50Cr5NiMoV alloy forging parameter optimization method
By optimizing the forging parameters of 50Cr5NiMoV alloy through damage model and finite element simulation, the cracking problem in the roughening process was solved, efficient and precise forming was achieved, and the yield and mechanical properties were improved.
Patent Information
- Application Number
- CN202510824326.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-19
- Publication Date
- 2025-09-16
AI Technical Summary
There is a significant cracking problem in the traditional roughening process. The existing technology lacks systematic research on the correlation mechanism between the geometry of the blank and the material damage value, resulting in process optimization relying on empirical trial and error, which is difficult to meet the requirements of modern manufacturing for efficient and precise forming.
The influence of the blank geometry on the surface cracking of the pier was analyzed through damage model simulation. The damage model was established by combining the Normalized Cockcroft&Latham and Zener-Hollomon parameters. The blank design was optimized to reduce the damage value. The cracking risk was predicted using finite element simulation and the process parameters were optimized.
It significantly improves the yield rate and mechanical properties, provides a scientific basis for process optimization, reduces the risk of cracking, and improves processing quality and efficiency.
Smart Images
Figure CN120654494A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of metal plastic forming, in particular to a method for optimizing forging parameters of a 50Cr5NiMoV alloy. Background Art
[0002] Roughening is a key forming method in metal plastic forming. However, conventional cylindrical blanks suffer from significant cracking during this process. This is primarily due to the significantly uneven internal stress distribution during axial compression. Constrained by friction at the die-blank interface, the metal material experiences significant circumferential tensile stress concentration in the central region of the blank during flow. When this stress exceeds the material's fracture limit, microcracks initiate and gradually expand on the blank's surface, ultimately leading to macroscopic cracking defects that severely impact product yield and mechanical properties.
[0003] At present, there are significant technical defects in the optimization of the upsetting process, which is mainly reflected in the fact that the process improvement method is still at the empirical adjustment stage and relies heavily on trial and error experiments to explore suitable process parameters. This traditional method not only consumes a lot of time and material costs, but also has a long optimization cycle, which makes it difficult to meet the requirements of modern manufacturing for efficient and precise forming. More importantly, the existing technology system fails to apply advanced damage mechanics theory to the process optimization process, and lacks a systematic study of the correlation mechanism between the geometry of the blank (such as key parameters such as diameter, aspect ratio, profile curvature) and the material damage value (including damage factor distribution, critical damage threshold, etc.). Therefore, the present invention proposes a 50Cr5NiMoV alloy forging parameter optimization method to solve the problems existing in the prior art. Summary of the Invention
[0004] In response to the above problems, the purpose of the present invention is to propose a 50Cr5NiMoV alloy forging parameter optimization method. This 50Cr5NiMoV alloy forging parameter optimization method analyzes the influence of billet geometry on the surface cracking of the upsetting through damage model simulation, and optimizes the billet design to reduce the damage value. Then, by combining the damage model simulation with the billet geometry optimization, the cracking risk is quantitatively predicted, which can solve the problems in the prior art.
[0005] To achieve the purpose of the present invention, the present invention is implemented by the following technical solution: a 50Cr5NiMoV alloy forging parameter optimization method, comprising the following steps:
[0006] Step 1: Prepare Cr5 backup roller steel as the metal material to be tested, conduct a hot tensile test on it, obtain tensile data, and then process the tensile data to extract the first data parameter;
[0007] Step 2: Based on the extracted first data parameters, calculate the critical damage values of Cr5 backup roller steel at different temperatures and speeds, and then establish a damage model by combining the Normalized Cockcroft & Latham and Zener-Hollomon parameters;
[0008] Step 3: Establish finite element models for the upsetting process of conventional cylindrical billets and thin waist-shaped billets. Combined with the damage model in step 2, simulate the damage evolution of the material during the upsetting process of different billet shapes and extract the second data parameters.
[0009] Step 4: Determine the spatial distribution of damage variables during the upsetting process of conventional cylindrical billets and thin waist-shaped billets by simulating different process parameters, and predict the crack propagation path to minimize damage and maximize forming quality.
