Preparation process of high-manganese aluminum bronze flange forge piece for marine environment

Abstract

The invention provides a preparation process of a high-manganese aluminum bronze flange forging for a marine environment. The preparation process comprises the following steps: S1, taking a thin-wall cylindrical high-manganese aluminum bronze casting as a to-be-forged part; s2, the to-be-forged part is placed in a forging die, the outer side wall of a cylinder of the to-be-forged part abuts against the die, and a first-stage forging procedure is carried out till the inner diameter of the to-be-forged part is forged to a first target size; and S3, the to-be-forged part is placed in a forging die, the inner side wall of a cylinder of the to-be-forged part abuts against the die, a second-stage forging procedure is carried out till the outer diameter of the to-be-forged part is forged to a second target size, and the high-manganese aluminum bronze flange forging finished product is manufactured. According to the method, the thin-wall cylindrical casting is subjected to graded forging, so that the density of the forging and the uniformity of a metallographic structure are improved, the mechanical property and the safety performance of a flange product are ensured, and meanwhile, the forging efficiency is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of copper alloys, and particularly to a preparation process for high-manganese aluminum bronze flange forgings used in marine environments. Specifically, it is for the preparation of high-density high-manganese aluminum bronze flange forgings with an outer diameter of more than 1 meter and a microshrinkage index that can reach grade 0. Background Art

[0002] High-manganese aluminum bronze alloys have the characteristics of good corrosion resistance, low density, high strength, excellent resistance to seawater erosion and cavitation corrosion, and are widely used in the field of marine engineering, such as components like seawater pumps, valves, pipe flanges, and propellers. For the high-manganese aluminum bronze alloy pipe flanges in the marine engineering field, casting processes are usually used for forming. Since the castings are flat rings with a relatively large diameter, it is difficult to compensate for shrinkage during the later stage of solidification, and the castings are prone to defects such as microshrinkage and shrinkage cavities, resulting in problems such as unstable finished product quality, low finished product rate, and unqualified comprehensive performance, seriously affecting the safe application and promotion of products. For the metallographic structure of cast high-manganese aluminum bronze flanges as Figure 1 , 2 shown, according to GB / T 14999.7-2010 "Methods for Determining Grain Size, Primary Dendrite Arm Spacing and Microshrinkage of Superalloy Castings", the microshrinkage ratings are all between grade 2 and grade 3.

[0003] In order to solve the problems of microshrinkage, shrinkage cavities, etc. existing in current cast flanges, some existing technologies are also trying to obtain high-density high-manganese aluminum bronze flanges through forging methods to improve product quality and achieve the safe application of products.

[0004] In the existing technologies for forging high-manganese aluminum bronze, it is often the forging of "solid ingots". For example: In the paper "Analysis of the Reasons for Forging Cracking of ZCuAl8Mn14Fe3Ni2" published by the applicant in 2023 ([1] Yang Huihui, Fan Fangxiong, Liu Xin. Analysis of the Reasons for Forging Cracking of ZCuAl8Mn14Fe3Ni2 [J]. Development and Application of Materials, 2023, 38(03): 59-62+68. DOI: 10.19515 / j.cnki.1003-1545.2023.03.010.), a large-sized flat ring with φ920mm (outer diameter) × φ440mm (inner diameter) × 110mm (height) was finally prepared by multi-directional repeated upsetting and drawing → punching → frame expanding → rounding of a solid ingot.

[0005] However, with further research by the applicant, due to the large size of the forgings, it is necessary to repeatedly reheat in the furnace and perform multi-pass forging to form, resulting in low forging efficiency and high costs. Moreover, to avoid forging folds, limited by the height-diameter ratio, the cross-sectional size of the solid ingot required for large-diameter flange forgings is also large, leading to easy occurrence of micro-porosity and shrinkage cavity problems in the ingot. After forging, there are still certain degrees of micro-porosity and shrinkage cavity problems, thus affecting the mechanical properties of the forgings and being unfavorable for mass production. Summary of the Invention

[0006] In view of this, the present invention aims to provide a preparation process for high-manganese aluminum bronze flange forgings used in marine environments to solve the problems of micro-porosity and shrinkage cavity in high-manganese aluminum bronze flanges in the prior art, as well as low forging efficiency and unqualified mechanical properties of solid ingots, so as to greatly improve the density of the flanges, improve the forming efficiency, reduce the manufacturing cost, and ensure the safe application of the flanges in the seawater environment.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] A preparation process for high-manganese aluminum bronze flange forgings used in marine environments includes: S1. Taking a thin-walled cylindrical high-manganese aluminum bronze casting as the workpiece to be forged; S2. Placing the workpiece to be forged into a forging die, with the outer sidewall of the cylinder of the workpiece to be forged in contact with the die, and performing the first-stage forging process until the inner diameter of the workpiece to be forged is forged to the first target size; S3. Placing the workpiece to be forged into a forging die, with the inner sidewall of the cylinder of the workpiece to be forged in contact with the die, and performing the second-stage forging process until the outer diameter of the workpiece to be forged is forged to the second target size, thus obtaining the finished high-manganese aluminum bronze flange forging.

