A method for preparing a QT state nickel-based alloy composite plate

Abstract

The present invention discloses a method for preparing a QT-state nickel-based alloy composite plate. Through welding, temperature-controlled rolling, post-rolling rapid cooling, and QT (quenching and tempering) heat treatment, a nickel-based alloy and pipeline steel composite plate with excellent comprehensive performance is produced. The composite plate achieves metallurgical bonding throughout the plate, with a shear strength of 320 MPa or higher. The nickel-based alloy cladding exhibits excellent corrosion resistance, with an intergranular corrosion rate of 0.9 mm / y or lower. This method addresses the issues of nickel-based alloy N06625 being difficult to deform at high temperatures and difficult to achieve metallurgical bonding with carbon steel, as well as the high hardness of the cladding material during hot-rolled cladding, which is unfavorable for subsequent forming and service.

Description

Technical Field

[0001] The present invention relates to the technical field of bimetallic composite manufacturing, and in particular to a method for preparing a QT state nickel-based alloy composite plate, particularly a method for preparing a QT state nickel-based alloy N06625 composite plate. Background Art

[0002] Metal composite panels combine the excellent corrosion resistance of the covering material with the good strength and toughness of the base material. They can maximize the respective advantages of the covering material and the base material, achieve comprehensive performance requirements that cannot be met by a single metal material, save precious metals, and reduce costs. They are a functional composite material with good development prospects.

[0003] With the continuous progress of the oil and gas industry, the world's energy demand is increasing, and the easily exploitable oil and natural gas resources are becoming increasingly scarce. In order to meet the demand for oil and gas from global industrial development, the exploration and development of oil and gas fields are gradually moving towards areas with more stringent environmental conditions. - , high H2S content, high temperature, high pressure and elemental sulfur oil and gas fields continue to appear. - In harsh environments with high corrosion rates such as CO2, the corrosion of oil and gas well casings and gathering pipelines made of ordinary 3 series stainless steel is relatively serious, especially under the combined effects of temperature and pressure, which can easily cause accidents such as perforation and cracking of the gathering pipelines. Pure nickel-based alloy pipes, on the other hand, are expensive and costly, and only one-third of the pure nickel-based alloy is used for corrosion resistance, resulting in a huge waste of materials. Nickel-based alloy pipeline composite plates combine the good corrosion resistance of the cladding nickel-based alloy with the high strength and toughness of the base pipeline steel. The bimetallic composite pipes prepared from them can significantly improve the corrosion resistance of the transmission pipeline and extend the service life of the pipeline. At the same time, the material price is also appropriate. Therefore, nickel-based alloy and pipeline steel composite plates have good application prospects as a substitute for single nickel-based alloy pipes.

[0004] Traditionally, nickel-based alloy clad plates are primarily produced using the explosive lamination method. However, this method not only poses noise and environmental pollution issues, but also results in welded joints in the cladding layer, preventing metallurgical bonding at the detonation point. These issues are unacceptable for highly corrosive oil and gas transmission composite pipes. The vacuum rolling lamination method is suitable for mass production of wide-width nickel-based alloy clad plates and offers high production efficiency. Although there have been some reports on the production of nickel-based alloy clad plates using the vacuum rolling lamination method, the preparation process still presents some challenges. For example, patent CN201710983510.9 "A 825 / X70 nickel-based alloy composite plate and its production method" discloses a method for preparing a nickel-based alloy 825 / X70 composite plate, which uses a vacuum electron beam for blanking. However, the electron beam has very high requirements on the flatness of the substrate and the covering material, the substrate blank yield is not high, and the blanking efficiency is also relatively low; patent CN202011002837.1 "Preparation method of high impact toughness nickel-based alloy composite material" uses hot rolling instead of solid solution treatment to prepare nickel-based alloy composite plates, obtaining excellent corrosion resistance of the covering material and good toughness of the substrate, but the hardness of the coating after hot rolling is generally high, which is not conducive to subsequent use.