[0010] Further improvement is that in step 1, the conditions of the tensile test are: deformation temperature is 900℃, 1000℃, 1100℃ and 1200℃, strain rate is 0.001s -1 , 0.01s -1 , 0.1s -1 and 1s -1 .
[0011] Further improvement is that the specific steps of the hot tensile test are:
[0012] S1. Cut the metal material to be tested into a uniaxial tensile specimen;
[0013] S2. Performing a uniaxial tensile test on the uniaxial tensile specimen to obtain tensile data of the metal material to be tested;
[0014] S3. Extract the stretching data to obtain a first data parameter.
[0015] A further improvement is that in step 1, the first data parameter includes elastic modulus, yield strength, fracture strain, ultimate true stress and tensile strength.
[0016] A further improvement is that in step 2, the specific steps of establishing the damage model are:
[0017] A1. Select the Normalized Cockcroft & Latham damage model, which is expressed as:
[0018]
[0019] Where C is the critical damage value, is the strain at material fracture, is the equivalent strain, σ1 is the principal stress, is the equivalent stress;
[0020] A2. Based on the damage model in A1 and the critical damage values at different temperatures and rates, a graph showing the change of critical damage value with thermal deformation parameters is obtained;
[0021] A3, coupled Zener-Hollomon parameter correction model;
[0022] A4. Then, the ln Z value at different deformation temperatures and strain rates is calculated, and the relationship between the critical damage value and Z is established. Finally, the Cr5 steel hot deformation damage cracking criterion is obtained after fitting:
[0023]
[0024] Where D is the damage evolution.
[0025] A further improvement is that in step three, the second data parameter includes damage variables, stress distribution and strain localization.
[0026] A further improvement is that in step 3, the specific steps of simulating damage evolution are:
[0027] B1. Based on the pier roughing design drawing and the pier roughing deformation distribution plan, use 3D software to draw the 3D geometric model of the initial blank;
[0028] B2. Import the 3D geometric model into the finite element software SIMUFACT FORMING and set the parameters;
[0029] B3. Use the hot forming module of finite element software SIMUFACT FORMING to perform simulation;
[0030] B4. Extract the second data parameter according to the simulation result.
[0031] A further improvement is that in step 4, the process parameters include temperature, pressing speed and upset ratio.
[0032] The beneficial effects of the present invention are:
[0033] This method combines damage model simulation with billet geometry optimization to quantitatively predict cracking risk. Thermal tensile testing is used to obtain material mechanical parameters at different temperatures and strain rates. The damage model is then developed using the Normalized Cockcroft & Latham damage criterion and Zener-Hollomon parameters to quantify the material fracture risk. Finite element simulation is then used to analyze the damage evolution of conventional cylindrical and waisted billets, optimizing billet shape and process parameters. This method provides a scientific, quantitative optimization basis for the roughening process, significantly improving yield and mechanical properties, and possesses significant engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 It is a schematic flow chart of the steps of the present invention.
[0035] Figure 2 It is a schematic diagram of stress-strain curves obtained by processing tensile test data at different temperatures and rates according to the present invention.
[0036] Figure 3 It is a schematic diagram of the change of the critical damage value with the thermal deformation parameter of the present invention.
[0037] Figure 4 It is a schematic diagram of the pre-processing model for roughening simulation of conventional cylindrical blanks and thin waist-shaped blanks of the present invention.
[0038] Figure 5 It is a schematic diagram of the damage value results of the post-processing of the upsetting simulation of the conventional cylindrical blank and the thin waist-shaped blank of the present invention. DETAILED DESCRIPTION
[0039] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the examples. The examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.
