T-shaped GH4169 die forging and production process and die thereof

Abstract

The application provides a T-shaped GH4169 die forging and a production process and a die thereof, and solves the problem of how to improve the material utilization rate of the T-shaped GH4169 part, refine the grain structure of the forging and improve the uniformity of the structure in the current field. Through reasonable design of the die structure and reasonable formulation of the forging and heat treatment process, the material utilization rate is greatly improved, and the material consumption is reduced. The material utilization rate of the T-shaped part is increased from 14.3% to 24.3%. Moreover, the internal structure of the forging can be fully refined and uniform, the grain size of the die forging reaches 9 levels, the overall uniformity of the grain is greatly improved, and the mechanical properties of the forging are better than the standard requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-temperature alloy forging, in particular to a T-shaped GH4169 die forging and its production process and die. BACKGROUND

[0002] GH4169 alloy is a high-performance nickel-based superalloy widely used in aerospace, nuclear energy, petroleum and chemical industries. Its main chemical components include nickel (Ni), chromium (Cr), iron (Fe), molybdenum (Mo), niobium (Nb), titanium (Ti), aluminum (Al) and other elements, among which the content of nickel is about 50-55%, the content of chromium is about 17-21%, and the content of niobium is about 4.75-5.5%. GH4169 alloy has excellent comprehensive performance, including high strength, good fatigue resistance, radiation resistance, oxidation resistance and corrosion resistance. In the temperature range of-253℃ to 650℃, the alloy shows excellent high-temperature strength and plasticity, especially the yield strength below 650℃ is in the forefront among deformed superalloys. From the microstructure, GH4169 alloy is mainly composed of face-centered cubic γ matrix phase, body-centered tetragonal γ" phase (Ni3Nb) and face-centered cubic γ' phase (Ni3AlTiNb). These precipitates are precipitated by aging treatment, which significantly improves the strength and creep resistance of the alloy.

[0003] GH4169 alloy also has good processing and welding performance, and is suitable for manufacturing complex-shaped parts, such as turbine discs, blades, shafts, fasteners of aircraft engines, etc. Therefore, GH4169 alloy is not only used for key components of aircraft engines, but also widely used in nuclear power industry, petroleum and chemical equipment. Its stability and reliability in extreme environments make it an indispensable material in these fields. With the development of technology, the application prospect of GH4169 alloy will be further expanded, especially in emerging technologies such as additive manufacturing.

[0004] T-shaped GH4169 forging is a new type of high-temperature alloy forging with special geometry in the art, which requires special forging process to ensure the mechanical properties and uniformity of the material. Therefore, the skilled person in the art needs to develop a production process and die that can not only improve the material utilization rate of T-shaped GH4169 parts, but also refine the grain structure of the forging and improve the uniformity of the structure. SUMMARY

[0005] To solve the above problems, the present application proposes a T-shaped GH4169 die forging and its production process and die, which can better reduce material consumption, improve part material utilization, refine the internal structure of the forging, solve the problem of "coarse grain", improve the deformation uniformity of the forging, and solve the problem of "mixed grain".

[0006] In order to achieve the above object, the present application provides the following technical solutions:

[0007] The present application optimizes a T-shaped GH4169 die forging, which is symmetrical along the central axis and sequentially comprises a cylindrical section, a transition section and a square platform section from the narrow end to the wide end along the central axis; the square platform section has an irregular cuboid shape with rounded corners and arc protrusions on the two long sides; the center of the top of the square platform section has a spherical pit; the transition section is a reversed trapezoid, which is the part of the T-shaped die forging that transitions from the cylindrical section to the square platform section; the length of the cylindrical section along the central axis is L1, the length of the transition section along the central axis is L2, and the length of the square platform section along the central axis is L3, and L1>L3>L2.

[0008] Further, the present application provides a forming die for T-shaped GH4169 die forging, which comprises a male die 1, a female die 3 and a ejector rod 4; the forming die is used for processing the T-shaped GH4169 die forging.

[0009] The inner shape of the female die 3 of the forming die matches the outer shape of the T-shaped die forging; the lower end of the male die 1 is provided with an arc-shaped protrusion that matches the spherical pit at the center of the top of the square platform section of the T-shaped die forging; the ejector rod 4 is located below the die and is used for supporting and fixing the die and ejecting the formed forging from the die so that the formed forging is separated from the die cavity.

[0010] Still further, the present application also provides a production process for T-shaped die forging, which comprises the following steps:

[0011] Step (1) blanking: sawing GH4169 bar stock and chamfering both ends of the raw material;

[0012] Step (2) spraying: uniformly spraying protective lubricant on the surface of the raw material after heating and keeping warm;

[0013] Step (3) heating of the blank: heating and keeping warm the blank in an electric furnace;

[0014] Step (4) preheating of the die: fully preheating the die;

[0015] Step (5) die forging forming: installing the fully preheated die on a forming equipment and transferring the heated blank to the die cavity for die forging forming;

[0016] Step (6) removing defects: removing surface cracks, folding and other defects of the die forging;

[0017] Step (7) solid solution treatment: solid solution treatment of the die forging;

[0018] Step (8) machining of the surface: turning the cylindrical section of the die forging and milling the square platform section to achieve a roughness of Ra3.2.

