CN114864007A - Method for establishing ultra-high strength steel high-temperature forming grain size evolution model - Google Patents

Method for establishing ultra-high strength steel high-temperature forming grain size evolution model Download PDF

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CN114864007A
CN114864007A CN202210574104.8A CN202210574104A CN114864007A CN 114864007 A CN114864007 A CN 114864007A CN 202210574104 A CN202210574104 A CN 202210574104A CN 114864007 A CN114864007 A CN 114864007A
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陈荣创
吕镓均
张世阳
张春
李建军
王敏
刘贤龙
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Hubei University of Automotive Technology
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Abstract

The invention discloses a method for establishing an evolution model of grain size of ultrahigh-strength steel during high-temperature forming, which is applied to a whole set of models for predicting grain growth, dynamic recrystallization, sub-dynamic recrystallization and static recrystallization of ultrahigh-strength steel in the processes of high-temperature compression, heat preservation, multi-pass compression and the like, and 14 parameters of the models are directly obtained by adopting an intelligent optimization algorithm based on 45 groups of hot compression test data to predict the grain size evolution of the ultrahigh-strength steel. The model of the invention takes into account the initial grain size
Figure DEST_PATH_IMAGE002
Thereby solving the problem of continuity of the grain size between different recrystallization processes; the influence of residual strain on recrystallization is considered by the model, so that the model can be well applied to the multi-pass compression process.

Description

Method for establishing ultra-high strength steel high-temperature forming grain size evolution model
Technical Field
The invention relates to the technical field of metal thermoplastic deformation, in particular to a method for establishing an evolution model of the high-temperature forming grain size of ultrahigh-strength steel.
Background
Ultra-high strength steel forging stock is usually subjected to multiple hot deformation to form a final shape. The main recrystallization processes that occur in the high temperature stage of the wrought billet grains are grain growth, dynamic recrystallization, sub-dynamic recrystallization, and static recrystallization. The method for accurately predicting the recrystallized grain evolution rule of the ultrahigh-strength steel in the whole thermal deformation process is the basis for the microstructure regulation and control of the ultrahigh-strength steel large forging and the establishment of the forging forming process.
In the process of implementing the invention, the inventor finds that:
the method is characterized in that a traditional corrosive metallographic method is adopted, Niuwenlong [1] is used for carrying out a double-pass hot compression test on the GH738 alloy, the influence of the initial grain size, the deformation temperature, the inter-pass heat preservation time and the strain rate on the evolution of the sub-dynamic recrystallization structure of the GH738 alloy is researched, and a sub-dynamic recrystallization Avrami model is established; the influence of parameters such as temperature, strain rate, initial grain size, inter-pass heat preservation time and the like on the heat preservation softening of the 300M steel inter-pass is researched through a double-pass compression test by the Liujie and the like [2], and a sub-dynamic recrystallization kinetic model is established; qi et al [3] studied the static recrystallization behavior of martensitic stainless steel based on a two-pass test, obtained the JMAK equation by fitting the rheological stress curve, and established a dynamic model of static recrystallization; the influence of 300M high-strength steel static recrystallization on inter-pass heat preservation softening is researched by Liu Ying steel and the like [4], and a dynamic model of static recrystallization is established; chen et al [5,6], Wen et al [7] studied the high temperature tensile rheological stress and microstructure evolution of 300M steel, and proposed a constitutive model combining the microstructure evolution; the relation between the rheological stress and the strain, the strain rate and the temperature of 4343/4A60 Nb-Ti steel is researched by A3-pass isothermal compression test in Tangerlan et al [8], and A3-pass compressive rheological stress model is established based on an Arrhenius model; o, Beltran et al [9] consider the grain boundary mobility in dynamic recrystallization and post-dynamic recrystallization, and establish a model of coupling the rheological stress and microstructure of 304L steel in the multi-pass compression process based on an average field model; H.E, Cho et al [10] develop multiple compression tests, study the influence of static recrystallization and dynamic recrystallization on the rheological stress and the grain size, use the integral number (X) of the recrystallized body as an internal variable, and establish the rheological stress model of various metals such as copper, AZ31 magnesium alloy, 1010 low-carbon steel and the like; E.S. Puchi-Cabrera et al [11,12] established a multi-pass compressive rheological stress model of silicon manganese steel and 20MnCr5, taking yield stress, recrystallization critical stress, saturation stress, steady state stress and the like as internal variables, and taking dynamic recrystallization, static recrystallization, post dynamic recrystallization and the like into consideration.
