High-precision experimental method for determining forging process parameters

Abstract

The invention relates to the technical field of forging, in particular to a high-precision experimental method for determining forging process parameters. Comprising the following steps: S1, designing an experimental forge piece; s2, blank design; s3, blank manufacturing; s4, blank treatment; and S5, sampling and detecting. According to the method, the consistency of other parameters except variables in the forging process is improved, the influence of other parameters except variables on an experimental result is eliminated, the test blocks representing different deformations are consistent in thickness and width, the test blocks are spliced to form the experimental forge piece, the blank is designed according to the deformations of the test blocks of the experimental forge piece, and the experimental forge piece is obtained. The heating temperature of the blank in the electric furnace, the transfer time after discharging, the forging speed on the forging equipment and the cooling speed after forging are all the same, the experimental piece is finally obtained, and the deformation of each section of the experimental piece is consistent with the deformation of the test block. According to the experimental scheme, the obtained technological parameters have high accuracy, the material structure performance and the essential law of the technological parameters can be truly reflected, and the influence of variable external factors on the experimental result is eliminated.

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 more and more difficult to deform, and performance is becoming more and more 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 block before forging deformation is the same, and the thickness of the test block after deformation is different. Then it is processed into the same thickness by mechanical processing, and finally the same heat treatment system is used for simultaneous heat treatment; the second is that the initial thickness of the test block before forging deformation is different, and the thickness of the test block after deformation is the same, and then the same heat treatment system is used for simultaneous heat treatment. 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 organizational properties, especially for materials where hardenability has a greater impact on performance. The second test method can eliminate the differences in the heat treatment process. However, due to the difference in thickness 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 deformation amounts, the deformation amounts of the test blocks are ε1, ε2, ... εn, where n ≥ 2, the size of each test block is a, the width is w, the height is h, and w = (1.1 ~ 1.2) h, arrange multiple test blocks along the length direction to form an experimental forging, and set connecting ends at both ends of the experimental forging, the length of the connecting ends is b, the width is w, and the height is h, the length of the experimental forging L = a*n+2b, and manufacture the mold according to the size 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, and then machine the raw material into billets;

[0008] S4: Billet processing: the billet processed in S3 is placed in an electric furnace for heating, and after being heated thoroughly, it is placed in a die for die forging, and then cooled after forging; the forging is subjected to flash removal, sand blowing, and grinding, and then heat treatment is performed on the forging to form a test piece;

[0009] S5: Sampling and testing. Samples are taken at the sampling positions of the test pieces for testing. According to the performance test results, statistical analysis is performed to obtain the influence of forging process parameters on microstructure and performance, and determine the optimal forging process parameters.

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

[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 in the forging process, eliminates the influence of different parameters other than variables on the experimental results, the thickness and width of each test block representing different deformation amounts are consistent, and the experimental forging is formed after splicing, 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 transportation time of the blank out of the furnace, the forging speed on the forging equipment, and the cooling speed after forging are 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 the experimental scheme have high accuracy, can truly reflect the essential laws of material organization 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] Embodiments of the present invention are described in detail below, examples of which 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 only used to explain the present invention, and cannot be understood 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, the deformation amounts of the test blocks are ε1, ε2, ...εn respectively, where n≥2, the dimensions of each test block are length a, width w, height h, and w=(1.1~1.2)h, arrange multiple test blocks into an experimental forging along the length direction, and set connecting ends at both ends of the experimental forging, 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 manufacture a mold according to the size of the experimental forging; wherein connecting ends are set at both ends of the experimental forging, and there is also a corresponding area on the mold for forming the connecting ends, and finally after the billet is forged into the experimental piece, there is also a corresponding part of the connecting ends 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 area 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 satisfies 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 times 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. Therefore, the length of the blank L1 = LX, 0 < X ​​< 0.5b, and the length of each step is consistent with the length of the corresponding test block. S3: Blank manufacturing, the raw materials are 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 the blanks.