[0009] Further, the height / wall thickness of the high-manganese aluminum bronze casting ≤ 3.

[0010] Further, the inner diameter of the high-manganese aluminum bronze casting > 1.2 times the finished inner diameter size.

[0011] Further, the weight of the high-manganese aluminum bronze casting > the finished weight, and the weight of the high-manganese aluminum bronze casting ≤ the finished weight + the weight of the 2-mm machining allowance on the surface.

[0012] Further, in step S2, the finished inner diameter size - 4 mm ≤ the first target size < the finished inner diameter size.

[0013] Further, in step S3, the finished outer diameter size < the second target size ≤ the finished outer diameter size + 4 mm.

[0014] Compared with the prior art, the preparation process for high-manganese aluminum bronze flange forgings used in marine environments of the present invention has the following advantages:

[0015] A preparation process for a high-manganese aluminum bronze flange forging used in a marine environment changes the traditional idea of using a "solid ingot" as the forging raw material, but instead uses a thin-walled cylindrical casting for hierarchical forging. It has the advantages of a relatively thin wall thickness, a short feeding path during the solidification process, less porosity and shrinkage cavities inside the casting, and better density, which is more conducive to improving the density of subsequent forgings.

[0016] At the same time, through the hierarchical forging of the thin-walled cylindrical casting in this application, on the one hand, the forging first deforms in the inner diameter, ensuring that the material in the area near the inner circle is fully deformed, avoiding the problem of coarse grains in the area near the inner circle, and being conducive to ensuring the uniformity of the metallographic structure in the whole product after forging. On the other hand, combining the outward expansion trend of the forging to be processed with the thin-walled cylindrical configuration, this application can more easily forge the forging to be processed to the target requirements with fewer pressing forging times, which helps to improve the forging efficiency. On the third hand, it solves the defects such as micro-porosity and shrinkage cavities existing in current cast flanges, and correspondingly overcomes the problems of unstable quality of flange finished products, low finished product rate, poor mechanical properties and safety performance caused by these defects from the root cause.

[0017] In addition, compared with forging of solid ingots, this application uses a thin-walled cylindrical casting with an open core, which does not require additional punching during forging. This not only helps to reduce the processing difficulty, but also improves the material utilization rate, is more economical, and is conducive to batch production. Brief Description of the Drawings

[0018] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 is a metallographic diagram of a high-manganese aluminum bronze flange obtained by a conventional casting process in the prior art;

[0020] Figure 2 is another metallographic diagram of a high-manganese aluminum bronze flange obtained by a conventional casting process in the prior art;

[0021] Figure 3 is a physical diagram of a casting formed by centrifugal casting in an embodiment of the present invention;

[0022] Figure 4 is for an embodiment of the present invention Figure 3 physical diagram of a forging after forging the casting;

[0023] Figure 5 is a metallographic diagram of the forging in an embodiment of the present invention. Detailed Embodiments

[0024] The inventive concepts of the present disclosure will hereinafter be described using the terms that are typically used by those skilled in the art to convey the substance of their work to other skilled artisans in the art. However, these inventive concepts may be embodied in many different forms and should not be construed as limited to the embodiments described herein.

[0025] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The "finished product weight, size", etc. involved in this application can all be regarded as target parameters in the forging process.

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0027] In order to solve the problems of micro porosity and shrinkage cavity existing in high manganese aluminum bronze flanges in the prior art, as well as the problems of low forging efficiency and unqualified mechanical properties of solid ingots, this embodiment proposes a preparation process for high manganese aluminum bronze flange forgings for marine environments, including:

[0028] S1. Take a thin-walled cylindrical high manganese aluminum bronze casting as the workpiece to be forged;

[0029] Among them, the high manganese aluminum bronze casting is prepared by a conventional centrifugal casting process, and can be directly adopted by the existing technology or ordered from the market. The present application will not elaborate on centrifugal casting.

[0030] Similarly, the material of the casting is high manganese aluminum bronze, and its chemical composition (weight percentage) is: Al: 7.0 - 12.0%, Mn: 10.0 - 18.0%, Fe: 2.0 - 4.0%, Ni: 1.0 - 4.0%, and the rest are Cu and common impurity elements, which belong to existing metal materials. The present application will not elaborate on them.

