Titanium alloy thick plate and rolling method thereof
By setting a pure titanium plate on the surface of a titanium alloy slab and combining it with multi-pass rolling and water cooling, the problem of inconsistent microstructure between the surface and core of the finished titanium alloy thick plate is solved, achieving microstructure consistency and making it suitable for the industrial production of titanium alloy thick plates.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CENT SOUTH UNIV
- Filing Date
- 2023-11-16
- Publication Date
- 2026-06-12
Smart Images
Figure CN117483431B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of titanium alloy materials technology, specifically to a thick titanium alloy plate and its rolling method. Background Technology
[0002] Titanium and titanium alloys are widely used in marine engineering due to their excellent corrosion resistance and specific strength. In recent years, with the further transformation and upgrading of marine equipment, the use of titanium and titanium alloy thick plates has become more and more widespread, and they are showing the characteristics of alloying and thicker specifications. For example, the thickness of thicker specifications has gradually increased from the previous conventional thickness of less than 25mm to 40-100mm.
[0003] The increase in the thickness of the finished product directly leads to an expansion in the thickness of the raw material slab, such as increasing the thickness of the raw material slab from 150-200mm in traditional processes to 250mm, 300mm, or even 350mm. This easily results in an increase in the deformation dead zone in the thickness direction of the finished product, preventing rolling deformation from penetrating to the core of the slab. This leads to severe inconsistencies in the microstructure between the surface and core of the finished product after rolling, making it difficult to control the microstructure during subsequent heat treatment, and even making it impossible to obtain titanium alloy plates that meet the requirements for microstructure consistency through heat treatment.
[0004] Therefore, there is a need to improve the titanium alloy thick plate and its rolling method to solve the problem of severe inconsistencies in the microstructure of the surface and core of existing thick-sized finished products. Summary of the Invention
[0005] The purpose of this invention is to provide a titanium alloy thick plate and its rolling method, the specific technical solution of which is as follows:
[0006] In a first aspect, the present invention provides a method for rolling a thick titanium alloy plate, characterized in that it comprises:
[0007] Step S1: Pure titanium plates are placed on the upper and lower surfaces of the pretreated titanium alloy slab to obtain a composite slab.
[0008] Step S2: Heat treat the composite slab to obtain an intermediate slab.
[0009] Step S3: Roll the intermediate slab into a pre-finished product of the target thickness using a rolling process; wherein the target thickness is 40-100mm; the thickness deformation of the intermediate slab in a single pass of the rolling process is not greater than 40mm, and the intermediate slab is water-cooled during the rolling process;
[0010] Step S4: Straighten the pre-finished product and then air-cool it to room temperature to obtain a titanium alloy thick plate.
[0011] Optionally, the rolling process used in step S3 includes:
[0012] Step S3.1: The intermediate slab is rolled in the first pass to reduce its thickness by 10-20 mm.
[0013] Step S3.2: Throw out the intermediate slab after the first pass of rolling, and at the same time measure its surface temperature T1 at the time of throwing; perform the first water cooling on the intermediate slab after throwing, and at the same time measure its surface temperature T2, until the difference between T2 and T1 is 100-150℃, and stop the first water cooling; perform the second rolling on the intermediate slab after the first water cooling, and control its thickness deformation to be 8%-10%;
[0014] Step S3.3: The intermediate slab after the second rolling is rolled in a third rolling pass to control its thickness deformation to be 10%-15%.
[0015] Step S3.4: Throw out the intermediate slab after the third rolling pass, and at the same time measure its surface temperature T3 at the time of throwing; perform a second water cooling on the intermediate slab after throwing, and at the same time measure its surface temperature T4, until the difference between T4 and T3 is 80-120℃, then stop the second water cooling; perform a fourth rolling pass on the intermediate slab after the second water cooling, and control its thickness deformation to be 7%-12%;
[0016] Step S3.5: Continue rolling the intermediate slab after rolling in step S3.4. When the target width is reached, reverse the rolling direction until the target thickness is reached to obtain the pre-finished product; control the final rolling temperature to be not less than T. β -250℃; where T β This indicates the actual β phase transformation point measured on the titanium alloy slab.
[0017] Optionally, in step S3.4, if the thickness of the intermediate slab after the previous rolling pass is less than 200 mm, water cooling treatment is not required before the next rolling pass. If the thickness of the intermediate slab after the third rolling pass is less than 200 mm, a second water cooling is not required. Conversely, if the thickness of the intermediate slab after the previous rolling pass is greater than 200 mm, water cooling treatment is required before the next rolling pass.
[0018] Optionally, before step S3.1, the roller table is cleaned, and the time interval between the two rolling passes of the intermediate slab is not less than 20 minutes.
