A low-expansion precision alloy thick plate and a method for manufacturing the same

Abstract

The application discloses a kind of low expansion precision alloy thick plate and manufacturing method thereof, solve the limited weight of ingot, it is difficult to meet the technical problems such as thick plate preparation demand.The composition of the low expansion precision alloy thick plate includes: C≤0.008%, Si≤0.15%, Mn: 0.30%-0.50%, P≤0.005%, S≤0.001%, Ni: 34.5%-35.5%, Co: 1.0%-1.5%, Ni+Co: 35.5%-36.5%, O≤10ppm, by converter oxygen blowing decarburization-LF refining-RH refining-mold casting method smelting raw material, then ingot forging breakdown, heating temperature 1200±20℃, first fire forging reduction ≤20mm, subsequent heating, final forging temperature ≥750℃, using 4 roll reversible mill rolling, heating temperature 1180±20℃, high pressure water descaling, first pass deformation ≤10%, subsequent pass deformation 10-15%, total deformation ≥70%, final rolling temperature ≥850℃, hot-rolled plate is treated twice at 800℃ and 315℃.The present application can prepare large single weight ingot to meet the preparation demand of low expansion precision alloy thick plate.

Description

Technical Field

[0001] This invention belongs to the field of alloy manufacturing technology, specifically relating to a low-expansion precision alloy thick plate and its manufacturing method. Background Technology

[0002] Fe-Ni based alloys, with a Ni content of 36 wt%, exhibit an extremely low coefficient of thermal expansion and are widely used in watches, astronomical equipment, and precision measuring instruments. With industrial development, electronic components made from this alloy have even broader application prospects in the automotive, home appliance, and liquefied natural gas storage and transportation sectors.

[0003] With the expansion of application fields, the demand for precision alloy thick plates is increasing. Currently, the smelting method for this precision alloy is vacuum induction furnace or vacuum induction furnace + electroslag remelting. However, this method is limited by furnace capacity, resulting in a limited weight of cast ingots, which is difficult to meet the needs of thick plate preparation. Furthermore, the alloy has a high coefficient of thermal expansion, which needs to be improved. Summary of the Invention

[0004] In order to solve all or part of the above problems, the present invention aims to provide a low-expansion precision alloy thick plate and a method for manufacturing the same, which can reduce the expansion coefficient of the alloy and prepare large single-weight ingots to meet the preparation requirements of low-expansion precision alloy thick plates.

[0005] In a first aspect, the present invention provides a low-expansion precision alloy thick plate, wherein the composition of the low-expansion precision alloy thick plate comprises, by mass percentage: C≤0.008%, Si≤0.15%, Mn:0.30%-0.50%, P≤0.005%, S≤0.001%, Ni:34.5%-35.5%, Co:1.0%-1.5%, Ni+Co:35.5%-36.5%, O≤10ppm, and the remainder being Fe and unavoidable impurities.

[0006] Secondly, the present invention provides a method for manufacturing a low-expansion precision alloy thick plate, comprising the following steps:

[0007] S1, smelting the raw materials to obtain ingots;

[0008] S2, Forging the ingot to obtain a forged billet;

[0009] S3, grinding and penetrant testing of the forging billet;

[0010] S4, rolling the forging billet to obtain alloy thick plate;

[0011] S5 involves heat treating the alloy thick plate to obtain a finished precision alloy thick plate.

[0012] Optionally, in S1, the raw materials are smelted using a converter oxygen blowing decarburization-LF refining-RH refining-ingot casting method, and an ingot with a thickness of 500mm is obtained.

[0013] Optionally, in S2, during the billet opening process of ingot forging, the furnace loading temperature is controlled to be ≤500℃, the heating rate is not more than 70℃ / h, the heating temperature is 1200±20℃, and the holding time is 1.4-1.8min / mm.

[0014] Optionally, in S2, during the billet forging process, the first forging reduction is controlled to be ≤20mm, followed by reheating in the furnace, with the furnace temperature controlled at 1200±20℃ and the heating time at 1.5h. The final forging temperature in subsequent forgings is ≥750℃, ultimately obtaining a billet thickness ≥300mm.

[0015] Optionally, in S4, during the forging rolling process, a 4-roll reversible rolling mill is used to roll the forging billet, controlling the deformation amount of the first pass to ≤10%, the deformation amount of subsequent passes to 10-15%, and the total deformation amount to ≥70%, controlling the final rolling temperature to ≥850℃, and rolling alloy thick plates with a specification of 60-100mm.