It should be noted that, at present, each recrystallization model is relatively independent, and the problem of connection between different recrystallization models is not considered, and the grain size is suddenly changed when the models are converted, which is obviously not consistent with the actual situation.
In addition, the invention patent of von Renwei et al [13] considers the connection between recrystallization models, and provides 'a prediction method of microstructure evolution law in the thermal deformation process of 20CrMnTiH steel', Luo et al [14] establishes a 300M steel average grain size evolution model based on a thermal compression test, but because the research does not consider the cumulative effect of strain and dislocation density in multi-pass deformation, according to documents [15,16], the judgment of the recrystallization critical point when the method is applied to multi-pass compression generates deviation; therefore, how to smoothly link up the grain size, dislocation density, residual strain and the like in different recrystallization processes is another key problem faced by grain size modeling; since these problems remain unsolved, accurately simulating grain size evolution of ultra-high strength steel throughout thermal deformation remains a major challenge in the field of plastic working.
The sources of the cited documents are respectively:
[1] niuwenlong, Guo Jing, Ma Si Wen, Zhang Mai cang, a dynamic model of dynamics of sub-dynamic recrystallization of a novel high-quality GH738 alloy [ J ] rare metal materials and engineering, 2022,51(01): 183-189).
[2] Liu J., Liu Y. G., Lin H., Li M. Q. The metadynamic recrystallization in the two-stage isothermal compression of 300M steel[J]. Mat. Sci. Eng. A. 2013 (565) 126–131.
[3]Qi Peng,Ren Facai,Xu Jinsha. Study on static recrystallization behavior of martensitic stainless steel[J]. Journal of Physics: Conference Series,2021,1965(1).
[4] Liu Y. G., Liu J., Li M. Q., Lin H. The study on kinetics of static recrystallization in the two-stage isothermal compression of 300M steel[J]. Comp. Mater. Sci. 2014 (84) 115–121.
[5] Chen R, Zhang S., Wang M., Liu X., Feng F. Unified Modelling of Flow Stress and Microstructural Evolution of 300M Steel under Isothermal Tension. Metals. 2021, 11, 1086.
[6] Chen R, Zhang S., Liu X., Feng F. A Flow Stress Model of 300M Steel for Isothermal Tension. Materials, 2021, 14, 252.
[7] D.X. Wen, T.Y. Yue, Y.B. Xiong, K. Wang, J.K. Wang, Z.Z. Zheng, J.J. Li, High-temperature tensile characteristics and constitutive models of ultrahigh strength steel, Mater. Sci. Eng. A. 803 (2021) 140491. doi:10.1016/j.msea.2020.140491.
[8] Tang C., Zhou Y., Weng H. Constitutive behavior of 4343/4A60 aluminum alloy at multi-pass hot deformation[J]. Strength Mater. 2017 (49) 83–92.
[9] Beltran O., Huang K., Logé R. A mean field model of dynamic and post-dynamic recrystallization predicting kinetics, grain size and flow stress[J]. Comp. Mater. Sci. 2015 (102) 293–303.
[10] Cho H. E., Hammi Y., Bowman A. L. A unified static and dynamic recrystallization Internal State Variable (ISV) constitutive model coupled with grain size evolution for metals and mineral aggregates[J]. Int. J. Plast. 2019, (112) 123–157.
[11]Puchi-Cabrera E. S., Staia M. H., Guérin J. D. An experimental analysis and modeling of the work-softening transient due to dynamic recrystallization[J]. Int. J. Plast. 2014 (54) 113–131.
[12] Puchi-Cabrera E. S., Guerin J. D., Barbera-Sosa J. G. Incremental constitutive description of SAE 5120 steel deformed under hot-working conditions[J]. Int. J. Mech. Sci. 2017 (133) 619–630.
[13] Von offer, waring, Hanxinhui, Qifei, Wushuting A method for predicting the microstructure evolution law of 20CrMnTiH steel in the thermal deformation process [ P ]. Hubei province: CN105373683B,2018-09-14.
[14] Luo J, Liu Y G, Miao-Quan L I, Three-dimensional Numerical Simulation and Experimental Analysis of Austenitic Grain Growth behavor in Hot Forming Processes of 300M Steel Large Components [ J ]. proceedings of iron and Steel research: english edition 2016, 23(10):8.
