GH4169 alloy small-specification bar and preparation method thereof

Abstract

The invention relates to the technical field of high-temperature alloy manufacturing, and discloses a GH4169 alloy small-specification bar and a preparation method thereof.The method comprises the steps that a GH4169 alloy cast ingot is subjected to two-stage homogenization treatment; performing forging cogging on the homogenized cast ingot by adopting a high-speed forging machine to obtain a rolled blank; and the rolled blank is fed into a continuous rolling unit to be rolled, and the GH4169 alloy small-specification bar is obtained. According to the method, the cast ingot is homogenized at high temperature for a long time, diffusion and migration of elements can be promoted, and the uniformity of internal components of the cast ingot is improved; the cast ingot is subjected to large-deformation forging cogging by a high-speed forging machine, and carbides and crystal grains can be obviously uniform and refined; and a continuous rolling unit is adopted for rolling into a material, so that uniform deformation can be further ensured, and uniform and fine grains and carbides are obtained.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy manufacturing technology, and in particular to a small-diameter bar of GH4169 alloy and its preparation method. Background Technology

[0002] GH4169 alloy is an iron-nickel-chromium based wrought superalloy with a microstructure consisting of a γ matrix, δ phase, carbides, and reinforcing phases γ" and γ′. It features high strength, oxidation resistance, radiation resistance, excellent hot working properties, and weldability, making it a key material widely used in the aerospace, nuclear energy, and petroleum industries.

[0003] Due to its alloy composition and ingot solidification characteristics, GH4169 ingots exhibit severe component segregation, requiring high-temperature homogenization to promote element diffusion and mitigate compositional inhomogeneity. Currently, the preparation of small-diameter GH4169 alloy bars primarily employs the following technical routes: First, a two-roll reversible rolling method using a 650mm two-roll reversible mill for single-pass rolling with a deformation rate of 80%–90%. This method suffers from low production efficiency and poor batch stability, making it difficult to meet the demands of large-scale stable production. Second, a cold-drawing method, suitable for bars ≤Φ20mm, but with limited specification range. Third, a radial forging method, suitable for bars Φ100–280mm, but unable to cover the Φ20–Φ45mm range. In summary, existing technologies struggle to balance production efficiency, specification range, and batch stability, failing to achieve large-scale, rapid, and stable preparation of GH4169 alloy small-diameter bars with specifications of Φ20–Φ45mm.

[0004] Therefore, there is a need to improve the existing technology for the preparation method of small-diameter bars of GH4169 alloy. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a small-diameter GH4169 alloy bar and its preparation method, for the rapid and stable mass production of GH4169 alloy bars with uniform and fine grains and carbides and excellent performance, with a diameter of Φ20~Φ45mm.

[0006] To achieve the above objectives, the method for preparing small-diameter GH4169 alloy bars provided in this embodiment of the invention includes the following steps: S1 is used to perform a two-stage homogenization treatment on GH4169 alloy ingots; S2 is used to forge the homogenized ingot to obtain rolled billets; S3 feeds the rolled billet into the continuous rolling mill for rolling to produce GH4169 alloy small-diameter bars with diameters of Φ20~Φ45mm.

[0007] In some implementations, in S1, the two-stage homogenization process includes: The first heat preservation stage involves maintaining the temperature at 1130~1170℃ for 24~48 hours. The second heat preservation stage involves maintaining the temperature at 1180~1200℃ for 24~48 hours.

[0008] In some embodiments, in S2, a high-speed forging machine is used to forge the homogenized ingot into a billet, wherein the forging ratio per heat of the high-speed forging machine is not less than 2.6, and the total forging ratio of the forged billet is greater than 10.

[0009] In some implementations, in S2, the forging process includes multiple upsetting and drawing operations.

[0010] In some implementations, in S3, the total deformation of the continuously rolled product is ≥90%.

[0011] In some embodiments, in S3, the final rolling temperature of the continuously rolled product is 950~990°C.

[0012] In another aspect, the present invention also provides a small-diameter GH4169 alloy bar, the diameter of which is Φ20~Φ45mm, the grain size of which is 10~11 in the axial and radial directions, and there are no banded carbides.

[0013] In some embodiments, the room temperature tensile properties of small-diameter GH4169 alloy bars include: tensile strength R m ≥1400MPa, yield strength R p0.2 ≥1200MPa, elongation A≥18%.

[0014] In some embodiments, the high-temperature tensile properties of GH4169 alloy small-diameter bars at 650°C include: tensile strength R m ≥1150MPa, yield strength R p0.2 ≥1000MPa, elongation A≥15%.

[0015] In some embodiments, the combined creep rupture properties of GH4169 alloy small-diameter bars at 650℃ / 690MPa include: the sample breaks at a smooth point, the fracture time t≥80h, and the elongation A≥10%.