[0005] Nickel-based alloy and pipeline steel clad plates, particularly nickel-based alloy N06625 clad plates, contain a high Mo content. During rolling, nickel-based alloy N06625 is not easily deformed at high temperatures. The four edges of the nickel-based alloy are free from the base carbon steel and are unconstrained, making it difficult to achieve metallurgical bonding on the four edges of the nickel-based alloy clad plates. Therefore, it is necessary to develop a targeted method for preparing QT-state nickel-based alloy N06625 clad plates to address the issues of nickel-based alloy N06625 being difficult to deform at high temperatures and difficult to achieve metallurgical bonding with carbon steel throughout the plate, as well as the high hardness of the cladding material under hot-rolled cladding conditions, which is not conducive to subsequent forming and processing and service use. Summary of the Invention

[0006] Purpose of the invention: In view of the shortcomings and defects of the existing technology, the present invention provides a method for preparing a QT state nickel-based alloy composite plate, which is prepared by welding blanking, differential temperature controlled rolling and rapid cooling after rolling, QT (quenching + tempering) heat treatment and other processes. A nickel-based alloy and pipeline steel composite plate with excellent comprehensive performance is prepared; the prepared composite plate achieves metallurgical bonding of the entire plate, and the shear strength is ≥320MPa; the cladding nickel-based alloy has excellent corrosion resistance, and the intergranular corrosion rate is ≤0.9mm / y.

[0007] Technical solution: A method for preparing a QT state nickel-based alloy composite plate of the present invention comprises the following steps:

[0008] 1) Raw material preparation: Prepare the base material and covering material for blank making, and polish the surface of the base material and covering material to be composited with a sanding belt or a flap wheel to remove the surface iron oxide and passivation layer; evenly apply the release agent on the non-composite surface of the covering material and dry it;

[0009] 2) Welding blank: punch an L-shaped hole in the middle of the short side of the substrate at a distance of 60mm-70mm from the side, with a hole diameter of 16mm±2mm; the cladding material and the substrate to be composited face each other, and overlap the cladding material in the center of the substrate, with the edge of the cladding material 50mm-65mm away from the edge of the substrate; press the cladding material and the substrate tightly, and weld the four corners of the cladding material to the substrate using gas shielded welding. The welding length of the gas shielded welding on both sides of each corner of the cladding material is 80mm-100mm; weld the four sides of the substrate at a distance of 20mm-40mm from the edge of the substrate Stand up the strips and weld them to form a frame; after gas shielded welding another pair of covering materials and the four corners of the base material, buckle them neatly on the strips to form a four-layer symmetrical composite blank of base material-covering material-covering material-base material; seal the strips and the base material with gas shielded welding, and after sealing, pre-vacuum them through the L-shaped hole, with the vacuum degree ≤20Pa; after vacuuming, use submerged arc welding to fill the grooves between the strips and the base material to form a four-layer symmetrical composite blank; after the submerged arc welding is completed, vacuum is again evacuated through the L-shaped hole, and the vacuum degree is controlled below 0.1Pa;

[0010] 3) Differential temperature controlled rolling and rapid cooling after rolling: The composite billet is heated in a walking beam heating furnace, the preheating section temperature is 400℃-800℃, the residence time is more than 1.5h, the soaking section temperature is 1180℃-1250℃, and the soaking section holding time is controlled according to the thickness of the composite billet at ≥1.5min / cm to burn through the core; after the composite billet is taken out of the furnace, it is first rolled in a forming pass, and the forming pass reduction rate is 8%-15%. After the forming pass is completed, the composite billet is sprayed with water on the upper and lower surfaces to cool the surface temperature of the composite billet to 900℃-1000℃, and the core of the composite billet is cooled. The temperature is between 1100℃ and 1250℃, and then the composite billet is sent to the rolling mill for differential temperature rolling. After every 2-3 rolling passes, the composite billet is sprayed with water to cool the core and surface of the composite billet to form a temperature difference of at least 100℃. The rolling process adopts large reduction rolling, with the maximum pass reduction of more than 30mm and the maximum pass reduction rate of more than 25%. The final rolling temperature of the composite billet is 800℃-900℃. The composite plate after rolling is cooled at a speed of 8℃ / s-20℃ / s, and the red-return temperature is controlled within the range of 350℃-550℃, followed by air cooling.

[0011] 4) QT heat treatment: The composite plate is first subjected to quenching heat treatment and then tempering treatment; the quenching temperature is 880℃-980℃, and the quenching heating time is controlled at 1.5min / mm-2.5min / mm according to the total thickness of the composite plate. After quenching, the surface temperature of the composite plate is controlled below 30℃; the tempering temperature is 500℃-700℃, and the tempering time is controlled at 2.0min / mm-4.0min / mm according to the total thickness of the composite plate;

[0012] 5) Plate separation and straightening: Cut the head and both sides to obtain two single-sided nickel-based alloy composite plates. After straightening, water polishing and grinding, the composite plates are obtained to obtain the final nickel-based alloy composite plate products.

