A QT state super-thick composite plate and a preparation method thereof
Patent Information
- Application Number
- CN202610849943.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-12
- Publication Date
- 2026-10-13
AI Technical Summary
[0004]本发明要解决的技术问题是，克服现有技术的缺陷，提供一种QT态特厚复合板及其制备方法，能够降低轧制厚度来解除轧机开口度限制，以及解决轧制厚度过高的引起的复合板质量和性能问题
[0021]有益效果：本发明提供一种QT态特厚复合板及其制备方法，将两组原材料中基材与覆材的结合面分别相对，采用覆材相应焊材进行焊接，焊接完成后进行抽真空处理，总共形成两个子坯，实现第一次组坯，再分别将两个子坯加热至变形温度，对两个子坯进行压缩变形，使基材和覆材初步结合，形成两个复合子坯，实现第一次成形，通过在后续第二次组坯和第二次成形之前先进行第一次组坯和第一次成形配合，复合子坯厚度只需要小于轧机开口度一半即可，相比于现有技术采用的一步组坯和成形，大大降低轧制厚度要求，能够解决采用轧制工艺生产特厚复合板时，特厚规格复合板所需的厚规格坯料受轧机开口度限制而无法轧制的问题，进一步扩大了特厚复合板的厚度上限，同时由于降低轧制厚度，能够解决轧制厚度过高的引起的复合板质量和性能问题。
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Abstract
Description
Technical Field
[0001] This invention relates to a QT-state extra-thick composite plate and its preparation method, belonging to the field of composite plate preparation technology. Background Technology
[0002] With the continuous development of major engineering equipment such as deep-sea resource development, ultra-large diameter pressure vessels, nuclear power plant containment vessels, and supercritical thermal power units towards extreme and large-scale applications, unprecedentedly stringent requirements have been placed on the comprehensive performance of key load-bearing structural materials. Such equipment often operates for extended periods under complex conditions involving high pressure, high temperature, strong corrosion, and alternating loads. A single homogeneous metal plate can no longer simultaneously achieve ultra-high strength, excellent low-temperature toughness, and superior corrosion resistance and fatigue resistance. Adopting ultra-thick metal composite plates with a low-cost, high-strength steel base and a stainless steel or nickel-based corrosion-resistant alloy cladding has become an ideal solution for balancing service performance and economy.
[0003] To impart sufficient strength and toughness to extra-thick composite plates, quenching and tempering (QT state) is a key process to ensure the formation of tempered sorbite or tempered bainite microstructures and achieve a balance between high strength and high toughness. However, the development of QT state for extra-thick composite plates faces a series of prominent technical bottlenecks: to guarantee the excellent performance of the composite plate, a certain compression ratio must be ensured. When using hot rolling, the thicker the composite plate, the larger the required billet thickness. This is limited by the capacity of the rolling mill, meaning the billet thickness must be less than the mill opening. Furthermore, setting extra-thick billets can lead to insufficient core cooling rate, a large microstructure gradient along the thickness direction, and difficulty in ensuring the depth of the hardened layer, further exacerbating problems and severely restricting the overall strength and toughness effect and bonding quality of the composite plate. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a QT state extra-thick composite plate and its preparation method, which can reduce the rolling thickness to remove the mill opening limit and solve the quality and performance problems of composite plate caused by excessive rolling thickness.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:
[0006] In a first aspect, the present invention discloses a method for preparing a QT-state extra-thick composite plate, comprising the following steps:
[0007] Step a: Select two sets of raw materials, each set including a substrate and a cover material. Polish the surfaces of the substrate and the cover material to be bonded until the surface shows a metallic luster.
[0008] Step b: Place the substrate and the cladding surfaces of the two sets of raw materials face to face, and weld them using the corresponding welding material for the cladding. After welding, perform vacuum treatment to form two sub-blanks in total.
[0009] Step c: Heat the two sub-blanks to the deformation temperature and compress and deform them to initially bond the substrate and the covering material to form two composite sub-blanks;
[0010] Step d: Assemble the two composite blanks. During assembly, the substrate and the cover material are placed face to face, and a release agent is applied between the face to face. Then, the welding and sealing process is carried out. After the welding and sealing is completed, a vacuum treatment is performed to obtain the composite blank.
[0011] Step e: After heating the composite billet to the deformation temperature, it is rolled into shape, and the rolling thickness is twice the thickness of the finished composite plate.
[0012] Step f: The hot-rolled composite billet is subjected to QT heat treatment to obtain quenched and tempered steel plate;
[0013] Step g: After cutting and separating the quenched and tempered steel plate, two QT-state composite plates can be obtained.
[0014] In step a, the thickness of the substrate and the coating material is the same in both sets of raw materials.
[0015] In step b, the vacuum level is controlled below 40 Pa.