[0019] Step (9) detection: according to the GJB1580 standard A class requirements on step 7 after processing die forgings ultrasonic inspection; take room temperature tensile test bar, room temperature impact test bar, high temperature tensile test bar, tissue detection test block for physical and chemical detection.

[0020] Preferably, the heating temperature in step (2) is 150-200 DEG C, the holding time is 60-120 min, and the protective lubricant spraying thickness is 0.2-0.8 mm.

[0021] The blank heating temperature in step (3) is 995-1025 DEG C, and the holding time is 120-240 min.

[0022] The mold preheating temperature in step (4) is 300-450 DEG C.

[0023] The forming equipment in step (5) is a screw press or a die forging hammer, the blank transfer time should be ≤20 s, and the formed die forgings should be placed in air cooling.

[0024] The solution treatment system in step (7) is to heat the die forgings to 950-980 DEG C, hold for 90-120 min, then take out and cool in air.

[0025] The T-shaped forging standard requirements of the application are: room temperature mechanical properties Rm≥1275Mpa, Rp0.2≥1035MPa, A5≥12%, Z≥15%, Aku≥32J, 650 DEG C high temperature mechanical properties Rm≥1000Mpa, Rp0.2≥860MPa, A5≥12%, Z≥15%, and grain size should be ≥4 levels. The T-shaped forging obtained by the die and production process of the application completely meets the requirements, and the related performance parameters are higher than the standard requirements.

[0026] The application has the following beneficial effects:

[0027] (1) Compared with free forging, the production method of the T-shaped die forging of the application can greatly improve the material utilization and reduce material consumption. The T-shaped GH4169 forging of the application, if free forging method is used, the material utilization is 14.3%; and the material utilization can be increased to 24.3% by using the die forging process of the application.

[0028] (2) This invention can refine the internal microstructure of forgings and solve problems such as "coarse grains" and "mixed grains". GH4169 high-temperature alloy has high deformation resistance and poor material fluidity. Free forging can easily cause uneven material deformation, resulting in uneven internal microstructure after heat treatment of the forging, producing microstructural defects such as "coarse grains" and "mixed grains", causing the forging to be scrapped. This invention, through reasonable mold structure design and reasonable forging and heat treatment process, can fully refine and homogenize the internal microstructure of the forging, achieving a grain size of grade 9 in the die forging, and significantly improving the overall uniformity of the grains. The mechanical properties of the forging are better than the standard requirements. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the T-shaped die forging structure of the present invention.

[0030] Figure 2 This is a schematic diagram of the forming mold for the T-shaped forging of the present invention; in the figure: 1. punch, 2. blank before forming, 3. die, 4. ejector pin, 5. T-shaped forging after forming.

[0031] Figure 3 This is the T-shaped forging part formed according to the present invention.

[0032] Figure 4 This invention provides a comparison between the flaw-detected die forging and the free forging.

[0033] Figure 5 Comparison of high-magnification microstructures of the die forging and free forging of the present invention; (a) high-magnification microstructure of the free forging; (b) high-magnification microstructure of the die forging of the present invention. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical methods of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Unless otherwise specified, all related terms used in the present invention are general terms in the art, and the technologies and methods described are general technologies and methods in the art.

[0035] Example 1: T-shaped forging and forming die of the present invention

[0036] like Figure 1 The diagram shows a schematic of the T-shaped forging structure after multiple simulations and optimizations. The T-shaped GH4169 die forging is symmetrical along its central axis and consists of three parts along the central axis: a cylindrical section, a transition section, and a square platform section, from bottom (narrow end) to top (wide end). The diameter of the cylindrical section is... The length of the transition section along the central axis is L2; the length of the square platform section along the central axis is L3, and L1>L3>L2. The square platform section has an irregular cuboid shape, with rounded corners R1 of 10-25 mm; two circular arc protrusions R2 of (original material diameter D + (2-8) mm) / 2 are designed on the two long sides of the square platform section; the draft angle of the square platform section is 0.3-2°; and the size of the spherical pit at the center of the top of the square platform section is SR.

[0037] Specifically, the diameter of the cylindrical section of the T-shaped forging in the present application is The length of the transition section along the central axis is L2=35 mm; the length of the square platform section along the central axis is L3=67 mm, the length of the top surface of the square platform section is H=114 mm, the width of the square platform section is B=84 mm, the rounded corners of the square platform section are R1=20 mm; two circular arc protrusions R2 of 95 mm are designed on the two long sides of the square platform section; the draft angle of the square platform section is 1°; and the size of the spherical pit at the center of the top of the square platform section is SR=63 mm.

