Forging method of crisscross TC32 titanium alloy die forging

Abstract

The invention belongs to the field of forging hot working, and relates to a forging method of a cross TC32 titanium alloy die forging. The method comprises the following steps: selecting a bar as a blank; upsetting the bar and shaping the bar into a cuboid; reversing the blank, drawing out along the short side, and shaping into a cube with an irregular octagonal section as the blank; the face, corresponding to a web of the cross TC32 titanium alloy die forging, of the cube is larger than the face, corresponding to a high rib of the cross TC32 titanium alloy die forging, of the cube, and the web is made of more materials than the high rib. The blank is vertically placed into a pre-forging die in the height direction of the blank to be subjected to upsetting forming, and a cross-shaped pre-forged piece is obtained; lugs are arranged at the two ends of the crisscross pre-forged piece; the large lugs are used for forming high ribs with bosses, the small lugs are used for forming high ribs, and the middle of the pre-forging piece is used for forming a web; and the pre-forged piece is rotated by 90 degrees, and the pre-forged piece is placed into a finish forging die with the large lug facing upwards to be subjected to cross reversing forging forming.

Description

Technical Field

[0001] The invention belongs to the field of forging hot processing and relates to a forging method of a cross-shaped TC32 titanium alloy die forging. Background Art

[0002] In view of the needs of high weight reduction, long life and cost control of a certain aircraft in my country, the development of a new generation of comprehensive high-performance and low-cost backbone structural titanium alloys has become an important development direction for aviation materials. TC32 titanium alloy is a low-cost and high-comprehensive performance titanium alloy, whose main chemical composition is Ti-5Al-3Mo-3Cr-1Zr. This alloy has the advantages of ultra-high toughness, medium strength and high plasticity. At the same time, this alloy has a wide hot processing process window and excellent strength and toughness matching, so it is used in the new generation of aircraft load-bearing key structural forgings.

[0003] Aircraft joint structural forgings are key connecting and load-bearing components. Because they need to withstand multi-directional forces, they are usually cross-shaped. It is difficult to make rough blanks for forgings of this shape, and it is difficult to form them by die forging. The main problems are as follows: 1. The rough structure is complex, and free forging operation is difficult; it is difficult to form during die forging, the equipment requires a large tonnage, many fires, and a long production cycle; 2. The forging structure is complex, the deformation of different parts is very different, and the uniformity of the organization is poor; 3. The weight of the blank is large, the material utilization rate is reduced, and the cost of forgings is increased; 4. The original streamline direction of the bar during the forging process is difficult to keep consistent with the final forging, which has a great impact on the organization and performance of the forging. Summary of the invention

[0004] Purpose of the invention: The present invention provides a forging method of a cross-shaped TC32 titanium alloy die forging to meet the use requirements of the new generation of aircraft load-bearing key joint components in my country, and at the same time provides a method for making and die forging a cross-shaped forging. By adopting a die forging process that combines two different types of forging equipment, hydraulic press pre-forging and spiral hammer reversing cross final forging, the fiber streamline direction of the blank is guaranteed to be consistent with the streamline shape of the forging, the tonnage required for the die forging equipment is reduced, the die forging fire times are reduced, the production efficiency is improved, the material utilization rate is improved, the production cost is reduced, the final forming of the forging and the reasonable matching of the organization and performance are guaranteed, and the product qualification rate is finally improved.

[0005] Technical solution:

[0006] Provided is a forging method for a cross-shaped TC32 titanium alloy die forging, comprising:

[0007] Select a bar as the blank;

[0008] The bar is upset and shaped into a rectangular parallelepiped;

[0009] The blank is reversed and elongated along the short side, and is reshaped into an irregular octagonal cross-section cube as the blank, ensuring that the streamline direction of the blank is parallel to the cross section and consistent with the original streamline direction of the bar; the surface corresponding to the web of the cross-shaped TC32 titanium alloy die forging on the cube is larger than the surface corresponding to the high rib of the cross-shaped TC32 titanium alloy die forging, and the web material is also more than the high rib material;

[0010] The blank is placed vertically into a pre-forging die along its own height direction for upsetting to obtain a cross-shaped pre-forging; the cross-shaped pre-forging has ears at both ends; the large ears are used to form high ribs with bosses, the small ears are used to form high ribs, and the middle of the pre-forging is used to form a web;

[0011] The pre-forged piece is rotated 90° and placed into the final forging die with the large ear facing upward for cross-reversing forging.

