Forging method for grain size refinement of GH4169 alloy direct aging disc forge piece

Abstract

The invention belongs to the technical field of forging, and relates to a forging method for grain size refinement of a GH4169 alloy direct aging disc forge piece. The method comprises the following steps: blanking and chamfering edges and corners of a GH4169 alloy bar; the blank is a big-end-up cake blank with a convex outer circle, a positioning groove is formed in the upper end of the cake blank, and a deformation groove is formed in the lower end of the cake blank; the convex outer circular surface is divided into an outer inclined section which is inclined outwards, a cylindrical section, an inner inclined section which is inclined inwards and a positioning curved surface section from top to bottom; the moulding bed cavity wall corresponding to the positioning curved surface section is used for fixing the lower end of the bar; die forging is carried out on the waste blank which is turned over up and down; the positioning groove is clamped in a lower forging die cavity to be used for forming an inner transition area of the leg part and the disc part of the disc forging piece, under the constraint of the forging die, rough blank metal flows outwards, the metal between the positioning groove and the outer inclined section fills the leg part, the cylindrical section fills the center of the disc part, the inner inclined section partially fills the center of the disc part, and the disc edge of the disc part is partially filled. And the disc edge is filled with the deformed groove and the positioning curved surface section metal.

Description

Technical Field

[0001] The invention belongs to the technical field of forging, and relates to a forging method for refining the grain size of a GH4169 alloy direct aging disc forging. Background Art

[0002] GH4169 alloy is an iron-nickel-chromium based deformable high temperature alloy. The alloy structure is composed of γ matrix, δ phase, carbide and γ''(Ni3Nb) and γ'(Ni3(Al,Ti)) as strengthening phases. It is mainly used in key parts of aerospace engines. A GH4169 disc forging is an important load-bearing component of an aerospace engine. The technical requirements for the process type are direct aging, the grain size of the bar is level 6, the grain size of the forging is required to be ≥10, and the die forging needs to be refined by at least 4 levels. In the early trial production process, it was found that after the billet is completed, the billet is sprayed with lubricant as a whole, and then the die forging process route forms a large temperature difference in the temperature field during the die forging process. The area with a small deformation cannot be completely recrystallized, resulting in low-magnification coarse grains and unevenness in the forging, and the grain size does not meet the requirements of ≥10. Summary of the invention

[0003] Purpose of the invention: The present invention proposes a forging method for grain refinement of GH4169 alloy direct aging disc forgings, which ensures the temperature field during the forging process and obtains GH4169 alloy direct aging disc forgings with qualified grain size (≥10 levels) and uniform structure.

[0004] Technical solution:

[0005] Provided is a forging method for refining the grain size of a GH4169 alloy direct aging disc forging, comprising:

[0006] Cut and chamfer the edges and corners of GH4169 alloy bar;

[0007] The blank is made by a tire mold, wherein the blank is a cake blank with a convex outer circle and a larger upper part and a smaller lower part. A positioning groove is provided at the upper end of the cake blank and a deformation groove is provided at the lower end. The convex outer circle surface is divided into an outwardly inclined outer inclined section, a cylindrical section, an inwardly inclined inner inclined section and a positioning curved surface section from top to bottom. The tire mold cavity wall corresponding to the positioning curved surface section is used to fix the lower end of the rod material.

[0008] The blank turned upside down is die forged; the positioning groove is stuck in the lower forging model cavity to form the leg and the inner transition zone of the disc forging. Under the constraint of the forging die, the blank metal flows outward, the metal between the positioning groove and the outer inclined section fills the leg, the metal of the cylindrical section fills the center of the disc, the metal of the inner inclined section partially fills the center of the disc, the disc edge is partially filled, and the metal of the deformation groove and the positioning curved surface section fills the disc edge.

[0009] Furthermore, before die forging, the method further comprises:

[0010] The blank is sprayed with thermal insulation coating in different areas. The outer inclined section, cylindrical section and inner inclined section of the outer circle of the blank used for forming disc forgings, where the temperature loss is faster, are sprayed with coating with better thermal insulation properties to better suppress the temperature drop and ensure that the temperature of the outer circle of the blank is always ≥930℃ during the deformation process. Other areas of the blank are sprayed with ordinary coating. The center temperature of the blank is ensured to be ≥930℃ during the deformation process, so that the temperature field of the outer edge of the disc forging is always close to the core during the forging process.

[0011] Further, the blank turned upside down is subjected to die forging, including:

[0012] The blank is heated to 980℃~1000℃, and is soft-wrapped with heat-insulating cotton during heating. During die forging, the blank is turned over so that the positioning surface of the blank contacts the die for positioning;

[0013] A 100MN hydraulic press is used for die forging, the preheating temperature of the forging die is 250℃~350℃, the pressing speed is fast at first and then slow, and the deformation is controlled at 30%~42%.

[0014] Furthermore, the speed of the initial stage is 8-10 mm / s, which is subsequently adjusted to 3-5 mm / s, and the ratio of the billet height in the initial stage to that in the subsequent stage is 4:1.