[0013] In the step 1), the substrate is pipeline steel, which comprises the following components in percentage by mass: C: 0.02%-0.12%, Si: 0.15%-0.40%, Mn: 1.10%-1.60%, P: ≤0.020%, S: ≤0.003%, Nb: 0.010%-0.050%, V: 0.010%-0.060%, Ti: 0.006%-0.060%, Cr: 0.10%-0.30%, Ni: ≤0.30%, Cu: ≤0.50%, Mo: ≤0.15%, N: ≤0.0100%, Alt: 0.015%-0.060%, and the balance being Fe and unavoidable impurities.

[0014] Wherein, the mass ratio of Alt / N in the pipeline steel is greater than 2, and the crack sensitivity index P of the pipeline steel is cm =C+(Mn+Cu+Cr) / 20+Si / 30+Ni / 60+Mo / 15+V / 10+B*5≤0.20.

[0015] Wherein, the cladding material in step 1) is nickel-based alloy N06625, whose chemical composition and performance meet the requirements of ASTM B443, and the mass percentage of C is ≤0.03%.

[0016] Wherein, the total thickness of the nickel-based alloy composite plate product in step 5) is 8mm-50mm, and the thickness of the cladding material is 2mm-5mm.

[0017] Wherein, the shear strength of the nickel-based alloy composite plate product in step 5) is ≥320MP, and the interface does not crack at a 180° internal bending.

[0018] Wherein, in said step 5), the thickness uniformity of the cladding material of the nickel-based alloy composite plate product is controlled within the range of ±10% of the nominal thickness.

[0019] Wherein, in said step 5), the cladding material of the nickel-based alloy composite plate product is tested for intergranular corrosion according to G28 method A, and the corrosion rate is ≤0.9 mm / y.

[0020] Beneficial Effects: Compared with existing technologies, the present invention offers the following significant advantages: Through processes such as welding, temperature-controlled rolling, post-rolling rapid cooling, and QT (quenching and tempering) heat treatment, the present invention produces a nickel-based alloy and pipeline steel composite plate with excellent overall performance. The composite plate achieves metallurgical bonding throughout the plate, with a shear strength of 320 MPa or higher. The nickel-based alloy cladding exhibits excellent corrosion resistance, with an intergranular corrosion rate of 0.9 mm / y or lower. This solves the problems of nickel-based alloy N06625 being difficult to deform at high temperatures and difficult to achieve metallurgical bonding throughout the plate with carbon steel, as well as the high hardness of the cladding material under hot-rolled cladding conditions, which is unfavorable for subsequent forming and service.

[0021] The present invention 1. forms a constraint between the covering material and the substrate by welding the four corners of the covering material to each other, and realizes cooperative deformation of the covering material and the substrate during the rolling process, which is beneficial to achieve good metallurgical bonding between the covering material and the substrate on the four sides of the composite plate; 2. Pre-vacuuming is performed after the composite blank is sealed, which reduces the oxygen content in the composite blank and prevents oxidation of the edges of the substrate to be composited during the subsequent submerged arc welding process, thereby reducing the non-bonding of the edges due to oxidation. 3. The rolling process adopts differential temperature rolling, and the surface temperature of the composite blank is lower than that of the core. The rolling deformation can more easily penetrate into the core, realizing effective deformation and extension of the covering material, which is not only beneficial to the metallurgical bonding of the interface, but also beneficial to the control of the thickness uniformity of the covering material. 4. After the nickel-based alloy composite plate undergoes QT heat treatment, the hardness of the covering material is significantly reduced, which is beneficial to the subsequent forming, processing and use of the composite plate. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0023] The preparation method of the QT state nickel-based alloy composite plate of the present invention mainly involves the following steps: raw material preparation, welding and blanking, differential temperature controlled rolling and rapid cooling after rolling, QT heat treatment, plate separation and straightening. The specific steps are as follows:

[0024] (1) Raw material preparation: Prepare the base material and cover material for blank making, and polish the surface of the base material and cover material to be laminated with a sanding belt or a flap wheel to remove the surface oxide scale and passivation layer, so that the entire surface of the plate to be laminated is exposed to fresh metal. Then, evenly apply the release agent on the non-laminated surface of the cover material and dry it to completely remove the moisture and crystal water in the release agent.