[15] Zeng R., Huang L., Li J. Quantification of multiple softening processes occurring during multi-stage thermoforming of high-strength steel[J]. Int. J. Plast. 2019 (120) 64–87.
[16] Chen R. C., Zeng J., Yao G., Feng F. Flow-Stress Model of 300M Steel for Multi-Pass Compression[J]. Metals, 2020 (10) 438。
Disclosure of Invention
In order to solve the problems, the invention provides a method for establishing an evolution model of the grain size of ultrahigh-strength steel high-temperature forming, which comprehensively considers the evolution of residual strain in multi-pass deformation and establishes the influence relation of deformation process parameters (temperature, strain rate, inter-pass heat preservation time, strain and the like) on the grain size, thereby solving the problem of accurate prediction of the grain size in high-strength steel high-temperature deformation.
The invention conception is as follows: the method provides a whole set of model for predicting grain growth, dynamic recrystallization, sub-dynamic recrystallization and static recrystallization in the processes of high-temperature compression, heat preservation, multi-pass compression and the like of the ultrahigh-strength steel, and based on 45 groups of hot compression test data, 14 parameters of the model are directly obtained by adopting an intelligent optimization algorithm to predict the grain size evolution of the ultrahigh-strength steel.
Therefore, the technical scheme of the invention is as follows: the method for establishing the evolution model of the grain size of the ultrahigh-strength steel formed at high temperature is characterized by comprising the following steps of:
grain growth occurs first on heating, and the evolution formula of the average grain size d is:
Figure 632122DEST_PATH_IMAGE002
wherein T is the heat preservation temperature and the unit is K;
Figure 346000DEST_PATH_IMAGE003
is the holding time in units of s;
starting compression deformation after the heat preservation is finished, if the absolute value of the compression strain is larger than the critical strain, dynamic recrystallization occurs, and the size of the dynamic recrystallization crystal grain is
Figure 797841DEST_PATH_IMAGE004
(μm) is:
Figure 862225DEST_PATH_IMAGE005
（2）
wherein the content of the first and second substances,
Figure 207756DEST_PATH_IMAGE006
(. mu.m) is the average grain size at the time of starting the deformation in this pass,
Figure 702322DEST_PATH_IMAGE007
（s -1 ) Is the rate of strain at which the strain is,
Figure 375880DEST_PATH_IMAGE008
(8.314J/(mol K)) is a universal gas constant,
Figure 105938DEST_PATH_IMAGE009
(K) is the temperature at which the film is deformed,
Figure 446921DEST_PATH_IMAGE010
、
Figure 112389DEST_PATH_IMAGE011
、
Figure 663456DEST_PATH_IMAGE012
、
Figure 806992DEST_PATH_IMAGE013
undetermined parameters for the model;
the average grain size d (μm) during dynamic recrystallization was:
Figure 861536DEST_PATH_IMAGE014
（3）
wherein the content of the first and second substances,
Figure 963484DEST_PATH_IMAGE015
is the dynamic recrystallization volume fraction, and the calculation formula is as follows:
Figure 611634DEST_PATH_IMAGE016
（4）
wherein the content of the first and second substances,
Figure 417916DEST_PATH_IMAGE017
is the absolute value of the compressive true strain,
Figure 470842DEST_PATH_IMAGE018
is the critical strain for dynamic recrystallization,
Figure 743691DEST_PATH_IMAGE019
is the peak strain;
Figure 675875DEST_PATH_IMAGE018
and
Figure 957952DEST_PATH_IMAGE019
are all determined by a compressive rheological stress curve, and the formula is as follows:
Figure 721508DEST_PATH_IMAGE020
（5）
Figure 899680DEST_PATH_IMAGE021
（6）
in the heat preservation process among the deformation passes, if the strain when the previous pass stops is smaller than the critical strain, dynamic recovery occurs among the passes, and the grain size is not changed; otherwise, static recrystallization and sub-dynamic recrystallization occur between passes; statically recrystallized grain size
