H2S corrosion resistant extra-thick steel plate and production method thereof

Abstract

The invention relates to an H2S corrosion resistant super-thick steel plate and a production method thereof, and belongs to the technical field of steel production. The steel plate comprises the following chemical components in percentage by weight: less than or equal to 0.31% of C, 0.10-0.50% of Si, 0.70-1.30% of Mn, less than or equal to 0.005% of P, less than or equal to 0.002% of S, less than or equal to 0.35% of Cr, less than or equal to 0.45% of Ni, less than or equal to 0.03% of Nb and the balance of Fe and inevitable impurities. The forging and rolling process is adopted, forging pressure stress and rolling tensile stress are fully utilized, and the internal structure of the steel plate is improved; the heat treatment process is carried out in a single furnace and a matched quenching tank. The produced 220-300 mm extra-thick steel plate has good H2S resistance and excellent low-temperature impact toughness, the yield strength is larger than or equal to 250 MPa, the tensile strength is 450-650 MPa, and the steel plate is suitable for manufacturing various corrosion-resistant pressure containers and auxiliary pipelines with the low-temperature impact requirement.

Description

Technical Field

[0001] The invention belongs to the technical field of steel production, and relates to an extra-thick steel plate resistant to H2S corrosion and a production method thereof. Background Art

[0002] Affected by market orientation and deterioration of resource quality, corrosion problems in low-temperature corrosion environments of sulfides are becoming more and more prominent, and accidents of cracking of pressure vessels and pipelines remain high, which seriously troubles the safe operation of petrochemical enterprises' production equipment. At present, with the safety upgrade of chemical equipment and the improvement of finished oil quality in the petrochemical field at home and abroad, petrochemical enterprises have put forward more and more stringent requirements for materials in low-temperature corrosion environments. Based on the demand of the application market for such steel plates with greater thickness and higher technical requirements, my country has stepped up the pace of research and development of ultra-thick HIC-resistant steel. According to the survey and statistical results, the annual compound growth rate (CAGR) of HIC steel in the Chinese market has been relatively fast in the past few years, and the market size and market share will further expand from 2024 to 2030. In terms of product types, extra-thick steel plates with a thickness of more than 200 mm occupy an important position and will continue to grow in the next few years.

[0003] In the prior art, forgings are often used to produce extra-thick steel plates, which has a long manufacturing cycle and is expensive. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an extra-thick steel plate resistant to H2S corrosion and a production method thereof, which adopts a combination of forging and rolling, has a simple process and controllable costs, fully utilizes the advantages of forging and rolling, and the obtained steel plate has a good match in strength and toughness.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: A H2S corrosion resistant extra-thick steel plate, whose chemical composition and mass percentage are: C≤0.31%, Si: 0.10-0.50%, Mn: 0.70-1.30%, P≤0.005%, S≤0.002%, Cr≤0.35%, Ni≤0.45%, Nb≤0.03%, and the balance is Fe and unavoidable impurities.

[0006] Furthermore, the thickness of the steel plate is 220-300 mm, and the weight of the steel plate is 50-57 t.

[0007] Furthermore, the yield strength of the steel plate is ≥250MPa, the tensile strength is 450-650MPa, the impact energy at -30°C is ≥120J, and the CLR, CTR, CSR and maximum crack length of a single cross-section of each H2S corrosion specimen are all 0.

[0008] The present invention also provides a method for producing the above-mentioned H2S corrosion-resistant extra-thick steel plate, which includes smelting, forging, rolling, and heat treatment steps; Smelting process: produced by ingots; Heat treatment process: normalizing + tempering process is adopted; it is carried out in a single furnace; after the normalizing and heat preservation is completed, quenching is carried out in the quenching tank.

[0009] Furthermore, the weight of the ingot is 88-100t.

[0010] Furthermore, in the forging process, the heating temperature is 1300-1350°C, after which the upper flat anvil and platform, the steel ingot is preheated to 120-480°C, the operating machine clamps the bottom of the steel ingot, presses the clamp handle, and then the operating machine clamps the clamp handle, chamfers, and cuts off the bottom cone of the steel ingot.