[0015] Further, the blank is made by using a tire mold, including:

[0016] The bar is heated to 975℃~995℃, and the blank is sprayed with thermal insulation coating before heating. The bar is placed in a die and upset slowly using a 2500t fast forging machine to form the rough shape required for die forging.

[0017] Further, the blank turned upside down is die forged, and then the method further comprises:

[0018] After forging, the forgings are heat treated.

[0019] Furthermore, the heat treatment regime is direct aging;

[0020] The aging temperature is: 720℃, keep warm for 480min, cool to 620℃ with the furnace at a cooling rate of 50±10℃ / h, keep warm for 480min, and air cool.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention firstly adopts a mold to make a blank, designs a reasonable rough shape for die forging, and makes a positioning platform in the mold. The mold protrusion not only increases the deformation amount and reduces the deformation dead zone, but also avoids adding a positioning platform to the bar material and the subsequent die forging machine, saving raw materials and reducing the process. Then, the rough shape is sprayed with a heat-insulating coating, and different coatings are sprayed in different zones, and the speed is changed to press down, so that the temperature field is evenly distributed during the forging process. Under the action of reasonable deformation, the grain size is refined, and a uniformly organized disc forging is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the final forging diagram.

[0024] Figure 2 This is a rough drawing of the tire die forging.

[0025] Figure 3 This is a wild type spray paint picture.

[0026] Figure 4 This is the die forging swing diagram. DETAILED DESCRIPTION

[0027] The present invention provides a forging method for refining the grain size of GH4169 alloy direct aging disc forgings, and obtains disc forgings with a grain size of ≥10 and a performance margin, such as Figure 1 As shown, the GH4169 alloy disc forging includes a disc portion, an upper and a lower mounting edge, and Figure 3 As shown, two kinds of coatings are sprayed on the upper and lower surfaces and the outer edge of the forging die respectively; the method comprises the following steps:

[0028] Step 1: Cut the material and chamfer the edges and corners of the GH4169 alloy bar. When making the blank, ensure that the blank is in the appropriate position of the tire mold. The protrusion in the tire mold forms a positioning platform. The bar does not need to be machined with a positioning platform, which saves materials and increases the deformation. The deformation is controlled at 30% to 42%, reducing the deformation dead zone and refining the grains;

[0029] Step 2: Heat the bar to 975℃~995℃, spray the heat-insulating coating on the blank during heating, place the bar in the die and use a 2500t fast forging machine to slowly upset (see Figure 2 ), to make the rough shape required for die forging;

[0030] Step 3: Spray lubricant on the blank in different areas, and spray two types of coating on the upper and lower end surfaces and outer edges (see Figure 3 );

[0031] Step 4: Heat the blank to 980℃~1000℃. Use heat preservation cotton to soft pack it during heating. Turn the blank over during die forging so that the positioning surface of the blank contacts the die for positioning (see Figure 4), a 100MN hydraulic press is used for die forging, the die preheating temperature is 250℃~350℃, the pressing speed is fast at first and then slow, the initial speed is 8~10mm / s, and the subsequent speed is adjusted to 3~5mm / s. The billet height in the initial stage and the subsequent stage is 4:1, and the deformation is controlled at 30%~42%. By spraying different types of coatings in different areas and adjusting the pressing speed, the temperature field uniformity during the forging process is guaranteed, which provides conditions for complete recrystallization and makes the organization uniform and refined.

[0032] Combined with the simulation results, the temperature at the center rises when the die forging starts, and the temperature field at the outer edge of the rough shape is relatively low. The metal flow at the outer edge will flow to the upper and lower mounting edges. The deformation of these two places is smaller than that of the rest. Low temperature will lead to incomplete recrystallization, coarse grains, and uneven macrostructure. Spray the paint in different areas, spray two types of paint on the upper and lower end faces and the outer edge, and spray the paint with better thermal insulation on the outer edge to ensure the uniformity of the overall temperature field, match the deformation, and refine the grains.

[0033] Step 5: After forging, the forging is heat treated. The heat treatment system is direct aging. The aging temperature is 720°C, and the temperature is kept for 480 minutes. The forging is cooled to 620°C with a cooling rate of (50±10)°C / h, and the temperature is kept for 480 minutes. The forging is air-cooled to obtain the final forging.

[0034] Example 1

[0035] The GH4169 alloy direct aging disc forgings described in the present invention have a disc outer diameter of Φ360mm, an upper mounting edge diameter of Φ280mm, a lower mounting edge diameter of Φ290mm, a forging height of 110mm, a forging weight of 62.7Kg, and a reasonably designed die blanking process. At the same time, the positioning of the bar material and the subsequent die forging machine with a positioning table is avoided. The positioning table is formed during the die blanking process, which increases the deformation amount, reduces the deformation dead zone and saves costs. The coating is sprayed in different areas and the speed is changed to press down, which ensures the temperature field during the forging process, makes the forging structure uniform, and the grain size and performance indicators meet the standard requirements of the forgings.

