A method for optimizing medium-high temperature control rolling parameters of marine high-magnesium aluminum alloy

Abstract

The application discloses a kind of high magnesium aluminum alloy of marine high temperature temperature control rolling parameter optimization method.This method is: from the square block sample of plane strain hot simulation in aluminium alloy;Hot simulation plane strain compression is carried out, and the orthogonal experimental data of high temperature hot simulation true stress-true strain is obtained;Based on the theory of irreversible thermodynamics, power dissipation diagram and plastic instability diagram are constructed;Power dissipation diagram and plastic instability diagram are superimposed to obtain the hot processing diagram of the aluminium alloy at the set temperature, and the safe area and instability area are divided, and the process parameters in the process of high temperature temperature control rolling are determined according to the safe area under different strains, to obtain the rolling piece that meets the requirements of size accuracy and mechanical properties.In the technical scheme of the application, three-dimensional processing diagram reflects the influence of deformation temperature, strain and strain rate on the hot deformation processability of material, and can comprehensively reflect the processability of material, and perfectly process design and optimization for high temperature temperature control rolling.

Description

Technical Field

[0001] This invention relates to three-dimensional hot working diagrams and belongs to the field of thermoplastic forming of non-ferrous metal materials. In particular, it relates to a method for optimizing medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloys. Background Technology

[0002] As ships grow larger, engineers have had to find alternative materials to reduce their weight. Meanwhile, technological advancements have enabled aluminum alloys to approach the conventional mechanical properties required by low-carbon steel in shipbuilding. Combined with aluminum alloys' superior lightweight, corrosion resistance, and low maintenance costs, they have gradually come to dominate half of the metal materials used in shipbuilding.

[0003] The preparation and processing of marine aluminum alloys mainly involves ingot casting, homogenization, hot rolling, intermediate annealing, cold rolling, stabilization annealing, and final product. Current research largely focuses on the impact of parameter variations at a specific step in the traditional process on the alloy, such as cold rolling deformation, stabilization annealing temperature, and holding time. However, the production of 5-series aluminum alloy sheets no longer requires so many steps; hot-rolled sheets are now the finished product. With continuous advancements in rolling technology, after homogenization, finished sheets can be obtained through medium-to-high temperature controlled rolling. While reducing the number of process steps, the performance of products produced using traditional methods can still be achieved. However, relying solely on empirical parameters currently results in low yield rates in industrial production, primarily due to processing cracks and insufficient strength. Therefore, it is necessary to optimize the medium-to-high temperature controlled rolling process parameters to improve product yield and meet the needs of the marine lightweight engineering structural materials field.

[0004] Patent CN114309117A discloses a temperature-controlled rolling method for manufacturing 5xxx aluminum alloy sheets. This patent establishes a temperature-controlled rolling process for 5083H321 marine high-magnesium alloy sheets (milling of ingots → heating → temperature-controlled rolling → stretching → cutting → packaging), which can replace the old production process (milling of ingots → heating → hot rolling → intermediate annealing → cold working → straightening → stabilization annealing → stretching → cutting → packaging), significantly reducing production costs. However, the most crucial parameter control method in temperature-controlled rolling relies on empirical parameters, which carries the risk of long trial-and-error times and inconsistent product yield. Therefore, it is necessary to combine theoretical methods to predict the thermal stability of the temperature-controlled rolling process.

[0005] Patent CN113158406A discloses a method for predicting the hot working stability of pure aluminum alloys. This patent conducts a cylindrical sample compression simulation experiment on pure aluminum alloys during rolling processing. It quantitatively establishes an instability diagram of pure aluminum alloys during hot deformation based on the Prasad instability criterion, thereby determining the stable and unstable regions of the alloy during plastic deformation, forming a two-dimensional hot working diagram, and identifying the optimal processing region and unstable region. This will be helpful in judging the machinability of materials under different processing conditions, optimizing the process parameters of the hot deformation process of pure aluminum alloys, and guiding the rolling processing of materials.

