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

Abstract

The invention provides a T-shaped GH4169 die forging as well as a production process and a die thereof. The problems of how to improve the material utilization rate of T-shaped GH4169 parts, refine the grain structure of forgings and improve the structure uniformity urgently required to be solved in the field at present are solved by adopting the T-shaped GH4169 die forging and the production process and the die thereof. By reasonably designing the die structure and reasonably formulating the forging and heat treatment process, the material utilization rate is greatly increased, the material consumption is reduced, and the material utilization rate of the T-shaped part is increased to 24.3% from 14.3%. And moreover, the internal structure of the forge piece can be fully refined and uniform, the grain size of the die forging reaches grade 9, the overall uniformity of grains is greatly improved, and the mechanical property of the forge piece is superior to the standard requirement.

Description

Technical Field

[0001] The invention relates to the field of high-temperature alloy forging, and in particular to a T-shaped GH4169 die forging, a production process and a die thereof. Background Art

[0002] GH4169 alloy is a high-performance nickel-based high-temperature alloy, which is widely used in aerospace, nuclear energy, petrochemical and other fields. Its main chemical components include nickel (Ni), chromium (Cr), iron (Fe), molybdenum (Mo), niobium (Nb), titanium (Ti), aluminum (Al) and other elements, of which the nickel content is about 50-55%, the chromium content is about 17-21%, and the niobium content is about 4.75-5.5%. GH4169 alloy has excellent comprehensive properties, including high strength, good fatigue resistance, radiation resistance, oxidation resistance and corrosion resistance. In the temperature range of -253℃ to 650℃, the alloy exhibits excellent high-temperature strength and plasticity, especially the yield strength below 650℃ ranks among the best in deformed high-temperature alloys. From the microstructural point of view, 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 precipitated phases are precipitated through aging treatment, which significantly improves the strength and creep resistance of the alloy.

[0003] GH4169 alloy also has good processing and welding properties, and is suitable for manufacturing parts with complex shapes, such as turbine disks, blades, shafts, fasteners, etc. of aircraft engines. Therefore, GH4169 alloy is not only used for key components of aircraft engines, but also widely used in nuclear energy 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 prospects of GH4169 alloy will be further expanded, especially in emerging processes such as additive manufacturing.

[0004] T-shaped GH4169 forgings are a new type of high-temperature alloy forgings with special geometric shapes in the field. Its production requires special forging processes to ensure the mechanical properties and structural uniformity of the material. Therefore, those skilled in the art are in urgent need of developing production processes and dies that can improve the material utilization rate of T-shaped GH4169 parts, refine the grain structure of forgings, and improve structural uniformity. Summary of the invention

[0005] To solve the above problems, the present invention 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 organizational structure of the forging, solve the "coarse grain" problem, improve the deformation uniformity of the forging, and solve the "mixed crystal" problem.

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

[0007] The present invention designs and optimizes a T-shaped GH4169 die forging, which is symmetrical along the central axis and is divided into a cylindrical section, a transition section and a square platform section in sequence from the narrow end to the wide end along the central axis; the square platform section is an irregular rectangular parallelepiped with rounded corners on all sides and arc protrusions on the long two side surfaces; there is a spherical pit at the top center of the square platform section; the transition section is an inverted trapezoid, which is the part where the cylindrical section of the T-shaped die forging transitions to the square platform section. The cylindrical section of the T-shaped GH4169 die forging has a length of L1 along the central axis, the transition section has a length of L2 along the central axis, and the square platform section has a length of L3 along the central axis, and L1>L3>L2.

[0008] Furthermore, the present invention provides a T-shaped GH4169 die forging forming die, which is composed of a punch 1, a die 3, and a push rod 4. The forming die is used for processing the T-shaped GH4169 die forging.

[0009] The inner shape of the concave die 3 of the forming die matches the outer shape of the T-die forging; the lower end of the punch 1 is provided with an arc-shaped protrusion, which matches the central spherical pit on the top of the square table section of the T-die forging; the ejector rod 4 in the die is located below the die, and is used to support and fix the die and eject the formed forging from the die to make it leave the die cavity.