[0038] The present application is designed to produce the above-mentioned Figure 1 T-shaped forging, and a forming die is designed, as shown in Figure 2 The forming die of the T-shaped GH4169 die forging is composed of a male die 1, a female die 3 and a ejector pin 4. The shape of the inner side of the female die 3 of the forming die matches the shape of the T-shaped die forging; the lower end of the male die 1 is provided with an arc-shaped protrusion which matches the spherical pit at the center of the top of the square platform section of the T-shaped die forging; the ejector pin 4 in the die is located below the die, and is used to support and fix the die and to eject the formed forging from the die so that the formed forging is separated from the die cavity.

[0039] Embodiment 2, a T-shaped die forging

[0040] The production process steps of the T-shaped die forging are as follows:

[0041] Step (1) blanking: sawing GH4169 bar material with a size of Φ90±1 mm×210-215 mm, and chamfering the two ends of the original material with a chamfer size of 5 mm×5 mm;

[0042] Step (2) spraying: heating the original material to 200°C, keeping warm for 80 min, and uniformly spraying protective lubricant on the surface with a spraying thickness of 0.5 mm;

[0043] Step (3) blank heating: heating to 1000°C in an electric furnace, keeping warm for 200 min;

[0044] Step (4) die preheating: preheating the die to 450°C according to the die in embodiment 1 of the present application;

[0045] Step (5) die forging forming: the mold is fully preheated and installed on a screw press, and the heated blank is transferred to the mold cavity for die forging forming, the blank transfer time is ≤20 s, and the formed die forging is cooled in air; the formed die forging is shown in Figure 3 ;

[0046] Step (6) defect removal: removing surface cracks, folds and other defects of the die forging;

[0047] Step (7) solution treatment: heating the die forging to 980℃, holding for 120 min, then taking out and cooling in air;

[0048] Step (8) surface machining: polishing the cylindrical section of the die forging and milling the square platform part to achieve a roughness of Ra3.2;

[0049] Step (9) detection: according to the A-class requirements of GJB1580 standard, the die forging after step (7) processing is subjected to ultrasonic inspection; one piece is destroyed for each batch, and room temperature tensile test bars, room temperature impact test bars, high temperature tensile test bars and microstructure test blocks are taken for physical and chemical detection.

[0050] Example 3, a T-shaped die forging

[0051] The production process steps of the T-shaped die forging are as follows:

[0052] Step (1) blanking: sawing GH4169 bar stock with a size of Φ90±1mm×210-215mm, and chamfering the two ends of the raw material with a chamfer size of 5mm×5mm;

[0053] Step (2) spraying: heating the raw material to 160℃, holding for 120 min, and uniformly spraying protective lubricant on the surface, with a spraying thickness of 0.5mm;

[0054] Step (3) blank heating: heating in an electric furnace to 1025℃, holding for 120 min;

[0055] Step (4) mold preheating: preheating the mold to 400℃ according to the mold of example 1 of the present application;

[0056] Step (5) die forging forming: the mold is fully preheated and installed on a screw press, and the heated blank is transferred to the mold cavity for die forging forming, the blank transfer time is ≤20 s, and the formed die forging is cooled in air; the formed die forging is shown in Figure 3 ;

[0057] Step (6) defect removal: removing surface cracks, folds and other defects of the die forging;

[0058] Step (7) solution treatment: heat the die forging to 950℃, keep for 120 min, then take out and cool in air;

[0059] Step (8) machining surface: polish the die forging cylindrical section and mill the square platform part to achieve roughness Ra3.2;

[0060] Step (9) detection: according to the A-class requirement of GJB1580 standard, the die forging after step (7) processing is subjected to ultrasonic inspection; one piece is destroyed in each batch, and room temperature tensile test bar, room temperature impact test bar, high temperature tensile test bar and microstructure test block are taken for physical and chemical detection.

[0061] Example 4, performance detection of T-shaped die forging

[0062] (1) Material utilization rate comparison

[0063] Comparative method, free forging process: the square block forging processed by free forging process is machined to obtain T-shaped GH4169 forging. The free forging used is a square block with length, width and height of 222mm, 120mm and 77mm respectively, and the forging delivery state is solution treated. Since the final part is T-shaped, most of the forging material is removed in machining, and the material utilization rate is low, only 14.3%.

[0064] As shown in Figure 4 , the die forging after step (8) processing of the present application and the free forging before improvement in the flaw detection state, by comparison, it is concluded that the part material utilization rate is increased from 14.3% before improvement to 24.3%.