[0006] The above method uses cylindrical specimens to conduct thermal simulation experiments to obtain two-dimensional thermal working diagrams to guide the rolling process of materials. However, this method does not eliminate the friction effect and edge effect at the specimen ends. During compression, the friction coefficient changes exponentially with the increase of true strain. Under large strain, the increase in friction coefficient will lead to a significant increase in rheological stress and may cause "bulging" deformation, that is, the specimen deformation is not uniform. The data obtained by this method deviates significantly from the actual rolling process. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art. By using plane strain compression, the stress state, heat conduction, and deformation state are more closely similar to rolling, providing a method for optimizing medium- and high-temperature controlled rolling parameters for marine high-magnesium aluminum alloys. This avoids the waste of materials caused by relying on empirical parameters for lengthy experiments, and can quickly and fully exploit the thermoplastic properties of the material. In the technical solution of this invention, the three-dimensional processing diagram reflects the influence of deformation temperature, strain, and strain rate on the hot deformation machinability of the material, comprehensively reflecting the material's machinability and providing complete process design and optimization for medium- and high-temperature controlled rolling.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for optimizing the medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloys includes the following steps:

[0010] Step (1): Cut a block sample for plane strain thermal simulation from the aluminum alloy after homogenization treatment before hot rolling.

[0011] Step (2): Based on the rolling process temperature range, strain rate and strain of different aluminum alloy materials, set the thermal simulation temperature, strain rate and strain, and perform thermal simulation plane strain compression at different temperatures and strain rates to obtain the medium and high temperature thermal simulation true stress-true strain orthogonal experimental data of the alloy.

[0012] Step (3): Obtain the stress peak values ​​corresponding to different strains, deformation temperatures, and strain rates through multiple sets of true stress-strain curves, and perform interpolation to calculate the flow stress values ​​at the selected node temperature and strain rate intervals.

[0013] Step (4): Based on the mechanics of large plastic deformation continuum, physical system simulation, and irreversible thermodynamics, the strain rate sensitivity index m is calculated, and then the dissipation rate factor η and the instability criterion are calculated. By matrixing the strain rate and deformation temperature data respectively, a power dissipation diagram based on a dynamic material model and a plastic instability diagram based on a plastic instability judgment criterion are constructed.

[0014] Step (5): Overlay the power dissipation diagram and the plastic instability diagram to obtain the hot working diagram of the aluminum alloy at the set temperature, and divide the safe zone and the unstable zone. Similarly, make hot working diagrams under different strains, and then draw a three-dimensional hot working diagram containing strain changes.

[0015] Step (6): Different reduction amounts in different rolling passes correspond to different strains. Based on the safe zone under different strains in the three-dimensional thermal processing diagram, it is helpful to select the temperature and strain rate for thermoplastic forming of aluminum alloy, determine the process parameters in the medium and high temperature controlled rolling process, and obtain rolled parts that meet the requirements of dimensional accuracy and mechanical properties.

[0016] Preferably, the aluminum alloy is a marine 5-series (Al-xMg) aluminum alloy.

[0017] Preferably, the size of the block sample used for plane strain thermal simulation in step (1) is 10×10×15mm or 10×15×20mm.

[0018] Preferably, in the plane strain thermal simulation experiment in step (2), the temperature range is 200-500℃ and the strain rate is 0.005-15s. -1 The orthogonal group setting should be at least 4×4 or higher; the dependent variable should be a reduction in height of 60% or higher.

[0019] Preferably, in step (3), the deformation temperature and strain rate data are interpolated using the cubic spline interpolation method with Origin software.

[0020] Preferably, in step (4), the strain rate is adjusted by the stress σ at each temperature. Differentiation yields the strain rate sensitivity index The dissipation rate factor is obtained by calculating the strain rate sensitivity index m. The instability criterion function and its range are obtained by calculating the strain rate sensitivity index m:

[0021]

[0022] Preferably, in step (5), at temperature T and strain rate... Range A matrix-based distribution diagram shows that rheological instability occurs in the negative value region; such a diagram is called an instability diagram, which corresponds to the instability region in a hot working diagram. Typical microscopic phenomena in the instability region of unstable rheology include adiabatic shear bands, local deformation, dynamic strain failure, mechanical twinning, and torsion; the safe region is characterized by microscopic mechanisms such as dynamic recrystallization, dynamic recovery, and superplastic deformation.