[0040] The improvement measures commonly used in current engineering practice mainly include optimizing the friction conditions of the mold surface and regulating the forming temperature field. Although these methods can alleviate the cracking problem to a certain extent, they still have obvious limitations: the adjustment range of the friction coefficient is limited by process conditions and cannot completely eliminate stress concentration; while temperature control faces new problems such as high-temperature oxidation and grain coarsening. More importantly, existing methods fail to start from the essential mechanism of material damage evolution and lack the ability to quantitatively characterize and analyze the cumulative behavior of material damage during deformation. As a result, process optimization lacks a scientific basis and still relies heavily on empirical trial and error. This is not only costly, but also difficult to achieve sustained and stable improvement results. This current situation of insufficient understanding of material damage behavior has become a key bottleneck restricting the improvement of the quality of the roughening process.
[0041] Therefore, according to Figure 1-Figure 5 As shown, this embodiment proposes a 50Cr5NiMoV alloy forging parameter optimization method, comprising the following steps:
[0042] Step 1: Prepare Cr5 support roller steel as the metal material to be tested, and then conduct a hot tensile test on it. Considering the actual hot working range of Cr5 steel, the deformation temperatures are selected as 900℃, 1000℃, 1100℃ and 1200℃, and the strain rate is 0.001s -1 , 0.01s -1 , 0.1s -1 and 1s -1, obtaining tensile data, and then processing the tensile data to extract first data parameters, including elastic modulus, yield strength, fracture strain, ultimate true stress and tensile strength;
[0043] Furthermore, the specific steps of the hot tensile test are as follows:
[0044] S1. Cut the metal material to be tested into a uniaxial tensile specimen;
[0045] S2. Conducting a uniaxial tensile test on the uniaxial tensile specimen to obtain tensile data of the metal material to be tested, which corresponds to a stress-strain curve of the metal material to be tested;
[0046] S3. Extract the stretching data to obtain a first data parameter.
[0047] The stress-strain curve after treatment is as follows Figure 2 shown.
[0048] Step 2: Based on the extracted first data parameters, calculate the critical damage values of Cr5 backup roller steel at different temperatures and speeds, and then establish a damage model by combining the Normalized Cockcroft & Latham and Zener-Hollomon parameters;
[0049] Specifically, the steps to establish the damage model are as follows:
[0050] A1. Select the Normalized Cockcroft & Latham damage model, which is expressed as:
[0051]
[0052] Where C is the critical damage value, is the strain at material fracture, is the equivalent strain, σ1 is the principal stress (MPa), is the equivalent stress (MPa). Since the cracks during thermal stretching are mainly caused by the stress in the tensile direction, ε1 can be used instead in the calculation.
[0053] A2. Based on the damage model in A1 and the critical damage values at different temperatures and rates, the graph showing the critical damage value changing with the thermal deformation parameters is obtained, as shown in Figure 3 As shown;
[0054] A3. Coupled Zener-Hollomon parameter correction model, that is, after comprehensively considering the influence of stress state and thermal deformation parameters on damage and fracture behavior, the new criterion function is established on the right side by using Zener-Hollomon that comprehensively considers temperature and strain rate. The parameter is replaced by the following:
[0055]
[0056] Where f1(σ) is the stress state function, is the thermal deformation parameter function, T is the deformation temperature, is the strain rate, σ is
[0057] A4. Then, the ln Z value at different deformation temperatures and strain rates is calculated, and the relationship between the critical damage value and Z (Zener-Hollomon parameter) is established. Finally, the Cr5 steel hot deformation damage cracking criterion is obtained after fitting:
[0058]
[0059] Where D is the damage evolution.
[0060] Step 3: Establish finite element models for the upsetting process of conventional cylindrical and waist-shaped billets. Combined with the damage model from Step 2, simulate the damage evolution of the material during the upsetting process of different billet shapes and extract secondary data parameters, including damage variables, stress distribution, and strain localization.