[0016] Optionally, in S4, during the rolling process of the forging billet, the heating temperature is controlled at 1180±20℃, and high-pressure water descaling is also controlled.

[0017] Optionally, in S5, a two-stage heat treatment method is used to heat treat the alloy thick plate, controlling the first stage heat treatment temperature at 800±20℃ and the heat treatment time at 30min, and controlling the second stage heat treatment temperature at 315±20℃ and the heat treatment time at 6h.

[0018] Optionally, the resulting low-expansion precision alloy thick plate has the following properties:

[0019] Grain size ≤ 5;

[0020] The linear coefficient of thermal expansion (20-100℃) ≤ 0.9 × 10 -6 / ℃.

[0021] As can be seen from the above technical solution, the low-expansion precision alloy thick plate and its manufacturing method provided by the present invention have the following advantages:

[0022] The precision alloy thick plate in this application replaces some of the Ni element in the alloy with Co, a member of the same group. Utilizing the magnetostriction of the material, it further counteracts the thermal expansion caused by atomic vibrations during temperature rise, thereby effectively reducing the alloy's coefficient of thermal expansion. Simultaneously, the carbon content is reduced through converter oxygen blowing decarburization and deep decarburization via RH refining, controlling the carbon content to below 0.008%, further reducing the alloy's coefficient of thermal expansion. Furthermore, the forging process used in this application results in a denser alloy microstructure, and the grain size is controlled through methods such as adjusting the heating process. This method can stably produce grains with a grain size ≤5 and a linear coefficient of thermal expansion (20-100℃) ≤0.9×10⁻⁶. -6 / Low-expansion alloy thick plates at ℃ are produced to meet the requirements for the preparation of low-expansion precision alloy thick plates.

[0023] Other features and advantages of the present invention will be set forth in the following description. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention are described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0025] Example 1

[0026] Embodiment 1 of this application discloses a low-expansion precision alloy thick plate. The composition of the low-expansion precision alloy thick plate by mass percentage includes: C = 0.007%, Si = 0.12%, Mn = 0.41%, P ≤ 0.005%, S ≤ 0.001%, Ni = 35.1%, Co = 1.0%, and O = 10ppm.

[0027] In this embodiment, the low-expansion precision alloy thick plate is made by replacing some of the Ni element in the alloy with Co element from the same group. The magnetostriction of the material is used to further counteract the thermal expansion caused by atomic vibration during the temperature rise, thereby effectively reducing the expansion coefficient of the alloy.

[0028] Embodiment 1 of this application also discloses a method for manufacturing a low-expansion precision alloy thick plate, comprising the following steps:

[0029] S1 uses a converter oxygen blowing decarburization-LF refining-RH refining-molding method to smelt the raw materials to obtain an ingot with a thickness of 500mm.

[0030] S2 involves forging the ingot into a billet. During this process, the furnace loading temperature is controlled at 450℃, the heating rate at 70℃ / h, the heating temperature at 1190℃, and the holding time at 720min. Simultaneously, the first forging reduction is controlled at 20mm, the reheating furnace temperature at 1200℃, and the heating time at 1.5h. Subsequent forgings have a final forging temperature ≥750℃, ultimately yielding a forged billet with a thickness of 360mm.

[0031] S3, grinding and penetrant testing of the forging billet;

[0032] S4 uses a 4-roll reversible rolling mill to roll the forging billet. During this process, the heating temperature is controlled at 1180℃, and high-pressure water descaling is controlled. At the same time, the deformation amount of the first pass is controlled at 10%, the deformation amount of subsequent passes is controlled at 10-15%, the total deformation amount is controlled at 72%, the rolling passes are 9, and the final rolling temperature is 900℃, finally obtaining an alloy plate with a specification of 100mm.

[0033] S5. The alloy thick plate is subjected to heat treatment, which is divided into a first stage heat treatment and a second stage heat treatment. The first stage heat treatment temperature is controlled at 780℃ and the heat treatment time is controlled at 30min. The second stage heat treatment temperature is controlled at 310℃ and the heat treatment time is controlled at 6h. Finally, the finished precision alloy thick plate is obtained.

[0034] Testing revealed that the alloy plate has a grain size of grade 5 and a linear coefficient of thermal expansion (20-100℃) of 0.66 × 10⁻⁶. -6 / ℃, meeting the manufacturing requirements of alloy thick plates.