Figure 115898DEST_PATH_IMAGE022
(. mu.m) taking into account the initial grain size
Figure 263982DEST_PATH_IMAGE006
(. mu.m) and accumulated strain
Figure 22991DEST_PATH_IMAGE017
The calculation formula is as follows:
Figure 496698DEST_PATH_IMAGE023
（7）
wherein the content of the first and second substances,
Figure 75578DEST_PATH_IMAGE024
、
Figure 27353DEST_PATH_IMAGE025
、
Figure 906447DEST_PATH_IMAGE026
、
Figure 551055DEST_PATH_IMAGE027
、
Figure 741865DEST_PATH_IMAGE028
all are model undetermined constants,
Figure 369768DEST_PATH_IMAGE006
updated as in formula (3)
Figure 696844DEST_PATH_IMAGE029
；
Similar to the formula for static recrystallization, the sub-dynamic recrystallization grain size
Figure 387720DEST_PATH_IMAGE030
(mum) also takes into account the initial grain size
Figure 331405DEST_PATH_IMAGE006
(. mu.m) and accumulated strain
Figure 765929DEST_PATH_IMAGE017
The calculation formula is as follows:
Figure 213090DEST_PATH_IMAGE031
（8）
wherein the content of the first and second substances,
Figure 933922DEST_PATH_IMAGE032
、
Figure 240269DEST_PATH_IMAGE033
、
Figure 71959DEST_PATH_IMAGE034
、
Figure 780152DEST_PATH_IMAGE035
、
Figure 406305DEST_PATH_IMAGE036
all are model undetermined constants;
then, the average grain size during the heat preservation between the deformation paths is calculated by the following formula
Figure 324583DEST_PATH_IMAGE029
：
Figure 835330DEST_PATH_IMAGE037
（9）
Wherein the content of the first and second substances,
Figure 991505DEST_PATH_IMAGE038
is the integrated recrystallization volume fraction, and the calculation formula is as follows:
Figure 319718DEST_PATH_IMAGE039
（10）
wherein the content of the first and second substances,
Figure 335078DEST_PATH_IMAGE040
and
Figure 774150DEST_PATH_IMAGE041
respectively, the static recrystallization volume fraction and the sub-dynamic recrystallization volume fraction, and the calculation formula is as follows:
Figure 191356DEST_PATH_IMAGE042
（11）
Figure 424891DEST_PATH_IMAGE043
（12）
wherein the content of the first and second substances,
Figure 52182DEST_PATH_IMAGE044
(s) is the inter-pass incubation time;
Figure 895942DEST_PATH_IMAGE045
and
Figure 292288DEST_PATH_IMAGE046
expressed as the time required to complete 50% recrystallization, the formula is:
Figure 837670DEST_PATH_IMAGE047
（13）
Figure 952257DEST_PATH_IMAGE048
（14）
when calculating the dynamic recrystallization of the subsequent pass, the cumulative effect of the strain needs to be considered, and the influence of the inter-pass heat preservation on the reduction of the cumulative strain is considered; firstly, calculating according to the formula (10) to obtain the integral number of the recrystallized body
Figure 467552DEST_PATH_IMAGE038
The accumulated strain at the end of the last (i-1) pass deformation and heat preservation
Figure 593771DEST_PATH_IMAGE049
Become into
Figure 434688DEST_PATH_IMAGE050
So the total deformation of the ith pass
Figure 911937DEST_PATH_IMAGE051
Should be modified to:
Figure 230922DEST_PATH_IMAGE052
（15）
wherein the content of the first and second substances,
Figure 601861DEST_PATH_IMAGE053
strain for the ith pass; the recrystallized grain size and the recrystallized volume fraction of the subsequent pass are the same as those of formula (4), wherein
Figure 223466DEST_PATH_IMAGE017
By
Figure 47066DEST_PATH_IMAGE051
Replacing;
through the whole set of 14 undetermined parameters: (
Figure 169743DEST_PATH_IMAGE024
、
Figure 270554DEST_PATH_IMAGE025
、
Figure 187694DEST_PATH_IMAGE026
、
Figure 639535DEST_PATH_IMAGE027
、
Figure 300324DEST_PATH_IMAGE028
、
Figure 380275DEST_PATH_IMAGE032
、
Figure 874842DEST_PATH_IMAGE033
、
Figure 673033DEST_PATH_IMAGE034
、
Figure 9949DEST_PATH_IMAGE035
、
Figure 944407DEST_PATH_IMAGE036
、
Figure 609875DEST_PATH_IMAGE010
、
Figure 629783DEST_PATH_IMAGE013
、
Figure 897954DEST_PATH_IMAGE012
、
Figure 827864DEST_PATH_IMAGE011
) The model of (2) simulates the evolution process of the grain size.