[0061] Specifically, the steps for simulating damage evolution are as follows:
[0062] B1. Based on the pier roughing design drawing and the pier roughing deformation distribution plan, use 3D software to draw a 3D geometric model of the initial blank. In this embodiment, SW software is used to draw the 3D geometric model of the initial blank and save it as an .STL file;
[0063] B2. Import the 3D geometric model (.STL file) into the finite element software SIMUFACT FORMING and set the parameters, including the positions of the cover plate, steel ingot and drain pan, such as Figure 3 As shown;
[0064] B3. Use the hot forming module in the finite element software SIMUFACT FORMING for simulation. Select the hot forming module in the software and define the constraints and load conditions for the upper and lower molds. Then, divide the steel ingot into a tetrahedral mesh and assign material properties. Manually define the performance values and damage values obtained from Cr5 steel experiments in the material library. Next, set the heat conductivity coefficients of the cover plate and drain pan to the environment and the heat transfer coefficients to the steel ingot. Set the ambient temperature and the ingot temperature. Finally, set the damage evolution law and start the simulation.
[0065] B4. Extract the second data parameter according to the simulation result.
[0066] Step 4: By simulating different process parameters (including temperature, reduction speed, and upset ratio), the spatial distribution of damage variables during the upset of conventional cylindrical and thin waisted billets is determined, and the crack propagation path is predicted to minimize damage and maximize forming quality. This involves comparing the maximum damage values on the surfaces of the two billets, analyzing the cracking risk areas, and analyzing the forming uniformity.
[0067] Furthermore, the simulation specific steps include:
[0068] SS1: Simulate the roughening process of conventional cylindrical blanks with a temperature of 1000℃, a pressing speed of 12mm / s and a roughening ratio of 2.1. Figure 4 (Right) It can be seen that the maximum damage value on the ingot surface is 0.46;
[0069] SS2: Simulate the roughening process of a thin waist-shaped billet with a temperature of 1000℃, a pressing speed of 12mm / s, and a roughening ratio of 2.1. Figure 4 (Left) It can be seen that the maximum damage value on the ingot surface is 0.30;
[0070] SS3: simulates the roughening process of a thin-waisted billet at a temperature of 1100°C, a reduction speed of 12 mm / s, and a roughening ratio of 2.1. The maximum damage value on the ingot surface is 0.37.
[0071] SS4: Simulating the roughening process of a thin-waisted billet at a temperature of 1200°C, a reduction speed of 12 mm / s, and a roughening ratio of 2.1. The maximum damage value on the ingot surface was 0.52, exceeding the critical damage value and posing a risk of cracking.
[0072] SS5: simulates the roughening process of a thin-waisted billet at a temperature of 1000°C, a reduction speed of 12 mm / s, and a roughening ratio of 2.2. The maximum damage value on the ingot surface is 0.38.
[0073] SS6: simulates the roughening process of a thin-waisted billet at a temperature of 1100°C, a reduction speed of 12 mm / s, and a roughening ratio of 2.2. The maximum damage value on the ingot surface is 0.44.
[0074] SS7: Simulating the roughening process of a thin-waisted billet at a temperature of 1200°C, a reduction speed of 12 mm / s, and a roughening ratio of 2.2. The maximum damage value on the ingot surface was 0.57, exceeding the critical damage value and posing a risk of cracking.
[0075] SS8: simulates the roughening process of a thin-waisted billet at a temperature of 1000°C, a reduction speed of 12 mm / s, and a roughening ratio of 2. The maximum damage value on the ingot surface is 0.28.
[0076] SS9: simulates the roughening process of a thin-waisted billet at a temperature of 1100°C, a reduction speed of 12 mm / s, and a roughening ratio of 2. The maximum damage value on the ingot surface is 0.31.
[0077] SS10: Simulating the roughening process of a thin-waisted billet at a temperature of 1200°C, a reduction speed of 12 mm / s, and a roughening ratio of 2. The maximum damage value on the ingot surface is 0.51, which exceeds the critical damage value and has a risk of cracking.