[0016] In step c, the compression ratio of the two sub-bills is controlled to be no less than 2.
[0017] In step c, the compression deformation is performed using forging or rolling processes.
[0018] In step d, the vacuum level is controlled below 50 Pa.
[0019] In step e, the rolling compression ratio is controlled to be no less than 3.
[0020] Secondly, this invention discloses a QT-state extra-thick composite plate, which is prepared by the aforementioned QT-state extra-thick composite plate preparation method.
[0021] Beneficial Effects: This invention provides a QT-state extra-thick composite plate and its preparation method. The bonding surfaces of the substrate and cladding materials in two sets of raw materials are aligned and welded using appropriate welding materials for the cladding. After welding, a vacuum process is performed to form two sub-bills, achieving the first billet assembly. The two sub-bills are then heated to their deformation temperature and compressed to deform them, allowing the substrate and cladding materials to initially bond, forming two composite sub-bills, achieving the first forming. By performing the first billet assembly and first forming before the subsequent second billet assembly and second forming, the thickness of the composite sub-bills only needs to be less than half the mill opening. Compared to the one-step billet assembly and forming used in existing technologies, this significantly reduces the rolling thickness requirement. It solves the problem that the thick billets required for extra-thick composite plates cannot be rolled due to the mill opening limitation when using rolling processes to produce extra-thick composite plates, further expanding the upper limit of the thickness of extra-thick composite plates. Simultaneously, by reducing the rolling thickness, it solves the quality and performance problems of composite plates caused by excessively high rolling thickness. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the cross-section of the composite blank prepared according to the present invention;
[0023] Figure 2 This is a schematic diagram of the bending test of the composite plate prepared by the present invention;
[0024] Figure 3 These are photographs showing the corrosion performance of the cladding material in the composite plate prepared according to the present invention. Detailed Implementation
[0025] The present invention will be further described below. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.
[0026] Example 1
[0027] This invention discloses a method for preparing a QT-state extra-thick composite plate, comprising the following steps:
[0028] Step 1, substrate and cladding treatment: Select two substrates and two claddings. The substrate thickness is 480mm and the cladding thickness is 30mm. Polish the surfaces of the substrates and claddings to be bonded until they have a metallic luster.
[0029] Step 2, initial blank assembly: Select a base material and a cladding material, with their mating surfaces facing each other, and weld them using appropriate welding materials for the cladding material. After welding, perform vacuum treatment, controlling the vacuum degree below 40 Pa; in this embodiment, 36 Pa is preferred. This step is repeated twice to form two sub-blanks, each with a thickness of 510 mm.
[0030] Step 3, One-time forming: The sub-bills are heated to the deformation temperature, and two sub-bills are compressed and deformed using forging or rolling processes respectively. The compression ratio is controlled at ≥2, so that the base material and the cladding material are initially bonded to form a composite sub-bills. In this embodiment, the compression ratio is equal to 2, and the thickness of the composite sub-bills is 255 mm. In this invention, the thickness of a single composite sub-bills is ≤ mill opening degree / 2. After the two composite sub-bills are stacked together, the total thickness is guaranteed to be < mill opening degree, so that they can be smoothly bitten and rolled during rolling.
[0031] Step four, secondary assembly: To prevent warping and delamination during subsequent heat treatment, a symmetrical structure is adopted, further welding the two composite parts into a single composite billet with a thickness of 510mm. Figure 1 As shown, during the assembly process, the substrate and the cladding material are placed face to face, and a release agent is applied between the facing surfaces. After welding and sealing, a vacuum treatment is performed, with the vacuum level controlled below 50 Pa; in this embodiment, 45 Pa is preferred.
[0032] Step 5, Secondary Forming: A suitable heating process is developed based on the product type. After heating the composite billet to the deformation temperature, it is rolled into shape, with a rolling thickness twice the finished product thickness. To ensure the mechanical properties of the composite plate, the rolling compression ratio is ≥3. In this embodiment, the compression ratio is equal to 3. The composite billet is heated to 1200℃ and then rolled to 170 mm. The final forming process uses hot rolling, which can produce wide and extra-thick composite plates, reducing splicing welds during equipment manufacturing.
[0033] Step Six, QT Heat Treatment: Develop a suitable QT process based on the product type and directly perform QT heat treatment on the hot-rolled composite billet. Using a symmetrical structure for QT heat treatment can prevent delamination at the bonding surface caused by large differences in the linear expansion coefficients of the base and cladding materials.
[0034] Step 7, Cutting and Separating the Plates: After cutting and separating the plates, two (5+80) mm thick QT-state composite plates can be obtained. In this invention, the finished thickness of the composite plate × 6 ≤ (base material thickness + cladding thickness) ≤ mill opening or maximum forging thickness of the forging equipment.