Has the advantages that: the model of the invention takes into account the initial grain size
Figure 523287DEST_PATH_IMAGE006
Thereby solving the problem of continuity of the grain size between different recrystallization processes; the model takes into account the influence of residual strain on recrystallization and can thusThe method is well applied to multiple compression processes.
Drawings
FIG. 1 is the effect of strain rate of the present invention (T7-T10).
FIG. 2 is the effect of temperature of the present invention (T11-T14, T8).
FIG. 3 is a comparison of the experimental and calculated average grain sizes for different inter-pass soak times (T21-24) according to the present invention.
FIG. 4 is a comparison of the experimental and calculated values of the average grain size (T35, T37, T39, T41) during two passes of the deformation process calculated by the present model.
FIG. 5 is a comparison of calculated and experimental values of average grain size under all experimental conditions of the present invention.
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings, but the embodiment should not be construed as limiting the present invention.
The invention is shown in fig. 1 to 5:
the specific application of the invention is described below by combining with the establishment example of the 300M steel high-temperature forming grain size evolution model, and the specific implementation steps are as follows:
1) processing 300M steel into a cylindrical sample with the diameter of 8mm and the height of 12mm, and carrying out a multi-pass compression test on a Gleeble3500 testing machine;
firstly, the temperature of a sample is increased to 1200 ℃ at 200 ℃/min, the sample is kept warm for 240s to homogenize the tissue, then the temperature is reduced to deformation temperatures (950 ℃, 1050 ℃ and 1150 ℃), and then the strain rate is constant (0.01, 0.1, 1 and 10 s) -1 ) Carrying out first-pass deformation; then carrying out subsequent pass strain (total strain is 0.9) at the same rate after keeping the temperature for a certain time, immediately carrying out water quenching after deformation, and keeping austenite grain boundaries; after the sample is cooled to room temperature, tempering for 2 hours at 560 ℃, air cooling, cutting from the axis of the sample, and then embedding, roughly grinding, finely grinding and corroding (the corrosive solution is 20ml of picric acid aqueous solution, 8ml of carbon tetrachloride, 1 drop of hydrochloric acid and a small amount of detergent, and the corrosion temperature is 40-60 ℃); finally, the sample is placed in an optical microscopeObserving the tissue, taking pictures, taking 5 pictures under each condition, and counting the grain size by using an Image-Pro Plus6.0 software by adopting a line cutting method;
TABLE 1 test protocol (where "-" indicates no value at this position)
Figure 905858DEST_PATH_IMAGE054
The description is as follows: firstly, heating to 1200 ℃ at 200 ℃/min, preserving heat for 4min, then cooling to the deformation temperature at 200 ℃/min, preserving heat for 4min, and beginning first-time deformation; and secondly, quenching the sample after the deformation or heat preservation is finished.
2) Establishing a multi-pass multi-scale coupling model function in Matlab, wherein the calculation flow of the function is as follows:
grain growth occurs first on heating, and the evolution formula of the average grain size d is:
Figure 712140DEST_PATH_IMAGE055
wherein the content of the first and second substances,Tthe insulation temperature is expressed in K;
Figure 886769DEST_PATH_IMAGE056
is the holding time in units of s;
starting compressive deformation after the heat preservation is finished, and if the absolute value of the compressive strain is larger than the critical strain, performing dynamic recrystallization; dynamic recrystallization grain size
Figure 362881DEST_PATH_IMAGE057
(μm) is:
Figure 622961DEST_PATH_IMAGE058
（2）
wherein the content of the first and second substances,
Figure 967355DEST_PATH_IMAGE059
(. mu.m) is the average grain size at the time of starting the deformation in this pass,
Figure 871857DEST_PATH_IMAGE060
（s -1 ) Is the rate of strain at which the strain is,
Figure 909083DEST_PATH_IMAGE061
(8.314J/(mol K)) is a universal gas constant,
Figure 266246DEST_PATH_IMAGE062
(K) is the temperature at which the film is deformed,
Figure 679910DEST_PATH_IMAGE063
、
Figure 297973DEST_PATH_IMAGE064
、
Figure 647046DEST_PATH_IMAGE065
、
Figure 616139DEST_PATH_IMAGE066
undetermined parameters for the model;