[0025] (2) Welding blank: Drill an L-shaped hole at the middle of the short side of the substrate, 60-70mm away from the side, with a hole diameter of about 16±2mm. The surfaces of the covering material and the substrate to be composited face each other, and the covering material is stacked in the center of the substrate, with the edge of the covering material about 50-65mm away from the edge of the substrate. Press the covering material and the substrate tightly, and weld the four corners of the covering material to the substrate using gas shielded welding. The welding length of the gas shielded welding on both sides of each corner of the covering material is about 80-100mm. Weld vertical strips at a position about 20-40mm away from the edge of the substrate on the four sides of the substrate, and weld the vertical strips to form a frame. Gas shielded weld another pair of covering materials and the four corners of the substrate, and then buckle them neatly on the vertical strips to form a symmetrical composite blank of substrate-covering material-covering material-substrate-substrate. Gas shielded welding is performed to seal the vertical strips and the substrate. After sealing, pre-vacuum is performed through the L-shaped hole, and the vacuum degree is ≤20Pa. After vacuuming, submerged arc welding is used to fill the grooves between the vertical strips and the base material, forming a stable four-layer symmetrical composite billet. After submerged arc welding, a second vacuuming is performed through the L-shaped right-angle hole, and the vacuum degree is further controlled below 0.1Pa.

[0026] (3) Differential temperature controlled rolling and rapid cooling after rolling: The composite billet is heated in a walking beam furnace, with the preheating section temperature at 400-800℃ and the dwell time at more than 1.5h. The soaking section temperature is 1180-1250℃, and the soaking section holding time is controlled at ≥1.5min / cm according to the thickness of the composite billet to ensure that the core is burned through. After the composite billet is taken out of the furnace, it is first rolled in a forming pass with a forming pass reduction rate of 8%-15%. After the forming pass, the composite billet is sprayed with water on the upper and lower surfaces to quickly reduce the surface temperature of the composite billet to 900-1000℃. The core temperature of the composite billet is still between 1100-1250℃. The composite billet is then quickly sent to the rolling mill for differential temperature rolling. After every 2-3 rolling passes, the composite billet is sprayed with water to cool the core and surface of the composite billet to form a temperature difference of at least 100℃. The rolling process adopts high-reduction rolling, with the maximum pass reduction of more than 30mm and the maximum pass reduction rate of more than 25%. The final rolling temperature of the composite billet is 800-900℃. After rolling, the composite plate is rapidly cooled at a rate of 8-20℃ / s, with the red-return temperature controlled within the range of 350-550℃, and then air-cooled.

[0027] (4) QT heat treatment: The composite plate is first subjected to quenching heat treatment and then tempering treatment. The quenching temperature is 880-980℃, and the quenching heating time is controlled at 1.5-2.5min / mm according to the total thickness of the composite plate. After quenching, the surface temperature of the composite plate is controlled below 30℃; the tempering temperature is 500-700℃, and the tempering time is controlled at 2.0-4.0min / mm according to the total thickness of the composite plate.

[0028] (5) Plate straightening: Cut the head and both sides to obtain two single-sided nickel-based alloy composite plates. After straightening, water polishing and grinding, the composite plates can be obtained as the final nickel-based alloy composite plate products.

[0029] In step 1), the base material is pipeline steel, which comprises the following components in mass percentages: C: 0.02%-0.12%, Si: 0.15%-0.40%, Mn: 1.10%-1.60%, P: ≤0.020%, S: ≤0.003%, Nb: 0.010%-0.050%, V: 0.010%-0.060%, Ti: 0.006%-0.060%, Cr: 0.10%-0.30%, Ni: ≤0.30%, Cu: ≤0.50%, Mo: ≤0.15%, N: ≤0.0100%, Alt: 0.015%-0.060%, and the balance is Fe and unavoidable impurities. The mass ratio of Alt / N in the pipeline steel is greater than 2, and the crack sensitivity index P of the pipeline steel is ≤0. cm =C+(Mn+Cu+Cr) / 20+Si / 30+Ni / 60+Mo / 15+V / 10+B*5≤0.20. The cladding material is nickel-based alloy N06625, whose chemical composition and properties meet the requirements of ASTM B443, and the mass percentage of C is ≤0.03%.

