A forming method for GH4169 alloy thin-walled ring

Abstract

The present invention relates to a forming method for a GH4169 alloy thin-walled ring. The technical solution includes two-piece joint forging in the height direction, as well as specific forging drawing design, bar stock preparation, blanking, rolling, heat treatment, turning, and flaw detection inspection steps. For example, the outer diameter and inner diameter of the forging drawing are designed with small allowances, the bar stock is made of specific specifications and smelted through a triple process, and the rolling process parameters are strictly controlled. The method has significant beneficial effects, improves rolling stability, refines grain structure, saves raw materials, doubles production efficiency, meets flaw detection requirements, is suitable for the manufacture of related parts in the aerospace field, and has broad application prospects and important promotion value.

Description

Technical Field

[0001] The present invention relates to the technical field of rolling forming of high-temperature alloys, and in particular to a forming method of a GH4169 alloy thin-walled ring. Background Art

[0002] High-temperature alloy materials are widely used in the field of aerospace to manufacture rotating parts, such as unit bodies such as engine casings and combustion chambers. Among them, GH4169 alloy is the most widely used high-temperature alloy material. GH4169 alloy is a nickel-based high-temperature alloy strengthened by precipitation of body-centered tetragonal γ" and face-centered cubic γ' phases. It has good comprehensive properties in the temperature range of -253℃ to 700℃, and its yield strength below 650℃ ranks first among deformed high-temperature alloys. Another feature is that the structure of the alloy is particularly sensitive to heat treatment technology. At the same time, the alloy material contains a large amount of cobalt, niobium, nickel and other elements, so the material cost is relatively high. For the thin-walled rings required in actual production, the structure is required to have a uniform grain size of 4 or finer, and the single discontinuity displayed during ultrasonic testing shall not exceed the equivalent 2.0mm flat-bottom hole index amplitude, and the bottom wave loss shall not exceed 6dB. Currently rolled Ring forming technology is an effective method for producing rough materials for such parts, especially when using radial-axial horizontal ring rolling equipment. Because the ratios of the ring's wall thickness to outer diameter and height to outer diameter are approximately 1 / 20 and 1 / 10, respectively, the ring is prone to instability during rolling, resulting in an elliptical ring of 4 to 6 mm. High roller climbing causes warping of 3 to 4 mm, and in severe cases, it cannot be formed. In addition, the thin wall thickness and rapid cooling result in uneven forging structure, which cannot meet the requirements of flaw detection. To this end, the conventional method is to increase the machining allowance to meet the maximum size and stable rolling requirements of the ring rolling equipment. In the industry, the single-sided allowance for rings with a diameter of approximately 500 mm is 5 to 6 mm. This is basically consistent with the standard JB / T 10478-2004 "Machining Allowances and Tolerances for Hot-Rolled Rings."

[0003] Patent CN102500705 A provides a method for hot bulging of rectangular high-temperature alloy rings. The rectangular ring is placed around a bulging block within a bulging machine, and the machine is activated to radially squeeze the ring. This method achieves dimensional accuracy of 1‰ to 2‰ of the corresponding dimension. However, this method increases the bulging process, wastes energy for reheating, and is not suitable for applications where bulging equipment is unavailable. Patent CN 117123727 A discloses a forging method for grain refinement of thin-walled high-temperature alloy rings. It describes a grain refinement method for GH4099 alloy and proposes that lowering the forging heating temperature can refine the grains, but this also increases the tendency to crack. This patent does not examine the grain refinement process parameters for the GH4169 alloy and lacks attention to microstructure uniformity and whether it can meet the requirements of ultrasonic testing. Patent CN102085550 A discloses a method for rolling nickel-based high-temperature alloy high-tube ring forgings, establishing a technical solution for rolling thin-walled high-tube rings with excellent microstructure and performance. Ring forgings rolled using this method have a minimum wall thickness of 25 mm and a maximum height-to-thickness ratio of 25 mm. These forgings are primarily used in rotating components such as front casings in aerospace applications. However, the addition of a follower die sleeve to the core roller results in poor rolling stability and is unsuitable for forming rings with wall thicknesses less than 25 mm. Summary of the Invention

[0004] In order to solve the above problems, the present invention discloses a forming method of a GH4169 alloy thin-walled ring.

[0005] The specific technical solutions are as follows:

[0006] A method for forming a GH4169 alloy thin-walled ring comprises the following steps:

[0007] Forging drawing design: master the tolerance of outer diameter and inner diameter; adopt the scheme of two-piece joint forging in height direction;

[0008] Bar preparation: prepare the bar through vacuum induction, electroslag remelting, and vacuum consumable smelting. The grain size difference between the edge, 1 / 2R and center of the bar cross section should not exceed two levels.

[0009] Blank making: The process route of using a fast forging machine to make blanks combined with a ring rolling machine to roll and form is adopted. The fast forging machine blanks require two fires to be completed. After heating in the first fire, the blanks are upset and punched with a deformation of 50%-65%; after heating in the second fire, the holes are expanded and shaped, the inner hole is expanded, and the leveling height is made to the nominal size of the forging.

