Low-expansion precision alloy thick plate and manufacturing method thereof

Abstract

The invention discloses a low-expansion precision alloy thick plate and a manufacturing method thereof, and solves the technical problems that the weight of a cast ingot is limited, and the preparation requirement of a thick plate is difficult to meet. The low-expansion precision alloy thick plate comprises, by mass, less than or equal to 0.008% of C, less than or equal to 0.15% of Si, 0.30%-0.50% of Mn, less than or equal to 0.005% of P, less than or equal to 0.001% of S, 34.5%-35.5% of Ni, 1.0%-1.5% of Co, 35.5%-36.5% of Ni + Co and less than or equal to 10 ppm of O. Raw materials are smelted through a converter oxygen blowing decarburization-LF refining-RH refining-die casting method, then cast ingots are forged and cogged, the heating temperature is 1200 + / -20 DEG C, the rolling reduction of first heating number forging is less than or equal to 20 mm, the rolling reduction of second heating number forging is less than or equal to 20 mm, the rolling reduction of third heating number forging is less than or equal to the final forging temperature is larger than or equal to 750 DEG C, a four-roller reversible rolling mill is adopted for rolling, the heating temperature is 1180 + / -20 DEG C, high-pressure water is adopted for descaling, the first-pass deformation is smaller than or equal to 10%, the subsequent-pass deformation is 10%-15%, the total deformation is larger than or equal to 70%, the final rolling temperature is larger than or equal to 850 DEG C, and a hot-rolled plate is subjected to two times of heat treatment at the temperature of 800 DEG C and the temperature of 315 DEG C. According to the method, the large-piece-weight cast ingot can be prepared, so that the preparation requirement of the low-expansion precise alloy thick plate is met.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy manufacturing, and in particular relates to a low expansion precision alloy thick plate and a manufacturing method thereof. Background Art

[0002] For Fe-Ni based alloys, when the Ni content is 36wt%, the alloy has an extremely low expansion coefficient and is widely used in clocks, astronomical equipment and precision measuring instruments. With the development of industry, electronic components using this alloy as raw material have a wider application prospect in the fields of automobiles, home appliances, liquefied natural gas storage and transportation, etc.

[0003] With the expansion of application fields, the demand for thick and medium-sized plates of precision alloys is increasing. At present, the smelting method of this precision alloy is vacuum induction furnace or vacuum induction furnace + electroslag remelting. However, this method is limited by the furnace capacity and the weight of the cast ingot is limited, which is difficult to meet the demand for thick plate preparation. In addition, the expansion coefficient of the alloy is high and needs to be improved. Summary of the invention

[0004] In order to solve all or part of the above problems, the purpose of the present invention is 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 can prepare large single weight ingots to meet the preparation needs of low expansion precision alloy thick plates.

[0005] In the first aspect, the present invention provides a low expansion precision alloy thick plate, the composition of which includes, 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 rest is Fe and unavoidable impurities.

[0006] In a second aspect, 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 and blanking the ingot to obtain a forging blank;

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

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

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

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

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

[0014] Optionally, in S2, during the ingot forging process, the first forging reduction is controlled to be ≤20mm, and then the ingot is returned to the furnace for heating, the furnace temperature is controlled to be 1200±20℃, the heating time is 1.5h, and the final forging temperature of the subsequent fire is ≥750℃, and finally the forging thickness is obtained to be ≥300mm.

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

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

[0017] Optionally, in S5, a two-stage heat treatment method is used to heat treat the alloy thick plate, and the first-stage heat treatment temperature is controlled to be 800±20°C and the heat treatment time is 30 minutes, and the second-stage heat treatment temperature is controlled to be 315±20°C and the heat treatment time is 6 hours.

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

[0019] Grain size ≤ grade 5;

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

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

[0022] The precision alloy thick plate in this application replaces part of the Ni element in the alloy with the same family Co element, and uses the magnetostriction of the material to further offset the thermal expansion caused by atomic vibration during the temperature increase, thereby effectively reducing the expansion coefficient of the alloy. At the same time, the carbon content is reduced, that is, oxygen decarburization is adopted in a converter, and deep decarburization is performed through the RH refining process to control the carbon content within 0.008%, thereby further reducing the expansion coefficient of the alloy. Not only that, the forging blanking process used in this application can make the alloy structure denser, and the grain size can be controlled by controlling the heating process and other methods, so that this method can stably produce grain size ≤5 levels, linear thermal expansion coefficient (20-100℃) ≤0.9×10 -6 / ℃ low expansion alloy thick plates, thus meeting the preparation needs of low expansion precision alloy thick plates.