[0012] Furthermore, the method further comprises:

[0013] If the maximum equivalent section thickness of a certain part of the cross-shaped die forging is greater than 120mm, the part shall be machined and reduced in thickness in advance;

[0014] Heat treatment of machined forgings.

[0015] Furthermore, the preheating temperature range of the hammer anvil and other auxiliary tooling before forging is 200°C to 300°C.

[0016] Furthermore, the pre-forging process of the blank is carried out on a hydraulic press, and the pressing rate is controlled at 2 to 5 mm / s;

[0017] The final forging process of the billet is carried out on a spiral hammer, the pressing rate is controlled at 0.3-0.5 m / s, and the energy of each hammer is set to increase.

[0018] Furthermore, the die preheating temperature of the die forging is 250°C to 350°C.

[0019] Further, pre-forging is performed on a hydraulic press.

[0020] Furthermore, the pre-forged piece is rotated 90 degrees and placed in a final forging die to be cross-reversed forged on a spiral hammer.

[0021] Furthermore, the machined forgings are heat treated, including:

[0022] The first annealing is performed on the machine-thickened forgings, wherein the temperature is heated to 850℃~900℃, the holding time is 3h, and the cooling method is air cooling; the uniformity of the electric furnace is ±10℃, and the transfer time of the forgings out of the furnace for air cooling is less than or equal to 90S;

[0023] The machine-thickened forgings are subjected to a second annealing, wherein the temperature is heated to 500°C to 580°C, kept at that temperature for 6 hours, and cooled in air; the uniformity of the electric furnace is ±5°C.

[0024] Furthermore, a gap of 100m or more is left between forgings in the electric furnace; the forgings are placed on a charging plate with air holes or the forgings are supported and padded to prevent deformation of the forgings during heating, resulting in uneven machining allowance of the forgings.

[0025] Furthermore, during free forging and die forging, the forging parameters include:

[0026] The blank is heated to 30℃~40℃ below the phase change point; the heating coefficient of cold material is 0.6~0.8min / mm, and the heating coefficient of hot material returning to the furnace is 0.4~0.6min / mm;

[0027] During forging, the deformation of each fire is 25% to 30%; the final forging temperature is greater than or equal to 750℃.

[0028] Beneficial Effects

[0029] A cross-shaped TC32 titanium alloy die forging method is used to meet the use requirements of key load-bearing joint components of my country's new generation of aircraft, and a cross-shaped forging blank making and die forging method is provided. The die forging process using two different types of forging equipment, hydraulic press pre-forging and spiral hammer reversing cross final forging, ensures that the fiber streamline direction of the blank is consistent with the streamline shape of the forging, reduces the tonnage required for the die forging equipment, reduces the number of die forging fires, improves production efficiency, improves material utilization, reduces production costs, ensures the final forming of the forging and reasonable matching of organization and performance, and ultimately improves the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1a This is a schematic diagram of the structure of a certain type of machine joint die forging 1.

[0031] Figure 1b The structure diagram of a certain type of machine joint die forging Figure 2 .

[0032] Figure 2 Schematic diagram of a cube with an irregular octagonal cross-section.

[0033] Figure 3a This is a schematic diagram of the swinging position of the blank in the pre-forging cavity.

[0034] Figure 3b Schematic diagram of the structure of the pre-forging.

[0035] Figure 4a Schematic diagram 1 is the phase relationship between the pre-forging and the final forging.

[0036] Figure 4b Schematic diagram of the phase relationship between the pre-forging and the final forging Figure 2 .

[0037] Figure 5 This is the forging flow chart of the cross-shaped TC32 titanium alloy die forging. DETAILED DESCRIPTION

[0038] The present invention provides a forging method for a cross-shaped TC32 titanium alloy die forging, comprising:

[0039] Select a bar as the blank;

[0040] Upsetting and shaping the bar into a cuboid

[0041] The blank is reversibly stretched to lengthen the short side and reshaped into an irregular octagonal cross-section cube to ensure that the blank streamline direction is parallel to the cross section and consistent with the original streamline direction of the bar.