[0030] In step 5), the total thickness of the nickel-based alloy composite plate product is 8 mm to 50 mm, and the cladding material thickness is 2 mm to 5 mm. The nickel-based alloy composite plate product has a shear strength of ≥320 MPa, and the interface does not crack during 180° bending. The cladding material thickness uniformity of the nickel-based alloy composite plate product is controlled within ±10% of the nominal thickness. The cladding material of the nickel-based alloy composite plate product is tested for intergranular corrosion according to G28 Method A, and the corrosion rate is ≤0.9 mm / y.

[0031] Example 1:

[0032] In this embodiment, the base material is a pipeline steel billet with a strength level of X52, the specific composition of which is shown in Table 1, and a thickness of 60 mm. The cladding material is a nickel-based alloy plate N06625 with a C content of 0.03% and a thickness of 20 mm.

[0033] The substrate and the cladding surface to be laminated are each sanded with a sanding belt to remove any surface oxide scale or passivation layer, exposing the entire surface of the cladding surface to fresh metal. Next, a release agent is evenly applied to the non-cladding surface of the cladding and dried to completely remove any moisture and crystallization water from the release agent.

[0034] Drill an L-shaped hole with a diameter of approximately 16mm in the middle of the short side of the substrate, 60mm from the side. With the cladding and base material facing each other, place the cladding material in the center of the base material, with the edge of the cladding material approximately 50mm from the edge of the base material. Press the cladding material and base material firmly together, and weld the four corners of the cladding material to the base material using gas shielded welding. The weld length of each corner of the cladding material is approximately 80mm. Weld upright strips approximately 20mm from the edge of the base material on all four sides of the base material, forming a frame. Gas shielded welding is performed on the four corners of the other pair of cladding materials and the base material, and then neatly fastened onto the upright strips to form a symmetrical four-layer composite blank: base material-cladding material-cladding material-base material. Gas shielded welding is used to seal the gaps between the upright strips and the base material. After sealing, pre-vacuum the L-shaped hole to a vacuum of 20Pa. After evacuation, submerged arc welding is used to fill the grooves between the upright strips and the base material, forming a stable four-layer symmetrical composite blank. After the submerged arc welding is completed, a second vacuum is carried out through the L-shaped right-angle hole, and the vacuum degree is further controlled at about 0.1 Pa. Finally, a vacuum composite blank is obtained, and the thickness of the composite blank is 160 mm.

[0035] The composite billet was heated in a walking beam furnace. The preheating section temperature, preheating section dwell time, soaking section temperature, and dwell time are shown in Table 2. The composite billet was rolled. Parameters such as the forming pass reduction, the upper and lower temperature difference during rolling, the cooling rate, and the red-return temperature are shown in Table 3. After rolling, the composite plate underwent QT heat treatment. The heat treatment process is shown in Table 4.

[0036] Finally, the head and both sides of the composite plate are cut to obtain two single-sided nickel-based alloy composite plates. After straightening, water polishing and grinding, the composite plate can be obtained as a nickel-based alloy composite plate N06625+X52 with a thickness of 2+6mm.

[0037] Example 2:

[0038] In this embodiment, the base material is a pipeline steel billet with a strength level of X60, the specific composition of which is shown in Table 1, and a thickness of 116 mm. The cladding material is a nickel-based alloy plate N06625 with a C content of 0.02% and a thickness of 20 mm.

[0039] The substrate and the cladding surface to be laminated are each sanded with a sanding belt to remove any surface oxide scale or passivation layer, exposing the entire surface of the cladding surface to fresh metal. Next, a release agent is evenly applied to the non-cladding surface of the cladding and dried to completely remove any moisture and crystallization water from the release agent.

[0040] Drill an L-shaped hole with a diameter of approximately 16mm in the middle of the short side of the substrate, 65mm from the side. With the cladding and base material facing each other, place the cladding material in the center of the base material, with the edge of the cladding material approximately 55mm from the edge of the base material. Press the cladding material and base material firmly together, and weld the four corners of the cladding material to the base material using gas shielded welding. The weld length of each corner of the cladding material is approximately 90mm. Weld upright strips approximately 25mm from the edge of the base material on all four sides of the base material, forming a frame. Gas shielded welding is performed on the four corners of the other pair of cladding materials and the base material, and then neatly fastened onto the upright strips to form a symmetrical four-layer composite blank: base material-cladding material-cladding material-base material. Gas shielded welding is used to seal the gaps between the upright strips and the base material. After sealing, pre-vacuum the L-shaped hole to a vacuum of 15Pa. After evacuation, submerged arc welding is used to fill the grooves between the upright strips and the base material, forming a stable four-layer symmetrical composite blank. After the submerged arc welding is completed, a second vacuum is carried out through the L-shaped right-angle hole, and the vacuum degree is further controlled at about 0.08 Pa. Finally, a vacuum composite blank is obtained, and the thickness of the composite blank is 272 mm.

