A forging method for annular GH4169 high temperature alloy forging

Abstract

The present invention relates to the field of metallurgy, and in particular to a die forging process of high-temperature alloy forgings, in particular to a forging method of an annular GH4169 high-temperature alloy forging, including blanking, pre-forging, cake blank machining, forming forging, forging demolding, and forging water cooling treatment. The present invention adopts step-by-step heating, and wraps and covers the cake blank with insulation cotton and a carbon powder layer during the heating stage, which can reduce the temperature drop during the forging process, improve the uniformity of forging deformation, and thus improve the molding quality and performance consistency of the forging; the forging is rapidly cooled and shrunk by a cooler and separated from the mold, which reduces the demolding force, reduces the demolding difficulty, and extends the mold life. At the same time, it shortens the demolding time, improves the water cooling timeliness, and reduces the incidence of structural defects such as grain boundary coarsening, thereby reducing the risk of scrapping due to slow cooling.

Description

Technical Field

[0001] The invention relates to the field of metallurgy, in particular to a die forging process of a high-temperature alloy forging, in particular to a forging method of an annular GH4169 high-temperature alloy forging. Background Art

[0002] GH4169 is a nickel-based precipitation-strengthened high-temperature alloy with excellent high-temperature strength, oxidation resistance and creep resistance. It can serve for a long time in the temperature range of -253℃ to 650℃. It is widely used in aerospace, marine and other fields, mainly used for the production of turbine rotor blades, disc forgings, ring parts, etc. The alloy has a high degree of alloying, high deformation resistance and a small hot working window, which makes it difficult to forge. Using conventional heating methods, the temperature of the billet drops quickly during the forging process, the deformation is uneven, and the forging performance is low. On the other hand, demolding is also a major problem for ring forgings. In the field of closed die forging metal material precision forming, the metal billet is heated to a certain temperature, and is squeezed by external force in the die to produce plastic flow to fill the cavity and form a forging. However, during the flow process, the metal will produce friction with the die to form an adhesion layer, which makes the forging and the die stick tightly together. Usually in the design process of forgings and dies, the demolding force is reduced by increasing the demolding angle to ensure smooth demolding of the forging. However, in the actual production process, a large ejection force is still required, and the ejection time is long. During the ejection process, it is easy to cause serious wear of the mold and roughening of the forging, and finally cause the mold to crack ( Figure 1 The following is a picture of a mold crack). In addition, after forging, GH4169 alloy structural parts need to be demolded and water-cooled as soon as possible. Severe mold sticking will prolong the demolding time, causing the water cooling after forging to turn into slow cooling, which will directly change the microstructure of the forging and create the risk of scrapping. Summary of the invention

[0003] The object of the present invention is to provide a forging method of an annular GH4169 high temperature alloy forging, which is intended to solve the technical problems of rapid temperature drop of the blank, uneven deformation and difficulty in demoulding in the prior art.

[0004] The forging method of the annular GH4169 high temperature alloy forging of the present invention comprises the following steps:

[0005] Step 1: a cutting step: sawing and cutting the GH4169 bar to obtain material segments;

[0006] Step 2: a pre-forging step: heat the material segment cut in step 1 to 950-1200°C, and then keep it warm for 1-2 hours. After the end of the heat preservation, place the material segment in a pre-forging die, forge it at a pressing speed of 1-3 mm / s to obtain a cake blank, and take out the cake blank for water cooling;

[0007] Step 3: machining the cake blank after water cooling in step 2 so that the cake blank can be placed in a forming mold;

[0008] Step 4: a forming forging step: heat the cake blank machined in step 3 to 940-970°C, then keep it warm for 1-2 hours, then cover the side and lower part of the cake blank with the first insulation cotton, and leave the upper part of the cake blank open, then heat the cake blank to 990-1200°C, then keep it warm for 45-120 minutes, then cover the upper part of the cake blank with the second insulation cotton, and lay a carbon powder layer on the upper surface of the second insulation cotton, then transfer the wrapped cake blank to the forming mold, and perform die forging at a pressing speed of 2-6 mm / s to obtain a forging;

[0009] Step 5: a step of demoulding a forging: the cooler is a container filled with water, the upper part of the cooler is open, a flexible water storage material is arranged in the cooler, and the forming die is extended into the cooler to make water overflow to the forging, and the forging is taken out after the forging is cooled and shrunk;

[0010] Step 6: Water-cool the forgings taken out in step 5.