[0023] Preferably, the temperature-controlled rolling strain rate in step (2) is achieved by controlling the thickness of the workpiece at the rolling inlet and outlet, the rolling speed, and the roll radius;

[0024] The process parameters for temperature-controlled forming of medium- and high-temperature rolling are determined based on the average strain rate in the vertical direction of the rolled plate. Average strain ε, inlet thickness h1, outlet thickness h2, rolling speed V R The relationship with the roll radius R was calculated as follows:

[0025]

[0026] Preferably, the steps of the plane strain thermal simulation experiment are as follows: the sample is heated at a rate of 5℃ / s, and after reaching 500℃, it is held at that temperature for three minutes. Then, the sample is cooled at a certain rate (1℃ / s before reaching 400℃, and 5℃ / s below 400℃). After cooling to the set temperature, the plane strain compression experiment is started according to the strain rate of the orthogonal experimental group. When the strain is 60% of the height reduction, the compression is stopped, and the sample is quickly quenched.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) Based on the true stress σ and true strain ε data obtained from the plane strain compression experiment, the stress state, heat conduction and deformation state are closer to the rolling process. It can more accurately reflect the hot deformation behavior of the alloy during the hot rolling process of aluminum alloy, and can reflect more information such as the adiabatic shear band, local deformation and dynamic strain failure in the microstructure. It has certain guiding significance for the optimization of aluminum alloy temperature control rolling process and microstructure.

[0029] (2) The present invention draws a three-dimensional hot working diagram that takes into account the effects of deformation temperature T, strain rate and strain ε. This diagram can comprehensively reflect the machinability of the material and provide complete process design and optimization for medium and high temperature controlled rolling. Processing within the determined safe area can not only effectively avoid instability defects such as local flow and grain coarsening, but also obtain a microstructure with complete dynamic recrystallization, which greatly improves the performance and quality of the product.

[0030] (3) The method described in this invention is applicable to the parameter optimization of medium and high temperature controlled rolling of various deformed aluminum alloys, which can reduce the cost of trial and error, save product development time, and effectively improve the yield rate. Attached Figure Description

[0031] Figure 1 The sample of Example 1 was subjected to strain rate True stress-strain curves under the given conditions.

[0032] Figure 2 The image shows the heat treatment process of the sample in Example 1 when the true strain is 1.0, as well as the deformation structure in the corresponding unstable region.

[0033] Figure 3 The image shows the heat treatment diagram and the corresponding deformation structure in the safe zone when the true strain of the sample in Example 1 is 1.0.

[0034] Figure 4 The image shown is a three-dimensional thermal processing diagram with strain changes as described in Example 1. The horizontal axis represents the deformation temperature, the vertical axis represents the strain rate, the vertical direction represents the strain, the gray area represents the safe zone, and the colored area represents the unstable zone.

[0035] Figure 5 The image shows the metallographic structure of the anodic coating of the defective product sample before adjustment as described in Example 1.

[0036] Figure 6 The image shows the metallographic structure of the anodic coating of the qualified product sample after adjustment as described in Example 1. Detailed Implementation

[0037] Figure 7 The image shown in Example 2 is a three-dimensional thermal processing diagram with strain changes. The horizontal axis represents the deformation temperature, the vertical axis represents the strain rate, the vertical direction represents the strain, the gray area represents the safe zone, and the colored area represents the unstable zone.

[0038] Figure 8 The image shown in Example 3 is a three-dimensional thermal processing diagram with strain changes. The horizontal axis represents the deformation temperature, the vertical axis represents the strain rate, the vertical direction represents the strain, the gray area represents the safe zone, and the colored area represents the unstable zone.

[0039] The following examples further illustrate the specific implementation of the present invention, but the implementation and protection of the present invention are not limited to the following embodiments.

[0040] Example 1

[0041] A method for optimizing the medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloys includes the following steps:

[0042] The material is grade 5383 aluminum alloy, which is an Al-4.0Mg high magnesium aluminum alloy.

[0043] Step (1): In this embodiment, a plane strain compression experiment was used to conduct a rolling heat simulation experiment. Twenty 10×10×15mm sections were machined from the aluminum alloy after homogenization treatment before hot rolling using wire cutting. 3 Square specimen.

[0044] Step (2): Based on the rolling process of 5383 aluminum alloy, the infeed temperature is 500℃ and the final product exit temperature is 300℃. Therefore, the thermal simulation temperature range is determined to be 300-500℃, with a level selected every 50℃, for a total of five levels. Using the existing rolling data from the factory and the formula for calculating the relationship between the reduction amount and strain rate for each pass, the strain rate range required for thermal simulation is obtained as 0.05s. -1 -10s -1 Therefore, the strain rates for the thermal simulation tests were designed to be 0.05, 0.5, 5, and 10 s⁻¹. -1 There are four levels in total.