[0023] Other features and advantages of the present invention will be set forth in the description which follows. DETAILED DESCRIPTION

[0024] To make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention are described in detail below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0025] Example 1

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

[0027] The low expansion precision alloy thick plate in this embodiment replaces part of the Ni element in the alloy with the Co element of the same group and utilizes the magnetostriction of the material to further offset the thermal expansion caused by atomic vibration during the temperature increase, thereby effectively reducing the expansion coefficient of the alloy.

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

[0029] S1, the raw material is smelted by a converter oxygen decarburization-LF refining-RH refining-mold casting method to obtain an ingot with a thickness of 500 mm.

[0030] S2, forging the ingot, during which the furnace temperature is controlled at 450℃, the heating rate is 70℃ / h, the heating temperature is 1190℃, and the holding time is 720min. At the same time, the first forging reduction is controlled at 20mm, the furnace temperature is 1200℃, and the heating time is 1.5h. The final forging temperature of the subsequent forging is ≥750℃, and finally a forging billet with a thickness of 360mm is obtained;

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

[0032] S4, rolling the forging billet with a 4-roll reversible rolling mill, during which the heating temperature is controlled at 1180°C, and high-pressure water descaling is controlled. At the same time, the deformation amount of the first pass is controlled to be 10%, the deformation amount of the subsequent passes is controlled to be 10-15%, the total deformation amount is controlled to be 72%, the rolling passes are 9, and the final rolling temperature is 900°C, and finally an alloy thick plate with a specification of 100 mm is obtained;

[0033] S5, heat treatment is performed on the alloy thick plate. The heat treatment is divided into the first stage heat treatment and the second stage heat treatment. The first stage heat treatment temperature is controlled to be 780°C and the heat treatment time is 30 minutes. The second stage heat treatment temperature is controlled to be 310°C and the heat treatment time is 6 hours. Finally, the finished precision alloy thick plate is obtained.

[0034] The test results show that the grain size of the alloy thick plate is level 5, and the linear thermal expansion coefficient (20-100℃) is 0.66×10 -6 / ℃, meeting the manufacturing requirements of thick alloy plates.

[0035] The manufacturing method of the low expansion precision alloy thick plate in this embodiment adopts converter oxygen blowing decarburization, and deep decarburization through RH refining process, and the carbon content is controlled within 0.008%, thereby further reducing the expansion coefficient of the alloy. For thick specification plates, due to the small deformation amount, the conventional production process will cause the grain size to be too large and the performance to decrease. The manufacturing method in this application adopts the forging blanking process to make the organization more compact, and the grain size is regulated by controlling the heating process. The first stage heat treatment temperature is higher than the recrystallization temperature to ensure that the deformed organization is completely recrystallized. Since the alloy thick plate often needs to be processed by milling, welding and the like during use, the residual stress requirements are high. In this application, a second stage heat treatment is added to eliminate the internal stress of the alloy thick plate and reduce the deformation after subsequent processing and heat treatment. Therefore, the manufacturing method can stably produce low expansion alloy thick plates with a grain size of ≤5 and a linear thermal expansion coefficient (20-100℃) ≤0.9×10-6 / ℃, thereby meeting the manufacturing needs of low expansion precision alloy thick plates.

[0036] Example 2

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

[0038] Embodiment 2 of the present application further 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 comprises the following steps:

[0039] S1, the raw material is smelted by a converter oxygen decarburization-LF refining-RH refining-mold casting method to obtain an ingot with a thickness of 500 mm.

[0040] S2, forging the ingot, during which the furnace temperature is controlled at 470℃, the heating rate is 70℃ / h, the heating temperature is 1200℃, and the holding time is 700min. At the same time, the first forging reduction is controlled at 20mm, the furnace temperature is 1190℃, and the heating time is 1.5h. The final forging temperature of the subsequent forging is ≥750℃, and finally a forging billet with a thickness of 320mm is obtained;

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

[0042] S4, rolling the forging billet with a 4-roll reversible rolling mill, during which the heating temperature is controlled at 1180°C, and high-pressure water descaling is controlled. At the same time, the deformation amount of the first pass is controlled to be 10%, the deformation amount of the subsequent passes is controlled to be 10-15%, the total deformation amount is controlled to be 75%, the rolling passes are 9, and the final rolling temperature is 885°C, and finally an alloy thick plate with a specification of 80 mm is obtained;

[0043] S5, heat treatment is performed on the alloy thick plate. The heat treatment is divided into the first stage heat treatment and the second stage heat treatment. The first stage heat treatment temperature is controlled to be 785°C and the heat treatment time is 30min. The second stage heat treatment temperature is controlled to be 315°C and the heat treatment time is 6h. Finally, the finished precision alloy thick plate is obtained.

[0044] The test results show that the grain size of the alloy thick plate is grade 6, and the linear thermal expansion coefficient (20-100℃) is 0.75×10 -6 / ℃, meeting the manufacturing requirements of thick alloy plates.