[0011] Furthermore, in the step 1, after sawing, the end surface of the material segment is flattened and chamfered to eliminate burrs.

[0012] Furthermore, in the step 2, before placing the material section into the pre-forging die, the pre-forging die is preheated to 950-1050° C., and kept warm for 1-2 hours after reaching the temperature for the first time.

[0013] Furthermore, the step three specifically includes: turning and trimming the cake blank with a larger ovality so that the cake blank can be placed in the forming mold; and grinding the surface folds and wrinkles of the cake blank with a sander to make the surface of the cake blank have a smooth transition.

[0014] Furthermore, the first insulation cotton and the second insulation cotton in the step four are both asbestos, the thickness of the first insulation cotton and the second insulation cotton are both 3~10mm, the first insulation cotton is a circular structure with teeth on the outside, the first insulation cotton is pasted on the bottom of the cake blank, the toothed structure of the first insulation cotton is pasted on the side of the cake blank, the second insulation cotton is a circular structure, and the thickness of the carbon powder layer is 1~5mm.

[0015] Furthermore, in step 4, before placing the wrapped dough into the molding mold, the molding mold is preheated to 600-700° C. and kept warm for 1-2 hours after reaching the temperature for the first time.

[0016] Furthermore, the forming mold includes an upper punch, a pad, and a lower die sleeve, the pad is movably mounted in the lower die sleeve, the upper surface of the pad and the upper inner side of the lower die sleeve form a lower die cavity, and a lower ejector device is arranged under the pad; in the step four, the wrapped cake blank is transferred to the lower die cavity in the forming mold, the cake blank is adjusted to a horizontal position by lightly pressing with the upper punch, the cake blank is adjusted to the middle position of the lower die cavity, and then the upper punch is used for die forging; in the step five, after the forging cools and shrinks, the pad is ejected upward with the lower ejector device, and then the forging is taken out.

[0017] Furthermore, the flexible water storage material is cotton cloth or chemical fiber cloth or sponge.

[0018] Compared with the prior art, the present invention has a positive and obvious effect. The present invention adopts step-by-step heating and wraps the cake blank with insulation cotton during the heating stage, which can reduce the temperature drop during the forging process, improve the uniformity of forging deformation, and lay a carbon powder layer on the upper surface of the blank before forming forging, which plays an effective lubricating role, thereby improving the forming quality and performance consistency of the forging; the forging is rapidly cooled and shrunk by the cooler and separated from the mold, which reduces the demolding force, reduces the demolding difficulty, and extends the mold life. At the same time, it shortens the demolding time, improves the water cooling timeliness, and reduces the incidence of structural defects such as grain boundary coarsening, thereby reducing the risk of scrapping due to slow cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the collapse of the forming die in the existing forging method.

[0020] Figure 2 It is a structural schematic diagram of the forming mold in the present invention.

[0021] Figure 3 It is a state diagram of the cooler being placed in the forging in step five of the present invention.

[0022] Figure 4 It is a schematic diagram of cooler-assisted demoulding in step five of the present invention.

[0023] Figure 5 It is a schematic diagram of demoulding of the lower ejection device in step five of the present invention.

[0024] Markings in the figure: 1. upper punch; 2. pad; 3. lower die sleeve; 4. forging; 5. cooler; 6. lower ejector device. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited thereto.

[0026] A forging method of an annular GH4169 high temperature alloy forging of the present invention comprises the following steps:

[0027] Step 1: A cutting step: GH4169 bar is sawed and cut to obtain material segments;

[0028] Step 2: a pre-forging step: heat the material segment cut in step 1 to 950-1200°C, and then keep it warm for 1-2 hours. After the end of the heat preservation, place the material segment in a pre-forging die, forge it at a pressing speed of 1-3 mm / s to obtain a cake blank, and take out the cake blank for water cooling;

[0029] Step 3: machining the cake blank after water cooling in step 2 so that the cake blank can be placed in the forming mold;

