Method for determining electroplasticity parameter and method for improving high-cycle fatigue performance of component

Abstract

The application discloses a method for determining an electroplasticity parameter and a method for improving high-cycle fatigue performance of a component, and belongs to the technical field of material processing. The method comprises the following steps: pre-deforming a metal component sample to obtain measured grain structure and measured microstructure after pre-deformation treatment; establishing a crystal model identical to the measured grain structure and the measured microstructure by simulation; simulating the results of electroplasticity treatment of the crystal model by a plurality of pulse current parameters; screening a plurality of pulse current parameters meeting the conditions by simulation; and further performing a real test on the metal component sample after pre-deformation treatment by using the screened plurality of pulse current parameters, so as to screen again by using the test method to obtain optimal pulse current parameters. The method can improve the high-cycle fatigue performance of the metal component by eliminating micro stress concentration without affecting the service performance of the metal component under actual working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material processing, in particular to a method for determining electroplasticity parameters and a method for improving high-cycle fatigue performance of a component. BACKGROUND

[0002] With the rapid development of the automobile and aviation industries, many metal components are in a working condition of alternating load, and the fatigue resistance of the metal components is crucial to the safety and durability of the automobile and aircraft equipment. The essential cause of fatigue failure is that defects such as dislocations and slip bands in the metal cause stress concentration under cyclic loading. High-cycle fatigue performance is particularly sensitive to microstructure, and dislocation entanglement regions are prone to cause stress concentration during fatigue cycling, leading to the initiation of fatigue cracks at these locations.

[0003] In related technologies, a pre-deformation treatment is used to improve the high-cycle fatigue performance of the metal component. However, there is still a problem of insufficient high-cycle fatigue performance of the component. SUMMARY

[0004] The present application provides a method for determining electroplasticity parameters and a method for improving high-cycle fatigue performance of a component. The technical solution is as follows:

[0005] On the one hand, a method for determining electroplasticity parameters is provided, comprising:

[0006] performing pre-deformation treatment on a metal component sample, and obtaining measured grain structure and measured microstructure of the metal component sample after pre-deformation treatment;

[0007] based on the measured grain structure and the measured microstructure, establishing a crystal model identical to the measured grain structure and the measured microstructure using a molecular dynamics simulation method;

[0008] performing electroplasticity treatment on the crystal model using a plurality of pulse current parameters, and selecting a plurality of pulse current parameters meeting the conditions according to the electroplasticity treatment results;

[0009] performing electroplasticity treatment on the metal component sample after pre-deformation treatment using the plurality of pulse current parameters selected, and selecting optimal pulse current parameters again according to the electroplasticity treatment results.

[0010] On the other hand, a method for improving high-cycle fatigue performance of a component is provided, comprising:

[0011] based on a metal component to be treated, determining the combination of pre-deformation treatment and optimal pulse current parameters corresponding to the metal component to be treated using the method for determining electroplasticity treatment process parameters described above;

[0012] The pre-deformation processing is performed on the metal component to be processed by using the processing type and processing degree of the pre-deformation processing in the combination.

[0013] The pre-deformation processed metal component to be processed is subjected to the electroplastic processing by using the optimal pulse current parameter in the combination, and the processed metal component is obtained.

[0014] The technical solution provided by the present application can bring at least the following beneficial effects

[0015] The pre-deformation processing is performed on the metal component sample, the measured grain structure and the measured microstructure after the pre-deformation processing are obtained, the same crystal model as the measured grain structure and the measured microstructure is established by simulation, and the results of the electroplastic processing of the crystal model by a plurality of groups of pulse current parameters are simulated, so as to screen a plurality of groups of pulse current parameters meeting the conditions by simulation, and further perform the real test on the metal component sample after the pre-deformation processing by using the screened plurality of groups of pulse current parameters, so as to screen the optimal pulse current parameter again by test. The present application can select the combination of the pre-deformation processing and the optimal pulse current parameter for improving the high-cycle fatigue performance of the component by combining simulation and test, and then perform the electroplastic processing on the metal component by using the combination, so as to improve the high-cycle fatigue performance of the metal component by eliminating the micro stress concentration without affecting the service performance of the metal component under the actual working condition. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0017] Figure 1 is a flow chart of a method for determining electroplastic processing process parameters provided by an embodiment of the present application;

