A high-precision experimental method for determining forging process parameters

Abstract

The present invention relates to the field of forging technology, and specifically to a high-precision experimental method for determining forging process parameters. The method comprises the following steps: S1: experimental forging design; S2: billet design; S3: billet manufacturing; S4: billet processing; S5: sampling and testing. The method improves the consistency of parameters other than variables in the forging process, eliminates the influence of parameters other than variables on the experimental results, and the thickness and width of each test block representing different deformation amounts are consistent. After splicing, the experimental forging is formed. The billet is designed according to the deformation amount of each test block of the experimental forging. The heating temperature of the billet in the electric furnace, the transportation time after being taken out of the furnace, the forging speed on the forging equipment, and the cooling speed after forging are all the same. Finally, the experimental piece is obtained, and the deformation amount of each section of the experimental piece is consistent with the deformation amount of the test block. The process parameters obtained by this experimental scheme have high accuracy, can truly reflect the essential laws of material structure properties and process parameters, and eliminate the influence of factors other than variables on the experimental results.

Description

Technical Field

[0001] The invention relates to the technical field of forging, in particular to a high-precision experimental method for determining forging process parameters. Background Art

[0002] With the development of aerospace equipment, new metal forgings such as titanium alloys, steels and high-temperature alloys are developing towards high performance and high quality. However, materials are becoming increasingly difficult to deform, and their performance is becoming increasingly difficult to control. In order to obtain the best organizational properties, forging process test research is usually required to obtain the best forging process parameters, which is especially important for newly developed materials. Existing forging process tests are usually carried out in two ways. The first is that the initial thickness of the test pieces before forging deformation is the same, and the thickness of the test pieces after deformation is different. Then they are processed into the same thickness by mechanical processing, and finally heat treated simultaneously with the same heat treatment system; the second is that the initial thickness of the test pieces before forging deformation is different, and the thickness of the test pieces after deformation is the same, and then heat treated simultaneously with the same heat treatment system. The first test method can basically eliminate the differences in the forging deformation process, but it cannot rule out the influence of post-forging cooling on the organizational properties, especially for materials where hardenability has a relatively large impact on performance. The second test method can eliminate the differences in the heat treatment process, but due to the thickness difference before forging, the heating time of the material will be different, the transfer time of different test blocks will also be different, and the forging time and forging rate during the forging process will also be different. These factors will inevitably have a certain impact on the final performance. Therefore, a forging process test method that eliminates different interference factors between experimental groups and improves the consistency of parameters other than variables is used to obtain high-precision forging process parameters to guide actual production and obtain the best forging microstructure and performance, which is of great significance to aerospace high-performance material forgings. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a high-precision experimental method for determining forging process parameters, which is used to reduce the influence of other variables on the experimental accuracy and ensure the accuracy of the experimental results.

[0004] The technical solution adopted by the present invention to solve the technical problem is a high-precision experimental method for determining forging process parameters, comprising the following steps:

[0005] S1: Experimental forging design: select N test blocks with different deformations, where the deformations of the test blocks are ε1, ε2, ..., εn, respectively, where n ≥ 2. Each test block has a length a, a width w, and a height h, and w = (1.1-1.2)h. Arrange the multiple test blocks along the length direction to form an experimental forging, and provide connecting terminals at both ends of the experimental forging. The connecting terminals have a length b, a width w, and a height h. The length of the experimental forging is L = a*n+2b. A mold is manufactured according to the dimensions of the experimental forging.

[0006] S2: Blank design. According to the position and deformation of each test block, the step corresponding to each test block on the blank is determined. The height of the step is h n =h / (1-εn), the length of each step is consistent with the length of the test block, and the width w1 of the blank satisfies 1 / 3h max ≤w1≤h min , and w1≤w; blank length L1=LX, 0<X<0.5b; where h max is the maximum thickness of the blank, h min is the minimum thickness of the blank;

[0007] S3: Billet manufacturing, the raw materials are divided into L1×w1×h max Cut to size or pre-forge, then machine the raw materials into billets;

[0008] S4: Billet processing: the billet processed in S3 is placed in an electric furnace for heating. After being heated thoroughly, it is placed in a die for die forging and cooled after forging. After the forging is finished, the flash is removed, sandblasted, and polished, and then the forging is heat treated to form a test piece.