[0045] The thermal simulation experiment simulated the rolling process as closely as possible. In multi-pass continuous rolling, the temperature drop was slower before 400℃ in the preceding passes and faster after 400℃. Therefore, the specific experimental procedure was as follows: 20 sets of tests were conducted on the Gleeble-3500 thermal simulation testing machine. The sample was heated at a rate of 5℃ / s, held at 500℃ for 3 minutes, and then cooled at a certain rate (1℃ / s before 400℃, and 5℃ / s below 400℃). A single-factor experimental method was adopted. After cooling to the set temperature, the plane strain compression experiment was started according to the strain rate of the orthogonal experimental group. The compression was stopped when the strain was 60% of the height reduction. The sample was then quickly quenched by water cooling to preserve the deformed structure as much as possible, which facilitated the study of the microstructure of the sample.

[0046] Step (3): Using the true stress-strain curve (e.g.) Figure 1 As shown, the stress peak values ​​corresponding to deformation temperature and strain rate when the strain is 0.3, 0.5, 0.7, and 1.0 are obtained, and interpolation is performed to calculate the flow stress value at the selected nodal temperature and strain rate interval.

[0047] Step (4): Based on the mechanics of large plastic deformation continuum, physical system simulation, and irreversible thermodynamics, the stress σ at each temperature is used to measure the strain rate. Differentiation yields the strain rate sensitivity index The dissipation rate factor is obtained by calculating the strain rate sensitivity index m. The instability criterion function and its range are obtained by calculating the strain rate sensitivity index m:

[0048]

[0049] By matrixing the strain rate and deformation temperature data, power dissipation diagrams based on a dynamic material model and plastic instability diagrams based on plastic instability judgment criteria are constructed. At temperature T and strain rate... Range A matrix-based distribution diagram of rheology shows rheological instability in the negative value region; such a diagram is called an instability diagram, corresponding to the instability region in a heat treatment diagram. Typical microscopic phenomena in the instability region of unstable rheology include adiabatic shear bands and localized deformation, such as... Figure 2 As shown; the safe region is characterized by microscopic mechanisms such as dynamic recrystallization, dynamic recovery, and superplastic deformation, such as... Figure 3 As shown.

[0050] Step (5): Overlay the power dissipation diagram and the plastic instability diagram to obtain the hot working diagram of the aluminum alloy at the set temperature, and divide the safe zone and the instability zone. Similarly, make hot working diagrams under different strains, and then draw a three-dimensional hot working diagram including strain changes, such as... Figure 4 As shown.

[0051] Step (6): Based on step (5) above, the temperature range of this embodiment during rolling is 300-500℃ and the strain rate is 0.05-10s. -1 The three-dimensional thermal processing diagram with strain ranging from 0.3 to 1 corresponds to the safe processing area as follows:

[0052]

[0053] The rolling process parameters were adjusted based on the three-dimensional hot working diagram shown in Table 1. Tensile tests were conducted on the rolled finished plates using a CMT510 universal testing machine. The results showed that the average room temperature tensile strength of the first and second five groups of hot-rolled plates increased from 322.3 MPa to 382.6 MPa, and the room temperature elongation after fracture increased from 6.24% to 10.16%. Furthermore, metallographic observation using an MJ-42 optical microscope revealed that two of the first five groups exhibited... Figure 5 The thermal shear bands shown, the last five groups of process parameters optimized using this method, are all as follows: Figure 6 The dynamic recrystallization and dynamic recovery of grains are shown.

[0054] Therefore, it can be seen that the method for optimizing the medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloy according to the present invention improves the yield of medium- and high-temperature controlled rolled parts.

[0055] Table 1 Comparison of rolling process parameters adjusted based on 3D thermal processing diagram

[0056]

[0057] Example 2

[0058] A method for optimizing the medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloys includes the following steps:

[0059] The material is grade 5383 aluminum alloy, which is an Al-5.0Mg high magnesium aluminum alloy.

[0060] Step (1): In this embodiment, a plane strain compression experiment was used to conduct a rolling heat simulation experiment. 24 10×15×20mm sections were machined from the aluminum alloy after homogenization treatment before hot rolling using wire cutting. 3 Square specimen.