[0016] The present invention has at least the following beneficial technical effects: (1) Advanced technology: The continuous rolling mill replaces the traditional Lauter rolling mill or two-roll reversible rolling mill, realizing large-scale, high-efficiency and high-stability production, significantly improving batch consistency and production efficiency.

[0017] (2) Uniform structure: The composition segregation is reduced by two-stage homogenization treatment. Combined with the large deformation forging of the fast forging machine and the large deformation rolling of the continuous rolling mill, the grain size of the bar in the axial and radial directions reaches level 10 to 11, the carbides are uniformly and finely distributed, and there are no banded carbides.

[0018] (3) Excellent performance: The small-sized bars with diameters of Φ20~Φ45mm have a room temperature tensile strength ≥1400MPa, a yield strength ≥1200MPa, an elongation ≥18%, and high temperature tensile and creep properties at 650℃, which meet the stringent requirements for use. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram illustrating an embodiment of the method for preparing small-diameter GH4169 alloy bars provided by the present invention; Figure 2 The diagram shows the carbide and grain size of various parts of the bar in Example 1 of this invention; Figure 3 The diagram shows the carbide and grain size of various parts of the bar in Example 2 of this invention; Figure 4 The diagram shows the carbide and grain size of various parts of the bar in Example 3 of this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0022] Unless otherwise defined, all technical and scientific terms used herein are consistent with the technical field of this invention. The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0023] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] like Figure 1 The figure shows a method for preparing small-diameter GH4169 alloy bars according to the present invention, comprising the following steps: S1 is used to perform a two-stage homogenization treatment on GH4169 alloy ingots; S2 is used to forge the homogenized ingot to obtain rolled billets; S3 feeds the rolled billet into the continuous rolling mill for rolling to produce GH4169 alloy small-diameter bars with diameters of Φ20~Φ45mm.

[0025] Furthermore, GH4169 alloy, containing multiple alloying elements such as Nb, Mo, and Ti, is prone to severe dendritic segregation and uneven element distribution during ingot solidification. In particular, Nb segregation leads to the formation of harmful Laves phases during subsequent hot working, affecting the material's hot working performance and final service performance. Therefore, this invention employs a two-stage homogenization process. Specifically, in S1, the two-stage homogenization process includes: The first heat preservation stage involves maintaining the temperature at 1130~1170℃ for 24~48 hours. The second heat preservation stage involves maintaining the temperature at 1180~1200℃ for 24~48 hours.

[0026] The first heat preservation stage (1130~1170℃ for 24~48h) aims to ensure that the brittle Laves phase formed during solidification is fully integrated into the matrix, and to prevent the Laves phase from melting and forming voids. The second heat preservation stage (1180~1200℃ for 24~48h) aims to further accelerate the diffusion and migration of solute atoms, so that elements such as Nb, Mo, and Ti are more evenly distributed in the matrix, and to reduce segregation.

[0027] Furthermore, in S2, the homogenized ingot still needs to undergo large deformation hot working to break up the as-cast structure and refine the grains. This invention uses a high-speed forging mill for forging the initial billet, with a forging ratio per heat not less than 2.6 and a total forging ratio controlled to be greater than 10. The high-speed forging mill features fast forging speed, large reduction, and precise temperature control, making it suitable for forging the initial billet of high-temperature alloys.

[0028] Furthermore, in S2, the forging process includes multiple upsetting and drawing operations. The ingot is repeatedly upset and drawn through a high-speed forging machine, which can fully break down the as-cast structure and refine and homogenize the grains and carbides.

[0029] Furthermore, in S3, a continuous rolling mill is used to roll the finished product, ensuring that the total rolling deformation is greater than 90%. The continuous rolling mill has a high degree of automation, fast rolling speed, and stable rolling process control, enabling efficient and stable control of product quality. Furthermore, in S3, the final rolling temperature of the continuously rolled product is 950~990℃. Controlling the total rolling deformation to ≥90% ensures that the billet undergoes sufficient dynamic and static recrystallization within the recrystallization temperature range, further refining the grains. Controlling the final rolling temperature to 950~990℃ avoids both excessively high temperatures leading to grain coarsening and excessively low temperatures causing work hardening and uneven microstructure.

[0030] This invention abandons the traditional Lauter-type rolling mill or two-roll reversible rolling mill, which suffer from low production efficiency and poor batch stability, and innovatively adopts a continuous rolling mill for final forming rolling. The continuous rolling mill consists of multiple stands arranged in a continuous manner, and the billet is continuously deformed between the stands without the need for reciprocating rolling, thus greatly improving production efficiency.