[0010] Ring rolling: After the ring blank is heated, it is rolled into shape on a CNC ring rolling machine. The stop forging temperature is controlled to be no less than 930°C. After the radial load is removed, the ring is rotated at least 2 turns to complete the circle.

[0011] Heat treatment: subject the forgings to solution treatment, heat thoroughly and then keep warm for 1 hour, then air cool or cool faster.

[0012] Turning: The forgings are turned, and the size tolerance after processing is controlled to ±0.5, and the surface roughness is not greater than Ra1.6μm. The last two rounds of processing are performed using a round head tool. After cutting in the height direction, an R knife is used to smooth the section.

[0013] Flaw detection: Ultrasonic water immersion flaw detection is carried out at a frequency of 5MHz-10MHz. GH4169 alloy comparison test blocks are used. The defect display does not exceed the equivalent amplitude of a 2.0mm flat-bottom hole, and the bottom wave loss does not exceed 6dB.

[0014] Blank making temperature: first fire heating temperature 1000℃~1060℃, second fire heating temperature 1000℃~1060℃.

[0015] In the rolling process, the main roll speed is 0.8m / s-1.0m / s, the core roll feed speed is 0.5mm / s-0.7mm / s, the rolling time is 20s-30s, and the rolling deformation is 30%-35%;

[0016] The grain size of the bar material is level 4 or finer, and the fillet transition should be smooth.

[0017] After the heat treatment, the forgings are extracted for aging treatment, and the metallographic structure of the forgings is required to have a grain size of 7-7.5 and a uniform structure.

[0018] The advantages of this invention are: for thin-walled GH4169 alloy rings, which are difficult to deform and have sensitive structures, the use of high-direction combined forging and low-temperature, high-deformation final rolling increases the ring's rigidity and improves rolling stability during rolling. It also achieves a refined grain structure. The design with a small diameter margin significantly saves raw material consumption. During rough production, two parts can be produced from one rough piece, doubling production efficiency. After high-direction shearing, automated water immersion testing is performed, meeting all inspection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the parts diagram after processing in Example 1;

[0020] Figure 2 Figure 1 of the forging designed for Example 1;

[0021] Figure 3 This is the metallographic structure diagram of Example 1;

[0022] Figure 4 This is the parts diagram after processing in Example 2;

[0023] Figure 5 Figure 2 of the forging designed for Example 2;

[0024] Figure 6 This is the metallographic structure diagram of Example 2. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Specific embodiment 1:

[0027] against Figure 1 For parts, first add machining allowance and design Figure 2 The forging diagram of the GH4169 alloy thin-walled ring forming method of the present invention requires the provision of equipment such as a forging heating furnace, a fast forging machine, and a ring rolling machine, as well as simple tooling such as a punch, a drain plate, and a horse frame. The specific implementation method is as follows:

[0028] Step 1: Cut the material using a sawing machine. Surface roughness should be no less than Ra 6.3μm. Cracks, folds, scars, and other defects are not permitted. The two sections should have an R10 radius, with local radius up to R15 permitted. The transition between the radiused corners should be smooth. The bar is smelted using a triple process, requiring a grain size of Grade 4 or finer. The grain size difference between the edge, 1 / 2R, and center of the bar cross section should not exceed 2 grades.

[0029] Step 2: Upsetting and punching after heating: After preheating, the heating temperature is 1000℃, the upsetting height is 85±3mm, and the punch and the plate are used for punching. The punching plate weighs about 9.3kg, and the upsetting deformation is about 60%.

[0030] Step 3: Reheat and then expand and shape. Heating temperature is 1000℃, expand the hole with a rack, the inner hole is Φ304±10, and the expansion deformation is about 50%. Level the height to 101±3mm.

[0031] Step 4: Return to the furnace for heating and then roll the ring. The heating temperature is 1010°C, the holding time is at least 30 minutes, the main roll speed is 1.0 m / s, the core roll feed speed is 0.5 mm / s, the rolling time is 30 seconds, the rolling deformation is approximately 34%, and the stop forging temperature is controlled to be no less than 930°C. After removing the radial load, rotate the ring at least two revolutions to complete the ring rounding.

[0032] Step 5: Heat treatment. Solution treat the forgings at a temperature within the range of 950℃~980℃±10℃, heat thoroughly for 1 hour, and then air cool or cool faster. Take a forging and inspect the cross-section metallographic structure after aging. Figure 3 . Grain size is 7 to 7.5, and the structure is uniform.

[0033] Step 6: Turning. Figure 1 After turning, the dimensional tolerance is ±0.5 and the surface roughness is not greater than Ra1.6μm. The last two turns are processed with a round head tool. After cutting in the height direction, the cross section is smoothed with an R knife.

[0034] Step 7: Nondestructive testing. Ultrasonic water immersion testing Figure 1 The raw material shown has a frequency of 5MHz to 10MHz and is a GH4169 alloy comparison test piece. The defect display does not exceed the amplitude of a 2.0mm flat-bottom hole, and the bottom wave loss does not exceed 6dB.