[0010] Furthermore, the present invention also provides a T-die forging production process, the steps are as follows:

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

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

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

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

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

[0016] Step (6) removing defects: removing defects such as cracks and folds on the surface of the die forging;

[0017] Step (7) solution treatment: performing solution treatment on the die forging;

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

[0019] Step (9) Testing: Perform ultrasonic testing on the die forgings processed in step 7 according to the requirements of GJB1580 standard A; take room temperature tensile test bars, room temperature impact test bars, high temperature tensile test bars, and tissue test blocks for physical and chemical testing.

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

[0021] In the step (3), the billet heating temperature is 995°C to 1025°C, and the holding time is 120min to 240min;

[0022] In step (4), the mold preheating temperature is 300° C. to 450° C.;

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

[0024] The solution treatment system in step (7) is to heat the die forging to 950-980°C, keep it at this temperature for 90-120 minutes, then take it out and cool it in the air.

[0025] The standard requirements of the T-shaped forgings of the present invention are: room temperature mechanical properties Rm≥1275Mpa, Rp0.2≥1035MPa, A5≥12%, Z≥15%, Aku≥32J, 650℃ high temperature mechanical properties Rm≥1000Mpa, Rp0.2≥860MPa, A5≥12%, Z≥15%, and grain size should be ≥4. The T-shaped forgings obtained by the mold and production process of the present invention fully meet the requirements, and the relevant performance parameters are higher than the standard requirements.

[0026] The present invention has the following beneficial effects:

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

[0028] (2) The present invention can refine the internal structure of forgings and solve problems such as "coarse crystals" and "mixed crystals". GH4169 high-temperature alloy has high deformation resistance and poor material fluidity. Free forging can easily cause uneven material deformation, resulting in uneven internal structure of forgings after heat treatment, and produce structural defects such as "coarse crystals and mixed crystals", causing forgings to be scrapped. The present invention makes the internal structure of forgings fully refined and uniform by reasonably designing the die structure and formulating the forging and heat treatment processes. The grain size of the die forgings reaches level 9, and the overall uniformity of the grains is greatly improved. The mechanical properties of the forgings are better than the standard requirements. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 2 Schematic diagram of the T-die forging forming die of the present invention; in the figure, 1. punch, 2. blank before forming, 3. die, 4. ejector pin, 5. T-die forging after forming.

[0031] Figure 3 The T-shaped die forging of the present invention is formed.

[0032] Figure 4 This is a comparison between the die forgings and free forgings of the present invention.

[0033] Figure 5 The high-magnification microstructure comparison between the die forging of the present invention and the free forging; (a) the high-magnification microstructure of the free forging; (b) the high-magnification microstructure of the die forging of the present invention. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical methods of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation methods. Unless otherwise specified in the present invention, the relevant terms involved are common terms in the field, and the technologies and methods described are common technologies and methods in the field.

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

[0036] like Figure 1 The schematic diagram of the structure of the T-shaped forging after multiple simulations and optimizations is shown in FIG. The T-shaped GH4169 die forging is symmetrical along the central axis and consists of three parts along the central axis, which are a cylindrical section, a transition section and a square table section from the bottom (narrow end) to the top (wide end). The diameter of the cylindrical section is The length along the central axis is L1; the transition section is an inverted trapezoid, and 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 shape of the square platform section is an irregular rectangular parallelepiped, with rounded corners R1 on all sides, R1=10mm~25mm; the square platform section is designed with two arc protrusions R2 on the two long sides, R2=(raw material diameter D+(2~8)mm) / 2; the draft angle of the square platform section α=0.3°~2°; the size of the central spherical pit on the top of the square platform section is SR.

[0037] Specifically, the cylindrical section diameter of the T-shaped forging in the present invention is The length along the central axis is L1=130mm; the length of the transition section along the central axis is L2=35mm; the length of the square platform section along the central axis is L3=67mm, the top surface of the square platform section is H=114mm long, B=84mm wide, and the chamfered corners are R1=20mm on all sides; two arc protrusions R2 are designed on the two long sides of the square platform section, R2=95mm; the draft angle of the square platform section is α=1°; the size of the spherical pit in the center of the top of the square platform section is SR=63mm.