[0031] The ingots produced by the method of the present invention undergo high-temperature and long-term homogenization treatment, which can promote element diffusion and migration and improve the uniformity of the composition inside the ingots. The ingots are forged by large deformation forging on a fast forging machine, which can significantly homogenize and refine carbides and grains. The continuous rolling mill is used to roll the finished products, which can further ensure uniform deformation, thereby obtaining uniform and fine grains and carbides.

[0032] In another aspect, the present invention provides a small-diameter GH4169 alloy bar, which is prepared using the method described above. The GH4169 alloy small-diameter bar has a diameter of Φ20~Φ45mm, and the grain size of each part of the axial and radial directions of the bar is grade 10~11. The carbides are uniformly and finely distributed, and there are no banded carbides.

[0033] Furthermore, the room temperature tensile properties of GH4169 alloy small-diameter bars include: tensile strength R m ≥1400MPa, yield strength R p0.2 ≥1200MPa, elongation A≥18%.

[0034] Furthermore, the high-temperature tensile properties of GH4169 alloy small-diameter bars at 650℃ include: tensile strength R m ≥1150MPa, yield strength R p0.2 ≥1000MPa, elongation A≥15%.

[0035] Furthermore, the combined creep rupture properties of GH4169 alloy small-diameter bars at 650℃ / 690MPa include: the sample breaks at a smooth point, the fracture time t≥80h, and the elongation A≥10%.

[0036] To better illustrate the present invention, the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the scope described in the embodiments.

[0037] Example 1 Homogenization treatment of ingots. Φ406mm ingots are homogenized in a chamber heating furnace, first held at 1140℃ for 26 hours, and then held at 1180℃ for 32 hours.

[0038] Forging and billet preparation. The Φ406mm ingot is forged and billet prepared using a 4500-ton high-speed forging machine. The billet preparation is completed by two consecutive upsetting and drawing processes to obtain a 150mm square rolling billet. The total forging ratio is 13.

[0039] Rolled into finished products. The billet is rolled into Φ22.3mm bars using a continuous rolling mill, with a total rolling deformation of 98% and a final rolling temperature of 985℃.

[0040] The carbide composition and grain size of different parts of the rod prepared in this example are shown in the appendix. Figure 2 .

[0041] Example 2 Homogenization treatment of ingots. Φ508mm ingots are homogenized in a chamber heating furnace, first held at 1150℃ for 42 hours, and then held at 1190℃ for 48 hours.

[0042] Forging and billet preparation. The Φ508mm ingot is forged and billet prepared using a 4500-ton high-speed forging machine. The billet preparation is completed by direct drawing, resulting in a 130mm square rolling billet. The total forging ratio is 11.5.

[0043] Rolled into finished products. The billet is rolled into Φ35.2mm bars using a continuous rolling mill, with a total rolling deformation of 94% and a final rolling temperature of 972℃.

[0044] The carbide composition and grain size of different parts of the rod prepared in this example are shown in the appendix. Figure 3 .

[0045] Example 3 Homogenization treatment of ingots. Φ406mm ingots are homogenized in a chamber heating furnace, first held at 1160℃ for 36 hours, and then held at 1200℃ for 32 hours.

[0046] Forging and billet preparation. The Φ406mm ingot was forged and billet prepared using a 3150-ton high-speed forging machine. The billet preparation was completed by two consecutive upsetting and drawing processes, resulting in a 145mm square rolling billet. The total forging ratio was 14.

[0047] Rolled into finished products. The billet is rolled into Φ42.3mm bars using a continuous rolling mill, with a total rolling deformation of 93% and a final rolling temperature of 965℃.

[0048] The carbide composition and grain size of different parts of the rod prepared in this example are shown in the appendix. Figure 4 .

[0049] Performance testing: Longitudinal specimens were prepared from the bars used in the examples, and after heat treatment, tensile and creep tests were performed; specimen preparation was carried out in accordance with GB / T2975. The testing was conducted according to the 1998 standard "Sampling Location and Specimen Preparation for Mechanical Property Testing of Steel and Steel Products"; tensile testing was conducted in accordance with GB / T228. Tested according to the 2015 standard "Tensive Testing of Metallic Materials"; high-temperature creep testing was conducted according to the GB / T2039-2024 standard "Uniaxial Tensile Creep Testing of Metallic Materials". The test results are as follows:

[0050] As can be seen from the above embodiments, the method for preparing small-diameter GH4169 alloy bars provided by the present invention has the following significant advantages: (1) The process is stable and controllable, and the batch consistency is good. Examples 1 to 3 used ingots of different specifications (Φ406mm, Φ508mm) and different combinations of process parameters (homogenization temperature and time, forging ratio, final rolling temperature, etc.), and successfully prepared bars with uniform structure and excellent performance of Φ20~Φ45mm. This shows that the method of the present invention has a wide process window, strong adaptability, and is feasible for large-scale stable production.