[0011] Furthermore, in the rolling process, the heating temperature is 1200-1300° C., and the reduction amount of each of the first three passes of rough rolling is 35-40 mm.

[0012] Furthermore, in the heat treatment process, the quenching time is ≥90 min.

[0013] Furthermore, in the heat treatment process, the tempering temperature is 500-600° C. and the tempering time in the furnace is 700-1000 min.

[0014] The design idea of ​​the present invention: 1. The present invention adjusts the contents of Cr, Ni and Nb and adopts multi-component composite alloying technology to improve the low-temperature impact toughness of the steel plate while ensuring the strength of the steel plate; at the same time, the Mn element is reduced in the composition design to further reduce the segregation of the steel plate.

[0015] 2. The forging + rolling composite production process is adopted in the rolling process, which makes full use of the forging compressive stress and rolling tensile stress and improves the internal structure of the steel plate.

[0016] 3. The heat treatment process is carried out in a single furnace + matching quenching tank. This furnace type has strong applicability and is easy to promote production.

[0017] The beneficial effect of adopting the above technical solution is that the present invention ensures that the steel plate has excellent impact toughness and H2S resistance by selecting appropriate alloy component ratios, innovating rolling processes and heat treatment process parameters. The steel plate of the present invention has excellent H2S corrosion resistance and good low-temperature impact toughness, with an impact energy of more than 120J at -30°C, a yield strength of ≥250MPa, and a tensile strength of 450-650MPa, and is suitable for the manufacture of various corrosion-resistant pressure vessels and associated pipelines with low-temperature impact requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a heat treatment diagram of a steel plate after normalizing and holding and preparing for quenching in Example 1 of the present invention. DETAILED DESCRIPTION Example 1

[0019] The thickness of the H2S corrosion-resistant extra-thick steel plate in this embodiment is 220 mm, the weight of the steel plate is 50 t, the corresponding weight of the ingot after smelting is 88 t, and its chemical composition and mass percentage are: C 0.21%, Si 0.10%, Mn 0.70%, P0.005%, S 0.002%, Cr 0.35%, Ni 0.45%, Nb 0.03%, and the balance is Fe and unavoidable impurities.

[0020] Forging process: The heating temperature is 1300℃, then the upper flat anvil and the platform are preheated to 120℃, the operator clamps the bottom of the ingot, presses the clamp handle to Φ1000mm, and then the operator clamps the clamp handle, chamfers, and cuts off the bottom cone of the ingot.

[0021] Rolling process: The billet heating temperature is 1200℃, and the reduction amount for each of the first three passes of rough rolling is 35mm.

[0022] Heat treatment process: carried out in a single furnace, in which after normalizing and heat preservation, quenching is carried out in a matching quenching tank, the quenching time is 90 minutes; the tempering temperature is 600℃, and the tempering time in the furnace is 700 minutes.

[0023] The steel plate obtained in this embodiment is as follows Figure 1 The mechanical properties are shown in Table 1.

[0024] Depend on Figure 1 It can be seen that the present invention performs heat treatment in a single furnace, and the heating effect of the entire steel plate is good, which lays a foundation for the excellent performance of the steel plate. Example 2

[0025] The thickness of the H2S corrosion-resistant extra-thick steel plate in this embodiment is 235 mm, the weight of the steel plate is 52 t, the corresponding weight of the ingot after smelting is 90 t, and its chemical composition and mass percentage are: C 0.23%, Si 0.15%, Mn 0.85%, P0.004%, S 0.002%, Cr 0.30%, Ni 0.40%, Nb 0.028%, and the balance is Fe and unavoidable impurities.

[0026] Forging process: The heating temperature is 1310℃, then the upper flat anvil and the platform are preheated to 200℃, the operator clamps the bottom of the ingot, presses the clamp handle to Φ1000mm, and then the operator clamps the clamp handle, chamfers, and cuts off the bottom cone of the ingot.

[0027] Rolling process: The billet heating temperature is 1220℃, and the reduction amount for each of the first three passes of rough rolling is 36mm.