average grain size during dynamic recrystallizationd(μm) is:
Figure 180631DEST_PATH_IMAGE067
（3）
wherein the content of the first and second substances,
Figure 184359DEST_PATH_IMAGE068
is the dynamic recrystallization volume fraction, and the calculation formula is as follows:
Figure 438754DEST_PATH_IMAGE069
（4）
wherein the content of the first and second substances,
Figure 629564DEST_PATH_IMAGE070
is the absolute value of the compressive true strain,
Figure 385031DEST_PATH_IMAGE071
is the critical strain for dynamic recrystallization,
Figure 118632DEST_PATH_IMAGE072
is the peak strain;
Figure 668562DEST_PATH_IMAGE071
and
Figure 487613DEST_PATH_IMAGE072
are all determined by a compressive rheological stress curve, and the formula is as follows:
Figure 781191DEST_PATH_IMAGE073
（5）
Figure 228353DEST_PATH_IMAGE074
（6）
in the heat preservation process between the deformation passes, if the strain when the previous pass stops is smaller than the critical strain, dynamic recovery occurs between passes, and the grain size is not changed; otherwise, static recrystallization and sub-dynamic recrystallization occur between passes; statically recrystallized grain size
Figure 90130DEST_PATH_IMAGE075
(. mu.m) taking into account the initial grain size
Figure 521111DEST_PATH_IMAGE059
(. mu.m) and accumulated strain
Figure 493746DEST_PATH_IMAGE076
The calculation formula is as follows:
Figure 60994DEST_PATH_IMAGE077
（7）
wherein the content of the first and second substances,
Figure 828093DEST_PATH_IMAGE078
、
Figure 746370DEST_PATH_IMAGE079
、
Figure 116172DEST_PATH_IMAGE080
、
Figure 678871DEST_PATH_IMAGE081
、
Figure 741505DEST_PATH_IMAGE082
all are model undetermined constants,
Figure 753936DEST_PATH_IMAGE059
updated as in formula (3)
Figure 193007DEST_PATH_IMAGE083
；
Similar to the formula for static recrystallization, the sub-dynamic recrystallization grain size
Figure 734847DEST_PATH_IMAGE084
(mum) also takes into account the initial grain size
Figure 843749DEST_PATH_IMAGE059
(. mu.m) and accumulated strain
Figure 471039DEST_PATH_IMAGE076
The calculation formula is as follows:
Figure 323589DEST_PATH_IMAGE085
（8）
wherein the content of the first and second substances,
Figure 985514DEST_PATH_IMAGE086
、
Figure 389951DEST_PATH_IMAGE087
、
Figure 379903DEST_PATH_IMAGE088
、
Figure 160778DEST_PATH_IMAGE089
、
Figure 286997DEST_PATH_IMAGE090
all are model undetermined constants;
the average grain size at the time of heat retention between deformation paths was calculated by the following formula
Figure 127914DEST_PATH_IMAGE083
：
Figure 464217DEST_PATH_IMAGE091
（9）
Wherein the content of the first and second substances,
Figure 924148DEST_PATH_IMAGE092
is the integrated recrystallization volume fraction, and the calculation formula is as follows:
Figure 29508DEST_PATH_IMAGE093
（10）
wherein the content of the first and second substances,
Figure 916692DEST_PATH_IMAGE094
and
Figure 474712DEST_PATH_IMAGE095
respectively, the static recrystallization volume fraction and the sub-dynamic recrystallization volume fraction, and the calculation formula is as follows:
Figure 862968DEST_PATH_IMAGE096
（11）
Figure 963780DEST_PATH_IMAGE097
（12）
wherein, the first and the second end of the pipe are connected with each other,
Figure 880920DEST_PATH_IMAGE098
(s) is the inter-pass incubation time;
Figure 347410DEST_PATH_IMAGE099
and
Figure 8198DEST_PATH_IMAGE100
expressed as the time required to complete 50% recrystallization, the formula is:
Figure 88149DEST_PATH_IMAGE101
（13）
Figure 582716DEST_PATH_IMAGE102
（14）
when calculating the dynamic recrystallization of the subsequent pass, the cumulative effect of the strain needs to be considered, and the influence of the inter-pass heat preservation on the reduction of the cumulative strain is considered; firstly, calculating according to the formula (10) to obtain the integral number of the recrystallized body
Figure 115328DEST_PATH_IMAGE092
Last one of (i-1) cumulative strain at the end of pass deformation and holding
Figure 455174DEST_PATH_IMAGE103
Become into
Figure 389632DEST_PATH_IMAGE104
Therefore, it is firstiTotal deformation of each pass
Figure 179733DEST_PATH_IMAGE105
Should be modified to:
Figure 809429DEST_PATH_IMAGE106
（15）
wherein the content of the first and second substances,
Figure 343179DEST_PATH_IMAGE107
is a firstiStrain of each pass; the recrystallized grain size and the recrystallized volume fraction of the subsequent pass are the same as those of formula (4), wherein
Figure 132143DEST_PATH_IMAGE076
By
Figure 702933DEST_PATH_IMAGE105
Instead.