[0018] Figure 2 is a flow chart of a method for improving the high-cycle fatigue performance of a component provided by an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0020] As described above, the problem of insufficient high-cycle fatigue performance of the component still exists in the treatment mode of pre-deformation.

[0021] Considering that the electron wind force generated by the pulse current in the metal component can drive dislocation movement and be used for regulating and controlling the microstructure inside the component and changing the mechanical properties of the material, it is very difficult to improve the high-cycle fatigue performance of the component without affecting the service performance of the component in actual working conditions.

[0022] Based on this, the inventive concept of the present application is to determine the optimal pulse current parameters by combining simulation and test, so as to use the optimal pulse current parameters to perform electroplastic treatment on the metal component, and improve the high-cycle fatigue performance of the metal component by eliminating micro stress concentration without affecting the service performance of the metal component in actual working conditions.

[0023] The specific implementation mode of the above concept will be described below.

[0024] Please refer to Figure 1 The method for determining the electroplastic treatment process parameters provided by the embodiments of the present application comprises the following steps.

[0025] In step 100, pre-deformation treatment is performed on the metal component sample, and the measured grain structure and the measured microstructure of the metal component sample after the pre-deformation treatment are obtained.

[0026] In step 102, the same crystal model as the measured grain structure and the measured microstructure is established by using a molecular dynamics simulation method based on the measured grain structure and the measured microstructure.

[0027] In step 104, the crystal model is subjected to electroplastic treatment by using a plurality of groups of pulse current parameters, and a plurality of groups of pulse current parameters meeting the conditions are selected according to the electroplastic treatment results.

[0028] In step 106, the pre-deformation treated metal component sample is subjected to electroplastic treatment by using the selected plurality of groups of pulse current parameters, and the optimal pulse current parameters are selected again according to the electroplastic treatment results.

[0029] In the embodiment of the present application, the pre-deformation processing is performed on the metal component sample to obtain the measured grain structure and the measured microstructure after pre-deformation processing, the same crystal model as the measured grain structure and the measured microstructure is established by simulation, and the results of the electroplastic effect of the crystal model under a plurality of groups of pulse current parameters are simulated to screen a plurality of groups of pulse current parameters meeting the conditions, and the pre-deformation processed metal component sample is further tested by using the screened plurality of groups of pulse current parameters to obtain the optimal pulse current parameters by re-screening by testing. The combination of the pre-deformation processing and the optimal pulse current parameters for improving the high-cycle fatigue performance of the component can be selected by combining simulation and testing.

[0030] The following describes Figure 1 The execution mode of each step is shown.

[0031] Firstly, for step 100, the pre-deformation processing is performed on the metal component sample, and the measured grain structure and the measured microstructure of the metal component sample after pre-deformation processing are obtained.

[0032] In the embodiment of the present application, if the metal component to be processed for improving the high-cycle fatigue performance of the component has been determined, the metal component sample is the determined metal component to be processed; if the metal component to be processed for improving the high-cycle fatigue performance of the component has not been determined, the metal component sample can be a component of any crystal structure and any metal material.

[0033] After obtaining the metal component sample, the high-cycle fatigue performance of the component can be initially improved by using the pre-deformation processing.

[0034] In one embodiment of the present application, the processing type of the pre-deformation processing includes one or more of shot peening, abrasive flow, deep rolling, laser shock peening, and surface mechanical grinding. Each processing type includes at least one processing degree. The pre-deformation processing can cause the component to be inhomogeneously plastically deformed and generate high-density dislocations in the component.