[0035] Example 2:

[0036] against Figure 4 For parts, first add machining allowance and design Figure 5 The forging diagram. The forming method of the GH4169 alloy thin-walled ring described in the present invention requires the provision of equipment such as a forging heating furnace, a fast forging machine and a ring rolling machine, as well as simple tooling such as a punch, a drain plate and a horse frame.

[0037] Step 1: Cut the material using a sawing machine. Surface roughness should be no less than Ra 6.3μm. Cracks, folds, scars, and other defects are not permitted. The two sections should have an R10 radius, with local radius up to R15 permitted. The transition between the radiused corners should be smooth. The bar is smelted using a triple process, requiring a grain size of Grade 4 or finer. The grain size difference between the edge, 1 / 2R, and center of the bar cross section should not exceed 2 grades.

[0038] Step 2: Upsetting and punching after heating: After preheating, the heating temperature is 1020℃, the upsetting height is 77±3mm, and the punch and the plate are used for punching. The punching base is about 8.4kg, and the upsetting deformation is about 50%.

[0039] Step 3: Reheat and then expand and shape. Heating temperature is 1020℃, expand the hole with a rack, the inner hole is Φ306±10, and the expansion deformation is about 53%. Level the height to 92±3mm.

[0040] Step 4: Return to the furnace for heating and then roll the ring. The heating temperature is 1020°C, the holding time is at least 30 minutes, the main roll speed is 0.9 m / s, the core roll feed speed is 0.6 mm / s, the rolling time is 25 seconds, the rolling deformation is approximately 31%, and the stop forging temperature is controlled to be no less than 930°C. After removing the radial load, rotate the ring at least two revolutions to complete the ring.

[0041] Step 5: Heat treatment. Solution treat the forgings at a temperature within the range of 950℃~980℃±10℃, heat thoroughly for 1 hour, and then air cool or cool faster. Take a forging and inspect the cross-section metallographic structure after aging. Figure 6. Grain size is 6.5 to 7, and the structure is uniform.

[0042] Step 6: Turning. Figure 4 After turning, the dimensional tolerance is ±0.5 and the surface roughness is not greater than Ra1.6μm. The last two turns are processed with a round head tool. After cutting in the height direction, the cross section is smoothed with an R knife.

[0043] Step 7: Nondestructive testing. Ultrasonic water immersion testing Figure 4 The raw material shown has a frequency of 5MHz to 10MHz and is a GH4169 alloy comparison test piece. The defect display does not exceed the amplitude of a 2.0mm flat-bottom hole, and the bottom wave loss does not exceed 6dB.

Claims

1. A forming method for a GH4169 alloy thin-walled ring, characterized in that: The following steps are involved: Forging drawing design: master the tolerance of outer diameter and inner diameter; adopt the scheme of two-piece joint forging in height direction; Bar preparation: bar is prepared by vacuum induction, electroslag remelting and vacuum consumable smelting. The grain size difference between the edge, 1 / 2R and center of the cross section of the bar is required to be no more than two levels. Blank making: The process route of using a fast forging machine to make blanks combined with a ring rolling machine to roll and form is adopted. The fast forging machine blank making requires two fires to be completed. After heating in the first fire, it is upsetting and punching with a deformation of 50%-65%. After heating in the second fire, it is expanded and shaped, the inner hole is expanded, and the height is leveled to the nominal size of the forging. Ring rolling: After the ring blank is heated, it is rolled into shape on a CNC ring rolling machine. The stop forging temperature is controlled to be no less than 930°C. After the radial load is removed, the ring is rotated at least 2 turns to complete the circle. Heat treatment: subject the forging to solution treatment, heat thoroughly and then keep warm for 1 hour, then air cool or cool faster; Turning: The forgings are turned, and the size tolerance after processing is controlled to ±0.5, and the surface roughness is not greater than Ra1.6μm. The last two rounds of processing are performed with a round head tool. After cutting in the height direction, an R knife is used to smooth the section; Flaw detection: Ultrasonic water immersion flaw detection is carried out at a frequency of 5MHz-10MHz. GH4169 alloy comparison test blocks are used. The defect display does not exceed the equivalent amplitude of a 2.0mm flat-bottom hole, and the bottom wave loss does not exceed 6dB.

2. The forming method of GH4169 alloy thin-walled ring according to claim 1 is characterized in that Blank making temperature: first fire heating temperature 1000℃~1060℃, second fire heating temperature 1000℃~1060℃.

3. The forming method of GH4169 alloy thin-walled ring according to claim 1 is characterized in that In the rolling process steps: the main roller speed is 0.8m / s-1.0m / s, the core roller feed speed is 0.5mm / s-0.7mm / s, the rolling time is 20s-30s, and the rolling deformation is 30%-35%.

4. The forming method of GH4169 alloy thin-walled ring according to claim 1, characterized in that: The grain size of the bar material is level 4 or finer, and the fillet transition should be smooth.

5. The forming method of GH4169 alloy thin-walled ring according to claim 1, characterized in that: After the heat treatment, the forgings are extracted for aging treatment, and the metallographic structure of the forgings is required to have a grain size of 7-7.5 and a uniform structure.

Images