Production method of nickel-based composite pipeline steel plate

Abstract

The invention discloses a production method of a nickel-based composite pipeline steel plate. A base material comprises the following chemical components in percentage by mass: 0.02%-0.04% of C, 0.05%-0.25% of Si, 1.6%-1.65% of Mn, less than or equal to 0.010% of P, less than or equal to 0.0015% of S, 0.025%-0.050% of Alt, 0.03%-0.060% of Nb, 0.010%-0.020% of Ti, 0.20%-0.25% of Cu, 0.24%-27% of Cr, 0.09%-0.13% of Ni and 0.03%-0.04% of V; the composite material comprises the following chemical components in percentage by mass: less than or equal to 0.05% of C, 0.25%-0.50% of Si, 19.5%-23.5% of Cr, 38%-46% of Ni and 0.28%-0.30% of Co. The N08825 + X70 composite pipeline steel with excellent strength is obtained by adopting a vacuum rolling composite technology, a low-speed deformation technology and an ultra-fast cooling technology, the maximum wall thickness of a base material reaches 45mm, and the thickness of the N08825 is 3mm.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy and relates to a production method of a nickel-based composite pipeline steel plate. Background Art

[0002] The main mode of transportation for oil and natural gas is pipeline transportation. Since oil and gas contain substances such as hydrogen sulfide and carbon dioxide, which will accelerate the corrosion of pipeline steel, accidents of failure or even rupture of oil pipelines due to corrosion and external environment occur from time to time, posing a considerable threat to the safety of life and property of the country and the people. For example, using nickel-based alloy as pipeline steel can solve the problem of insufficient corrosion resistance, but its price is expensive and its comprehensive mechanical properties are not as good as pipeline steel. Therefore, the use of nickel-based composite plates has become the first choice.

[0003] The nickel-based alloy composite plate is a bimetallic composite plate made of carbon steel as the base layer and nickel-based alloy as the composite layer, which is combined together by rolling or other methods. Therefore, the nickel-based alloy composite plate not only has the good mechanical properties of the base layer, but also has the good corrosion resistance and oxidation resistance of the nickel-based alloy, which greatly reduces the production cost and saves resources, while meeting customer and market needs. This also makes the nickel-based alloy composite plate widely used in nuclear power, bridges, water conservancy, aerospace and other fields. In this context, the research and production of nickel-based alloy composite plates can not only ensure its corrosion resistance and excellent mechanical properties, but also greatly reduce production costs. Summary of the invention

[0004] The present invention aims to provide a method for producing a nickel-based composite pipeline steel plate, which adopts vacuum rolling composite + low-speed deformation technology + ultra-fast cooling process to obtain N08825+X70 composite pipeline steel with excellent strength, wherein the maximum wall thickness of the base material reaches 45mm and the thickness of N08825 is 3mm.

[0005] In order to realize the above invention, the present invention adopts the following technical solutions: A production method for a nickel-based composite pipeline steel plate, the process flow of which is substrate surface treatment - packaging assembly welding - primary heating - primary rolling - secondary heating after re-pitting - secondary rolling - cooling - heat treatment - plate opening and finishing - flaw detection - warehousing. The chemical composition mass percentage of the substrate is C=0.02%~0.04%, Si=0.05%~0.25%, Mn=1.6%~1.65%, P≤0.010%, S≤0.0015%, Alt=0.025%~0.050%, Nb=0.03%~0.060%, Ti=0.010%~0.020%, Cu=0.20%~0.25%, Cr=0.24%~27%, Ni=0.09%~0.13%, V=0.03~0.04%, and the balance is Fe and unavoidable impurities; the chemical composition mass percentage of the composite is C≤0.05%, Si=0.25%~0.50%, Cr=19.5%~23.5%, Ni=38~46%, Co=0.28~0.30%, and the balance is Fe and unavoidable impurities. The key process steps include: (1) Preparation of composite billet: "X70+ N08825+ N08825+ X70" double-sided symmetrical composite welding, add an isolation agent between the two composite materials, the thickness of the isolation agent is 0.2~0.3mm, the thickness of the submerged arc welding cladding is 200~300mm, the thickness of the composite billet is 500~600mm, and vacuum is drawn after welding, and the vacuum degree is ≤-1 Pa; (2) Primary heating: soaking pit heating is adopted, the temperature of the steel core is 1150~1160℃, the total heating time is 18~24h, and the temperature difference between the core and the surface of the steel billet is ≤15℃; (3) Primary rolling: Rough rolling to 350-380 mm, three passes with a reduction of 45-50 mm, final rolling temperature ≥ 1100 °C, and cooling down to room temperature after the steel is removed from the line; (4) Secondary heating: Heating is carried out in a walking beam heating furnace, the temperature of the steel core is 1130~1150℃, the total heating time is 5-6h, and the temperature difference between the core and the surface of the steel billet is ≤20℃; (5) Secondary rolling: the intermediate billet is set to 150~180mm, the second stage rolling temperature is 840~860℃, the single pass rolling speed is 2~3m / s, the last two passes are controlled in the two-phase rolling zone, and the final rolling temperature is 690~730℃; (6) Cooling: Ultra-fast swing cooling mode is adopted, with a swing cooling time of 60~120s and a final cooling temperature of 320~360℃.