[0051] (2) Excellent tissue uniformity. (See attached image) Figures 2-4 As shown, the bars obtained in each embodiment exhibit a grain size of 10-11 at the head, middle, and tail sections, as well as at the center, 1 / 2R, and edge radial positions. The carbides are uniformly and finely distributed, without banded carbides. The method of this invention effectively eliminates ingot segregation, fully breaks down the as-cast structure, and achieves homogeneous control of the microstructure.

[0052] (3) Excellent mechanical properties. The mechanical property test results for each embodiment after standard heat treatment are as follows: Room temperature tensile strength: tensile strength reaches 1440~1460MPa, yield strength reaches 1210~1240MPa, elongation reaches 18.5%~21%; High-temperature tensile testing at 650℃: tensile strength reaches 1184~1197MPa, yield strength reaches 1017~1053MPa, and elongation reaches 18.5%~22.5%; Creep test at 650℃ / 690MPa: fracture time reached 89.1~92.7h, elongation reached 11%~19%, and all samples broke at smooth points.

[0053] The above performance indicators fully demonstrate that the GH4169 alloy small-diameter bars prepared by the method of this invention have excellent comprehensive mechanical properties and can meet the application requirements of high-end fields such as aviation and aerospace.

[0054] In summary, the S1 two-stage homogenization process addresses the issue of compositional segregation; the S2 high-speed forging mill with large deformation forging solves the problem of coarse as-cast microstructure; and the S3 continuous rolling mill with efficient and stable rolling solves the problems of production efficiency and microstructure uniformity. These three interconnected and synergistic processes ultimately achieve the large-scale, high-efficiency, and stable production of GH4169 alloy bars with diameters of Φ20~Φ45mm. The products exhibit uniform grain size of 10~11, fine and uniform carbides, and excellent mechanical properties, significantly superior to existing technologies. This invention successfully solves the problems of low production efficiency, poor batch stability, and limited specification range in existing technologies, enabling the large-scale, high-efficiency, and stable production of GH4169 alloy bars with diameters of Φ20~Φ45mm. The products also exhibit uniform microstructure and excellent performance, demonstrating significant industrial application value and promising prospects for wider application.

[0055] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0056] It should be understood that, as used herein, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" means any and all possible combinations of one or more of the associated listed items.

[0057] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0058] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for preparing small-diameter bars of GH4169 alloy, characterized in that, include: S1 is used to perform a two-stage homogenization treatment on GH4169 alloy ingots; S2 is used to forge the homogenized ingot to obtain a rolled billet; S3 feeds the rolled billet into a continuous rolling mill for rolling to obtain GH4169 alloy small-diameter bars with a diameter of Φ20~Φ45mm.

2. The method for preparing small-diameter GH4169 alloy bars according to claim 1, characterized in that, In S1, the two-stage homogenization process includes: The first heat preservation stage involves maintaining the temperature at 1130~1170℃ for 24~48 hours. The second heat preservation stage involves maintaining the temperature at 1180~1200℃ for 24~48 hours.

3. The method for preparing small-diameter GH4169 alloy bars according to claim 1, characterized in that, In S2, a high-speed forging machine is used to forge the homogenized ingot into billets. The forging ratio per pass of the high-speed forging machine is not less than 2.6, and the total forging ratio of the forged billets is greater than 10.

4. The method for preparing small-diameter GH4169 alloy bars according to claim 1, characterized in that, In S2, the forging process includes multiple upsetting and drawing operations.

5. The method for preparing small-diameter GH4169 alloy bars according to claim 1, characterized in that, In S3, the total deformation of the continuously rolled product is ≥90%.

6. The method for preparing small-diameter bars of GH4169 alloy according to claim 1, characterized in that, In S3, the final rolling temperature of the continuously rolled product is 950~990℃.

7. A small-diameter bar of GH4169 alloy, prepared by the method described in any one of claims 1-6, characterized in that, The GH4169 alloy small-diameter bars have a grain size of 10-11 in both the axial and radial directions, and are free of banded carbides.

8. The GH4169 alloy small-diameter bar according to claim 7, characterized in that, The room temperature tensile properties of the GH4169 alloy small-diameter bars include: tensile strength R m ≥1400MPa, yield strength R p0.2 ≥1200MPa, elongation A≥18%.

9. The GH4169 alloy small-diameter bar according to claim 7, characterized in that, The 650℃ high-temperature tensile properties of the GH4169 alloy small-diameter bars include: tensile strength R m ≥1150MPa, yield strength R p0.2 ≥1000MPa, elongation A≥15%.

10. The GH4169 alloy small-diameter bar according to claim 7, characterized in that, The combined creep rupture properties of the GH4169 alloy small-diameter bars at 650℃ / 690MPa include: the sample breaks at a smooth point, the fracture time t≥80h, and the elongation A≥10%.

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