[0030] Step 4: a forming forging step: heat the cake blank repaired in step 3 to 940-970°C, then keep it warm for 1-2 hours, then cover the side and lower part of the cake blank with the first insulation cotton, and leave the upper part of the cake blank open, then heat the cake blank to 990-1200°C, keep it warm for 45-120 minutes, then cover the upper part of the cake blank with the second insulation cotton, and lay a carbon powder layer on the upper surface of the second insulation cotton, then transfer the wrapped cake blank to the forming mold, and perform die forging at a pressing speed of 2-6 mm / s to obtain a forging;

[0031] Step 5: a step of demoulding a forging: a cooler filled with water is sent into the forging, the cooler is a container filled with water, the upper part of the cooler is open, a flexible water storage material is arranged in the cooler, and the forming die is extended into the cooler to make the water overflow to the forging, and the forging is taken out after the forging is cooled and shrunk;

[0032] Step 6: Water-cool the forgings taken out in step 5.

[0033] Furthermore, in the step 1, after sawing, the end surface of the material segment is flattened and chamfered to eliminate burrs.

[0034] Furthermore, in step 2, before placing the material section into the pre-forging die, the pre-forging die is preheated to 950-1050°C in advance, and kept warm for 1-2 hours after reaching the temperature for the first time. Specifically, preheating the pre-forging die can avoid temperature drop during pre-forging, and keeping warm for 1-2 hours can make the temperature of the pre-forging die heated evenly.

[0035] Furthermore, the step three specifically includes: turning and trimming the cake blank with a large ovality so that the cake blank can be placed in the forming mold; grinding the folded and wrinkled areas on the surface of the cake blank with a sander to make the surface of the cake blank smooth. Specifically, grinding the folded and wrinkled areas to smooth can prevent stress concentration during subsequent forming and forging, making the forging more uniform.

[0036] Furthermore, the first insulation cotton and the second insulation cotton in step 4 are both asbestos, the thickness of the first insulation cotton and the second insulation cotton are both 3-10 mm, the first insulation cotton is a circular structure with teeth on the outside, the first insulation cotton is pasted on the bottom of the cake blank, the toothed structure of the first insulation cotton is pasted on the side of the cake blank, the second insulation cotton is a circular structure, and the thickness of the carbon powder layer is 1-5 mm. Specifically, the first insulation cotton is a toothed high-viscosity pasteable insulation cotton, the toothed structure is pasted on the side of the cake blank to achieve a heat preservation effect; the carbon powder layer covers the upper side of the second insulation cotton to play a lubricating role during forming and forging.

[0037] Furthermore, in step 4, before placing the wrapped dough into the forming mold, the forming mold is preheated to 600-700°C in advance, and kept warm for 1-2 hours after reaching the temperature for the first time. Specifically, preheating the forming mold can avoid temperature drop during forming and forging, and keeping warm for 1-2 hours can make the temperature of the forming mold evenly heated.

[0038] Further, the forming die comprises an upper punch 1, a cushion block 2, and a lower die sleeve 3. The cushion block 2 is movably sleeved in the lower die sleeve 3, and the upper surface of the cushion block 2 and the upper inner side of the lower die sleeve 3 form a lower die cavity. A lower ejector device 6 is provided below the cushion block 2. In the fourth step, the wrapped cake blank is transferred to the lower die cavity in the forming die, and the cake blank is adjusted to a horizontal position by lightly pressing the upper punch 1, and the cake blank is adjusted to the middle position of the lower die cavity, and then the upper punch 1 is used for die forging. In the fifth step, after the forging cools and shrinks, the cushion block is ejected upward by the lower ejector device 6, and then the forging 4 is taken out. The lower ejector device 6 can be a driving device such as a hydraulic cylinder.

[0039] Furthermore, the flexible water storage material is cotton cloth, chemical fiber cloth or sponge. Specifically, putting a flexible water storage material such as cotton cloth, chemical fiber cloth or sponge in the cooler 5 can prevent water from shaking and overflowing when the cooler 5 is carried; the shape of the cooler 5 is designed according to the groove in the middle of the annular forging 4 to ensure that it fits the inner wall of the forging 4 as much as possible.