[0031] However, for the castings used as workpieces to be forged, before obtaining them, the present application needs to clearly define the following casting product conditions, specifically:

[0032] 1. The weight of the casting > the weight of the finished product, and the weight of the casting ≤ the weight of the finished product + the weight of the machining allowance of 2 mm on the surface. Thus, on the one hand, the weight of the finished product is ensured, and on the other hand, allowance is provided for further machining of the forging after forging. Among them, surface machining is a process of machining all the outer surfaces (including the inner wall of the cylinder) of the forging after forging.

[0033] 2. The height / wall thickness of the casting ≤ 3, ensuring that the thin-walled cylindrical casting has a sufficiently thin wall thickness. On the one hand, it is easy to forge and can be formed with fewer pressing forging times, which helps improve the forging efficiency. On the other hand, its wall thickness is small. Even if there are problems such as micro-porosity and shrinkage cavities inside the casting, they can be relatively easily solved through forging, which helps improve the density of the finished product after forging and ensures the safe application of the flange in the seawater environment.

[0034] 3. The inner diameter of the casting > 1.2 times the finished inner diameter size. Since during the forging process, the forging piece often mainly expands outward, in order to avoid insufficient deformation of the thin-walled cylindrical casting at the inner circle, by limiting the inner diameter of the casting, it is ensured that during the forging process, the inner circle of the casting has sufficient deformation inward (i.e., towards its axis direction), ensuring that the material in the near-inner circle area is fully deformed and avoiding coarse grains in the near-inner circle area, which is beneficial to ensuring the uniformity of the metallographic structure of the entire product after forging and ensuring the uniformity of the flange itself in terms of mechanical properties.

[0035] S2. Place the forging piece to be forged into the forging die, with the outer side wall of the cylinder of the forging piece to be forged in contact with the die, and perform the first-stage forging process until the inner diameter of the forging piece to be forged is forged to the first target size.

[0036] S3. Place the forging piece to be forged into the forging die, with the inner side wall of the cylinder of the forging piece to be forged in contact with the die, and perform the second-stage forging process until the outer diameter of the forging piece to be forged is forged to the second target size, obtaining the finished product of the high manganese aluminum bronze flange forging.

[0037] Among them, the finished inner diameter size - 4 mm (which can be regarded as the maximum machining allowance) ≤ the first target size < the finished inner diameter size; the finished outer diameter size < the second target size ≤ the finished outer diameter size + 4 mm (which can be regarded as the maximum machining allowance).

[0038] Specifically, during the first-stage forging process, the temperature of the forging piece to be forged is controlled at 550 - 850 °C; during the second-stage forging process, the temperature of the forging piece to be forged is controlled at 550 - 850 °C.

[0039] For forging equipment and forging dies, existing technologies can be directly adopted and will not be elaborated.

[0040] Compared with the existing technology, this application changes the traditional idea of using "solid ingots" as forging raw materials and instead uses thin-walled cylindrical castings for graded forging. Among them, the advantages of "thin-walled cylindrical castings" compared to "original centrifugal flat castings" and "solid ingots" are: thinner wall thickness, shorter feeding path during solidification, fewer internal porosities and shrinkage cavities in the casting, better density, and more conducive to improving the density of subsequent forgings.

[0041] Meanwhile, in this application, by performing graded forging on the thin-walled cylindrical casting, on the one hand, the forging first undergoes deformation in the inner diameter, ensuring that the material in the area near the inner circle is fully deformed, avoiding the problem of coarse grains in the area near the inner circle, and being conducive to ensuring the uniformity of the metallographic structure of the entire product after forging. On the other hand, combining the outward expansion trend of the workpiece to be forged with the thin-walled cylindrical configuration, this application can relatively easily forge the workpiece to be forged to the target requirements with fewer pressing forging times, which helps improve the forging efficiency. On the third hand, it solves the defects such as micro-porosity and shrinkage in the current cast flange, and correspondingly overcomes the problems of unstable quality, low yield, poor mechanical properties and safety performance of the flange finished product caused by these defects from the root cause.

[0042] In addition, compared with the forging of solid ingots, this application uses a thin-walled cylindrical casting with an open core, which does not require additional punching during forging. This not only helps reduce the processing difficulty, but also improves the material utilization rate, is more economical, and is conducive to mass production.

[0043] Specifically, in step S2, the outer sidewall of the cylindrical body of the workpiece to be forged is abutted by a mold to restrict the outer diameter of the workpiece to be forged. During the first-stage forging process, the outward expansion trend of the workpiece to be forged is suppressed as much as possible, so that the workpiece to be forged first undergoes deformation in the inner diameter to ensure that the material in the area near the inner circle is fully deformed, so as to avoid the problem of coarse grains in the area near the inner circle.