[0035] The pre-deformation processing in this step is a pre-deformation of a determined processing type and processing degree. Taking the processing type of shot peening as an example, the shot peening includes a plurality of processing degrees, and each processing degree has corresponding processing parameters. For example, the pre-deformation processing in this step is shot peening, and the processing degree is level one. It should be noted that when the processing type includes a plurality of processing degrees, the plurality of processing degrees can be set according to the upper and lower limit ranges of the processing parameters.

[0036] In addition, the above pre-deformation processing can also be a combination of a plurality of processing types, and each processing type selects a corresponding processing degree, so that a plurality of combined pre-deformation processes can be obtained.

[0037] In the embodiment of the present application, when the processing type and the processing degree of the pre-deformation processing are determined, the optimal pulse current parameters determined subsequently form a combination with the pre-deformation processing, which can be used to perform the pre-deformation processing and the electroplastic processing on the same metal component as the metal component sample to improve the high-cycle fatigue performance of the component.

[0038] In order to obtain a plurality of combination modes of the pre-deformation processing and the optimal pulse parameters for improving the high-cycle fatigue performance of the same metal component as the metal component sample, in an embodiment of the present application, the processing type or the processing degree of the pre-deformation processing can be changed, and the determination method of the electroplastic processing process parameters is repeatedly performed by using the changed pre-deformation processing to obtain the optimal pulse current parameters corresponding to the changed pre-deformation processing.

[0039] In the embodiment of the present application, the measured grain structure and the measured microstructure of the metal component sample after the pre-deformation processing can be obtained by the following manner: the grain structure of the metal component sample after the pre-deformation processing is observed by using a scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and the like, and the nanoscale microstructure such as dislocation and twin crystal can be observed by using a transmission electron microscope (TEM).

[0040] Then, for step 102, based on the measured grain structure and the measured microstructure, a crystal model same as the measured grain structure and the measured microstructure is established by using a molecular dynamics simulation method.

[0041] In the embodiment of the present application, in order to quickly obtain the pulse current parameters suitable for the metal component sample after the pre-deformation processing and reduce the cost in the whole process, the crystal model same as the measured grain structure and the measured microstructure can be established by using the molecular dynamics simulation method, which is used to screen the pulse current parameters by simulation means.

[0042] In an implementation manner, the step can specifically include the following steps 1020-1022.

[0043] Step 1020: a corresponding three-dimensional complete crystal of the metal component sample is established by using a molecular dynamics simulation method; the complete crystal is the actual crystal structure of the metal component sample, and the grain structure is the measured grain structure;

[0044] Step 1022: the complete crystal is subjected to the pre-deformation processing to simulate that the internal complete crystal after the pre-deformation processing reaches the measured microstructure, and a crystal model is obtained; wherein the pre-deformation processing performed on the complete crystal is the same as the pre-deformation processing performed on the metal component sample.

[0045] The molecular dynamics simulation software in the embodiment of the application can be Lammps, Materials studio, Ls1-MarDyn, IMD and CoMD, etc.

[0046] In order to ensure the accuracy of the simulation result, and to accurately obtain the optimal pulse current parameter after the metal component sample subjected to pre-deformation treatment is subjected to electroplasticity by the several pulse current parameters screened out subsequently, the simulation process also tries to conform to the actual situation, that is, the pre-deformation treatment on the complete crystal is the same as the pre-deformation treatment on the metal component sample in terms of the treatment type and the treatment degree. After the pre-deformation treatment on the complete crystal, the internal microstructure of the complete crystal is simulated, at this time, the grain structure of the crystal model is the same as the measured grain structure, and the microstructure of the crystal model is the same as the measured microstructure.

[0047] Next, the crystal model is subjected to electroplasticity treatment by using the plurality of groups of pulse current parameters, and several groups of pulse current parameters meeting the condition are screened out according to the electroplasticity treatment result.

[0048] In the embodiment of the application, a plurality of groups of pulse current parameters need to be obtained. The pulse current parameters include: pulse period, pulse interval time, pulse current type, pulse waveform, current density amplitude and total pulse current treatment time.