[0061] Step (2): Based on the rolling process of 5383 aluminum alloy, the infeed temperature is 500℃ and the final product exit temperature is 250℃. Therefore, the thermal simulation temperature range is determined to be 250-500℃, with a level selected every 50℃, for a total of six levels. Using the existing rolling data from the factory and the formula for calculating the relationship between the reduction amount and strain rate for each pass, the strain rate range required for thermal simulation is obtained as 0.05s. -1 -10s -1 Therefore, the strain rates for the thermal simulation tests were designed to be 0.05, 0.5, 5, and 10 s⁻¹. -1 There are four levels in total.

[0062] The thermal simulation experiment simulated the rolling process as closely as possible. In multi-pass continuous rolling, the temperature drop was slower before 400℃ in the preceding passes and faster after 400℃. Therefore, the specific experimental procedure was as follows: 20 sets of tests were conducted on the Gleeble-3500 thermal simulation testing machine. The sample was heated at a rate of 5℃ / s, held at 500℃ for 3 minutes, and then cooled at a certain rate (1℃ / s before 400℃, and 5℃ / s below 400℃). A single-factor experimental method was adopted. After cooling to the set temperature, the plane strain compression experiment was started according to the strain rate of the orthogonal experimental group. The compression was stopped when the strain was 60% of the height reduction. The sample was then quickly quenched by water cooling to preserve the deformed structure as much as possible, which facilitated the study of the microstructure of the sample.

[0063] Step (3): Obtain the stress peak values ​​corresponding to deformation temperature and strain rate when the strain is 0.3, 0.5, 0.7, and 1.0 using the true stress-strain curve, and perform interpolation to calculate the flow stress value at the selected node temperature and strain rate interval.

[0064] Step (4): Based on the mechanics of large plastic deformation continuum, physical system simulation, and irreversible thermodynamics, the stress σ at each temperature is used to measure the strain rate. Differentiation yields the strain rate sensitivity index The dissipation rate factor is obtained by calculating the strain rate sensitivity index m. The instability criterion function and its range are obtained by calculating the strain rate sensitivity index m:

[0065]

[0066] By matrixing the strain rate and deformation temperature data, power dissipation diagrams based on a dynamic material model and plastic instability diagrams based on plastic instability judgment criteria are constructed. At temperature T and strain rate... Range A matrix-based distribution diagram shows rheological instability in the negative value region; such a diagram is called an instability diagram, which corresponds to the instability region in a hot working diagram. Typical microscopic phenomena in the instability region of unstable rheology include adiabatic shear bands and localized deformation; the safe region is characterized by microscopic mechanisms such as dynamic recrystallization, dynamic recovery, and superplastic deformation.

[0067] Step (5): Overlay the power dissipation diagram and the plastic instability diagram to obtain the hot working diagram of the aluminum alloy at the set temperature, and divide the safe zone and the instability zone. Similarly, make hot working diagrams under different strains, and then draw a three-dimensional hot working diagram including strain changes, such as... Figure 7 As shown.

[0068] Step (6): Based on step (5) above, the temperature range of this embodiment during rolling is 250-500℃ and the strain rate is 0.05-10s. -1 The three-dimensional thermal processing diagram with strain ranging from 0.3 to 1 corresponds to the safe processing area as follows:

[0069]

[0070] The rolling process parameters were adjusted based on the three-dimensional hot working diagram shown in Table 2. Tensile tests were conducted on the finished hot-rolled plates using a CMT510 universal testing machine. The results showed that the average room temperature tensile strength of the five groups of hot-rolled plates before and after the initial test increased from 332.3 MPa to 385.4 MPa, and the room temperature elongation after fracture increased from 7.16% to 10.35%. Metallographic observation using an MJ-42 optical microscope revealed that the latter five groups, with optimized process parameters using this method, all exhibited dynamic recrystallization and dynamic grain recovery.

[0071] Therefore, it can be seen that the method for optimizing the medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloy according to the present invention improves the yield of medium- and high-temperature controlled rolled parts.

[0072] Table 2 Comparison of Rolling Process Parameters Adjusted Based on 3D Thermal Processing Diagram

[0073]

[0074] Example 3

[0075] A method for optimizing the medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloys includes the following steps:

[0076] The material is grade 5383 aluminum alloy, which is an Al-4.5Mg high magnesium aluminum alloy.