[0006] Principle of the invention: In terms of composition design, the ultra-low carbon Mo-free + appropriate amount of Cr+Ni+Cu microalloy Nb+Ti composition design is adopted, which can not only refine the grains, but also make the Ar3 line move up, which is very beneficial to the control of two-phase rolling. Regarding step (2), the heating process ensures that the alloy is fully dissolved, the grains are completely austenitized and there is no coarsening and growth phenomenon. The ingot absorbs heat sufficiently and the temperature is uniform, which can not only improve the low-temperature fracture toughness of the material, but also help to improve the shear strength of the joint surface. Regarding step (3), the high-temperature and high-pressure finishing rolling refines the original austenite grain size, and the ingot is air-cooled to room temperature after rolling to further refine the ingot grain size. Regarding steps (5) and (6) of reducing the finishing rolling speed, the low rolling speed further reduces the grain size and greatly improves the bonding degree between the substrate and the composite material; the two passes of two-phase rolling promote the modification and flattening of polygonal ferrite, further improve the low-temperature toughness of the core of the material, and cooperate with the ultra-fast cold swing cooling mode to make the strength and toughness of the material well matched.

[0007] The beneficial effects of the present invention are as follows: the difficult problems of low shear strength and drop hammer low-temperature toughness of the current high-grade nickel-based composite pipeline steel are solved, and the problem of thickness bounce between the nickel base and the substrate during rolling is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is the metallographic structure diagram of the steel plate produced in Example 1. DETAILED DESCRIPTION

[0009] The present invention is further described below with reference to the embodiments.

[0010] Example 1: Production method of 42+3mm X70+ N08825 nickel-based composite pipeline steel plate The chemical composition of the composite board substrate is C=0.03%, Si=0.15%, Mn=1.62%, P=0.008%, S=0.0012%, Alt=0.028%, Nb=0.045%, Ti=0.01%, Cu=0.22%, Cr=0.26%, Ni=0.09%~0.13%, V=0.036%, and the balance is Fe and unavoidable impurities; the chemical composition of the composite material is C=0.04%, Si=0.45%, Cr=22.8%, Ni=42%, Co=0.29%, and the balance is Fe and unavoidable impurities. The key process steps include: (1) Composite billet preparation: "X70+ N08825+ N08825+ X70" double-sided symmetrical composite welding, adding an isolation agent between the two composite materials, the isolation agent thickness is 0.28mm, the surrounding submerged arc welding thickness is 240mm, and the composite billet thickness is 560mm. After welding, vacuum is applied, with the vacuum degree ≤-1 Pa.

[0011] (2) Primary heating: Heating in a soaking pit is used, the core temperature of the steel is 1156°C, the total heating time is 20.6 h, and the temperature difference between the core and the surface of the steel billet is 14°C.

[0012] (3) Primary rolling: Rough rolling to 365 mm, three passes with a reduction of 42 mm, final rolling temperature of 1116 °C, and cooling down to room temperature.

[0013] (4) Secondary heating: Heating is carried out in a walking beam heating furnace. The core temperature of the steel is 1142°C, the total heating time is 5.6 h, and the temperature difference between the core and the surface of the steel billet is 16°C.

[0014] (5) Secondary rolling: The intermediate billet is set at 162 mm, the second-stage rolling temperature is 858 °C, the single-pass rolling speed is 2.8 m / s, and the last two passes are controlled in the two-phase rolling zone, with a final rolling temperature of 700-720 °C.

[0015] (6) Cooling: Ultra-fast swing cooling mode is adopted, with a swing cooling time of 88s and a final cooling temperature of 350℃.