[0049] In the embodiment of the application, the ranges of the pulse current parameters are as follows respectively:

[0050] The range of the pulse period is 0.01-10 ms;

[0051] The range of the pulse interval time is 0.005-10 ms;

[0052] The pulse current type is direct current or alternating current;

[0053] The pulse waveform is square wave, sine wave, triangular wave, sawtooth wave or damped decay wave;

[0054] The range of the current density amplitude is 1-1000 A / mm 2 ;

[0055] The total pulse current treatment time is 1-10000 ms.

[0056] According to the ranges of the pulse current parameters, a plurality of groups of pulse current parameters can be obtained, and the parameter values in each group of pulse current parameters are not completely the same.

[0057] After the multiple sets of pulse current parameters are determined, since the crystal model is obtained by the molecular dynamics simulation software, the crystal model can be respectively subjected to the electroplastic effect treatment by using each set of pulse current parameters to simulate the electroplastic effect treatment result.

[0058] Since the electron wind force generated by the pulse current in the metal component can drive the dislocation movement, the microstructure inside the component can be adjusted to change the mechanical properties of the material, and therefore the electroplastic effect treatment result is used to represent the change of the microstructure after the pulse current treatment.

[0059] In an embodiment of the present application, when the multiple sets of pulse current parameters meeting the condition are screened according to the electroplastic effect treatment result, the following steps can be specifically included: for the multiple electroplastic effect results corresponding to the multiple sets of pulse current parameters, it is determined whether the electroplastic effect result is that the crystal only changes in the nanometer scale but not in the micron scale, and the change amount of the microstructure meets the set condition, if yes, it is determined that the electroplastic effect result meets the condition, and the pulse current parameter corresponding to the electroplastic effect result is screened out.

[0060] If the crystal only changes in the nanometer scale but not in the micron scale, it indicates that the grain structure does not change significantly.

[0061] The change of the microstructure is the change of the dislocation entanglement degree, the dislocation density and the twin crystal quantity, if the dislocation entanglement degree and the dislocation density decrease and the twin crystal quantity increases, it indicates that the microstructure is improved. Therefore, the set condition can be the change amount threshold of the corresponding microstructure parameter, or the result of the maximum change amount.

[0062] When the set condition is the change amount threshold of the corresponding microstructure parameter, for example, if the dislocation entanglement degree of the microstructure decreases by at least A%, the dislocation density decreases by at least B%, and the twin crystal quantity increases by at least C% in the electroplastic effect treatment result, it is determined that the change amount of the microstructure meets the set condition.

[0063] When the set condition is the result of the maximum change amount, for example, the multiple electroplastic effect treatment results in which the dislocation entanglement degree decreases by the maximum amount, the dislocation density decreases by the maximum amount, and the twin crystal quantity increases by the maximum amount can be determined, and then the multiple pulse current parameters are determined. It should be noted that in this condition, if the dislocation entanglement degree decreases by the maximum amount, the dislocation density decreases by the maximum amount, and the twin crystal quantity increases by the maximum amount in the same result, the three cannot be realized at the same time, and the selection can be made according to the pre-set priority selection mode to ensure that the selected electroplastic effect treatment result has the largest dislocation entanglement degree decrease amount, the largest dislocation density decrease amount, and the largest twin crystal quantity increase amount as possible.

[0064] Finally, for step 106, the pre-deformation processed metal component samples are subjected to electroplastic processing using the screened several groups of pulse current parameters respectively, and the optimal pulse current parameters are screened again according to the electroplastic processing results.

[0065] In an embodiment of the present application, the electroplastic processing in this step can specifically include:

[0066] Step 1060: Based on the number of the screened several groups of pulse current parameters, the same number of pre-deformation processed metal component samples are obtained; wherein the same number of pre-deformation processed metal component samples are the measured grain structure and the measured microstructure;

[0067] Step 1062: The several groups of pulse current parameters and the same number of pre-deformation processed metal component samples are correspondingly composed into test pairs.