[0044] Thus, after ensuring that the deformation of the workpiece to be forged in the inner diameter meets the requirements in step S2 first, step S3 is continued. The inner sidewall of the cylindrical body of the workpiece to be forged is abutted by a mold to restrict the inner diameter of the workpiece to be forged. During the second-stage forging process, the workpiece to be forged mainly undergoes deformation in the outer diameter. Due to the existence of the outward expansion trend of the workpiece to be forged and combined with the thin-walled cylindrical configuration, the outer diameter of the workpiece to be forged can be relatively easily forged to the target requirements with fewer pressing forging times, which helps improve the forging efficiency.

[0045] Example 1

[0046] Taking the manufacture of a high-manganese aluminum bronze flange forging with a target size of φ1066mm×φ524mm×85mm as an example.

[0047] A commercially available centrifugally cast "thin-walled cylindrical" high-manganese aluminum bronze casting is used as the workpiece to be forged (its size is φ910mm×φ700mm×230mm).

[0048] A 2500T press is used to perform the first-stage forging process and the second-stage forging process on the workpiece to be forged in sequence to obtain the high-manganese aluminum bronze flange forging.

[0049] Among them, in the first-stage forging process, the outer sidewall of the cylinder of the workpiece to be forged is in full contact with the die until the inner diameter of the workpiece to be forged is forged to 520 mm; in the second-stage forging process, the inner sidewall of the cylinder of the workpiece to be forged is in full contact with the die until the outer diameter of the workpiece to be forged is forged to 1070 mm. Correspondingly, the temperature of the workpiece to be forged in the first-stage forging process and the second-stage forging process remains the same as described above and will not be elaborated.

[0050] For the high manganese aluminum bronze flange forging, according to GB / T 14999.7-2010 "Methods for Determining Grain Size, Primary Dendrite Arm Spacing and Microshrinkage of Superalloy Castings", the microshrinkage rating is 0, and the specific metallographic diagram is as attached Figure 5 shown.

[0051] The mechanical properties of the high manganese aluminum bronze flange forging are detected in accordance with GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature" and GB / T 231.1-2018 "Metallic materials - Brinell hardness testing - Part 1: Test method", and the specific test results are shown in Table 1.

[0052] Table 1 Mechanical properties of high manganese aluminum bronze flange forgings

[0053]

[0054] It can be seen from this that:

[0055] The high manganese aluminum bronze flange forging prepared by this application has significantly denser and more uniform metallographic structure compared with the conventional cast flange, which can effectively solve the defects such as microshrinkage and shrinkage cavity existing in the current cast flange, and correspondingly overcome the problems of unstable quality, low yield rate, poor mechanical properties and safety performance of the flange finished product caused by these defects from the root. Correspondingly, this application can effectively guarantee the mechanical properties of the high manganese aluminum bronze flange forging and improve the reliability and safety of the final flange application.

[0056] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation process for a high manganese aluminum bronze flange forging used in a marine environment, characterized in that, The preparation process includes: S1. Take a thin-walled cylindrical high manganese aluminum bronze casting as the forging workpiece to be processed; S2. Place the forging workpiece to be processed into a forging die, with the outer side wall of the cylinder of the forging workpiece to be processed in contact with the die, and perform the first-stage forging process until the inner diameter of the forging workpiece to be processed is forged to the first target size; S3. Place the forging workpiece to be processed into a forging die, with the inner side wall of the cylinder of the forging workpiece to be processed in contact with the die, and perform the second-stage forging process until the outer diameter of the forging workpiece to be processed is forged to the second target size, thus obtaining the finished high manganese aluminum bronze flange forging.

2. The preparation process of a high manganese aluminum bronze flange forging for marine environment according to claim 1, characterized in that, The height / wall thickness of the high manganese aluminum bronze casting ≤ 3.

3. The preparation process of a high-manganese aluminum bronze flange forging for marine environment according to claim 1, characterized in that, The inner diameter of the high manganese aluminum bronze casting > 1.2 times the finished inner diameter size.

4. The preparation process of a high manganese aluminum bronze flange forging for marine environment according to claim 1, characterized in that, The weight of the high manganese aluminum bronze casting > the finished product weight, and the weight of the high manganese aluminum bronze casting ≤ the finished product weight + the weight of the 2 mm machining allowance on the surface.

5. The preparation process of a high manganese aluminum bronze flange forging for marine environment according to claim 1, characterized in that, In step S2, the finished inner diameter size - 4 mm ≤ the first target size < the finished inner diameter size.

6. The preparation process of a high manganese aluminum bronze flange forging for marine environment according to claim 1, characterized in that, In step S3, the finished outer diameter size < the second target size ≤ the finished outer diameter size + 4 mm.

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