[0041] The composite billet was heated in a walking beam furnace. The preheating section temperature, preheating section dwell time, soaking section temperature, and dwell time are shown in Table 2. The composite billet was rolled. Parameters such as the forming pass reduction, the upper and lower temperature difference during rolling, the cooling rate, and the red-return temperature are shown in Table 3. After rolling, the composite plate underwent QT heat treatment. The heat treatment process is shown in Table 4.

[0042] Finally, the head and both sides of the composite plate are cut to obtain two single-sided nickel-based alloy composite plates. After straightening, water polishing and grinding, the composite plate can be obtained as a nickel-based alloy composite plate N06625+X60 with a thickness of 3+17.5mm.

[0043] Example 3:

[0044] The base material of this embodiment is a pipeline steel billet with a strength level of X65, the specific composition of which is shown in Table 1, and a thickness of 178 mm. The cladding material is a nickel-based alloy plate N06625 with a C content of 0.01% and a thickness of 28 mm.

[0045] The substrate and the cladding surface to be laminated are each sanded with a sanding belt to remove any surface oxide scale or passivation layer, exposing the entire surface of the cladding surface to fresh metal. Next, a release agent is evenly applied to the non-cladding surface of the cladding and dried to completely remove any moisture and crystallization water from the release agent.

[0046] Drill an L-shaped hole with a diameter of approximately 16mm in the middle of the short side of the substrate, 65mm from the side. With the cladding and base material facing each other, place the cladding material in the center of the base material, with the edge of the cladding material approximately 60mm from the edge of the base material. Press the cladding material and base material tightly together, and weld the four corners of the cladding material to the base material using gas shielded welding. The weld length of each corner of the cladding material is approximately 100mm. Weld vertical strips to the four sides of the base material approximately 30mm from the edge of the base material, forming a frame with these strips. Gas shielded welding is then performed on the four corners of the base material, and then the vertical strips are placed neatly and facing each other, forming a four-layer symmetrical composite blank: base material-cladding material-cladding material-base material. Gas shielded welding is used to seal the vertical strips and base material. After sealing, pre-vacuum is applied through the L-shaped hole to a vacuum of 10Pa. After evacuation, the grooves between the vertical strips and base material are filled using submerged arc welding, forming a stable four-layer symmetrical composite blank. After the submerged arc welding is completed, a second vacuum is carried out through the L-shaped right-angle hole, and the vacuum degree is further controlled at about 0.05 Pa. Finally, a vacuum composite blank is obtained, and the thickness of the composite blank is 412 mm.

[0047] The composite billet was heated in a heating furnace. The preheating section temperature, preheating section dwell time, soaking section temperature, and dwell time are shown in Table 2. The composite billet was rolled. Parameters such as the forming pass reduction, the upper and lower temperature difference during rolling, the cooling rate, and the red-return temperature are shown in Table 3. After rolling, the composite plate underwent QT heat treatment. The heat treatment process is shown in Table 4.

[0048] Finally, the head and both sides of the composite plate are cut to obtain two single-sided nickel-based alloy composite plates. After straightening, water polishing and grinding, the composite plate can be obtained as a nickel-based alloy composite plate N06625+X65 with a thickness of 4+25.4mm.

[0049] Example 4:

[0050] In this embodiment, the base material is a pipeline steel billet with a strength level of X70, the specific composition of which is shown in Table 1, and a thickness of 284 mm. The cladding material is a nickel-based alloy plate N06625 with a C content of 0.006% and a thickness of 32 mm.

[0051] The substrate and the cladding surface to be laminated are each sanded with a sanding belt to remove any surface oxide scale or passivation layer, exposing the entire surface of the cladding surface to fresh metal. Next, a release agent is evenly applied to the non-cladding surface of the cladding and dried to completely remove any moisture and crystallization water from the release agent.