[0068] Step 1064: The pulse current parameters in the test pairs are subjected to electroplastic processing on the metal component samples.

[0069] The actual electroplastic processing is performed according to the screened pulse current parameters in a test manner, so that after the metal component samples are subjected to electroplastic processing once, the next electroplastic processing cannot be restored, and therefore the metal component samples corresponding to each pulse current parameter need to be obtained. The same number of pre-deformation processed metal component samples are tried to ensure the same measured grain structure and measured microstructure.

[0070] In the screening of the optimal pulse current parameters using the test manner, specifically, the target electroplastic processing result with the smallest change scale and the largest microstructure improvement in the electroplastic processing results corresponding to the several test pairs is determined, and the pulse current parameters corresponding to the target electroplastic processing result are determined as the optimal pulse current parameters.

[0071] Similarly, the largest microstructure improvement indicates the largest decrease in dislocation tangling degree, the largest decrease in dislocation density, and the largest increase in twin crystal number, and the largest decrease in dislocation tangling degree, the largest decrease in dislocation density, and the largest increase in twin crystal number cannot be achieved simultaneously in the same result. The comprehensive evaluation of the decrease in dislocation tangling degree, the decrease in dislocation density, and the increase in twin crystal number in the selected electroplastic processing result can be evaluated according to the pre-set comprehensive evaluation method to ensure the best comprehensive evaluation of the decrease in dislocation tangling degree, the decrease in dislocation density, and the increase in twin crystal number.

[0072] The optimal pulse current parameter finally selected can make the grain structure of the component not change, the microstructure can be improved, the mechanical properties (yield strength, tensile strength, elongation, etc.) of the material of the component can be ensured not to change, the high cycle fatigue performance of the component can be improved by eliminating micro stress concentration without affecting the service performance of the component under actual working conditions.

[0073] Please refer to Figure 2 The embodiment of the present application also provides a method for improving the high cycle fatigue performance of a component, comprising:

[0074] Step 200: based on a metal component to be processed, the combination of the pre-deformation processing corresponding to the metal component to be processed and the optimal pulse current parameter is determined by using the method for determining the electroplastic processing process parameter in any one of the above embodiments.

[0075] Step 202: the metal component to be processed is subjected to pre-deformation processing by using the processing type and processing degree of the pre-deformation processing in the combination.

[0076] Step 204: the metal component to be processed after pre-deformation processing is subjected to electroplastic processing by using the optimal pulse current parameter in the combination, so as to obtain a processed metal component.

[0077] The microstructure of the metal component after electroplastic processing can be effectively improved, so that the mechanical properties (yield strength, tensile strength, elongation, etc.) of the material of the component can be ensured not to change, the high cycle fatigue performance of the component can be improved by eliminating micro stress concentration without affecting the service performance of the component under actual working conditions.

[0078] Those skilled in the art can clearly understand that the present application can be realized by means of software and necessary general hardware platform. Based on such understanding, the technical solutions of the present application or the part of the prior art can be embodied in the form of software product, which can be stored in a storage medium, such as ROM / RAM, magnetic disc, optical disc, etc., and includes a plurality of instructions for making a computer device (which can be a personal computer, server, or network device, etc.) execute the method described in various embodiments or some parts of the embodiments of the present application.