[0078] Results show that the surface damage value of thin-waisted billets can be significantly reduced at temperatures between 1000 and 1100°C and an upset ratio of 2 to 2.1, with the maximum damage value dropping from 0.46 to 0.30, effectively suppressing cracking. This invention combines damage model simulation with billet geometry optimization to quantitatively predict cracking risk. Damage model simulation demonstrates that thin-waisted billets can effectively reduce surface damage values, and forging at processing temperatures between 1000 and 1100°C and upset ratios between 2 and 2.1 reduces the risk of cracking. This method can provide a quantitative optimization basis for upset process parameters (such as die design and billet shape). It has high practical value and broad application prospects.
[0079] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the framework and scope of application of the present invention. Such changes and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for optimizing forging parameters of 50Cr5NiMoV alloy, characterized by: The following steps are involved: Step 1: Prepare Cr5 backup roller steel as the metal material to be tested, conduct a hot tensile test on it, obtain tensile data, and then process the tensile data to extract the first data parameter; Step 2: Based on the extracted first data parameters, calculate the critical damage values of Cr5 backup roller steel at different temperatures and speeds, and then establish a damage model by combining the Normalized Cockcroft & Latham and Zener-Hollomon parameters; Step 3: Establish finite element models for the upsetting process of conventional cylindrical billets and thin waist-shaped billets. Combined with the damage model in step 2, simulate the damage evolution of the material during the upsetting process of different billet shapes and extract the second data parameters. Step 4: Determine the spatial distribution of damage variables during the upsetting process of conventional cylindrical billets and thin waist-shaped billets by simulating different process parameters, and predict the crack propagation path to minimize damage and maximize forming quality.
2. The 50Cr5NiMoV alloy forging parameter optimization method according to claim 1, characterized in that: In step 1, the conditions of the tensile test are as follows: deformation temperatures are 900°C, 1000°C, 1100°C and 1200°C, respectively, and strain rates are 0.001s -1 , 0.01s -1 , 0.1s -1 and 1s -1 .
3. The 50Cr5NiMoV alloy forging parameter optimization method according to claim 1, characterized in that: The specific steps of the hot tensile test are: S1. Cut the metal material to be tested into a uniaxial tensile specimen; S2. Performing a uniaxial tensile test on the uniaxial tensile specimen to obtain tensile data of the metal material to be tested; S3. Extract the stretching data to obtain a first data parameter.
4. The method for optimizing forging parameters of a 50Cr5NiMoV alloy according to claim 1, wherein: In the step 1, the first data parameters include elastic modulus, yield strength, fracture strain, ultimate true stress and tensile strength.
5. The method for optimizing forging parameters of a 50Cr5NiMoV alloy according to claim 1, wherein: In step 2, the specific steps of establishing the damage model are: A1. Select the Normalized Cockcroft & Latham damage model, which is expressed as: Where C is the critical damage value, is the strain at material fracture, is the equivalent strain, σ1 is the principal stress, is the equivalent stress; A2. Based on the damage model in A1 and the critical damage values at different temperatures and rates, a graph showing the change of critical damage value with thermal deformation parameters is obtained; A3, coupled Zener-Hollomon parameter correction model; A4. Then, the ln Z value at different deformation temperatures and strain rates is calculated, and the relationship between the critical damage value and Z is established. Finally, the Cr5 steel hot deformation damage cracking criterion is obtained after fitting: Where D is the damage evolution.
6. The method for optimizing forging parameters of a 50Cr5NiMoV alloy according to claim 1, wherein: In step three, the second data parameters include damage variables, stress distribution, and strain localization.
7. The method for optimizing forging parameters of a 50Cr5NiMoV alloy according to claim 1, wherein: In step 3, the specific steps of simulating damage evolution are as follows: B1. Based on the pier roughing design drawing and the pier roughing deformation distribution plan, use 3D software to draw the 3D geometric model of the initial blank; B2. Import the 3D geometric model into the finite element software SIMUFACT FORMING and set the parameters; B3. Use the hot forming module of finite element software SIMUFACT FORMING to perform simulation; B4. Extract the second data parameter according to the simulation result.
8. The method for optimizing forging parameters of a 50Cr5NiMoV alloy according to claim 1, wherein: In the step 4, the process parameters include temperature, pressing speed and roughness ratio.