[0065] (2) High magnification structure comparison

[0066] In the free forging process, due to the large deformation resistance and poor material flowability of GH4169 high temperature alloy, free forging is easy to cause uneven deformation of the material, resulting in uneven internal structure of the forging after heat treatment, and producing "coarse grain, mixed grain" and other organizational defects Figure 5 a).

[0067] As shown in Figure 5 , the high magnification structure of the free forging before improvement Figure 5 a) and the high magnification structure of the die forging after improvement of the present application Figure 5 b) are compared, the grain in the internal structure of the forging before improvement is coarse and uneven, and there is a mixed grain problem, and the grain morphology is 3+5 grade mixed structure; the grain of the forging of the present application is uniform and fine, reaching 9 grade grain size.

[0068] (3) Mechanical property detection of die forging

[0069] The mechanical properties of the test bar after sampling and testing in step (9) were determined, and the aging system of the test bar was 710-730 °C, holding for 8 h. The actual measured value of the mechanical properties of the die forging had a large margin compared with the standard requirement. Test samples 1 and 2 were T-shaped die forgings obtained from examples 2 and 3, respectively. The test results are shown in Table 1.

[0070] Table 1 Test results of the mechanical properties of the die forgings

[0071]

[0072]

Claims

1. A process for the production of a T-shaped GH4169 die forging, characterized in that, The method comprises the following steps: (1) blanking: sawing GH4169 rod stock, the rod stock size is Φ90±1mm×210-215mm, and the original material two ends are bevelled, the bevel size is 5mm×5mm; (2) spraying: the original material obtained in step (1) is heated, the heating temperature is 150-200 DEG C and the heat preservation time is 60-120 minutes, then the surface is uniformly sprayed with protective lubricant, and the spraying thickness is controlled to be 0.2-0.8mm; (3) blank heating: the blank treated in step (2) is heated in an electric furnace to a temperature of 995-1025 DEG C and is heat preserved for 120-240 minutes; (4) mold preheating: the forming mold is preheated to 300-450 DEG C; the forming mold comprises a male die, a female die and a ejector rod, and the lower end of the male die is provided with an arc-shaped protrusion; (5) die forging forming: the mold preheated in step (4) is installed on a screw press or a die forging hammer, the blank heated in step (3) is transferred into the mold cavity of the preheated mold within 20 seconds to form a die forging, and the die forging is cooled in air; the die forging is symmetrical along the central axis and comprises a cylindrical section, a transition section and a square platform section in sequence, the square platform section has a spherical pit at the top center, the arc-shaped protrusion at the lower end of the male die is matched with the spherical pit at the top center of the square platform section, and the square platform section of the die forging is designed with two arc protrusions R2 on the two long side faces, R2=(the diameter of the original material D+(2-8)mm) / 2; (6) removing defects: removing the cracks and folding defects on the surface of the die forging obtained in step (5); (7) solution treatment: the die forging obtained in step (6) is heated to a temperature of 950-980 DEG C, heat preserved for 90-120 minutes, then taken out and cooled in air; (8) machining: the cylindrical section of the die forging treated in step (7) is polished, and the square platform section is milled to make the surface roughness reach Ra3.2; (9) detection: the die forging treated in step (8) is subjected to ultrasonic flaw detection, and samples are taken for room temperature tensile test, room temperature impact test, high temperature tensile test and metallographic structure test; The material utilization rate of the production process of the T-shaped GH4169 die forging can be increased to 24.3%, and the grain size of the die forging reaches grade 9.

2. The production process according to claim 1, characterized in that, In step (2), the heating temperature is 200 DEG C, and the heat preservation time is 80 minutes; or the heating temperature is 160 DEG C, and the heat preservation time is 120 minutes.

3. The production process according to claim 1, characterized in that, In step (3), the heating temperature is 1000 DEG C; and in step (4), the mold is preheated to 450 DEG C.

4. The production process according to claim 1, characterized in that, In step (3), the heating temperature is 1025 DEG C; and in step (4), the mold is preheated to 400 DEG C.

5. The production process according to claim 1, characterized in that, In step (5), the blank transfer time is ≤15s.

6. The production process according to claim 1, characterized in that, In step (7), the solution treatment is heating to a temperature of 980 DEG C and heat preserving for 120 minutes.

7. A forming die for T-shaped GH4169 die forgings for implementing the production process according to claim 1, comprising a punch (1), a die (3) and a ejector rod (4), characterized in that, The lower end of the male die (1) is provided with an arc-shaped protrusion, which is matched with the spherical pit at the top center of the square platform section of the die forging; and the square platform section of the die forging is designed with two arc protrusions on the two long side faces.

8. The forming mold of claim 7, wherein, The square platform section of the die forging is rounded with a radius R1 of 10-25mm.

9. The forming mold of claim 7, wherein The draft angle α of the table section of the die forging is 0.3°-2°.

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