[0079] Finally, it needs to be pointed out that, in this document, relational terms such as first, second, third and fourth and the like can only be used to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual relationship or order between or among such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0080] The above description is only the preferred embodiment of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method of determining electroplastic treatment process parameters, characterized in that, The method comprises the following steps: a metal component sample is pre-deformed, and a measured grain structure and a measured microstructure of the pre-deformed metal component sample are obtained; a crystal model identical to the measured grain structure and the measured microstructure is established based on the measured grain structure and the measured microstructure by using a molecular dynamics simulation method; the crystal model is subjected to electroplastic processing by using a plurality of sets of pulse current parameters, and a plurality of sets of pulse current parameters meeting a condition are screened out according to the electroplastic processing result; the pre-deformed metal component sample is subjected to electroplastic processing by using the screened plurality of sets of pulse current parameters, and an optimal pulse current parameter is screened out again according to the electroplastic processing result; the screening of the plurality of sets of pulse current parameters meeting the condition according to the electroplastic processing result comprises: for a plurality of electroplastic results corresponding to the plurality of sets of pulse current parameters, it is determined whether the electroplastic result is that the crystal only changes in nanometer scale but not in micrometer scale, and the change amount of the microstructure meets a set condition, if yes, it is determined that the electroplastic result meets the condition, and the pulse current parameter corresponding to the electroplastic result is screened out; the electroplastic processing of the pre-deformed metal component sample by using the screened plurality of sets of pulse current parameters comprises: based on the number of the screened plurality of sets of pulse current parameters, a same number of pre-deformed metal component samples are obtained; wherein the same number of pre-deformed metal component samples are all the measured grain structure and the measured microstructure; the plurality of sets of pulse current parameters and the same number of pre-deformed metal component samples are correspondingly combined to form test pairs; and the pulse current parameters in the test pairs are used to perform electroplastic processing on the metal component samples; the screening of the optimal pulse current parameter again according to the electroplastic processing result comprises: determining a target electroplastic result in the electroplastic results corresponding to the plurality of test pairs, the target electroplastic result being that the crystal only changes in nanometer scale and has the smallest change scale and the largest microstructure improvement, and determining the pulse current parameter corresponding to the target electroplastic result as the optimal pulse current parameter.

2. The method of claim 1, wherein, The processing type of the pre-deformation processing comprises one or more of shot peening, abrasive flow, deep roll peening, laser shock peening and surface mechanical grinding peening; and each processing type comprises at least one processing degree.

3. The method of claim 2, wherein, The method further comprises: changing the processing type or the processing degree of the pre-deformation processing, and repeatedly performing the method for determining the electroplastic processing process parameter by using the changed pre-deformation processing to obtain an optimal pulse current parameter corresponding to the changed pre-deformation processing.

4. The method of claim 1, wherein, The method for establishing the crystal model identical to the measured grain structure and the measured microstructure based on the measured grain structure and the measured microstructure by using the molecular dynamics simulation method comprises: a corresponding three-dimensional complete crystal of the metal component sample is established by using the molecular dynamics simulation method; the complete crystal is an actual crystal structure of the metal component sample, and the grain structure is the measured grain structure. The complete crystal is pre-deformed to simulate the measured microstructure inside the complete crystal after pre-deformation, and a crystal model is obtained; wherein the pre-deformation of the complete crystal is the same as the pre-deformation of the metal component sample.

5. The method according to any one of claims 1 to 4, characterized in that, The pulse current parameters include: pulse period, pulse interval time, pulse current type, pulse waveform, current density amplitude and total pulse current processing time.

6. The method of claim 5, wherein, the pulse period ranges from 0.01 to 10 ms; the pulse interval time ranges from 0.005 to 10 ms; the pulse current type is direct current or alternating current; the pulse waveform is square wave, sine wave, triangular wave, sawtooth wave or damped decay wave; The current density amplitude ranges from 1 to 1000 A / mm 2 ; the total pulse current processing time is 1 to 10000 ms.

7. A method for improving the high cycle fatigue performance of a component, characterized by, The method comprises: based on the metal component to be processed, using the determination method of the electroplastic processing process parameters in any one of claims 1-6 to determine the combination of the pre-deformation processing and the optimal pulse current parameters corresponding to the metal component to be processed; using the processing type and processing degree of the pre-deformation processing in the combination to pre-deform the metal component to be processed; using the optimal pulse current parameters in the combination to electroplastic process the metal component to be processed after pre-deformation, and obtaining the processed metal component.

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