[0038] The present invention is to produce the above Figure 1 For T-shaped forgings, a forming die is designed, such as Figure 2 As shown, the T-shaped GH4169 die forging forming die is composed of a punch 1, a die 3, and a push rod 4. The inner shape of the die 3 of the forming die matches the outer shape of the T-shaped die forging; the lower end of the punch 1 is provided with an arc-shaped protrusion, which matches the central spherical pit at the top of the square platform section of the T-shaped die forging; the push rod 4 in the die is located below the die, which is used to support and fix the die and to eject the formed forging from the die to make it separate from the die cavity.

[0039] Example 2: A T-shaped die forging

[0040] The production process steps of T-die forgings are as follows:

[0041] Step (1) Cutting: sawing GH4169 bar material into a size of Φ90±1mm×210~215mm, chamfering both ends of the raw material, and the chamfering size is 5mm×5mm;

[0042] Step (2) spraying: heat the raw material to 200°C, keep it warm for 80 minutes, and evenly spray the protective lubricant on the surface with a spraying thickness of 0.5 mm;

[0043] Step (3) heating the blank: heating to 1000° C. in an electric furnace and keeping the temperature for 200 min;

[0044] Step (4) preheating the mold: preheating the mold described in Example 1 of the present invention to 450° C.

[0045] Step (5) die forging: install the preheated die on the screw press, and transfer the heated blank to the die cavity for die forging. The blank transfer time is ≤ 20s. The die forging is placed in the air for cooling. Figure 3 ;

[0046] Step (6) removing defects: removing defects such as cracks and folds on the surface of the die forging;

[0047] Step (7) Solution treatment: heat the die forging to 980°C, keep it at this temperature for 120 minutes, then take it out and cool it in air;

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

[0049] Step (9) Inspection: The die forgings processed in step (7) are subjected to ultrasonic inspection according to the requirements of GJB1580 standard A; one piece is destroyed from each batch, and room temperature tensile test bars, room temperature impact test bars, high temperature tensile test bars, and tissue inspection test blocks are taken for physical and chemical inspection.

[0050] Example 3: A T-shaped die forging

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

[0052] Step (1) Cutting: sawing GH4169 bar material into a size of Φ90±1mm×210~215mm, chamfering both ends of the raw material, and the chamfering size is 5mm×5mm;

[0053] Step (2) spraying: heat the raw material to 160°C, keep it warm for 120 minutes, and evenly spray the protective lubricant on the surface with a spraying thickness of 0.5 mm;

[0054] Step (3) heating the blank: heating to 1025° C. in an electric furnace and keeping the temperature for 120 min;

[0055] Step (4) preheating the mold: preheating the mold described in Example 1 of the present invention to 400° C.

[0056] Step (5) die forging: install the preheated die on the screw press, and transfer the heated blank to the die cavity for die forging. The blank transfer time is ≤ 20s. The die forging is placed in the air for cooling. Figure 3 ;

[0057] Step (6) removing defects: removing defects such as cracks and folds on the surface of the die forging;

[0058] Step (7) Solution treatment: heat the die forging to 950°C, keep it at this temperature for 120 minutes, then take it out and cool it in air;

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

[0060] Step (9) Inspection: The die forgings processed in step (7) are subjected to ultrasonic inspection according to the requirements of GJB1580 standard A; one piece is destroyed from each batch, and room temperature tensile test bars, room temperature impact test bars, high temperature tensile test bars, and tissue inspection test blocks are taken for physical and chemical inspection.

[0061] Example 4: Performance testing of T-die forgings

[0062] (1) Comparison of material utilization

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

[0064] like Figure 4 A comparison between the die forging in the flaw detection state after processing in step (8) of the present invention and the free forging in the flaw detection state before improvement shows that the material utilization rate of the parts is increased from 14.3% before improvement to 24.3%.

[0065] (2) High-magnification tissue contrast

[0066] In the free forging process, due to the large deformation resistance and poor material fluidity of GH4169 high-temperature alloy, free forging easily causes uneven material deformation, resulting in uneven internal structure of forgings after heat treatment, and producing organizational defects such as "coarse grains and mixed grains" ( Figure 5 a).