[0019] Optionally, in step S1, the thickness of the titanium alloy slab is 200-350 mm; the pretreatment includes surface cleaning of the titanium alloy slab; the surface roughness of the pretreated titanium alloy slab is not greater than Ra 3.2 μm.
[0020] Optionally, in step S1, the thickness of the pure titanium plate is 2-3 mm; the pure titanium plate is bonded to the titanium alloy slab by an explosive bonding method; the pure titanium plate is a TA1 titanium plate.
[0021] Optionally, in step S2, the heat treatment includes heating the composite slab at a temperature 30±10°C below the β phase transformation point of the titanium alloy slab, and controlling the upper surface temperature of the composite slab to be 10-20°C higher than the lower surface temperature. After the temperature reaches the heating temperature, the slab is held for 1.5D minutes, where D represents the thickness of the pretreated titanium alloy slab.
[0022] Optionally, in step S4, the straightening process uses a straightening temperature greater than 600°C.
[0023] In a second aspect, the present invention provides a titanium alloy thick plate, which is prepared by the rolling method of the aforementioned titanium alloy thick plate.
[0024] The application of the technical solution of the present invention has at least the following beneficial effects:
[0025] (1) The present invention provides a rolling method for thick titanium alloy plates. In step S3, the rolling process combines thickness deformation with water cooling. Water cooling is used to achieve micro-hardening of the surface of the intermediate-state slab with thick specifications. Under the condition of controlling the thickness deformation, the deformation penetrates into the core of the intermediate-state slab, improving the uniformity of the core structure and ensuring consistency with the surface structure. Therefore, the present invention can solve the problem of severe inconsistency between the surface and core structures of thick-specification finished products. Moreover, the present invention can be stably implemented in industrial applications and has practicality.
[0026] (2) In step S3.4 of this invention, multi-pass rolling and water cooling are combined to achieve the following: When the thickness of the intermediate slab is greater than 200 mm, water cooling is also required to ensure that the surface of the intermediate slab is slightly hardened. Under the condition of controlling the amount of thickness deformation, the deformation penetrates into the core of the intermediate slab, improving the uniformity of the core structure and ensuring consistency with the surface structure. When the thickness of the intermediate slab is less than 200 mm, water cooling is not required to avoid delamination deformation or even cracking of the intermediate slab.
[0027] (3) The titanium alloy thick plate obtained by the present invention has a thickness of 40-100mm, and the surface structure and core structure are consistent.
[0028] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description
[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0030] Figure 1 These are metallographic photographs of the surface microstructure of the titanium alloy thick plate obtained in Example 1 of this invention;
[0031] Figure 2 These are metallographic photographs of the core structure of the titanium alloy thick plate obtained in Example 1 of this invention;
[0032] Figure 3 These are metallographic photographs of the surface microstructure of the titanium alloy thick plate prepared in Comparative Example 1 of this invention.
[0033] Figure 4 This is a metallographic photograph of the core structure of the titanium alloy thick plate prepared in Comparative Example 1 of the present invention.
[0034] Figure 5 These are metallographic images of the surface structure of the titanium alloy thick plate obtained in Example 1 of this invention after heat treatment experiment;
[0035] Figure 6 These are metallographic images of the core structure of the titanium alloy thick plate prepared in Example 1 of this invention after heat treatment experiment;
[0036] Figure 7 These are metallographic photographs of the surface microstructure of the titanium alloy thick plate prepared in Comparative Example 1 of this invention after heat treatment.
[0037] Figure 8 This is a metallographic photograph of the core structure of the titanium alloy thick plate prepared in Comparative Example 1 of this invention after heat treatment. Detailed Implementation
[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.
[0039] Example 1:
[0040] See Figure 1 A method for rolling a thick titanium alloy plate, comprising:
[0041] Step S1: Pure titanium plates (specifically TA1 titanium plates; dimensions of 3mm thickness × 1250mm width × 2500mm length, β phase transformation point of 950℃) are respectively placed on the upper and lower surfaces of the pretreated titanium alloy slab (specifically TC4ELI, with dimensions of 300mm thickness × 1250mm width × 2500mm length) to obtain a composite slab. Specifically, the pure titanium plates are bonded to the titanium alloy slab using a conventional explosive bonding method. Pure titanium plates are used to control the oxidation of the titanium alloy slab surface. Pure titanium plates have stronger oxidation resistance than general alloys, and the risk of rolling cracking after surface cooling is also relatively small.
[0042] Step S2: Heat treat the composite slab to obtain an intermediate slab.
[0043] Step S3: Roll the intermediate slab into a pre-finished product of a target thickness using a rolling process; wherein the target thickness is 70mm; the thickness deformation of the intermediate slab in a single pass of the rolling process is no more than 40mm, and the intermediate slab is water-cooled during the rolling process;
[0044] Step S4: The pre-finished product is straightened and then air-cooled to room temperature to obtain a thick titanium alloy plate. The straightening temperature used in the straightening process is greater than 600℃, specifically 650℃.