[0052] Drill an L-shaped hole with a diameter of approximately 16mm in the middle of the short side of the substrate, 70mm from the side. With the cladding and base material facing each other, place the cladding material in the center of the base material, with the edge of the cladding material approximately 65mm from the edge of the base material. Press the cladding material and base material tightly together, and weld the four corners of the cladding material to the base material using gas shielded welding. The weld length of each corner of the cladding material is approximately 100mm. Weld vertical strips to the four sides of the base material approximately 40mm from the edge of the base material, forming a frame. Gas shielded welding is performed on the four corners of the other pair of cladding materials and the base material, and then neatly fastened onto the vertical strips to form a symmetrical four-layer composite blank: base material-cladding material-cladding material-base material. Gas shielded welding is used to seal the vertical strips and base material. After sealing, pre-vacuum is applied through the L-shaped hole to a vacuum of 10Pa. After evacuation, the grooves between the vertical strips and the base material are filled using submerged arc welding, forming a stable four-layer symmetrical composite blank. After the submerged arc welding is completed, a second vacuum is performed through the L-shaped right-angle hole, and the vacuum degree is further controlled at about 0.01 Pa. Finally, a vacuum composite blank is obtained, and the thickness of the composite blank is 632 mm.

[0053] The composite billet was heated in a heating furnace. The preheating section temperature, preheating section dwell time, soaking section temperature, and soaking time are shown in Table 2. The composite billet was rolled. Parameters such as the forming pass reduction, the upper and lower temperature difference during the rolling process, the final rolling temperature, the cooling rate, and the red-return temperature are shown in Table 3. After rolling, the composite plate underwent QT heat treatment. The heat treatment process is shown in Table 4.

[0054] Finally, the head and both sides of the composite plate are cut to obtain two single-sided nickel-based alloy composite plates. After straightening, water polishing and grinding, the composite plate can be obtained as a nickel-based alloy composite plate N06625+X70 with a thickness of 5+45mm.

[0055] Table 1: Metallurgical composition of steel grades of substrate blanks in the embodiment of the present invention

[0056]

[0057] Table 2: Composite billet heating process parameters according to the present invention

[0058]

[0059] Table 3: Rolling cooling process parameters of the embodiment of the present invention

[0060]

[0061] Table 4: Heat treatment process parameters of composite plates according to embodiments of the present invention

[0062]

[0063] The various properties and coating thickness uniformity of the nickel-based alloy N06625 composite plates of Examples 1-4 are shown in Table 5. After flaw detection, the nickel-based alloy N06625 composite plates of Examples 1-4 all achieved good metallurgical bonding at the interface between the substrate and the covering. As can be seen from the table, the nickel-based alloy N06625 composite plates prepared in Examples 1-4 have high shear strength and excellent bending performance within 180°. After the covering was tested for intergranular corrosion using G28 method A, the intergranular corrosion rate was below 0.33 mm / y, and the covering had excellent corrosion resistance. At the same time, the thickness of the composite plate covering was uniform, there was no local thickening, and the covering thickness was within the range of ±9% of the nominal thickness. It can be seen that the nickel-based alloy N06625 composite plates prepared by this invention have uniform and controllable covering thickness, good interface metallurgical bonding, and excellent corrosion resistance.

[0064] Table 5: Properties and coating thickness uniformity of composite panels according to the present invention

[0065]

