A short process preparation method of high-strength Inconel 718 high-temperature alloy plate strip

Abstract

This invention discloses a short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip, comprising: smelting alloy liquid according to a set composition; thin strip continuous casting process; homogenization treatment; primary cold rolling; recrystallization annealing; secondary warm rolling; and single-stage aging. This invention utilizes a short-process technology of thin strip continuous casting to prepare Inconel 718 high-temperature alloy sheet and strip, omitting forging and hot rolling processes, significantly simplifying the production process, shortening the production line length, and substantially reducing enterprise production costs. Furthermore, utilizing warm rolling deformation to promote the precipitation of the γ” strengthening phase simplifies the subsequent aging process, shortening the conventional 18-hour two-stage aging process to 4 hours, while ensuring that the Inconel 718 alloy possesses excellent tensile properties.

Description

Technical Field

[0001] This invention belongs to the field of metal materials technology and relates to a short-process preparation method for high-strength Inconel 718 high-temperature alloy plates and strips. Background Technology

[0002] Inconel 718 alloy is an age-hardening nickel-based wrought superalloy. During the aging process, a large amount of γ”-Ni3Nb strengthening phase precipitates to improve the alloy's strength. Inconel 718 alloy has excellent mechanical properties, and its sheets and strips are widely used in aerospace, nuclear energy, and automotive industries, making it a key representative of "multi-purpose" alloys.

[0003] The manufacturing process of conventional Inconel 718 alloy sheet and strip is highly complex, involving a series of intricate steps including melting, homogenization, forging, hot rolling, heat treatment, and cold rolling. Furthermore, the material is prone to cracking during repeated deformation processes, leading to unstable product performance and quality. With the continuous development of modern industrial technology, the performance requirements for Inconel 718 alloy are becoming increasingly stringent, and traditional cold rolling-aging processes are no longer sufficient to meet the demands of extreme environments. Therefore, further improving the quality stability and optimizing the mechanical properties of Inconel 718 alloy sheet and strip is of great significance for promoting technological progress and industrial development. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this invention is to provide a short-process preparation method for high-strength Inconel 718 high-temperature alloy plates and strips.

[0005] This invention provides a short-process method for preparing high-strength Inconel 718 high-temperature alloy sheet and strip, comprising:

[0006] (1) The alloy liquid is smelted according to the set composition, which contains, by weight percentage, Ni 50-55%, Cr 17-21%, Mo 2.8-3.3%, Nb 4.75-5.5%, Al 0.2-0.8%, Ti 0.65-1.15%, Co≤1%, C≤0.8%, Si≤0.35%, P≤0.015%, B≤0.006%, with the balance being Fe and unavoidable impurities;

[0007] (2) Thin strip continuous casting process: The alloy liquid is poured into the tundish, and then the alloy liquid is poured into the triangular molten pool composed of two counter-rotating water-cooled casting rolls and two side sealing plates. After casting and rolling, a casting strip with a thickness of 1.8 to 2.3 mm is obtained. After the casting strip exits the rolls, it is water-cooled to room temperature.

[0008] (3) Homogenization treatment: The casting strip is kept at 1150℃ for 1 hour, and then air-cooled to room temperature after the heat preservation is completed;

[0009] (4) Cold rolling: The homogenized cast strip is cold rolled at room temperature;

[0010] (5) Recrystallization annealing: Hold the cold-rolled sheet and strip at 1010℃ for 10 min, and air cool to room temperature after the holding period;

[0011] (6) Secondary warm rolling: The strip after recrystallization annealing is held at 720℃ for 5 minutes, and then warm rolled at 720℃, with a 5-minute holding time between warm rolling passes;

[0012] (7) Single-stage aging: The strip after secondary warm rolling is kept at 720℃ for 1 to 4 hours. After the heat preservation is completed, it is air-cooled to room temperature to finally obtain Inconel 718 alloy strip with ultra-high strength.

[0013] Furthermore, the superheat of the intermediate ladle in step (2) is controlled at 30-40°C.

[0014] Furthermore, the cold rolling reduction in step (4) is 30-40%.

[0015] Furthermore, in step (6), the total reduction during warm rolling is 60-80%.

[0016] Furthermore, in the homogenization process, the timer starts when the cast strip is heated to 1150℃, and the holding time is recorded as t1; the time used for the secondary warm rolling process is recorded as t2; the recrystallization annealing time after rolling deformation is recorded as t3; and the single-stage aging time is recorded as t4.

[0017] The total time required is t_total = t1 + t2 + t3 + t4, and t_total should be controlled to be less than 9 hours.