[0045] The rolling process used in step S3 includes:
[0046] Step S3.1: The intermediate slab is rolled in the first pass to reduce its thickness by 15 mm.
[0047] Step S3.2: Throw out the intermediate slab after the first rolling pass, and simultaneously measure its surface temperature T1 at the time of throwing; perform the first water cooling on the thrown intermediate slab (using an intermediate slab cooling system to complete the first water cooling, controlling the water flow rate to 60-80 m / s). 3 / min; water temperature is 35℃), and at the same time, its surface temperature T2 is measured until the difference between T2 and T1 is 100-150℃, then the first water cooling is stopped; the intermediate slab after the first water cooling is rolled in a second pass to control its thickness deformation to 8%-10%;
[0048] Step S3.3: The intermediate slab after the second rolling is rolled in a third rolling pass to control its thickness deformation to be 10%-15%.
[0049] Step S3.4: Throw out the intermediate slab after the third rolling pass, and simultaneously measure its surface temperature T3 at the time of throwing; perform a second water cooling on the thrown intermediate slab (using an intermediate slab cooling system to complete the second water cooling, controlling the water flow rate to 60-80 m / s). 3 / min; water temperature is 35℃), and at the same time, its surface temperature T4 is measured until the difference between T4 and T3 is 80-120℃, then the second water cooling is stopped; the intermediate slab after the second water cooling is rolled in the fourth pass, and its thickness deformation is controlled to be 7%-12%;
[0050] Step S3.5: The intermediate slab rolled in step S3.4 is rolled using conventional rolling technology. When the target width is reached, the rolling direction is reversed until the target thickness is reached to obtain the pre-finished product; the final rolling temperature is controlled to be not less than T. β -250℃; where T β This indicates the actual β phase transformation point measured on the titanium alloy slab, specifically 730℃.
[0051] If the thickness of the intermediate slab after the first rolling pass is less than 200 mm, then the first and second water cooling are not required.
[0052] If the thickness of the intermediate slab after the third rolling pass is less than 200 mm, then a second water cooling is not required.
[0053] The process includes cleaning the roller table before step S3.1, and the time interval between the two rolling passes of the intermediate slab is not less than 20 minutes.
[0054] In step S1, the pretreatment includes cleaning the surface of the titanium alloy slab to remove the surface emulsion; the surface roughness of the pretreated titanium alloy slab is no greater than Ra 3.2 μm.
[0055] In step S2, the heat treatment involves heating the composite slab in an electric heating furnace at a temperature 30 ± 10°C below the phase transformation point of the titanium alloy slab. The temperature of the upper surface of the composite slab (specifically 950°C) is controlled to be 10°C higher than the temperature of the lower surface (specifically 940°C). After the temperature reaches the heating temperature (specifically 950°C), it is held for 1.5D minutes, where D represents the thickness of the pretreated titanium alloy slab.
[0056] To prevent uneven cooling of the upper and lower surfaces of the composite slab, the heat-insulated composite slab needs to be rapidly transported to the roller table within 30 seconds, the roller cooling water is turned off, and the rolling process in step S3 is performed. The rolling parameters used in step S3 are shown in Table 1.
[0057] Table 1 shows the rolling parameters used in step S3 of Example 1.
[0058]
[0059]
[0060] Comparative Example 1:
[0061] Unlike Example 1, a first and second water cooling process is not used. Therefore, the rolling parameters used in step S3 differ from the data in Table 1, as shown in Table 2.
[0062] Table 2 shows the rolling parameters used in step S3 of Comparative Example 1.
[0063] Order of lanes Inlet thickness Export thickness Thickness deformation rate / % Thickness deformation / mm 1 300 280 7.00％ 20 2 280 252 10.00％ 28 3 252 225 11.00％ 27 4 225 202 10.00％ 23 5 202 185 8.00％ 17 6 185 170 8.00％ 15 7 170 152 11.00％ 18 8 152 125 18.00％ 27 9 125 102 18.00％ 23 10 102 84 18.00％ 18 11 84 76 10.00％ 8 12 76 69 9.00％ 7
[0064] The microstructure of the titanium alloy thick plates prepared in Example 1 and Comparative Example 1 was examined using an optical microscope. For specific results, please refer to [link to relevant documentation]. Figure 1-4 .Depend on Figure 1-4 It can be seen that the titanium alloy thick plate prepared by Example 1 has consistency in surface microstructure and core microstructure, while the titanium alloy thick plate prepared by Comparative Example 1 has poor consistency in surface microstructure and core microstructure.
[0065] The titanium alloy thick plates prepared in Example 1 and Comparative Example 1 were subjected to heat treatment experiments. The specific experimental methods are as follows: the titanium alloy thick plates were annealed at 860℃ and held at that temperature for 80 minutes.