[0042] The blank is placed vertically into the pre-forging die for upsetting to obtain a cross-shaped pre-forging.

[0043] The pre-forged piece is rotated 90° and placed into the final forging die for cross-reversing forging.

[0044] Furthermore, the method further comprises:

[0045] The parts of the formed cross-shaped die forgings whose maximum equivalent section thickness is greater than the preset thickness are machined to reduce the thickness;

[0046] Heat treatment of machined forgings.

[0047] Furthermore, the preset thickness is 120 mm.

[0048] Furthermore, the preheating temperature range of the hammer anvil and other auxiliary tooling before forging is 200°C to 300°C.

[0049] Furthermore, the pre-forging of the billet is carried out on a hydraulic press, and the pressing rate is controlled at 2-5 mm / s; the final forging of the billet is carried out on a spiral hammer, and the pressing rate is controlled at 0.3-0.5 m / s, and the energy of each hammer is set to increase.

[0050] Furthermore, the die preheating temperature of the die forging is 250°C to 350°C.

[0051] Furthermore, when the bar is made into a blank, it is first upset and then reversing and elongating into an irregular octagonal cross-section cube to match the pre-forging cavity;

[0052] The blank is placed vertically into the pre-forging die for upsetting to obtain a cross-shaped pre-forging.

[0053] The pre-forged piece is rotated 90° and placed into the final forging die for cross-reversing forging.

[0054] Furthermore, the machined forgings are heat treated, including:

[0055] The first annealing is performed on the machine-thickened forgings, wherein the temperature is heated to 850℃~900℃, the holding time is 3h, and the cooling method is air cooling; the uniformity of the electric furnace is ±10℃, and the transfer time of the forgings out of the furnace for air cooling is less than or equal to 90S;

[0056] The machine-thickened forgings are subjected to a second annealing, wherein the temperature is heated to 500°C to 580°C, kept at that temperature for 6 hours, and cooled in air; the uniformity of the electric furnace is ±5°C.

[0057] Furthermore, a gap of 100 mm or more is left between the internal parts of the electric furnace; the forgings are placed on a charging plate with air holes or the charging plate is supported and padded to prevent the forgings from deforming during the heating process, resulting in uneven machining allowance of the forgings.

[0058] Furthermore, during free forging and die forging, the forging parameters include:

[0059] The blank is heated to 30℃~40℃ below the phase change point; the heating coefficient of cold material is 0.6~0.8min / mm, and the heating coefficient of hot material returning to the furnace is 0.4~0.6min / mm;

[0060] During forging, the deformation of each fire is 25% to 30%; the final forging temperature is greater than or equal to 750℃.

[0061] The present invention provides a forging method for a cross-shaped TC32 titanium alloy die forging, such as Figure 5 As shown, the specific steps are as follows:

[0062] Step 1: Design the die forging according to the shape of the part. Usually the parting surface is the largest projection plane to facilitate the forming and parting of the die forging.

[0063] Preferably, the forging allowance, draft angle, and fillet size are determined according to the part characteristics. For narrow high ribs and areas that are difficult to fill in the die forging, a design concept of large arc transition, variable allowance, and draft angle is adopted.

[0064] Step 2: Select a bar as the blank: the length and diameter ratio of the blank is controlled between 2 and 3 times, which is conducive to upsetting and forming;

[0065] Step 3: First, the bar is upset and shaped into a cuboid; then the blank is reversibly stretched to lengthen the short sides and shaped into an irregular octagonal cross-section cube, ensuring that the streamline direction of the blank is parallel to the cross section and consistent with the original streamline direction of the bar;

[0066] The octagonal cross-section cube can be placed vertically into the pre-forging cavity, and its outer dimensions are similar to those of the pre-forging cavity (see Figure 2 );

[0067] During forging, the hammering should be slow to prevent the core from overheating; during upsetting, the amount of each hammer pressing down is 30 to 50 mm, the hammer is lifted once, and then the second hammer is pressed, and the upsetting speed is slow and uniform, controlled at 5 to 8 mm / s. During elongation, the amount of each hammer feeding is 80 to 100 mm of the current pressing height, and the amount of each hammer pressing down is ≤ 35 mm;

[0068] The corners of the octagonal cube should not be too small, generally controlled between R50 and 100

[0069] The side lengths of the octagonal cubes corresponding to the four cross-intersecting cavities of the pre-forging cavity should be strictly controlled to avoid damage to the die bridge.