[0018] Furthermore, the high-strength Inconel 718 high-temperature alloy sheet and strip exhibits a tensile strength of over 1700 MPa and an elongation of over 6% under room temperature tensile conditions. Under tensile conditions at 650℃, it exhibits a tensile strength of over 1200 MPa and an elongation of over 13%.

[0019] The present invention provides a short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip, which has at least the following beneficial effects:

[0020] 1. The short-process preparation method of the present invention eliminates the traditional forging and hot rolling processes, and directly produces Inconel 718 alloy strips with a thickness of 1.8 to 2.3 mm;

[0021] 2. The short-process preparation method of the present invention shortens the traditional high-temperature long-time homogenization process of tens of hours to less than 1 hour;

[0022] 3. The short-process preparation method of the present invention can effectively simplify the aging process, shortening the traditional 18-hour two-stage aging process to less than 4 hours;

[0023] 4. In the short-process preparation method of the present invention, the timer starts when the cast strip is heated to 1150°C during the homogenization treatment, and the holding time is recorded as t1; the time used for the secondary warm rolling process is recorded as t2; the recrystallization annealing time after rolling deformation is recorded as t3; and the single-stage aging time is recorded as t4; the required time ttotal = t1 + t2 + t3 + t4, and ttotal is controlled to be < 9h.

[0024] 5. In the short-process preparation method of the present invention, the combination of warm rolling and single-stage aging treatment can effectively control the precipitation behavior of the γ” strengthening phase, and change the traditional disk-shaped precipitation of the γ” phase into a near-spherical precipitation.

[0025] 6. The Inconel 718 alloy sheet and strip prepared by the short-process preparation method of the present invention has a room temperature tensile strength of ≥1700MPa and an elongation of ≥6%. Under tensile conditions at 650℃, the tensile strength is ≥1200MPa and the elongation is ≥13%. Attached Figure Description

[0026] Figure 1 This is a flowchart of a short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip according to the present invention;

[0027] Figure 2 The metallographic structure of the homogenized casting strip in Examples 1-3;

[0028] Figure 3(a) shows the precipitation morphology of the γ” strengthening phase in Example 1;

[0029] Figure 3(b) shows the size and distribution of the γ” strengthening phase in Example 1;

[0030] Figure 4 The engineering stress-strain curves of the high-strength Inconel 718 high-temperature alloy sheet and strip specimens in Example 1 are shown. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0032] Example 1

[0033] like Figure 1 As shown in this embodiment, a short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip includes:

[0034] (1) The alloy liquid is smelted according to the set composition, which contains Ni 53%, Cr 18%, Mo 3.2%, Nb 5.3%, Al 0.5%, Ti 0.87%, Co 0.4%, C 0.5%, Si 0.15%, P 0.013%, B 0.005% by weight, with the balance being Fe and unavoidable impurities.

[0035] (2) Thin strip continuous casting process: The alloy liquid is poured into the tundish and the superheat is controlled at +35°C. Then the alloy liquid is poured into a triangular molten pool composed of two counter-rotating casting rolls and side sealing plates. After casting and rolling, a casting strip with a thickness of 2 mm is obtained. After the casting strip exits the rolls, it is water cooled to room temperature.

[0036] (3) Homogenization treatment: The cast strip is subjected to homogenization treatment at 1150℃ for 1 hour, and then air-cooled to room temperature after the heat preservation is completed. Figure 2 The metallographic structure diagram is for homogenized casting strips.

[0037] (4) Cold rolling: The homogenized cast strip is cold rolled at room temperature with a reduction of 40%.

[0038] (5) Recrystallization annealing: Cold-rolled sheet and strip are kept at 1010℃ for 10 minutes, and then air-cooled to room temperature after the heat preservation is completed.

[0039] (6) Secondary warm rolling: The strip after recrystallization annealing is held at 720℃ for 5 minutes, and then warm rolled at 720℃. The warm rolling passes are held for 5 minutes between each pass, and the total reduction is 70%.

[0040] (7) Single-stage aging: The strip after secondary warm rolling was held at 720℃ for 4 hours. The corresponding morphology of the strengthening phase precipitation is shown in Figure 3(a) and Figure 3(b). Figure 3(a) shows the precipitation morphology of the γ” strengthening phase in Example 1, and Figure 3(b) shows the size and distribution of the γ” strengthening phase in Example 1. After the holding period, the strip was air-cooled to room temperature, and finally, Inconel 718 alloy strip with ultra-high strength was obtained.