[0035] The manufacturing method of the low-expansion precision alloy thick plate in this embodiment employs converter oxygen blowing decarburization and deep decarburization through an RH refining process to control the carbon content to within 0.008%, thereby further reducing the alloy's expansion coefficient. For thick plates, due to their small deformation, conventional production processes can lead to larger grain sizes and decreased performance. The manufacturing method in this application uses a forging process to achieve a denser microstructure and controls the grain size by adjusting the heating process. The first heat treatment temperature is higher than the recrystallization temperature to ensure complete recrystallization of the deformed microstructure. Since the alloy thick plate often requires milling and welding during use, which places high demands on residual stress, a second heat treatment is added in this application to eliminate the internal stress of the alloy thick plate and reduce deformation after subsequent processing and heat treatment. Therefore, this manufacturing method can stably produce low-expansion alloy thick plates with a grain size ≤5 and a linear thermal expansion coefficient (20-100℃) ≤0.9×10-6 / ℃, thus meeting the manufacturing requirements for low-expansion precision alloy thick plates.

[0036] Example 2

[0037] Embodiment 2 of this application discloses a low-expansion precision alloy thick plate. The difference between this embodiment and Embodiment 1 is that the composition of the low-expansion precision alloy thick plate by mass percentage includes: C = 0.008%, Si = 0.10%, Mn = 0.43%, P ≤ 0.005%, S ≤ 0.001%, Ni = 34.8%, Co = 1.1%, and O = 9ppm.

[0038] Embodiment 2 of this application also discloses a method for manufacturing a low-expansion precision alloy thick plate. The difference between this embodiment and Embodiment 1 is that the method for manufacturing a low-expansion precision alloy thick plate includes the following steps:

[0039] S1 uses a converter oxygen blowing decarburization-LF refining-RH refining-molding method to smelt the raw materials to obtain an ingot with a thickness of 500mm.

[0040] S2 involves forging the ingot into a billet. During this process, the furnace loading temperature is controlled at 470℃, the heating rate at 70℃ / h, the heating temperature at 1200℃, and the holding time at 700min. Simultaneously, the first forging reduction is controlled at 20mm, the reheating furnace temperature at 1190℃, and the heating time at 1.5h. Subsequent forgings result in a final forging temperature ≥750℃, ultimately yielding a forged billet with a thickness of 320mm.

[0041] S3, grinding and penetrant testing of the forging billet;

[0042] S4 uses a 4-roll reversible rolling mill to roll the forging billet. During this process, the heating temperature is controlled at 1180℃, and high-pressure water descaling is controlled. At the same time, the deformation amount of the first pass is controlled at 10%, the deformation amount of subsequent passes is controlled at 10-15%, the total deformation amount is controlled at 75%, the rolling passes are 9, and the final rolling temperature is 885℃, finally obtaining an alloy plate with a specification of 80mm.

[0043] S5. The alloy thick plate is subjected to heat treatment, which is divided into a first stage heat treatment and a second stage heat treatment. The first stage heat treatment temperature is controlled at 785℃ and the heat treatment time is controlled at 30min. The second stage heat treatment temperature is controlled at 315℃ and the heat treatment time is controlled at 6h. Finally, the finished precision alloy thick plate is obtained.

[0044] Testing revealed that the alloy plate has a grain size of grade 6 and a linear coefficient of thermal expansion (20-100℃) of 0.75 × 10⁻⁶. -6 / ℃, meeting the manufacturing requirements of alloy thick plates.

[0045] Example 3

[0046] Embodiment 3 of this application discloses a low-expansion precision alloy thick plate. The difference between this embodiment and Embodiment 1 is that the composition of the low-expansion precision alloy thick plate by mass percentage includes: C = 0.006%, Si = 0.09%, Mn = 0.41%, P ≤ 0.005%, S ≤ 0.001%, Ni = 35.5%, Co = 1.0%, and O = 10ppm.

[0047] Embodiment 3 of this application also discloses a method for manufacturing a low-expansion precision alloy thick plate. The difference between this embodiment and Embodiment 1 is that the method for manufacturing a low-expansion precision alloy thick plate includes the following steps:

[0048] S1 uses a converter oxygen blowing decarburization-LF refining-RH refining-molding method to smelt the raw materials to obtain an ingot with a thickness of 500mm.