Claims

1. A method for preparing a QT state nickel-based alloy composite plate, characterized by: The method includes the following steps: 1) Raw material preparation: Prepare the base material and covering material for blank making, and polish the surface of the base material and covering material to be composited with a sanding belt or a flap wheel to remove the surface iron oxide and passivation layer; evenly apply the release agent on the non-composite surface of the covering material and dry it; 2) Welding blank: punch an L-shaped hole in the middle of the short side of the substrate at a distance of 60mm-70mm from the side, with a hole diameter of 16mm±2mm; the cladding material and the substrate to be composited face each other, and overlap the cladding material in the center of the substrate, with the edge of the cladding material 50mm-65mm away from the edge of the substrate; press the cladding material and the substrate tightly, and weld the four corners of the cladding material to the substrate using gas shielded welding. The welding length of the gas shielded welding on both sides of each corner of the cladding material is 80mm-100mm; weld the four sides of the substrate at a distance of 20mm-40mm from the edge of the substrate Stand up the strips and weld them to form a frame; after gas shielded welding another pair of covering materials and the four corners of the base material, buckle them neatly on the strips to form a four-layer symmetrical composite blank of base material-covering material-covering material-base material; seal the strips and the base material with gas shielded welding, and after sealing, pre-vacuum them through the L-shaped hole, with the vacuum degree ≤20Pa; after vacuuming, use submerged arc welding to fill the grooves between the strips and the base material to form a four-layer symmetrical composite blank; after the submerged arc welding is completed, vacuum is again evacuated through the L-shaped hole, and the vacuum degree is controlled below 0.1Pa; 3) Differential temperature controlled rolling and rapid cooling after rolling: The composite billet is heated in a walking beam heating furnace, the preheating section temperature is 400℃-800℃, the residence time is more than 1.5h, the soaking section temperature is 1180℃-1250℃, and the soaking section holding time is controlled according to the thickness of the composite billet at ≥1.5min / cm to burn through the core; after the composite billet is taken out of the furnace, it is first rolled in a forming pass, and the forming pass reduction rate is 8%-15%. After the forming pass is completed, the composite billet is sprayed with water on the upper and lower surfaces to cool the surface temperature of the composite billet to 900℃-1000℃, and the core of the composite billet is cooled. The temperature is between 1100℃ and 1250℃, and then the composite billet is sent to the rolling mill for differential temperature rolling. After every 2-3 rolling passes, the composite billet is sprayed with water to cool the core and surface of the composite billet to form a temperature difference of at least 100℃. The rolling process adopts large reduction rolling, with the maximum pass reduction of more than 30mm and the maximum pass reduction rate of more than 25%. The final rolling temperature of the composite billet is 800℃-900℃. The composite plate after rolling is cooled at a speed of 8℃ / s-20℃ / s, and the red-return temperature is controlled within the range of 350℃-550℃, followed by air cooling. 4) QT heat treatment: The composite plate is first subjected to quenching heat treatment and then tempering treatment; the quenching temperature is 880℃-980℃, and the quenching heating time is controlled at 1.5min / mm-2.5min / mm according to the total thickness of the composite plate. After quenching, the surface temperature of the composite plate is controlled below 30℃; the tempering temperature is 500℃-700℃, and the tempering time is controlled at 2.0min / mm-4.0min / mm according to the total thickness of the composite plate; 5) Plate separation and straightening: Cut the head and both sides to obtain two single-sided nickel-based alloy composite plates. After straightening, water polishing and grinding, the composite plates are obtained to obtain the final nickel-based alloy composite plate products.

2. The method for preparing the QT state nickel-based alloy composite plate according to claim 1, characterized in that: In step 1), the substrate is pipeline steel, which comprises the following components in percentage by mass: C: 0.02%-0.12%, Si: 0.15%-0.40%, Mn: 1.10%-1.60%, P: ≤0.020%, S: ≤0.003%, Nb: 0.010%-0.050%, V: 0.010%-0.060%, Ti: 0.006%-0.060%, Cr: 0.10%-0.30%, Ni: ≤0.30%, Cu: ≤0.50%, Mo: ≤0.15%, N: ≤0.0100%, Alt: 0.015%-0.060%, and the balance being Fe and unavoidable impurities.

3. The method for preparing the QT state nickel-based alloy composite plate according to claim 2, characterized in that: The Alt / N mass ratio of the pipeline steel is greater than 2, and the crack sensitivity index P of the pipeline steel is cm =C+(Mn+Cu+Cr) / 20+Si / 30+Ni / 60+Mo / 15+V / 10+B*5≤0.

20.

4. The method for preparing the QT state nickel-based alloy composite plate according to claim 1, characterized in that: In the step 1), the cladding material is nickel-based alloy N06625, whose chemical composition and performance meet the requirements of ASTM B443, and the mass percentage of C is ≤0.03%.

5. The method for preparing the QT state nickel-based alloy composite plate according to claim 1, characterized in that: In the step 5), the total thickness of the nickel-based alloy composite plate product is 8mm-50mm, and the thickness of the cladding material is 2mm-5mm.

6. The method for preparing the QT state nickel-based alloy composite plate according to claim 1, characterized in that: The shear strength of the nickel-based alloy composite plate product in step 5) is ≥320MP, and the interface does not crack when bent within 180°.

7. The method for preparing the QT state nickel-based alloy composite plate according to claim 1, characterized in that: In the step 5), the thickness uniformity of the nickel-based alloy composite plate product is controlled within the range of ±10% of the nominal thickness.

8. The method for preparing the QT state nickel-based alloy composite plate according to claim 1, characterized in that: In the step 5), the cladding material of the nickel-based alloy composite plate product is tested for intergranular corrosion according to G28 method A, and the corrosion rate is ≤0.9 mm / y.

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