[0009] S5: Sampling and testing: Take samples at the sampling position of the experimental piece for testing. According to the performance test results, statistical analysis is performed to obtain the influence of forging process parameters and microstructure properties, and determine the optimal forging process parameters.

[0010] Furthermore, the test blocks are arranged in order from small to large according to the amount of deformation.

[0011] Furthermore, a saw cut is provided between two adjacent test blocks, and the length of the saw cut is 5 to 20 mm.

[0012] Furthermore, the sampling position of the test piece is an area corresponding to the center position of the test block.

[0013] Furthermore, the length of the connecting end is b=0.5h.

[0014] Furthermore, the electric furnace meets GJB904 Class II and has an accuracy of ±5°C.

[0015] The beneficial effects of the present invention are as follows: the experimental method improves the consistency of parameters other than variables during the forging process, eliminates the influence of differences in parameters other than variables on the experimental results, the thickness and width of each test block representing different deformation amounts are consistent, and after splicing, the experimental forging is formed. The blank is designed according to the deformation amount of each test block of the experimental forging, the heating temperature of the blank in the electric furnace, the time for transporting the blank out of the furnace, the forging speed on the forging equipment, and the cooling speed after forging are all the same, and finally the experimental piece is obtained, and the deformation amount of each section of the experimental piece is consistent with the deformation amount of the test block. The process parameters obtained by this experimental scheme have high accuracy, can truly reflect the essential laws of material structure performance and process parameters, and eliminate the influence of factors other than variables on the experimental results. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the experimental forging structure of the present invention;

[0017] Figure 2 is a schematic diagram of the blank;

[0018] Figure 3 It is a schematic diagram of the experimental piece. DETAILED DESCRIPTION

[0019] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0020] like Figure 1-Figure 3 As shown, the present invention provides a high-precision experimental method for determining forging process parameters, comprising the following steps:

[0021] S1: Experimental forging design, see Figure 1 , select N test blocks with different deformation amounts, and the deformation amounts of the test blocks are ε1, ε2, ...εn, respectively, where n≥2, and the dimensions of each test block are length a, width w, and height h, and w=(1.1~1.2)h, and arrange multiple test blocks into an experimental forging along the length direction, and set connecting ends at both ends of the experimental forging, and the length of the connecting ends is b, the width is w, and the height is h. The length of the experimental forging is L=a*n+2b, and a mold is manufactured according to the size of the experimental forging; wherein connecting ends are set at both ends of the experimental forging, and corresponding areas for forming the connecting ends also exist on the mold, and finally, after the billet is forged into the experimental piece, corresponding parts of the connecting ends also exist on the experimental piece, and the existence of the connecting ends makes the heating and cooling states of the heat treatment of each position of the experimental piece, i.e., the corresponding areas of the experimental piece and the test block consistent.

[0022] S2: Blank design, see Figure 2, according to the position and deformation of each test block, determine the step corresponding to each test block on the blank, and the height of the step is h n =h / (1-εn), the length of each step is consistent with the length of the test block, and the width w1 of the blank satisfies 1 / 3h max ≤w1≤h min , and w1≤w; blank length L1=LX, 0<X<0.5b; where h max is the maximum thickness of the blank, h min is the minimum thickness of the blank; by setting steps of different heights, these steps will form an area with the same deformation as the test block after die forging, and the width w1 of the blank meets 1 / 3h max ≤w1, in order to prevent instability and defects during forging, control w1≤h min The purpose is to achieve the minimum cross-sectional size of each step of the blank to be w1, and then achieve the same heating state, that is, heat through at the same time, eliminating the influence of different heating time on the results. In order to place the blank in the mold, the blank length needs to be less than the length of the mold, so the length of the blank L1 = LX, 0 < X ​​< 0.5b, the length of each step is consistent with the length of the corresponding test block. S3: Blank manufacturing, the raw material is placed according to L1 × w1 × h max The raw materials are cut to specifications or pre-forged, and then the raw materials are processed into steps through mechanical processing to form blanks.