[0070] It is allowed to repeatedly return the hot material to the furnace for shaping, and use a sample or mold to check the shape.

[0071] Step 4: Place the octagonal cubic blank vertically into the cavity of the pre-forging die for upsetting to obtain a cross-shaped pre-forging with a thick middle and thin wings.

[0072] Furthermore, the pre-forging and upsetting is generally carried out by using a hydraulic press. The blank is placed in an electric furnace at 100-150°C for preheating for 10-20 minutes, and the lubricant is sprayed. The coating should be uniform and cover the entire surface of the blank.

[0073] Further, the blank is heated to a temperature of 30°C to 40°C below the phase transition point;

[0074] The heating coefficient of cold material is 0.6~0.8min / mm, and the heating coefficient of hot material returning to the furnace is 0.4~0.6min / mm; during forging, the deformation amount of each fire is 25%~30%; the final forging temperature is greater than or equal to 750℃; the cooling method is air cooling.

[0075] Further: the mold preheating temperature is 250°C to 350°C;

[0076] Step 5: Rotate the pre-forged part 90° and place it into the final forging die cavity for cross-reversing forging.

[0077] Furthermore, the two wings of the pre-forging are vertically placed in the final forging cavity to form the narrow high ribs on the upper and lower sides of the final forging, and the middle thick section position parallel to the mold cavity is used to form the large web part of the final forging.

[0078] Furthermore, the final forging is performed on a spiral hammer, the pressing rate is controlled at 0.3-0.5 m / s, and the energy of each hammer is set to increase gradually.

[0079] Step 6: Perform cross-section reduction processing on a part of the cross-shaped die forging formed in step 5 to reduce the effective heat treatment thickness of the forging;

[0080] Preferably, a Φ45 through hole coaxial with the part is added by machining in the solid part of the cross-shaped die forging head where the equivalent cross-sectional thickness (inscribed circle diameter) is greater than 120 mm. The purpose is to reduce the effective thickness of the forging, prepare for the subsequent heat treatment annealing, and meet the matching of forging structure and performance.

[0081] Step 7: heat treating the forging of step 6;

[0082] Further, step 7 includes: primary annealing: heating to a temperature of 850°C to 900°C, and keeping the temperature for 3 hours; cooling method: air cooling;

[0083] Preferably: the uniformity of the electric furnace is ±10°C;

[0084] Preferably: the transfer time of the forgings out of the furnace for air cooling is less than or equal to 2 minutes;

[0085] Furthermore, step 7 also includes: secondary annealing: heating the forging to a temperature of 500° C. to 580° C., keeping the temperature for 6 hours, and cooling by air cooling;

[0086] Preferably, the furnace uniformity is ±5°C;

[0087] Preferably, step 7 specifically also includes: placing the charging plate and forgings in the effective qualified area of ​​the electric furnace; the number of forgings loaded into the furnace is selected according to the outer dimensions and weight of the forgings, the effective qualified area of ​​the electric furnace and the heating power of the electric furnace; leaving a gap of ≥50mm between the forgings; the forgings are placed on the charging plate in a single layer and supported and padded to prevent deformation of the forgings during heating.

[0088] Example 1

[0089] A certain type of machine joint die forging (see Figure 1a and Figure 1b ), the material is TC32, the outline size of the forging is 630×530×405mm, the design margin of the forging from the single side of the part is 10mm, the die draft is 7°, and the maximum projection area is 0.27m 2 The overall cross-sectional thickness of the forging varies greatly, with the maximum vertical dimension of 405mm and the minimum vertical dimension of 57mm, with a ratio of 7:1, and the consistency of forging deformation is difficult to control; there are 160-240mm high ribs on both sides of the web, with a rib width of 65mm and a rib height-to-width ratio of 3:1, which makes forging difficult.

[0090] The present invention provides a forging method for a cross-shaped TC32 titanium alloy die forging, comprising the following steps:

[0091] Step 1: According to the shape of the part, the die forging is designed with a single-side margin of 10mm from the part, a die draft of 7°, and the maximum projected section of 630×530mm is selected as the forging parting surface.