[0040] The present invention adopts stepped heating and insulation cotton wrapping, which can reduce the temperature drop rate of the cake blank. A carbon powder layer is laid on the upper surface to play a lubricating role, improve the deformation uniformity of the forging, and improve the material utilization rate. The demolding difficulty is greatly reduced by means of a cooler. Combined with the bottom ejection mode, the demolding force can be effectively reduced, the mold life is extended, the demolding time is shortened, the water cooling timeliness is improved, and the occurrence rate of structural defects such as grain boundary coarsening is reduced.

[0041] Example 1

[0042] Use GH4169 bars with a specification of φ100mm and saw them into φ100mm×200mm. Then flatten and chamfer the end faces to eliminate burrs.

[0043] The pre-forging die is preheated to 950°C in advance, and the sawn material segments are placed in a heating furnace and kept warm for 1 hour. After the insulation is completed, the blank is quickly transferred to the pre-forging die furnace, and the material segment is pressed to a height of 65mm at a downward pressing speed of 2mm / s to obtain a cake blank, which is then immediately water-cooled to inhibit grain coarsening.

[0044] The water-cooled cake blank is machined, the cake blank with excessive ovality is turned and trimmed, and the surface folds and wrinkles are polished with a sander to achieve a smooth transition of the surface.

[0045] like Figure 2 As shown, the forming mold includes an upper punch 1, a cushion block 2, and a lower die sleeve 3. The cushion block 2 can be movably mounted in the lower die sleeve 3 up and down. The upper surface of the cushion block 2 and the upper inner side of the lower die sleeve 3 form a lower die cavity. A lower ejection device 6 is arranged below the cushion block 2.

[0046] Preheat the molding mold to 650℃ in advance and keep it warm for 1h.

[0047] Heat the trimmed cake blank to 950℃ and keep it warm for 1h. Then, wrap the side and bottom of the cake blank with the first insulation cotton, leaving only the top open. After wrapping, heat the cake blank to 1100℃ and keep it warm for 45min. Prepare the second insulation cotton of φ250mm before die forging. Cover the upper part of the cake blank with the second insulation cotton after it comes out of the oven, and evenly lay a 1mm thick carbon powder layer on the upper surface of the second insulation cotton.

[0048] The wrapped dough is quickly transferred to the lower die cavity of the forming die, and the dough is adjusted to a horizontal position by lightly pressing the upper punch 1, and the dough is adjusted to the middle of the lower die cavity, and forged at a pressing speed of 4 mm / s until the lower die cavity is filled.

[0049] After die forging is completed, Figure 3 As shown, retract the upper punch 1, and use a robot to clamp the cooler 5 filled with cooling water. Specifically, the cooler 5 is a container filled with cold water, the upper part of the container is open, and a flexible water storage material such as cotton cloth or chemical fiber cloth or sponge is arranged in the cooler. The cooler 5 is sent into the groove of the forging 4, and the outer side of the cooler 5 fits with the groove of the forging 4.

[0050] Then as Figure 4 As shown, the upper punch 1 is lowered and inserted into the cooler 5 to squeeze the flexible water storage material, squeeze out the cooling water in the flexible water storage material, and make the cooling water evenly overflow to the inner wall of the forging. It is kept for 1.5 minutes, and the gap between the forging 4 and the lower die sleeve 3 is expanded and separated by the thermal shrinkage effect, and the upper punch 1 is retracted.

[0051] Then as Figure 5As shown, the lower ejector device 6 is started, and the forging 4 and the cooler 5 are ejected out of the lower die cavity together through the lower ejector device 6 and the cushion block 2, thereby completing demoulding.

[0052] Finally, the forging 4 is subjected to water cooling treatment.

[0053] By adopting the process parameters of this embodiment, the temperature drop rate of the billet can be reduced by 40%~50%, the deformation uniformity of the forging can be improved to more than 90%, the material utilization rate can be increased by 15%~20%, and the forming quality and performance consistency of the forging can be improved; the adhesion wear of the mold is reduced by 80%, the mold life is increased by 4~5 times compared with the traditional solution, and the annual production capacity can be increased by 25%~30%; at the same time, the demolding time is shortened, the timely rate of water cooling after forging is increased by 30%, the incidence of structural defects such as grain boundary coarsening is reduced by 20%, the qualified rate of forgings can be increased to 98%, and the overall production cost is reduced by 22%~25%.