[0077] Step (1): In this embodiment, a plane strain compression experiment was used to conduct a rolling heat simulation experiment. Twenty 10×10×15mm sections were machined from the aluminum alloy after homogenization treatment before hot rolling using wire cutting. 3 Square specimen.

[0078] Step (2): Based on the rolling process of 5383 aluminum alloy, the infeed temperature is 500℃ and the final product exit temperature is 300℃. Therefore, the thermal simulation temperature range is determined to be 300-500℃, with a level selected every 50℃, for a total of five levels. Using the existing rolling data from the factory and the formula for calculating the relationship between the reduction amount and strain rate for each pass, the strain rate range required for thermal simulation is obtained as 0.05s. -1 -10s -1 Therefore, the strain rates for the thermal simulation tests were designed to be 0.05, 0.5, 5, and 10 s⁻¹. -1 There are four levels in total.

[0079] The thermal simulation experiment simulated the rolling process as closely as possible. In multi-pass continuous rolling, the temperature drop was slower before 400℃ in the preceding passes and faster after 400℃. Therefore, the specific experimental procedure was as follows: 20 sets of tests were conducted on the Gleeble-3500 thermal simulation testing machine. The sample was heated at a rate of 5℃ / s, held at 500℃ for 3 minutes, and then cooled at a certain rate (1℃ / s before 400℃, and 5℃ / s below 400℃). A single-factor experimental method was adopted. After cooling to the set temperature, the plane strain compression experiment was started according to the strain rate of the orthogonal experimental group. The compression was stopped when the strain was 60% of the height reduction. The sample was then quickly quenched by water cooling to preserve the deformed structure as much as possible, which facilitated the study of the microstructure of the sample.

[0080] Step (3): Obtain the stress peak values ​​corresponding to deformation temperature and strain rate when the strain is 0.3, 0.5, 0.7, and 1.0 using the true stress-strain curve, and perform interpolation to calculate the flow stress value at the selected node temperature and strain rate interval.

[0081] Step (4): Based on the mechanics of large plastic deformation continuum, physical system simulation, and irreversible thermodynamics, the stress σ at each temperature is used to measure the strain rate. Differentiation yields the strain rate sensitivity index The dissipation rate factor is obtained by calculating the strain rate sensitivity index m. The instability criterion function and its range are obtained by calculating the strain rate sensitivity index m:

[0082]

[0083] By matrixing the strain rate and deformation temperature data, power dissipation diagrams based on a dynamic material model and plastic instability diagrams based on plastic instability judgment criteria are constructed. At temperature T and strain rate... Range A matrix-based distribution diagram shows rheological instability in the negative value region; such a diagram is called an instability diagram, which corresponds to the instability region in a hot working diagram. Typical microscopic phenomena in the instability region of unstable rheology include adiabatic shear bands and localized deformation; the safe region is characterized by microscopic mechanisms such as dynamic recrystallization, dynamic recovery, and superplastic deformation.

[0084] Step (5): Overlay the power dissipation diagram and the plastic instability diagram to obtain the hot working diagram of the aluminum alloy at the set temperature, and divide the safe zone and the instability zone. Similarly, make hot working diagrams under different strains, and then draw a three-dimensional hot working diagram including strain changes, such as... Figure 8 As shown.

[0085] Step (6): Based on step (5) above, the temperature range of this embodiment during rolling is 300-500℃ and the strain rate is 0.05-10s. -1 The three-dimensional thermal processing diagram with strain ranging from 0.3 to 1 corresponds to the safe processing area as follows:

[0086]

[0087] According to Table 3, the rolling process parameters were adjusted based on the three-dimensional hot working diagram. Tensile tests were conducted on the rolled finished plates using a CMT510 universal testing machine. The results showed that the average room temperature tensile strength of the five groups of hot-rolled plates before and after the initial test increased from 316.3 MPa to 368.5 MPa, and the room temperature elongation after fracture increased from 8.57% to 12.31%. Metallographic observation using an MJ-42 optical microscope revealed that the latter five groups, with optimized process parameters using this method, all exhibited dynamic recrystallization and dynamic grain recovery. Therefore, it can be concluded that the method for optimizing medium- and high-temperature controlled rolling parameters for marine high-magnesium aluminum alloys according to this invention improves the yield of medium- and high-temperature controlled rolled parts.