[0092] Step 2: Select Φ300 bar as the blank, calculate the blanking length of 700mm according to the weight of the forging and the material utilization rate of the numerical simulation, and the bar upsetting height-to-diameter ratio = 7 / 3 < 3, which meets the forging upsetting ratio requirements;

[0093] Step 3: First, the bar is upset and shaped into a cuboid of 375×350 mm; then the blank is reversed and pulled to lengthen and lengthen the short sides, and shaped into an irregular octagonal cross-section cube (see Figure 2 ) to ensure that the streamline direction of the billet is parallel to the cross section and consistent with the original streamline direction of the bar;

[0094] During forging, the hammering should be slow to prevent the core from overheating; during upsetting, the amount of each hammer pressing down is 30 to 50 mm, the hammer is lifted once, and then the second hammer is pressed, and the upsetting speed is slow and uniform, controlled at 5 to 8 mm / s. During elongation, the amount of each hammer feeding is 80 to 100 mm of the current pressing height, and the amount of each hammer pressing down is ≤ 35 mm;

[0095] The corners of the octagonal cube should not be too small, generally controlled between R50 and 100;

[0096] The side lengths of the octagonal cubes corresponding to the four cross-intersecting cavities of the pre-forging cavity should be strictly controlled to avoid damage to the die bridge.

[0097] It is allowed to repeatedly return the hot material to the furnace for shaping, and use a sample or mold to check the shape.

[0098] Step 4: Place the octagonal cube blank vertically into the pre-forging die cavity for upsetting to obtain a cross-shaped pre-forging with a thick middle and thin wings (see Figure 3a and Figure 3b ).

[0099] Furthermore, the pre-forging and upsetting is generally carried out by using a hydraulic press, the blank is placed in an electric furnace at 100-150°C for preheating for 10-20 minutes, and the lubricant is sprayed, the coating should be uniform and cover the entire surface of the blank;

[0100] Further, the blank is heated to a temperature of 30°C to 40°C below the phase transition point;

[0101] The heating coefficient of cold material is 0.6~0.8min / mm, and the heating coefficient of hot material returning to the furnace is 0.4~0.6min / mm; during forging, the deformation amount of each fire is 25%~30%; the final forging temperature is greater than or equal to 750℃; the cooling method is air cooling.

[0102] Further: the mold preheating temperature is 250°C to 350°C;

[0103] Step 5: Rotate the pre-forged piece 90° and place it into the final forging die cavity for cross-reversing forging (see Figure 4a and Figure 4b );

[0104] Furthermore, the two wing ears of the pre-forging are placed vertically into the final forging cavity, with the small ears facing downward, for forming narrow high ribs on the upper and lower sides of the final forging, and the middle thick section position parallel to the mold cavity is used to form the large belly plate part of the final forging.

[0105] Furthermore, the final forging is performed on a spiral hammer, the pressing rate is controlled at 0.3-0.5 m / s, and the energy of each hammer is set to increase gradually.

[0106] Step 6: Perform cross-section reduction processing on a part of the cross-shaped die forging formed in step 5 to reduce the effective heat treatment thickness of the forging;

[0107] Preferably, a Φ45 through hole coaxial with the part is added by machining in the solid part of the cross-shaped die forging head where the equivalent cross-sectional thickness (inscribed circle diameter) is greater than 120 mm. The purpose is to reduce the effective thickness of the forging, prepare for the subsequent heat treatment annealing, and meet the matching of forging structure and performance.

[0108] Step 7: heat treating the forging of step 6;

[0109] Further, step 7 includes: primary annealing: heating to a temperature of 880° C., and keeping the temperature for 3 hours;

[0110] Cooling method: air cooling.

[0111] Preferably: the uniformity of the electric furnace is ±10°C,

[0112] Preferably: the transfer time of the forgings out of the furnace for air cooling is less than or equal to 2 minutes;

[0113] Furthermore, step 7 also includes: secondary annealing: heating the forging to a temperature of 550° C. and keeping the temperature for 6 hours;

[0114] Cooling method: air cooling.

[0115] Preferably, the furnace uniformity is ±5°C;

[0116] Preferably, step 7 specifically also includes: placing the charging plate and forgings in the effective qualified area of ​​the electric furnace; the number of forgings loaded into the furnace is selected according to the outer dimensions and weight of the forgings, the effective qualified area of ​​the electric furnace and the heating power of the electric furnace; leaving a gap of ≥50mm between the forgings; the forgings are placed on the charging plate in a single layer and supported and padded to prevent deformation of the forgings during heating.