[0016] Example 2: Production method of 54+3mm X70+ N08825 nickel-based composite pipeline steel plate The chemical composition of the composite board substrate is C=0.02%, Si=00.22%, Mn=1.62%, P=0.006%, S=0.0008%, Alt=0.028%, Nb=0.045%, Ti=0.015%, Cu=0.23%, Cr=0.26%, Ni=0.10%, V=0.038%, and the balance is Fe and unavoidable impurities; the chemical composition of the composite material is C=0.03%, Si=0.45%, Cr=21.8%, Ni=45%, Co=0.29%, and the balance is Fe and unavoidable impurities. The key process steps include: (1) Composite billet preparation: "X70+ N08825+ N08825+ X70" double-sided symmetrical composite welding, adding an isolation agent between the two composite materials, the isolation agent thickness is 0.28mm, the surrounding submerged arc welding thickness is 289mm, and the composite billet thickness is 580mm. After welding, vacuum is applied, with the vacuum degree ≤-1 Pa.

[0017] (2) Primary heating: Heating in a soaking pit is used, the core temperature of the steel is 1156°C, the total heating time is 22h, and the temperature difference between the core and the surface of the steel billet is 14°C.

[0018] (3) Primary rolling: Rough rolling to 370 mm, three passes with a reduction of 48 mm, final rolling temperature of 1122 °C, and cooling down to room temperature.

[0019] (4) Secondary heating: Heating is carried out in a walking beam heating furnace. The core temperature of the steel is 1138°C. The total heating time is 5.8 h. The temperature difference between the core and the surface of the steel billet is 16°C.

[0020] (5) Secondary rolling: The intermediate billet is set at 178 mm, the second-stage rolling temperature is 845 °C, the single-pass rolling speed is 2.5 m / s, and the last two passes are controlled in the two-phase rolling zone, with a final rolling temperature of 695-715 °C.

[0021] Table 1 Mechanical properties test results of composite pipeline produced in Example .

Claims

1. A method for producing nickel-based composite pipeline steel plates, the process flow of which is substrate surface treatment - packaging assembly welding - primary heating - primary rolling - secondary heating after re-pitting - secondary rolling - cooling - heat treatment - plate opening and finishing - flaw detection - storage, characterized in that: The chemical composition mass percentage of the substrate is C=0.02%~0.04%, Si=0.05%~0.25%, Mn=1.6%~1.65%, P≤0.010%, S≤0.0015%, Alt=0.025%~0.050%, Nb=0.03%~0.060%, Ti=0.010%~0.020%, Cu=0.20%~0.25%, Cr=0.24%~27%, Ni=0.09%~0.13%, V=0.03~0.04%, and the balance is Fe and unavoidable impurities; the chemical composition mass percentage of the composite is C≤0.05%, Si=0.25%~0.50%, Cr=19.5%~23.5%, Ni=38~46%, Co=0.28~0.30%, and the balance is Fe and unavoidable impurities; The key process steps include: (1) Composite billet preparation: "X70+ N08825+ N08825+ X70" double-sided symmetrical composite welding, adding an isolation agent between the two composite materials, the thickness of the isolation agent is 0.2~0.3mm, the thickness of the submerged arc welding is 200~300mm, the thickness of the composite billet is 500~600mm, and vacuum is drawn after welding, and the vacuum degree is ≤-1 Pa; (2) Primary heating: soaking pit heating is adopted, the temperature of the steel core is 1150~1160℃, the total heating time is 18~24h, and the temperature difference between the core and the surface of the steel billet is ≤15℃; (3) Primary rolling: Rough rolling to 350-380 mm, three passes with a reduction of 45-50 mm, final rolling temperature ≥ 1100 °C, and cooling down to room temperature after the steel is removed from the line; (4) Secondary heating: Heating is carried out in a walking beam heating furnace, the temperature of the steel core is 1130~1150℃, the total heating time is 5-6h, and the temperature difference between the core and the surface of the steel billet is ≤20℃; (5) Secondary rolling: the intermediate billet is set to 150~180mm, the second stage rolling temperature is 840~860℃, the single pass rolling speed is 2~3m / s, the last two passes are controlled in the two-phase rolling zone, and the final rolling temperature is 690~730℃; (6) Cooling: Ultra-fast swing cooling mode is adopted, with a swing cooling time of 60~120s and a final cooling temperature of 320~360℃.

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