[0088] Table 3 Comparison of Rolling Process Parameters Adjusted Based on 3D Thermal Processing Diagram

[0089]

[0090] The embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for optimizing medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloys, characterized in that, Includes the following steps: Step (1): Cut a block sample for plane strain thermal simulation from the aluminum alloy after homogenization treatment before hot rolling; the size of the block sample for plane strain thermal simulation is 10×10×15mm or 10×15×20mm. Step (2): Based on the different rolling process temperature ranges, strain rates, and strains of various aluminum alloy materials, set the thermal simulation temperature, strain rate, and strain. Perform thermal simulation plane strain compression at different temperatures and strain rates to obtain the orthogonal experimental data of true stress-true strain for the alloy at medium and high temperatures. In the plane strain thermal simulation experiment, the temperature range is 200-500℃, and the strain rate is 0.05-10s. -1 The orthogonal group setting is at least 4×4 or higher; the strain is a height reduction of 60% or higher; the temperature-controlled rolling strain rate is achieved by controlling the thickness of the workpiece at the rolling inlet and outlet, the rolling speed, and the roll radius. The process parameters for temperature-controlled forming of medium- and high-temperature rolling are determined based on the average strain rate in the vertical direction of the rolled plate. Mean strain , Inlet thickness h1, Outlet thickness h2, Rolling speed V R The relationship with the roll radius R was calculated as follows: Step (3): Obtain the stress peak values ​​corresponding to different strains, deformation temperatures, and strain rates through multiple sets of true stress-strain curves, and perform interpolation to calculate the flow stress values ​​at the selected node temperature and strain rate intervals. Step (4): Based on the mechanics of large plastic deformation continuum, physical system simulation, and irreversible thermodynamics, the strain rate sensitivity index m is calculated, and then the dissipation rate factor is calculated. Instability Criteria The data were matrixed with strain rate and deformation temperature data respectively to construct a power dissipation diagram based on a dynamic material model and a plastic instability diagram based on a plastic instability judgment criterion; the stress at each temperature was then used to construct the power dissipation diagram based on a dynamic material model and the plastic instability diagram based on a plastic instability judgment criterion. For strain rate Differentiation yields the strain rate sensitivity index The dissipation rate factor is obtained by calculating the strain rate sensitivity index m. The instability criterion function and its range are obtained by calculating the strain rate sensitivity index m. Step (5): Overlay the power dissipation diagram and the plastic instability diagram to obtain the hot working diagram of the aluminum alloy at the set temperature, and divide the safe zone and the instability zone. Similarly, draw the hot working diagrams under different strains, and then draw a three-dimensional hot working diagram containing strain changes; at temperature T and strain rate Range The matrix distribution diagram shows that rheological instability occurs in the negative value region. Such a diagram is called an instability diagram, which corresponds to the instability region in the hot working diagram. Typical microscopic phenomena in the instability region of unstable rheology include adiabatic shear bands, local deformation, dynamic strain failure, mechanical twinning, and torsion. The safe region is characterized by microscopic mechanisms such as dynamic recrystallization, dynamic recovery, and superplastic deformation. Step (6): Different reduction amounts in different rolling passes correspond to different strains. Based on the safe zone under different strains in the three-dimensional thermal processing diagram, it is helpful to select the temperature and strain rate for thermoplastic forming of aluminum alloy, determine the process parameters in the medium and high temperature controlled rolling process, and obtain rolled parts that meet the requirements of dimensional accuracy and mechanical properties. The steps of the plane strain thermal simulation experiment are as follows: the sample is heated at a rate of 5℃ / s to 500℃ and held for three minutes. Then, the temperature is lowered. After cooling to the set temperature, the plane strain compression experiment is started according to the strain rate of the orthogonal experimental group. When the strain is 60% of the height reduction, the compression is stopped and the sample is quickly quenched. The cooling is specifically as follows: the temperature is lowered at 1℃ / s before reaching 400℃, and at 5℃ / s below 400℃.

2. The method for optimizing the medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloy according to claim 1, characterized in that, In step (3), the deformation temperature and strain rate data are interpolated using the cubic spline interpolation method with Origin software.

3. The method for optimizing medium- and high-temperature controlled rolling parameters of marine high-magnesium aluminum alloy according to claim 1, characterized in that, In step (1), the aluminum alloy is a 5-series Al-xMg aluminum alloy.

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