[0023] S4: Billet processing: the billet processed in S3 is placed in an electric furnace for heating. After being heated thoroughly, it is placed in a die for die forging and cooled after forging. After the forging is finished, the flash is removed, sandblasted, and polished, and then the forging is heat treated to form a test piece.

[0024] S5: Sampling and testing, see Figure 3 , at the sampling location of the experimental piece, samples are taken for testing. Based on the performance test results, statistical analysis is performed to derive the influence of forging process parameters and microstructure properties, and to determine the optimal forging process parameters. During the sampling process, it is necessary to sample areas with different deformation amounts. For example, if the test block constituting the experimental forging has five different deformation amounts, then there are five deformation areas on the experimental piece corresponding to the deformation amounts of the test block, and sampling is required for these five areas.

[0025] In order to facilitate the processing of raw materials into blanks, further see Figure 2 The test blocks are arranged in descending order according to the amount of deformation. This arrangement makes the step heights on the blank also arranged from large to small, which is more conducive to machining.

[0026] In order to more conveniently distinguish different deformation areas when the billet is forged into a test piece, see Figure 1A saw cut is provided between two adjacent test blocks, with a length of 5 to 20 mm. The cross-sectional dimensions of the saw cut are smaller than those of the test blocks, and the saw cut is waist-shaped. This creates an area on the mold that matches the saw cut. After the blank is formed into a test piece, the saw cut also appears on the test piece, allowing for differentiation of regions of different deformation on the test piece, facilitating subsequent sampling.

[0027] Furthermore, the sampling location of the test piece is the area corresponding to the center of the test block. Because the mold is designed based on the shape of the test forging, which is composed of multiple test blocks, there is a one-to-one correspondence between the test piece and the test block. The center of the test block refers to the rectangular or cylindrical area at 1 / 2h and 1 / 2W of the test block, with a length of 1 / 2a. The sampling location of the test piece is the same position on the corresponding test block for different performance test items.

[0028] Furthermore, the length of the connecting end is b = 0.5h. The purpose of adding the connecting end is to ensure that the cooling state of the billet at both ends is consistent with that in the middle during cooling after forging. The longer the end, the more wasteful the raw material, so b = 0.5h is selected.

[0029] Furthermore, the electric furnace meets GJB904 Class II and has an accuracy of ±5°C.

[0030] Example 1

[0031] S1: Design and study the effects of five different deformation amounts (15%, 25%, 35%, 45%, and 55%) on the microstructure and properties of TC21 titanium alloy forgings. The test block dimensions were determined to be 110 mm × 90 mm × 75 mm (length × width × height). Multiple test blocks were arranged along the length to form an experimental forging. Each test block of 110 mm in length represented one deformation amount. Connecting ends of 40 mm were provided at both ends of the test blocks. A 10 mm diameter saw cut was reserved for each test block. The experimental forging dimensions were 680 mm × 90 mm × 75 mm (length × width × height). The corresponding mold was manufactured based on the experimental forgings.

[0032] S2: Billet design. Based on the dimensions of the experimental forging, the billet length was designed to be 670 mm and the width to be 80 mm. The final step heights were determined to be 88 mm, 100 mm, 115 mm, 136 mm, and 166 mm respectively.

[0033] S3: Cut the raw materials into the specifications of 670×80×166mm, and then use mechanical processing to process the 166mm thickness into steps of 88mm, 100mm, 115mm, 136mm, and 166mm respectively.