[0035] like Figure 2 As shown in the figure, the composite board prepared by the present invention is subjected to a bending test to detect the bonding between the two layers of the composite board. It can be seen from the figure that there is no delamination at the bonding surface between the two materials, indicating that the two layers of materials are well bonded.
[0036] The corrosion performance of the cladding material in the composite plate prepared according to this invention was tested (test standard: ASTM A262-15(2021)). The test time was 15 hours after the solution was slightly boiled; the test solution was copper acid-16% sulfuric acid solution; the sensitization treatment regime was 675±5℃ for 1 hour. After the test, the working surface of the sample was bent at a bending angle of 180 degrees with an indenter diameter of 5 mm. The results are as follows. Figure 3 As shown in the figure, no intergranular corrosion cracks were observed when the object was bent and observed under 10x magnification, which meets the standard requirements.
[0037] In the preparation process of this invention, the thickness of the composite billet only needs to be less than half of the mill opening. Compared with the one-step billet assembly and forming used in the prior art, the rolling thickness requirement is greatly reduced. This can solve the problem that the thick billet required for the extra-thick composite plate cannot be rolled due to the mill opening limitation when using the rolling process to produce extra-thick composite plates. It further expands the upper limit of the thickness of extra-thick composite plates. At the same time, by reducing the rolling thickness, the quality and performance problems of composite plates caused by excessive rolling thickness can be solved.
[0038] Example 2
[0039] This invention discloses a method for preparing a QT-state extra-thick composite plate, comprising the following steps:
[0040] Step 1, substrate and cladding treatment: Select two substrates and two claddings. The substrate thickness is 460mm and the cladding thickness is 20mm. Polish the surfaces of the substrates and claddings to be bonded until they have a metallic luster.
[0041] Step 2, initial assembly: Select a base material and a cladding material, with their mating surfaces facing each other, and weld them using appropriate welding materials for the cladding material. After welding, perform vacuum treatment, controlling the vacuum level below 40 Pa; in this embodiment, 35 Pa is preferred. This step is repeated twice to form two sub-blanks, each with a thickness of 480 mm.
[0042] Step 3, One-time forming: The sub-bills are heated to the deformation temperature, and two sub-bills are compressed and deformed using forging or rolling processes respectively. The compression ratio is controlled at ≥2, so that the base material and the cladding material are initially bonded to form a composite sub-bills. In this embodiment, the compression ratio is equal to 2.09, and the thickness of the composite sub-bills is 230 mm. In this invention, the thickness of a single composite sub-bills is ≤ mill opening degree / 2. After two composite sub-bills are stacked together, the total thickness can be guaranteed to be < mill opening degree, so that they can be smoothly bitten and rolled during rolling.
[0043] Step four, secondary assembly: To prevent warping and delamination during subsequent heat treatment, a symmetrical structure is adopted, further welding the two composite components into a single composite billet with a thickness of 460mm. Figure 1As shown, during the assembly process, the substrate and the cladding material are placed face to face, and a release agent is applied between the facing surfaces. After welding and sealing, a vacuum treatment is performed, with the vacuum level controlled below 50 Pa; in this embodiment, 42 Pa is preferred.
[0044] Step 5, Secondary Forming: A suitable heating process is developed based on the product type. After heating the composite billet to the deformation temperature, it is rolled into shape, with a rolling thickness twice the finished product thickness. To ensure the mechanical properties of the composite plate, the rolling compression ratio is ≥3. In this embodiment, the compression ratio is 3.07. The composite billet is heated to 1200℃ and then rolled to 150 mm. The final forming process uses hot rolling, which can produce wide and extra-thick composite plates, reducing splicing welds during equipment manufacturing.
[0045] Step Six, QT Heat Treatment: Develop a suitable QT process based on the product type and directly perform QT heat treatment on the hot-rolled composite billet. Using a symmetrical structure for QT heat treatment can prevent delamination at the bonding surface caused by large differences in the linear expansion coefficients of the base and cladding materials.
[0046] Step 7, Cutting and Separating the Plates: After cutting and separating the plates, two QT-state composite plates with a thickness of (3.1 + 71.9) mm can be obtained. In this invention, the finished thickness of the composite plate × 6 ≤ (base material thickness + cladding thickness) ≤ mill opening or maximum forging thickness of the forging equipment.
[0047] Example 3
[0048] This invention discloses a method for preparing a QT-state extra-thick composite plate, comprising the following steps:
[0049] Step 1, substrate and cladding treatment: Select two substrates and two claddings. The substrate thickness is 500mm and the cladding thickness is 40mm. Polish the surfaces of the substrates and claddings to be bonded until they have a metallic luster.