Claims

1. A forging method for an annular GH4169 high temperature alloy forging, characterized in that: The following steps are involved: Step 1: a cutting step: sawing and cutting the GH4169 bar to obtain material segments; Step 2: a pre-forging step: heat the material segment cut in step 1 to 950-1200°C, and then keep it warm for 1-2 hours. After the end of the heat preservation, place the material segment in a pre-forging die, forge it at a pressing speed of 1-3 mm / s to obtain a cake blank, and take out the cake blank for water cooling; Step 3: machining the cake blank after water cooling in step 2 so that the cake blank can be placed in a forming mold; Step 4: a forming forging step: heat the cake blank machined in step 3 to 940-970°C, then keep it warm for 1-2 hours, then cover the side and lower part of the cake blank with the first insulation cotton, and leave the upper part of the cake blank open, then heat the cake blank to 990-1200°C, then keep it warm for 45-120 minutes, then cover the upper part of the cake blank with the second insulation cotton, and lay a carbon powder layer on the upper surface of the second insulation cotton, then transfer the wrapped cake blank to the forming mold, and perform die forging at a pressing speed of 2-6 mm / s to obtain a forging; Step 5: a step of demoulding a forging: a cooler is put into the forging, the cooler is a container filled with water, the upper part of the cooler is open, a flexible water storage material is arranged in the cooler, and the forming die is extended into the cooler to make water overflow to the forging, and the forging is taken out after the forging is cooled and shrunk; Step 6: Water-cool the forgings taken out in step 5.

2. The forging method of the annular GH4169 high temperature alloy forging according to claim 1, characterized in that: In the step 1, after sawing, the end surface of the material section is flattened and chamfered to eliminate burrs.

3. The forging method of the annular GH4169 high temperature alloy forging according to claim 1, characterized in that: In the step 2, before placing the material section into the pre-forging die, the pre-forging die is preheated to 950-1050° C., and kept warm for 1-2 hours after reaching the temperature for the first time.

4. The forging method of the annular GH4169 high temperature alloy forging according to claim 1, characterized in that: The step three specifically includes: turning and trimming the cake blank with a larger ovality so that the cake blank can be placed in the forming mold; and grinding the surface folds and wrinkles of the cake blank with a sander so that the surface of the cake blank has a smooth transition.

5. The forging method of the annular GH4169 high temperature alloy forging according to claim 1, characterized in that: The first insulation cotton and the second insulation cotton in the step four are both asbestos, and the thickness of the first insulation cotton and the second insulation cotton are both 3~10mm. The first insulation cotton is a circular structure with teeth on the outside. The first insulation cotton is pasted on the bottom of the cake blank, and the toothed structure of the first insulation cotton is pasted on the side of the cake blank. The second insulation cotton is a circular structure, and the thickness of the carbon powder layer is 1~5mm.

6. The forging method of the annular GH4169 high temperature alloy forging according to claim 1, characterized in that: In the step 4, before placing the wrapped dough into the molding mold, the molding mold is preheated to 600-700° C. and kept warm for 1-2 hours after reaching the temperature for the first time.

7. The forging method of the annular GH4169 high temperature alloy forging according to claim 1, characterized in that: The forming die comprises an upper punch, a cushion block and a lower die sleeve, wherein the cushion block is movably mounted in the lower die sleeve up and down, the upper surface of the cushion block and the upper inner side of the lower die sleeve form a lower die cavity, and a lower ejection device is arranged under the cushion block; in the step four, the wrapped cake blank is transferred to the lower die cavity in the forming die, the cake blank is adjusted to be horizontal by lightly pressing with the upper punch, the cake blank is adjusted to the middle position of the lower die cavity, and then the upper punch is used for die forging; in the step five, after the forging cools and shrinks, the cushion block is ejected upward with the lower ejection device, and then the forging is taken out.

8. The forging method of the annular GH4169 high temperature alloy forging according to claim 1, characterized in that: The flexible water storage material is cotton cloth or chemical fiber cloth or sponge.

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