[0028] Heat treatment process: carried out in a single furnace, in which after normalizing and heat preservation, quenching is carried out in a matching quenching tank, the quenching time is 100 minutes; the tempering temperature is 570℃, and the tempering time in the furnace is 780 minutes.

[0029] The steel plate obtained in this embodiment Figure 1 Similar, so omitted, mechanical properties see Table 1. Example 3

[0030] The thickness of the H2S corrosion-resistant extra-thick steel plate in this embodiment is 251 mm, the weight of the steel plate is 53.5 t, the corresponding weight of the ingot after smelting is 92 t, and its chemical composition and mass percentage are: C 0.25%, Si 0.17%, Mn 0.94%, P0.005%, S 0.001%, Cr 0.23%, Ni 0.33%, Nb 0.020%, and the balance is Fe and unavoidable impurities.

[0031] Forging process: The heating temperature is 1320℃, then the upper flat anvil and the platform are preheated to 300℃, the operator clamps the bottom of the ingot, presses the clamp handle to Φ1000mm, and then the operator clamps the clamp handle, chamfers, and cuts off the bottom cone of the ingot.

[0032] Rolling process: The billet heating temperature is 1240℃, and the reduction amount for each of the first three passes of rough rolling is 37mm.

[0033] Heat treatment process: carried out in a single furnace, in which after normalizing and heat preservation, quenching is carried out in a matching quenching tank, the quenching time is 110 minutes; the tempering temperature is 550℃, and the tempering time in the furnace is 850 minutes.

[0034] The steel plate obtained in this embodiment Figure 1 Similar, so omitted, mechanical properties see Table 1. Example 4

[0035] The thickness of the H2S corrosion-resistant extra-thick steel plate in this embodiment is 277 mm, the weight of the steel plate is 55 t, the corresponding weight of the ingot after smelting is 96 t, and its chemical composition and mass percentage are: C 0.28%, Si 0.19%, Mn 1.09%, P0.004%, S 0.001%, Cr 0.18%, Ni 0.25%, Nb 0.014%, and the balance is Fe and unavoidable impurities.

[0036] Forging process: The heating temperature is 1335℃, then the upper flat anvil and the platform are preheated to 400℃, the operator clamps the bottom of the ingot, presses the clamp handle to Φ1000mm, and then the operator clamps the clamp handle, chamfers, and cuts off the bottom cone of the ingot.

[0037] Rolling process: The billet heating temperature is 1260℃, and the reduction amount for each of the first three passes of rough rolling is 38.5mm.

[0038] Heat treatment process: carried out in a single furnace, in which after normalizing and heat preservation, quenching is carried out in a matching quenching tank, the quenching time is 125 minutes; the tempering temperature is 530℃, and the tempering time in the furnace is 920 minutes.

[0039] The steel plate obtained in this embodiment Figure 1 Similar, so omitted, mechanical properties see Table 1. Example 5

[0040] The thickness of the H2S corrosion-resistant extra-thick steel plate in this embodiment is 290 mm, the weight of the steel plate is 56 t, the corresponding weight of the ingot after smelting is 98 t, and its chemical composition and mass percentage are: C 0.30%, Si 0.44%, Mn 1.25%, P0.003%, S 0.002%, Cr 0.15%, Ni 0.20%, Nb 0.012%, and the balance is Fe and unavoidable impurities.

[0041] Forging process: The heating temperature is 1340℃, then the upper flat anvil and the platform are preheated to 450℃, the operator clamps the bottom of the ingot, presses the clamp handle to Φ1000mm, and then the operator clamps the clamp handle, chamfers, and cuts off the bottom cone of the ingot.

[0042] Rolling process: The billet heating temperature is 1280℃, and the reduction amount for each of the first three passes of rough rolling is 39mm.

[0043] Heat treatment process: carried out in a single furnace, in which after normalizing and heat preservation, quenching is carried out in a matching quenching tank, the quenching time is 138min; the tempering temperature is 515℃, and the tempering time in the furnace is 950min.