[0036] The manufacturing steps are detailed as follows:

[0037] 1. Cutting: sawing machine, cutting size φ200×260mm;

[0038] 2. Billet machining: bar chamfering R20;

[0039] 3. Billet making: Heat the bar to 985℃. When the cold material is heated, apply the heat-insulating coating. Place the bar in the die and use a 2500t fast forging machine for upsetting. See the attached diagram for the placement of the bar. Figure 2 After the bar is positioned, the punch is placed to upset the bar into the rough shape required for die forging, the positioning table is formed, and the bulge in the tire mold increases the deformation amount, and the deformation amount is controlled at 30% to 42%, reducing the deformation dead zone and refining the grains;

[0040] 4. Die forging: Use 100MN hydraulic press for die forging, die preheating temperature 300℃, preheating time ≥20h, rough billet heated to 990℃, before heating, lubricant sprayed on rough billet in different areas, two types of coating sprayed on upper and lower end faces and outer edges (see Figure 3 ), spray the outer edge with a coating with better thermal insulation, turn the blank over during die forging, make the blank positioning surface contact the die for positioning, press the attachment Figure 4 Place the billet, the initial pressing speed is 8mm / s, when the underpressure is 30mm, the forging speed is adjusted to 5mm / s, the deformation is controlled at 30%~42%, and different types of thermal insulation coatings are sprayed in different areas and the pressing speed is adjusted to ensure the uniformity of the temperature field during the forging process, provide conditions for complete recrystallization, and make the structure uniform and refined.

[0041] 5. After forging, the forgings are heat treated. The heat treatment system is direct aging. The aging temperature is: 720℃, keep warm for 480min, cool to 620℃ with the furnace at a cooling rate of (50±10)℃ / h, keep warm for 480min, and air cool to obtain the final forgings.

[0042] The GH4169 alloy direct aging disc forgings obtained by the forging method were tested: the grain size of the forging 1 / 2R and the center was uniform at level 10, and the room temperature tensile strength was: σ b =1552MPa,σ 0.2 =1385MPa, δ5=15%, ψ=29%, and the microstructure and performance indicators of the forging meet the requirements of direct aging disc forgings.

Claims

1. A forging method for grain refinement of GH4169 alloy direct aging disc forgings, characterized in that: include: Cut and chamfer the edges and corners of GH4169 alloy bar; The blank is made by a tire mold, wherein the blank is a cake blank with a convex outer circle and a larger upper part and a smaller lower part. A positioning groove is provided at the upper end of the cake blank and a deformation groove is provided at the lower end. The convex outer circle surface is divided into an outwardly inclined outer inclined section, a cylindrical section, an inwardly inclined inner inclined section and a positioning curved surface section from top to bottom. The tire mold cavity wall corresponding to the positioning curved surface section is used to fix the lower end of the rod material. The blank turned upside down is die forged; the positioning groove is stuck in the lower forging model cavity to form the leg and the inner transition zone of the disc forging. Under the constraint of the forging die, the blank metal flows outward, the metal between the positioning groove and the outer inclined section fills the leg, the metal of the cylindrical section fills the center of the disc, the metal of the inner inclined section partially fills the center of the disc, the disc edge is partially filled, and the metal of the deformation groove and the positioning curved surface section fills the disc edge.

2. The method according to claim 1, characterized in that Before die forging, the method further comprises: The blank is sprayed with thermal insulation coating in different areas. The outer inclined section, cylindrical section and inner inclined section of the outer circle of the blank used for forming disc forgings, where the temperature loss is faster, are sprayed with coating with better thermal insulation properties to better suppress the temperature drop and ensure that the temperature of the outer circle of the blank is always ≥930℃ during the deformation process. Other areas of the blank are sprayed with ordinary coating. The center temperature of the blank is ensured to be ≥930℃ during the deformation process, so that the temperature field of the outer edge of the disc forging is always close to the core during the forging process.

3. The method according to claim 2, characterized in that Die forging the blank that is turned upside down, including: The blank is heated to 980℃~1000℃, and is soft-wrapped with heat-insulating cotton during heating. During die forging, the blank is turned over so that the positioning surface of the blank contacts the die for positioning; A 100MN hydraulic press is used for die forging, the preheating temperature of the forging die is 250℃~350℃, the pressing speed is fast at first and then slow, and the deformation is controlled at 30%~42%.

4. The method according to claim 3, characterized in that The initial stage speed is 8-10 mm / s, which is subsequently adjusted to 3-5 mm / s. The ratio of the billet height between the initial stage and the subsequent stage is 4:

1.

5. The method according to claim 1, characterized in that The blank is made by using a tire mold, including: The bar is heated to 975℃~995℃, and the blank is sprayed with thermal insulation coating before heating. The bar is placed in a die and upset slowly using a 2500t fast forging machine to form the rough shape required for die forging.

6. The method according to claim 5, characterized in that The blank turned upside down is subjected to die forging, and then the method further comprises: After forging, the forgings are heat treated.

7. The method according to claim 6, characterized in that The heat treatment system is direct aging; The aging temperature is: 720℃, keep warm for 480min, cool to 620℃ with the furnace at a cooling rate of 50±10℃ / h, keep warm for 480min, and air cool.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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