[0050] Step 2, initial assembly: Select a base material and a cladding material, with their mating surfaces facing each other, and weld them using appropriate welding materials for the cladding material. After welding, perform vacuum treatment, controlling the vacuum level below 40 Pa; in this embodiment, 38 Pa is preferred. This step is repeated twice to form two sub-blanks, each with a thickness of 540 mm.
[0051] Step 3, One-time forming: The sub-bills are heated to the deformation temperature, and two sub-bills are compressed and deformed using forging or rolling processes respectively. The compression ratio is controlled at ≥2, so that the base material and the cladding material are initially bonded to form a composite sub-bills. In this embodiment, the compression ratio is equal to 2.16, and the thickness of the composite sub-bills is 250 mm. In this invention, the thickness of a single composite sub-bills is ≤ mill opening degree / 2. After two composite sub-bills are stacked together, it can be ensured that the total thickness is < mill opening degree, so that they can be smoothly bitten and rolled during rolling.
[0052] Step four, secondary assembly: To prevent warping and delamination during subsequent heat treatment, a symmetrical structure is adopted, further welding the two composite parts into a single composite billet with a thickness of 500mm. Figure 1 As shown, during the assembly process, the substrate and the cladding material are placed face to face, and a release agent is applied between the facing surfaces. After welding and sealing, a vacuum treatment is performed, with the vacuum level controlled below 50 Pa; in this embodiment, 48 Pa is preferred.
[0053] Step 5, Secondary Forming: A suitable heating process is developed based on the product type. After heating the composite billet to the deformation temperature, it is rolled into shape, with a rolling thickness twice the finished product thickness. To ensure the mechanical properties of the composite plate, the rolling compression ratio is ≥3. In this embodiment, the compression ratio is 3.125. The composite billet is heated to 1200℃ and then rolled to 160 mm. The final forming process uses hot rolling, which can produce wide and extra-thick composite plates, reducing splicing welds during equipment manufacturing.
[0054] Step Six, QT Heat Treatment: Develop a suitable QT process based on the product type and directly perform QT heat treatment on the hot-rolled composite billet. Using a symmetrical structure for QT heat treatment can prevent delamination at the bonding surface caused by large differences in the linear expansion coefficients of the base and cladding materials.
[0055] Step 7, Cutting and Separating the Plates: After cutting and separating the plates, two QT-state composite plates with a thickness of (5.9 + 74.1) mm can be obtained. In this invention, the finished thickness of the composite plate × 6 ≤ (base material thickness + cladding thickness) ≤ mill opening or maximum forging thickness of the forging equipment.
[0056] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a QT-state extra-thick composite plate, characterized in that: Includes the following steps: Step a: Select two sets of raw materials, each set including a substrate and a cover material. Polish the surfaces of the substrate and the cover material to be bonded until the surface has a metallic luster. Step b: Place the substrate and the cladding surfaces of the two sets of raw materials face each other, and weld them using the corresponding welding material for the cladding. After welding, perform vacuum treatment to form two sub-blanks in total. Step c: Heat the two sub-blanks to the deformation temperature and compress and deform them to initially bond the substrate and the covering material to form two composite sub-blanks; Step d: Assemble the two composite blanks. During assembly, the substrate and the cover material are placed face to face, and a release agent is applied between the face to face. Then, the welding and sealing process is carried out. After the welding and sealing is completed, a vacuum treatment is performed to obtain the composite blank. Step e: After heating the composite billet to the deformation temperature, it is rolled into shape, and the rolling thickness is twice the thickness of the finished composite plate. Step f: The hot-rolled composite billet is subjected to QT heat treatment to obtain quenched and tempered steel plate; Step g: After cutting and separating the quenched and tempered steel plate, two QT-state composite plates can be obtained.
2. The method for preparing a QT-state extra-thick composite plate according to claim 1, characterized in that: In step a, the thickness of the substrate and the coating material is the same in both sets of raw materials.
3. The method for preparing a QT-state extra-thick composite plate according to claim 1, characterized in that: In step b, the vacuum level is controlled below 40 Pa.
4. The method for preparing a QT-state extra-thick composite plate according to claim 1, characterized in that: In step c, the compression ratio of the two sub-bills is controlled to be no less than 2.
5. The method for preparing a QT-state extra-thick composite plate according to claim 1, characterized in that: In step c, the compression deformation is performed using forging or rolling processes.
6. The method for preparing a QT-state extra-thick composite plate according to claim 1, characterized in that: In step d, the vacuum level is controlled below 50 Pa.
7. The method for preparing a QT-state extra-thick composite plate according to claim 1, characterized in that: In step e, the rolling compression ratio is controlled to be no less than 3.
8. A QT-state extra-thick composite plate, characterized in that: It is prepared by the method for preparing QT state extra-thick composite plate according to any one of claims 1 to 7.