[0034] S4: The processed blank is placed in an electric furnace for heating. The electric furnace meets GJB904 Class II and has an accuracy of ±5°C. After being heated thoroughly, the blank is placed in a die for die forging and cooled after forging. After the forging is deburred, sandblasted, and polished, the forging is then heat treated to form a test piece.

[0035] S5: Sampling and testing. Samples are taken from the sampling positions of the test piece, that is, the positions where the deformation of the test piece is 15%, 25%, 35%, 45%, and 55%, for testing. According to the performance test results, statistical analysis is performed to obtain the influence of forging process parameters and microstructure properties, and determine the optimal forging process parameters.

[0036] The final tissue properties are shown in the following table:

[0037] Longitudinal mechanical properties of TC21 titanium alloy forgings

[0038]

[0039] From the above table, we can know that when the deformation of TC21 titanium alloy is 55%, the tensile strength is the highest; when the deformation is 55%, the yield strength is the highest; when the deformation is 25%, the elongation is the highest; when the deformation is 35%, the section shrinkage is the highest; when the deformation is 35%, the impact toughness is the highest; therefore, when selecting the forging deformation, if you want to ensure high tensile strength of the forging, select a deformation of 55% for TC21 titanium alloy; if you want to ensure high yield strength of the forging, select a deformation of 55% for TC21 titanium alloy; if you want to ensure high elongation of the forging, select a deformation of 25% for TC21 titanium alloy; if you want to ensure high shrinkage of the forging, select a deformation of 35% for TC21 titanium alloy; if you want to ensure high impact toughness of the forging, select a deformation of 35% for TC21 titanium alloy;

[0040] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-precision experimental method for determining forging process parameters, characterized by: The following steps are included: S1: Experimental forging design: select N test blocks with different deformations, with the deformations of the test blocks being ε1, ε2, ..., εn, respectively, where n ≥ 2. Each test block has a length a, a width w, and a height h, and w = (1.1-1.2) h. Arrange the test blocks along the length direction to form an experimental forging, and set connecting ends at both ends of the experimental forging. The connecting ends have a length b, a width w, and a height h. The length of the experimental forging is L = a*n+2b. Make a mold according to the size of the experimental forging. S2: Blank design. According to the position and deformation of each test block, the step corresponding to each test block on the blank is determined. The height of the step is h n =h / (1-εn), the length of each step is consistent with the length of the test block, and the width w1 of the blank satisfies h max / 3≤w1≤h min , and w1≤w; Blank length L1=LX, 0<X<0.5b; where h max is the maximum thickness of the blank, h min is the minimum thickness of the blank; S3: Billet manufacturing, the raw materials are divided into L1×w1×h max Cut to size or pre-forge, then machine the raw materials into billets; S4: Billet processing: the billet processed in S3 is placed in an electric furnace for heating. After being heated thoroughly, it is placed in a die for die forging and cooled after forging. After the forging is finished, the flash is removed, sandblasted, and polished, and then the forging is heat treated to form a test piece. S5: Sampling and testing: Take samples at the sampling position of the experimental piece for testing. According to the performance test results, statistical analysis is performed to obtain the influence of forging process parameters and microstructure properties, and determine the optimal forging process parameters.

2. A high-precision experimental method for determining forging process parameters according to claim 1, characterized in that: The test blocks are arranged in order from small to large deformation amounts.

3. A high-precision experimental method for determining forging process parameters according to claim 1, characterized in that: A saw cut is provided between two adjacent test blocks, and the length of the saw cut is 5 to 20 mm.

4. A high-precision experimental method for determining forging process parameters according to claim 1, characterized in that: The sampling position of the test piece is an area corresponding to the center position of the test block.

5. A high-precision experimental method for determining forging process parameters according to claim 1, characterized in that: The length of the connecting end is b=0.5h.

6. A high-precision experimental method for determining forging process parameters according to claim 1, characterized in that: The electric furnace meets GJB904 Class II and has an accuracy of ±5°C.

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