[0117] After the implementation of the present invention, a forging method of a cross-shaped TC32 titanium alloy die forging is provided to meet the use requirements of the key load-bearing joint components of the new generation of aircraft in my country. At the same time, a method for making a cross-shaped forging is provided, and a die forging process combining different forging equipment such as hydraulic press pre-forging and spiral hammer reversing cross final forging is adopted to ensure that the streamline direction of the blank fiber is consistent with the streamline shape of the forging, reduce the tonnage required for the die forging equipment, reduce the number of die forging fires, improve production efficiency, improve material utilization, reduce production costs, ensure the final forming of the forging and reasonable matching of organization and performance, and ultimately improve the qualified rate of the product.

Claims

1. A forging method for a cross-shaped TC32 titanium alloy die forging, characterized in that: include: Select a bar as the blank; The bar is upset and shaped into a rectangular parallelepiped; The blank is reversed and elongated along the short side, and is reshaped into an irregular octagonal cross-section cube as the blank, ensuring that the streamline direction of the blank is parallel to the cross section and consistent with the original streamline direction of the bar; the surface corresponding to the web of the cross-shaped TC32 titanium alloy die forging on the cube is larger than the surface corresponding to the high rib of the cross-shaped TC32 titanium alloy die forging, and the web material is also more than the high rib material; The blank is placed vertically into a pre-forging die along its own height direction for upsetting to obtain a cross-shaped pre-forging; the cross-shaped pre-forging has ears at both ends; the large ears are used to form high ribs with bosses, the small ears are used to form high ribs, and the middle of the pre-forging is used to form a web; The pre-forged piece is rotated 90° and placed into the final forging die with the large ear facing upward for cross-reversing forging.

2. The method according to claim 1, characterized in that The method further comprises: If the maximum equivalent section thickness of a certain part of the cross-shaped die forging is greater than 120mm, the part shall be machined and reduced in thickness in advance; Heat treatment of machined forgings.

3. The method according to claim 1, characterized in that The preheating temperature range of the hammer anvil and other auxiliary tooling before forging is 200℃~300℃.

4. The method according to claim 1, characterized in that: The pre-forging process of the billet is carried out on a hydraulic press, and the pressing rate is controlled at 2 to 5 mm / s; The final forging process of the billet is carried out on a spiral hammer, the pressing rate is controlled at 0.3-0.5 m / s, and the energy of each hammer is set to increase.

5. The method according to claim 1, characterized in that: The die preheating temperature for die forging is 250℃~350℃; the fetal membrane preheating temperature is 250℃~350℃.

6. The method according to claim 1, characterized in that Pre-forging is carried out on a hydraulic press.

7. The method according to claim 1, characterized in that The pre-forged piece is rotated 90° and placed in the final forging die for cross-reversing forging on a spiral hammer.

8. The method according to claim 1, characterized in that Heat treatment of machined forgings, including: The first annealing is performed on the machine-thickened forgings, wherein the temperature is heated to 850℃~900℃, the holding time is 3h, and the cooling method is air cooling; the uniformity of the electric furnace is ±10℃, and the transfer time of the forgings out of the furnace for air cooling is less than or equal to 90S; The machine-thickened forgings are subjected to a second annealing, wherein the temperature is heated to 500°C to 580°C, kept at that temperature for 6 hours, and cooled in air; the uniformity of the electric furnace is ±5°C.

9. The method according to claim 8, characterized in that There is a gap of 100m or more between the forgings in the electric furnace; the forgings are placed on the charging plate with air holes or the forgings are supported and padded to prevent deformation of the forgings during heating, which may lead to uneven machining allowance of the forgings.

10. The method according to claim 1, characterized in that During free forging and die forging, the forging parameters include: The blank is heated to 30℃~40℃ below the phase change point; the heating coefficient of cold material is 0.6~0.8min / mm, and the heating coefficient of hot material returning to the furnace is 0.4~0.6min / mm; During forging, the deformation of each fire is 25% to 30%; the final forging temperature is greater than or equal to 750℃.

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