[0044] The steel plate obtained in this embodiment Figure 1 Similar, so omitted, mechanical properties see Table 1. Example 6

[0045] The thickness of the H2S corrosion-resistant extra-thick steel plate in this embodiment is 300 mm, the weight of the steel plate is 57 t, the corresponding weight of the ingot after smelting is 100 t, and its chemical composition and mass percentage are: C 0.31%, Si 0.50%, Mn 1.30%, P0.003%, S 0.001%, Cr 0.10%, Ni 0.13%, Nb 0.010%, and the balance is Fe and unavoidable impurities.

[0046] Forging process: The heating temperature is 1350℃, then the upper flat anvil and the platform are preheated to 480℃, the operator clamps the bottom of the ingot, presses the clamp handle to Φ1000mm, and then the operator clamps the clamp handle, chamfers, and cuts off the bottom cone of the ingot.

[0047] Rolling process: The billet heating temperature is 1300℃, and the reduction amount for each of the first three passes of rough rolling is 40mm.

[0048] Heat treatment process: carried out in a single furnace, in which after normalizing and heat preservation, quenching is carried out in a matching quenching tank, and the quenching time is 150 minutes; the tempering temperature is 500℃, and the tempering time in the furnace is 1000 minutes.

[0049] The steel plate obtained in this embodiment Figure 1 Similar, so omitted, mechanical properties see Table 1.

[0050] The samples of the extra thick steel plates produced in Examples 1 to 6 were processed and tested for tensile, impact and hydrogen-induced cracking resistance in accordance with the requirements of GB / T 228 "Metallic Materials Tensile Test Methods", GB / T 229 "Metallic Materials Charpy Pendulum Impact Test Methods" and GB / T 8650 "Evaluation Method for Hydrogen-Induced Cracking Resistance of Pipeline Steels and Pressure Vessel Steels". The results are shown in Table 1.

[0051] Table 1 Mechanical properties of extra thick steel plates produced in Examples 1-6 .

Claims

1. A H2S corrosion resistant extra thick steel plate, characterized in that: The chemical composition of the steel plate and its mass percentage are: C≤0.31%, Si: 0.10-0.50%, Mn: 0.70-1.30%, P≤0.005%, S≤0.002%, Cr≤0.35%, Ni≤0.45%, Nb≤0.03%, and the balance is Fe and unavoidable impurities.

2. The H2S corrosion resistant extra thick steel plate according to claim 1, characterized in that: The thickness of the steel plate is 220-300 mm, and the weight of the steel plate is 50-57 t.

3. The H2S corrosion resistant extra thick steel plate according to claim 2, characterized in that: The steel plate has a yield strength of ≥250MPa, a tensile strength of 450-650MPa, an impact energy of ≥120J at -30°C, and a single cross-section CLR, CTR, CSR, and maximum crack length of each H2S corrosion specimen is 0.

4. The method for producing the H2S corrosion resistant extra thick steel plate according to any one of claims 1 to 3, characterized in that: Including smelting, forging, rolling and heat treatment processes; Smelting process: produced by ingots; Heat treatment process: normalizing + tempering process is adopted; it is carried out in a single furnace; after the normalizing and heat preservation is completed, quenching is carried out in the quenching tank.

5. The method for producing H2S corrosion resistant extra thick steel plate according to claim 4, characterized in that: The weight of the ingot is 88-100t.

6. The method for producing an extra-thick steel plate resistant to H2S corrosion according to claim 5, characterized in that: In the forging process, the heating temperature is 1300-1350°C, then the upper flat anvil and the platform, the steel ingot are preheated to 120-480°C, the manipulator clamps the bottom of the steel ingot, presses the clamp handle, and then the manipulator clamps the clamp handle, chamfers, and cuts off the bottom cone of the steel ingot.

7. The method for producing an extra-thick steel plate resistant to H2S corrosion according to claim 6, characterized in that: In the rolling process, the heating temperature is 1200-1300° C., and the reduction amount of each of the first three passes of rough rolling is 35-40 mm.

8. The method for producing an extra-thick steel plate resistant to H2S corrosion according to claim 7, characterized in that: In the heat treatment process, the quenching time is ≥90min.

9. The method for producing an extra-thick steel plate resistant to H2S corrosion according to claim 8, characterized in that: In the heat treatment process, the tempering temperature is 500-600° C. and the tempering time in the furnace is 700-1000 minutes.

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