[0041] The high-strength Inconel 718 high-temperature alloy sheet and strip prepared in this embodiment has a tensile strength of 1860 MPa and an elongation of 6% under room temperature tensile conditions. Under tensile conditions at 650°C, the tensile strength is above 1360 MPa and the elongation is 15%. Figure 4 The engineering stress-strain curves of the high-strength Inconel 718 high-temperature alloy sheet and strip specimens in Example 1 are shown.

[0042] Example 2

[0043] This embodiment provides a short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip, comprising:

[0044] (1) The steel is smelted according to the set composition, which contains Ni 54%, Cr 17%, Mo 3.1%, Nb 5.0%, Al 0.4%, Ti 1.05%, Co 0.3%, C 0.3%, Si 0.25%, P 0.012%, B 0.004% by weight, with the balance being Fe and unavoidable impurities.

[0045] (2) Thin strip continuous casting process: The alloy liquid is poured into the tundish and the superheat is controlled at +40℃. Then the alloy liquid is poured into a triangular molten pool composed of two counter-rotating casting rolls and side sealing plates. After casting and rolling, a casting strip with a thickness of 2.1mm is obtained. After the casting strip exits the rolls, it is water cooled to room temperature.

[0046] (3) Homogenization treatment: The cast strip is subjected to homogenization treatment at 1150℃ for 1 hour, and then air-cooled to room temperature after the heat treatment is completed. Figure 2 The metallographic structure diagram is for homogenized casting strips.

[0047] (4) Cold rolling: The homogenized cast strip is cold rolled at room temperature with a reduction of 30%.

[0048] (5) Recrystallization annealing: Hold the cold-rolled strip at 1010℃ for 10 minutes, and then air cool to room temperature after the holding period.

[0049] (6) Secondary warm rolling: The strip after recrystallization annealing is held at 720℃ for 5 minutes, and then warm rolled at 720℃. The warm rolling passes are held for 5 minutes between each pass, and the total reduction is 80%.

[0050] (7) Single-stage aging: The strip after secondary warm rolling is kept at 720℃ for 2 hours, and after the heat preservation is completed, it is air-cooled to room temperature to finally obtain Inconel 718 alloy strip with ultra-high strength.

[0051] The high-strength Inconel 718 high-temperature alloy sheet and strip prepared in this embodiment exhibits a tensile strength of over 1800 MPa and an elongation of 7% under room temperature tensile conditions. Under tensile conditions at 650°C, the tensile strength exceeds 1280 MPa and the elongation is 16%.

[0052] Example 3

[0053] This embodiment provides a short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip, comprising:

[0054] (1) The molten steel is smelted according to the set composition, which contains, by weight percentage, Ni 55%, Cr 18%, Mo 2.9%, Nb 5.5%, Al 0.5%, Ti 0.85%, Co 0.2%, C 0.4%, Si 0.28%, P 0.011%, B 0.003%, with the balance being Fe and unavoidable impurities;

[0055] (2) Thin strip continuous casting process: The alloy liquid is poured into the tundish and the superheat is controlled at +30℃. Then the alloy liquid is poured into a triangular molten pool composed of two counter-rotating casting rolls and side sealing plates. After casting and rolling, a casting strip with a thickness of 2.2mm is obtained. After the casting strip exits the rolls, it is water cooled to room temperature.

[0056] (3) Homogenization treatment: The cast strip is subjected to homogenization treatment at 1150℃ for 1 hour, and then air-cooled to room temperature after the heat treatment is completed. Figure 2 The metallographic structure diagram is for homogenized casting strips.

[0057] (4) Cold rolling: The homogenized cast strip is cold rolled at room temperature with a reduction of 35%;

[0058] (5) Recrystallization annealing: Hold the cold-rolled sheet and strip at 1010℃ for 10 min, and air cool to room temperature after the holding period;

[0059] (6) Secondary warm rolling: The strip after recrystallization annealing is held at 720℃ for 5 minutes, and then warm rolled at 720℃. The warm rolling passes are held for 5 minutes between each pass, and the total reduction is 60%.

[0060] (7) Single-stage aging: The strip after secondary warm rolling is kept at 720℃ for 1 hour, and after the heat preservation is completed, it is air-cooled to room temperature to finally obtain Inconel 718 alloy strip with ultra-high strength.

[0061] The high-strength Inconel 718 high-temperature alloy sheet and strip prepared in this embodiment exhibits a tensile strength of over 1700 MPa and an elongation of 8% under room temperature tensile conditions. Under tensile conditions at 650°C, the tensile strength exceeds 1200 MPa and the elongation is 17%.