[0049] S2 involves forging the ingot into a billet. During this process, the furnace loading temperature is controlled at 500℃, the heating rate at 70℃ / h, the heating temperature at 1200℃, and the holding time at 700min. Simultaneously, the first forging reduction is controlled at 20mm, the reheating furnace temperature at 1180℃, and the heating time at 1.5h. Subsequent forgings result in a final forging temperature ≥750℃, ultimately yielding a forged billet with a thickness of 300mm.

[0050] S3, grinding and penetrant testing of the forging billet;

[0051] S4 uses a 4-roll reversible rolling mill to roll the forging billet. During this process, the heating temperature is controlled at 1180℃, and high-pressure water descaling is controlled. At the same time, the deformation amount of the first pass is controlled at 10%, the deformation amount of subsequent passes is controlled at 10-15%, the total deformation amount is controlled at 80%, the rolling passes are 11, and the final rolling temperature is 855℃, finally obtaining an alloy plate with a specification of 60mm.

[0052] S5. The alloy thick plate is subjected to heat treatment, which is divided into a first stage heat treatment and a second stage heat treatment. The first stage heat treatment temperature is controlled at 810℃ and the heat treatment time is controlled at 30min. The second stage heat treatment temperature is controlled at 320℃ and the heat treatment time is controlled at 6h. Finally, the finished precision alloy thick plate is obtained.

[0053] Testing revealed that the alloy plate has a grain size of grade 6 and a linear coefficient of thermal expansion (20-100℃) of 0.74 × 10⁻⁶. -6 / ℃, meeting the manufacturing requirements of alloy thick plates.

[0054] It should be noted that, unless otherwise stated, the technical or scientific terms used in this invention should have the ordinary meaning as understood by one of ordinary skill in the art.

[0055] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for manufacturing a low-expansion precision alloy thick plate, characterized in that, Includes the following steps: S1, smelting the raw materials to obtain ingots; S2, Forging the ingot to obtain a forged billet; S3, grinding and penetrant testing of the forging billet; S4, rolling the forging billet to obtain alloy thick plate; S5 involves heat treating the alloy thick plate to obtain a finished precision alloy thick plate. In S1, the raw materials are smelted using a converter oxygen blowing decarburization-LF refining-RH refining-ingot casting method, and the ingot thickness is 500mm. In S2, during the billet opening process of ingot forging, the furnace charging temperature is controlled to be ≤500℃, the heating rate is not more than 70℃ / h, the heating temperature is 1200±20℃, and the holding time is 1.4-1.8min / mm; In S2, during the billet forging process, the reduction of the first forging is controlled to be ≤20mm. Then, the billet is reheated in the furnace, with the furnace temperature controlled at 1200±20℃ and the heating time at 1.5h. The final forging temperature of subsequent forgings is ≥750℃, and the billet thickness is ≥300mm. The composition of the low-expansion precision alloy thick plate, by mass percentage, includes: C≤0.008%, Si≤0.15%, Mn:0.30%-0.50%, P≤0.005%, S≤0.001%, Ni:34.5%-35.5%, Co:1.0%-1.5%, Ni+Co:35.5%-36.5%, O≤10ppm, with the remainder being Fe and unavoidable impurities; In S4, during the forging process, a 4-roll reversible mill is used to roll the forging billet, controlling the deformation amount of the first pass to ≤10%, the deformation amount of subsequent passes to 10-15%, and the total deformation amount to ≥70%, controlling the final rolling temperature to ≥850℃, and rolling alloy thick plates with a specification of 60-100mm. In S5, a two-stage heat treatment method is used to heat treat the alloy thick plate. The first stage heat treatment temperature is controlled at 800±20℃ and the heat treatment time is controlled at 30min. The second stage heat treatment temperature is controlled at 315±20℃ and the heat treatment time is controlled at 6h.

2. The method for manufacturing a low-expansion precision alloy thick plate according to claim 1, characterized in that, In S4, during the rolling process of the forging billet, the heating temperature is controlled at 1180±20℃, and high-pressure water descaling is also controlled.

3. The method for manufacturing a low-expansion precision alloy thick plate according to claim 1, characterized in that, The resulting low-expansion precision alloy thick plate has the following properties: Grain size ≤ 5; The linear thermal expansion coefficient at 20-100℃ is ≤0.9×10⁻⁶. -6 / ℃.