[0067] like Figure 5 As shown, the high-multiple structure of the free forging before improvement ( Figure 5 a) Compared with the improved die forging high-multiple structure of the present invention ( Figure 5 b) By comparison, the grains inside the forgings before improvement were coarse and uneven, there was a mixed crystal problem, and the grain morphology was a 3+5 grade mixed structure; the grains of the forgings made by the method of the present invention were uniform and fine, reaching a 9 grade grain size.

[0068] (3) Mechanical properties testing of die forgings

[0069] After the mechanical properties of the test bar are tested by sampling in step (9), the aging system of the sample is 710-730°C and the temperature is kept for 8 hours. The measured values ​​of the mechanical properties of the die forgings have a large margin compared with the standard requirements. Samples 1 and 2 are T-shaped die forgings obtained in Examples 2 and 3, respectively. The test results are shown in Table 1.

[0070] Table 1 Mechanical properties test results of die forgings

[0071]

[0072]

Claims

1. A T-shaped GH4169 die forging, characterized in that: The T-shaped GH4169 die forging is symmetrical along the central axis, and is divided into a cylindrical section, a transition section and a square table section in sequence from the narrow end to the wide end along the central axis; the square table section is an irregular rectangular parallelepiped with rounded corners on all sides and arc protrusions on the two long sides; there is a spherical pit in the center of the top of the square table section; the transition section is an inverted trapezoid, which is the part where the cylindrical section of the T-shaped die forging transitions to the square table section.

2. A T-shaped GH4169 die forging as claimed in claim 1, characterized in that: The cylindrical section of the T-shaped GH4169 die forging has a length L1 along the central axis, the transition section has a length L2 along the central axis, and the square platform section has a length L3 along the central axis, wherein L1>L3>L2.

3. A T-shaped GH4169 die forging forming die, characterized in that: The forming die is composed of a punch (1), a die (3), and a push rod (4); the forming die is used to process the T-shaped GH4169 die forging described in claim 1 or 2; the inner shape of the die (3) of the forming die matches the outer shape of the T-shaped die forging; the lower end of the punch (1) is provided with an arc-shaped protrusion, which matches the central spherical pit on the top of the square table section of the T-shaped die forging.

4. A T-die forging production process, characterized in that the steps as follows: Step (1) Cutting: sawing GH4169 bar material and chamfering both ends of the raw material; Step (2) spraying: after heating and keeping the raw material warm, spray the protective lubricant evenly on the surface; Step (3) heating the blank: heating the blank in an electric furnace and keeping it warm; Step (4) preheating the mold: fully preheating the mold; Step (5) die forging: installing the fully preheated die on the forming equipment, and transferring the heated blank to the die cavity for die forging; Step (6) removing defects: removing defects such as cracks and folds on the surface of the die forging; Step (7) solution treatment: performing solution treatment on the die forging; Step (8) machining the surface: lathe the cylindrical section of the die forging and mill the square section to achieve a roughness of Ra3.2; Step (9) Testing: Perform ultrasonic testing on the die forgings processed in step 7; take room temperature tensile test bars, room temperature impact test bars, high temperature tensile test bars, and tissue test blocks for physical and chemical testing.

5. A T-die forging production process as claimed in claim 4, characterized in that: The mold is the forming mold according to claim 3.

6. A T-die forging production process as claimed in claim 4, characterized in that: In the step (2), the heating temperature is 150° C. to 200° C., the heat preservation time is 60 min to 120 min, and the protective lubricant spraying thickness is 0.2 mm to 0.8 mm.

7. A T-die forging production process as claimed in claim 4, characterized in that: In the step (3), the heating temperature of the blank is 995° C. to 1025° C., and the insulation time is 120 min to 240 min.

8. A T-die forging production process as claimed in claim 4, characterized in that: In the step (4), the mold preheating temperature is 300°C to 450°C.

9. A T-die forging production process as claimed in claim 4, characterized in that: The forming equipment in step (5) is a screw press or a die forging hammer, the blank transfer time should be ≤ 20s, and the die forging after forming should be placed in the air for cooling.

10. A T-die forging production process as claimed in claim 4, characterized in that: The solution treatment system in step (7) is to heat the die forging to 950-980°C, keep it at this temperature for 90-120 minutes, then take it out and cool it in the air.

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