[0062] In the three embodiments of the present invention, the short-process preparation method of high-strength Inconel 718 high-temperature alloy sheet and strip is as follows: during the homogenization treatment, the time is started when the cast strip is heated to 1150°C, and the holding time is recorded as t1; the time used for the secondary warm rolling process is recorded as t2; the recrystallization annealing time after rolling deformation is recorded as t3; and the single-stage aging time is recorded as t4; the required time ttotal = t1 + t2 + t3 + t4, and ttotal is controlled to be < 9h.

[0063] This invention discloses a short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip, characterized by sub-rapid solidification and a short process, enabling the direct preparation of alloy thin strips from molten metal. Compared to conventional processes, thin strip continuous casting technology significantly simplifies the production process of Inconel 718 alloy sheet and strip, shortens the production line length, and thus reduces production costs for enterprises. Furthermore, the sub-rapid solidification characteristic can suppress element segregation and refine the solidification structure, which is beneficial for improving alloy properties.

[0064] The innovations of this invention are as follows: 1) This invention utilizes thin-strip continuous casting technology to prepare Inconel 718 alloy sheet and strip, eliminating forging, hot rolling, and other processes, significantly shortening the production process; 2) In this invention, the thin-strip continuously cast Inconel 718 alloy sheet and strip only requires homogenization treatment within 1 hour to achieve uniform distribution of alloy elements; 3) Warm rolling process promotes the precipitation of γ” strengthening phase, thereby improving the morphology of γ” phase precipitation, and shortens the traditional 18-hour two-stage aging process to 4 hours; 4) Warm rolling combined with a single-stage aging process can significantly improve the mechanical properties of Inconel 718 alloy sheet and strip. In this invention, the room temperature tensile strength of the thin-strip continuously cast Inconel 718 alloy after single-stage aging treatment can reach 1860 MPa, with an elongation of approximately 6%; under tensile conditions at 650℃, the tensile strength can reach 1360 MPa, with an elongation maintained at 15%.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the ideas of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip, characterized in that, include: (1) The alloy liquid is smelted according to the set composition, which contains, by weight percentage, Ni 50~55%, Cr 17~21%, Mo 2.8~3.3%, Nb 4.75~5.5%, Al 0.2~0.8%, Ti 0.65~1.15%, Co≤1%, C≤0.8%, Si≤0.35%, P≤0.015%, B≤0.006%, with the balance being Fe and unavoidable impurities; (2) Thin strip continuous casting process: The alloy liquid is poured into the tundish, and then the alloy liquid is poured into the triangular molten pool composed of two counter-rotating water-cooled casting rolls and two side sealing plates. After casting and rolling, a casting strip with a thickness of 1.8~2.3mm is obtained. After the casting strip exits the rolls, it is water-cooled to room temperature. (3) Homogenization treatment: The cast strip is kept at 1150℃ for 1 hour, and then air-cooled to room temperature after the heat preservation is completed; (4) Cold rolling: The homogenized cast strip is cold rolled at room temperature; (5) Recrystallization annealing: Hold the cold-rolled strip at 1010℃ for 10 min, and then air cool to room temperature after the holding period; (6) Secondary warm rolling: The recrystallized annealed strip is held at 720°C for 5 minutes, and then warm rolled at 720°C with a 5-minute holding time between warm rolling passes; (7) Single-stage aging: The strip after secondary warm rolling is kept at 720℃ for 1~4h, and after the heat preservation is completed, it is air-cooled to room temperature to finally obtain high-strength Inconel 718 high-temperature alloy strip.

2. The short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip as described in claim 1, characterized in that, The superheat of the intermediate ladle in step (2) is controlled at 30~40℃.

3. The short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip as described in claim 1, characterized in that, In step (4), the cold rolling reduction is 30-40%.

4. The short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip as described in claim 1, characterized in that, In step (6), the total reduction during warm rolling is 60-80%.

5. The short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip as described in claim 1, characterized in that, The time for heating the cast strip to 1150℃ during the homogenization process is recorded as t1; the time for the secondary warm rolling process is recorded as t2; the recrystallization annealing time after rolling deformation is recorded as t3; and the single-stage aging time is recorded as t4. The total time required is t_total = t1 + t2 + t3 + t4, and t_total should be controlled to be less than 9 hours.

6. The short-process preparation method for high-strength Inconel 718 high-temperature alloy sheet and strip as described in claim 1, characterized in that, The high-strength Inconel 718 high-temperature alloy sheet and strip have a tensile strength of over 1700 MPa and an elongation of over 6% under room temperature tensile conditions; and a tensile strength of over 1200 MPa and an elongation of over 13% under 650℃ tensile conditions.

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