[0023] S4: Billet processing: the billet processed in S3 is placed in an electric furnace for heating, and after being heated thoroughly, it is placed in a die for die forging, and then cooled after forging; the forging is subjected to flash removal, sand blowing, and grinding, and then heat treatment is performed on the forging to form a test piece;

[0024] S5: Sampling and testing, see Figure 3 , at the sampling position of the experimental piece, take samples for testing respectively, and statistically analyze the results of the performance test to obtain the influence of forging process parameters and organizational properties, and determine the optimal forging process parameters. In the sampling process, it is necessary to sample all areas with different deformation amounts. For example, if the deformation amounts of the test block constituting the experimental forging are 5, then there are 5 deformation areas on the experimental piece corresponding to the deformation amounts of the test block, and these 5 areas need to be sampled.

[0025] In order to facilitate the processing of raw materials into blanks, further see Figure 2 The test blocks are arranged in order from large to small according to the deformation amount. 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, and the length of the saw cut is 5 to 20 mm. The cross-sectional dimension of the saw cut is smaller than the cross-sectional dimension of the test block, and the saw cut is waist-shaped as a whole, so that there is also an area on the mold that matches the saw cut. After the blank is formed into a test piece, the test piece also presents a saw cut, so that the areas with different deformation amounts on the test piece can be distinguished, which is convenient for subsequent sampling.

[0027] Furthermore, the sampling position of the test piece is the area corresponding to the center position of the test block. Since the mold is designed according to the shape of the test forging, and the test forging is composed of multiple test blocks, the test piece and the test block have a one-to-one correspondence. The center position of the test block refers to the rectangular or cylindrical area at 1 / 2h and 1 / 2W of the test block and with a length of 1 / 2a. For different performance test items, the sampling position of the test piece is at the same position of the corresponding test block.

[0028] Furthermore, the length of the connecting end is b = 0.5h. The purpose of adding the connecting end is to make the cooling state of the billet at both ends consistent with that in the middle during cooling after forging. The longer the length of the end, the more the raw material is wasted, 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 5 groups of different deformations (15%, 25%, 35%, 45%, 55%) on the microstructure and properties of TC21 titanium alloy forgings. Determine the test block size of 110mm×90mm×75mm (length×width×height). Arrange multiple test blocks along the length direction to form an experimental forging. Each test block with a length of 110 represents a deformation. Set the connecting ends of the test blocks at both ends with 40mm. Each test block has a reserved saw cut of 10mm in diameter. The size of the experimental forging is 680mm×90mm×75mm (length×width×height). Make the corresponding mold according to the experimental forging.

[0032] S2: Billet design. According to the size of the experimental forging, the billet length is designed to be 670 mm and the width is 80 mm. The heights of the steps are finally determined to be 88 mm, 100 mm, 115 mm, 136 mm, and 166 mm respectively.

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

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

[0035] S5: Sampling and testing. Samples are taken at the sampling positions of the test piece, that is, at 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 organizational 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 the high tensile strength of the forging, select the deformation of TC21 titanium alloy as 55%;, if you want to ensure the high yield strength of the forging, select the deformation of TC21 titanium alloy as 55%;, if you want to ensure the high elongation of the forging, select the deformation of TC21 titanium alloy as 25%;, if you want to ensure the high shrinkage of the forging, select the deformation of TC21 titanium alloy as 35%; if you want to ensure the high impact toughness of the forging, select the deformation of TC21 titanium alloy as 35%;

[0040] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope 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 protection scope of the present invention.

Claims

1. A high-precision experimental method for determining forging process parameters, characterized in that: The following steps are included: S1: Experimental forging design, select N test blocks with different deformation amounts, the deformation amounts of the test blocks are ε1, ε2, ... εn, where n ≥ 2, the size of each test block is a, the width is w, the height is h, and w = (1.1 ~ 1.2) h, arrange multiple test blocks along the length direction to form an experimental forging, and set connecting ends at both ends of the experimental forging, the length of the connecting ends is b, the width is w, and the height is h, the length of the experimental forging L = a*n+2b, and manufacture the 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; S3: Billet manufacturing, the raw materials are divided into L1×w1×h max Cut to size or pre-forge, and then machine the raw material into billets; S4: Billet processing: the billet processed in S3 is placed in an electric furnace for heating, and after being heated thoroughly, it is placed in a die for die forging, and then cooled after forging; the forging is subjected to flash removal, sand blowing, and grinding, and then heat treatment is performed on the forging to form a test piece; S5: Sampling and testing. Samples are taken at the sampling positions of the test pieces for testing. According to the performance test results, statistical analysis is performed to obtain the influence of forging process parameters on microstructure and performance, 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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