intermediate billet rolling, quenching process, and tempering process. The specific implementation steps are as follows:

[0042] Ingot forging process: cylindrical ingots are used, and the ingot shape is 82t. The initial forging temperature is 1090℃, and the final forging temperature is 880℃.

[0043] Intermediate billet rolling process: The steel ingot is forged into an intermediate billet with a thickness of 1000mm, a width of 2050mm, a length of 3500mm and a weight of 56.3 tons. The starting rolling temperature is 1140℃, the final rolling temperature is 835℃, the steel plate after rolling is 190mm thick, 2500mm wide and 12500mm long, and air cooling is performed after rolling.

[0044] Quenching process: The steel plate is heated to 930℃, kept warm for 380min, and then quickly cooled in the quenching machine after being taken out of the furnace. The water temperature of the quenching machine is 28℃, the roller speed is 1.9m / min, and the water volume in the high-pressure zone is 5000m 3 / h, water pressure in high pressure zone is 570kPa, steel plate in high pressure zone does not swing, cooling rate of steel plate surface in high pressure zone is 2.8℃ / s, cooling rate of steel plate core is 0.58℃ / s; steel plate surface cools to below 330℃ and enters low pressure zone, water volume in low pressure zone is 1700m 3 / h, the water pressure in the low-pressure zone is 235kPa, the swing time of the steel plate in the low-pressure zone is 11min, when the measured temperature of the steel plate surface is 120℃ and the calculated temperature of the steel plate core is 180℃, the steel plate leaves the quenching machine to complete the quenching.

[0045] Tempering process: Heat the steel plate to 730℃, keep it warm for 570min, and cool it to room temperature with a fan after it comes out of the furnace.

[0046] Example 5

[0047] The weight of a single SA387Gr22CL2 steel plate in this embodiment is 49.1 tons and the thickness is 200 mm. The production method includes steel ingot forging, intermediate billet rolling, quenching process, and tempering process. The specific implementation steps are as follows:

[0048] Ingot forging process: cylindrical ingots are used, and the ingot shape is 90t. The initial forging temperature is 1095℃, and the final forging temperature is 885℃.

[0049] Intermediate billet rolling process: The steel ingot is forged into an intermediate billet with a thickness of 1000mm, a width of 2100mm, a length of 3500mm and a weight of 57.7 tons. The starting rolling temperature is 1150℃, the final rolling temperature is 845℃, the steel plate after rolling is 200mm thick, 2500mm wide and 12500mm long, and air cooling is performed after rolling.

[0050] Quenching process: The steel plate is heated to 930℃, kept warm for 400min, and then quickly cooled in the quenching machine after being taken out of the furnace. The water temperature of the quenching machine is 28℃, the roller speed is 1.8m / min, and the water volume in the high-pressure zone is 5100m 3 / h, water pressure in high pressure zone is 580kPa, steel plate in high pressure zone does not swing, cooling rate of steel plate surface in high pressure zone is 2.8℃ / s, cooling rate of steel plate core is 0.55℃ / s; steel plate surface cools to below 325℃ and enters low pressure zone, water volume in low pressure zone is 1800m 3 / h, the water pressure in the low-pressure zone is 235kPa, the swing time of the steel plate in the low-pressure zone is 13min, when the measured temperature of the steel plate surface is 135℃ and the calculated temperature of the steel plate core is 205℃, the steel plate leaves the quenching machine to complete the quenching.

[0051] Tempering process: Heat the steel plate to 710℃, keep it warm for 600min, and cool it to room temperature with a fan after it comes out of the furnace.

[0052] The tensile strength, yield strength and -30°C impact properties of the steel plates produced in Examples 1 to 5 and the steel plates of the same thickness manufactured by the conventional flat ingot production process at 1 / 2 of the plate thickness are shown in Table 2. The structure of the steel plate surface, 1 / 4 of the thickness and 3 / 4 of the thickness is tempered troostite, and the structure of the 1 / 2 thickness is more than 90% tempered troostite and a very small amount of ferrite, which can well ensure that the steel plate has both high strength and excellent low-temperature toughness.

[0053] Table 2 Tensile strength, yield strength and impact properties of the steel plates produced in each embodiment

[0054]

[0055] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A method for producing large-size SA387Gr22CL2 steel plates for pressure-bearing equipment, characterized in that: include Step 1, ingot forging: take the ingot and forge it into an intermediate billet, the ingot shape is 70t~90t, the ingot is a cylindrical ingot, the thickness of the intermediate billet is 850mm~1000mm, the width is 1800mm~2200mm, and the length is 3500~3600mm; Step 2, intermediate billet rolling: starting rolling temperature 1000-1150°C, final rolling temperature 750-900°C, thickness of rolled steel plate 150-200mm, air cooling after rolling or air cooling to nearly 500°C and then slow cooling with a hood, slow cooling to room temperature and exiting the slow cooling hood; Step 3: Quenching heat treatment: Heat the steel plate to 900-950℃, keep warm for 300-400min, and cool it in the quenching machine after it comes out of the furnace. The quenching water temperature is ≤29℃, the roller speed is 1.4-2.5m / min, and the cooling water volume in the high-pressure zone is 4000-5100m 3 / h, water pressure in high pressure zone ≥520kPa, steel plate in high pressure zone does not swing, cooling rate of steel plate surface in high pressure zone ≥2℃ / s, cooling rate of steel plate core ≥0.5℃ / s; when steel plate surface cools to below 400℃, it enters low pressure zone, cooling water volume in low pressure zone 1000-3000m 3 / h, water pressure in low pressure zone ≥210kPa, swing time of steel plate in low pressure zone ≥6min, when the measured temperature of steel plate surface ≤100℃ and the calculated temperature of steel plate core ≤200℃, the steel plate leaves the quenching machine; Step 4: Tempering heat treatment; The structure of the steel plate obtained by the method is tempered troostite at the surface and near the surface thickness, and tempered troostite and a very small amount of ferrite at 1 / 2 thickness of the steel plate, wherein the proportion of tempered troostite in the metallographic diagram is more than 90%; The -30℃ impact energy at 1 / 2 thickness of the steel plate is ≥100J, the yield strength is ≥450MPa, and the tensile strength is ≥600MPa.

2. The method according to claim 1, characterized in that: Step 1: The initial forging temperature of the steel ingot is 1000-1100°C, and the final forging temperature is 820-920°C.

3. The method according to claim 1, characterized in that: Step 2: During the rolling process, the maximum reduction rate of a single pass is ≥15%.

4. The method according to claim 1, characterized in that: Step 4: Tempering heating temperature is 700-750°C, keeping temperature for 450-600min, and cooling to room temperature by air or blowing after being taken out of the furnace.

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