[0066] The microstructure of the titanium alloy thick plates prepared in Example 1 and Comparative Example 1 after heat treatment was scanned and tested using an optical microscope. Specific results can be found in [reference needed]. Figure 5-8 .Depend on Figure 5-8 It can be seen that the titanium alloy thick plate prepared in Example 1 has consistent surface and core microstructure after heat treatment, while the titanium alloy thick plate prepared in Comparative Example 1 has poorer consistency in surface and core microstructure after heat treatment.
[0067] In summary, the titanium alloy thick plate prepared by Example 1 of this invention has consistency in both surface and core microstructure, and also exhibits consistency in both surface and core microstructure after heat treatment.
[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A rolling method for thick titanium alloy plates, characterized in that, include: Step S1: Pure titanium plates are placed on the upper and lower surfaces of the pretreated titanium alloy slab to obtain a composite slab. Step S2: Heat treat the composite slab to obtain an intermediate slab. Step S3: Roll the intermediate slab into a pre-finished product of the target thickness using a rolling process; wherein the target thickness is 40-100mm; the thickness deformation of the intermediate slab in a single pass of the rolling process is not greater than 40mm, and the intermediate slab is water-cooled during the rolling process; Step S4: Straighten the pre-finished product and then air-cool it to room temperature to obtain a titanium alloy thick plate. The rolling process used in step S3 includes: Step S3.1: The intermediate slab is rolled in the first pass to reduce its thickness by 10-20 mm. Step S3.2: Throw out the intermediate slab after the first rolling pass, and at the same time measure its surface temperature at the time of throwing. T 1; The intermediate slab after casting is subjected to a first water cooling, and its surface temperature is measured simultaneously. T 2, until T 2 and T When the temperature difference is 100-150℃, the first water cooling is stopped; the intermediate slab after the first water cooling is rolled in a second pass to control its thickness deformation to 8%-10%; Step S3.3: The intermediate slab after the second rolling pass is rolled in a third pass to control its thickness deformation to be 10%-15%; Step S3.4: Throw out the intermediate slab after the third rolling pass, and simultaneously measure its surface temperature at the time of throwing. T 3; The intermediate slab after being ejected is subjected to a second water cooling, and its surface temperature is measured simultaneously. T 4, until T 4 and T When the temperature difference between the two temperatures reaches 80-120℃, the second water cooling is stopped; the intermediate slab after the second water cooling is then subjected to a fourth rolling pass, controlling its thickness deformation to be 7%-12%; Step S3.5: Continue rolling the intermediate slab after rolling in step S3.
4. When the target width is reached, reverse the rolling direction until the target thickness is reached to obtain the pre-finished product; control the final rolling temperature to be not less than T β -250℃; among which, T β This indicates the actual measured value of the titanium alloy slab. β Phase transition point.
2. The rolling method for titanium alloy thick plates according to claim 1, characterized in that, In step S3.4, if the thickness of the intermediate slab after the previous rolling is less than 200 mm, water cooling treatment is not required before the next rolling; conversely, if the thickness of the intermediate slab after the previous rolling is greater than 200 mm, water cooling treatment is required before the next rolling.
3. The rolling method for titanium alloy thick plates according to claim 1, characterized in that, The process includes cleaning the roller table before step S3.1, and the time interval between the two rolling passes of the intermediate slab is not less than 20 minutes.
4. The rolling method for titanium alloy thick plates according to claim 1, characterized in that, In step S1, the thickness of the titanium alloy slab is 200-350 mm.
5. The rolling method for titanium alloy thick plates according to claim 1, characterized in that, In step S1, the pretreatment includes surface cleaning of the titanium alloy slab; the surface roughness of the pretreated titanium alloy slab is no greater than Ra 3.2 μm.
6. The rolling method for titanium alloy thick plates according to claim 1, characterized in that, In step S1, the thickness of the pure titanium plate is 2-3 mm; the pure titanium plate is bonded to the titanium alloy slab by an explosive bonding method; the pure titanium plate is a TA1 titanium plate.
7. The rolling method for titanium alloy thick plates according to claim 1, characterized in that, In step S2, the heat treatment includes heating the composite slab at a temperature equal to that of the titanium alloy slab. β The temperature is set 30±10℃ below the phase transformation point, and the upper surface temperature of the composite slab is controlled to be 10-20℃ higher than the lower surface temperature. After reaching the heating temperature, the temperature is held for 1.5 seconds. D minutes, of which, D This indicates the thickness of the pretreated titanium alloy slab.
8. The rolling method for titanium alloy thick plates according to claim 1, characterized in that, In step S4, the straightening process uses a straightening temperature greater than 600°C.
9. A titanium alloy thick plate, characterized in that, It is prepared by the rolling method of any one of claims 1-8 for thick titanium alloy plates.