[0045] Example 3

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

[0047] Embodiment 3 of the present application further 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 comprises the following steps:

[0048] S1, the raw material is smelted by a converter oxygen decarburization-LF refining-RH refining-mold casting method to obtain an ingot with a thickness of 500 mm.

[0049] S2, forging the ingot, during which the furnace temperature is controlled at 500℃, the heating rate is 70℃ / h, the heating temperature is 1200℃, and the holding time is 700min. At the same time, the first forging reduction is controlled at 20mm, the furnace temperature is 1180℃, and the heating time is 1.5h. The final forging temperature of the subsequent forging is ≥750℃, and finally a forging billet with a thickness of 300mm is obtained;

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

[0051] S4, rolling the forging billet with a 4-roll reversible rolling mill, during which the heating temperature is controlled at 1180°C, and high-pressure water descaling is controlled. At the same time, the deformation of the first pass is controlled to be 10%, the deformation of the subsequent passes is controlled to be 10-15%, the total deformation is controlled to be 80%, the rolling passes are 11, and the final rolling temperature is 855°C, and finally an alloy thick plate with a specification of 60 mm is obtained;

[0052] S5, heat treatment is performed on the alloy thick plate. The heat treatment is divided into the first stage heat treatment and the second stage heat treatment. The first stage heat treatment temperature is controlled to be 810°C and the heat treatment time is 30 minutes. The second stage heat treatment temperature is controlled to be 320°C and the heat treatment time is 6 hours. Finally, the finished precision alloy thick plate is obtained.

[0053] The test results show that the grain size of the alloy thick plate is grade 6, and the linear thermal expansion coefficient (20-100℃) is 0.74×10 -6 / ℃, meeting the manufacturing requirements of thick alloy plates.

[0054] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present invention should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0055] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in 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 each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A low expansion precision alloy thick plate, It is characterized in that The composition of the low expansion precision alloy thick plate includes, 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 rest is Fe and unavoidable impurities.

2. A method for manufacturing a low expansion precision alloy thick plate according to claim 1, It is characterized in that The steps include: S1, smelting the raw materials to obtain ingots; S2, forging and blanking the ingot to obtain a forging blank; S3, grinding and penetrant testing of forging blanks; S4, rolling the forged billet to obtain an alloy thick plate; S5, heat treating the alloy thick plate to obtain a finished precision alloy thick plate.

3. The method for manufacturing a low expansion precision alloy thick plate according to claim 2, It is characterized in that In S1, the raw material is smelted by a method of converter oxygen decarburization-LF refining-RH refining-die casting, and an ingot with a thickness of 500 mm is obtained.

4. The method for manufacturing a low expansion precision alloy thick plate according to claim 2, It is characterized in that In S2, during the ingot forging process, the furnace charging temperature is controlled to be ≤500°C, the heating rate is not more than 70°C / h, the heating temperature is 1200±20°C, and the holding time is 1.4-1.8min / mm.

5. The method for manufacturing a low expansion precision alloy thick plate according to claim 4, It is characterized in that In S2, during the ingot forging process, the first forging reduction is controlled to be ≤20mm, and then the ingot is returned to the furnace for heating, the furnace temperature is controlled to be 1200±20℃, the heating time is 1.5h, and the final forging temperature of the subsequent fire is ≥750℃, and the final forging thickness is ≥300mm.

6. The method for manufacturing a low expansion precision alloy thick plate according to claim 2, It is characterized in that In S4, during the rolling process of the forging billet, a 4-roll reversible rolling mill is used to roll the forging billet, and the deformation of the first pass is controlled to be ≤10%, the deformation of the subsequent passes is 10-15%, and the total deformation is ≥70%. The final rolling temperature is controlled to be ≥850°C, and the specification of the rolled alloy thick plate is 60-100mm.

7. The method for manufacturing a low expansion precision alloy thick plate according to claim 6, It is characterized in that In S4, during the rolling process of the forging billet, the heating temperature is controlled to be 1180±20°C, and the high-pressure water descaling is controlled.

8. The method for manufacturing a low expansion precision alloy thick plate according to claim 2, It is characterized in that In S5, a two-stage heat treatment method is used to heat treat the alloy thick plate, and the first-stage heat treatment temperature is controlled to be 800±20°C and the heat treatment time is 30min, and the second-stage heat treatment temperature is controlled to be 315±20°C and the heat treatment time is 6h.

9. The method for manufacturing a low expansion precision alloy thick plate according to claim 2, It is characterized in that The finished low expansion precision alloy thick plate has the following properties: Grain size ≤ grade 5; Linear thermal expansion coefficient (20-100℃) ≤ 0.9×10 -6 / ℃.