3) The 14 undetermined constants in the above model were optimized using the method of immittance to minimize the mean deviation Γ between the calculated and experimental values of grain size in all experimental results, i.e.:
Figure RE-GDA0003711439710000121
Γ is the objective function, d i (. mu.m) is a test value of the grain size,
Figure RE-GDA0003711439710000122
(μm) is a calculated value of crystal grain size, and N is the number of experimental groups; the optimized parameter combinations are shown in table 2;
TABLE 2 model parameter identification results
Figure RE-GDA0003711439710000123
FIG. 1 is a comparison of the experimental and calculated values for average grain size at different strain rates (T7-T10), FIG. 2 is a comparison of the experimental and calculated values for average grain size at different temperatures (T11-T14, T8), FIG. 3 is a comparison of the experimental and calculated values for average grain size at different inter-pass soak times (T21-24), FIG. 4 is a comparison of the experimental and calculated values for average grain size during model-calculated two-pass deformation (T35, T37, T39, T41), FIG. 5 is a comparison of the calculated and experimental values for average grain size under all experimental conditions,
as can be seen from the above figures, the calculated values can be matched with the experimental values; the average percent deviation of the model predictions was 2.48% and the average absolute deviation was 0.9878 μm.
Those skilled in the art will appreciate that the details of the present invention are not described in detail herein.
From the above description of the modeling method, those skilled in the art will appreciate that the present invention is not limited to the above-described embodiments, and that modifications and substitutions based on the known technology in the art are within the scope of the present invention, which is defined by the claims.

Claims (1)

1. The method for establishing the evolution model of the grain size of the ultrahigh-strength steel formed at high temperature is characterized by comprising the following steps of:
grain growth occurs first on heating, and the evolution formula of the average grain size d is:
Figure 370747DEST_PATH_IMAGE002
wherein T is the heat preservation temperature and the unit is K;
Figure 407973DEST_PATH_IMAGE003
is the holding time in units of s;
starting compression deformation after the heat preservation is finished, if the absolute value of the compression strain is larger than the critical strain, dynamic recrystallization occurs, and the size of the dynamic recrystallization crystal grain is
Figure 27786DEST_PATH_IMAGE004
(μm) is:
Figure 441450DEST_PATH_IMAGE005
（2）
wherein the content of the first and second substances,
Figure 528354DEST_PATH_IMAGE006
(. mu.m) is the average grain size at the time of starting the deformation in this pass,
Figure 611848DEST_PATH_IMAGE007
（s -1 ) Is the rate of strain at which the strain is,
Figure 580941DEST_PATH_IMAGE008
(8.314J/(mol K)) is a universal gas constant,
Figure 939241DEST_PATH_IMAGE009
(K) is the temperature at which the film is deformed,
Figure 677390DEST_PATH_IMAGE010
、
Figure 931785DEST_PATH_IMAGE011
、
Figure 388174DEST_PATH_IMAGE012
、
Figure 19007DEST_PATH_IMAGE013
undetermined parameters for the model;
the average grain size d (μm) during dynamic recrystallization was:
Figure 80504DEST_PATH_IMAGE014
（3）
wherein the content of the first and second substances,
Figure 505800DEST_PATH_IMAGE015
is the dynamic recrystallization volume fraction, and the calculation formula is as follows:
Figure 856010DEST_PATH_IMAGE016
（4）
wherein, the first and the second end of the pipe are connected with each other,
Figure 149588DEST_PATH_IMAGE017
is the absolute value of the compressive true strain,
Figure 728906DEST_PATH_IMAGE018
is the critical strain for dynamic recrystallization,
Figure 715317DEST_PATH_IMAGE019
is the peak strain;
Figure 21664DEST_PATH_IMAGE018
and
Figure 791037DEST_PATH_IMAGE019
are all determined by a compressive rheological stress curve, and the formula is as follows:
Figure 92705DEST_PATH_IMAGE020
（5）
Figure 922121DEST_PATH_IMAGE021
（6）
in the heat preservation process between the deformation passes, if the strain when the previous pass stops is smaller than the critical strain, dynamic recovery occurs between passes, and the grain size is not changed; otherwise, static recrystallization and sub-dynamic recrystallization occur between passes; statically recrystallized grain size
Figure 184606DEST_PATH_IMAGE022
(. mu.m) taking into account the initial grain size
Figure 85566DEST_PATH_IMAGE006
(. mu.m) and accumulated strain
Figure 445003DEST_PATH_IMAGE017
The calculation formula is as follows:
Figure 648583DEST_PATH_IMAGE023
（7）
wherein the content of the first and second substances,
Figure 788577DEST_PATH_IMAGE024
、
Figure 634173DEST_PATH_IMAGE025
、
Figure 314029DEST_PATH_IMAGE026
、
Figure 219668DEST_PATH_IMAGE027
、
Figure 722325DEST_PATH_IMAGE028
all are model undetermined constants,
Figure 637191DEST_PATH_IMAGE006
updated as in formula (3)
Figure 299117DEST_PATH_IMAGE029
；
Similar to the formula for static recrystallization, the sub-dynamic recrystallization grain size
Figure 844499DEST_PATH_IMAGE030
(mum) also takes into account the initial grain size
Figure 896768DEST_PATH_IMAGE006
(. mu.m) and accumulated strain
Figure 943222DEST_PATH_IMAGE017
The calculation formula is as follows:
Figure 335020DEST_PATH_IMAGE031
（8）
wherein the content of the first and second substances,
Figure 441516DEST_PATH_IMAGE032
、
Figure 653186DEST_PATH_IMAGE033
、
Figure 237751DEST_PATH_IMAGE034
、
Figure 811952DEST_PATH_IMAGE035
、
Figure 964715DEST_PATH_IMAGE036
all are model undetermined constants;
then, the average grain size during the heat preservation between the deformation paths is calculated by the following formula
Figure 53894DEST_PATH_IMAGE029
：
Figure 379833DEST_PATH_IMAGE037
（9）
Wherein the content of the first and second substances,
Figure 749153DEST_PATH_IMAGE038
is the integrated recrystallization volume fraction, and the calculation formula is as follows:
Figure 931873DEST_PATH_IMAGE039
（10）
wherein the content of the first and second substances,
Figure 383714DEST_PATH_IMAGE040
and
Figure 310082DEST_PATH_IMAGE041
the calculation formula is respectively a static recrystallization volume fraction and a sub-dynamic recrystallization volume fraction:
Figure 858875DEST_PATH_IMAGE042
（11）
Figure 87862DEST_PATH_IMAGE043
（12）
wherein, the first and the second end of the pipe are connected with each other,
Figure 151633DEST_PATH_IMAGE044
(s) is the inter-pass incubation time;
Figure 757058DEST_PATH_IMAGE045
and
Figure 957095DEST_PATH_IMAGE046
representing the time required to complete 50% recrystallization, the formula is:
Figure 684879DEST_PATH_IMAGE047
（13）
Figure 845733DEST_PATH_IMAGE048
（14）
when calculating the dynamic recrystallization of the subsequent pass, the cumulative effect of the strain needs to be considered, and the influence of the inter-pass heat preservation on the reduction of the cumulative strain is considered; firstly, calculating according to the formula (10) to obtain the integral number of the recrystallized body
Figure 645062DEST_PATH_IMAGE038
The accumulated strain at the end of the last (i-1) pass deformation and heat preservation
Figure 574972DEST_PATH_IMAGE049
Become into
Figure 473658DEST_PATH_IMAGE050
So the total deformation of the ith pass
Figure 246442DEST_PATH_IMAGE051
Should be modified to:
Figure 459249DEST_PATH_IMAGE052
（15）
wherein the content of the first and second substances,
Figure 368299DEST_PATH_IMAGE053
strain for the ith pass; the recrystallized grain size and the recrystallized volume fraction in the subsequent pass are the same as those in the formula (4), wherein
Figure 375569DEST_PATH_IMAGE017
By
Figure 573332DEST_PATH_IMAGE051
Replacing;
through the whole set of 14 undetermined parameters: (
Figure 448884DEST_PATH_IMAGE024
、
Figure 350457DEST_PATH_IMAGE025
、
Figure 653262DEST_PATH_IMAGE026
、
Figure 338321DEST_PATH_IMAGE027
、
Figure 627351DEST_PATH_IMAGE028
、
Figure 776573DEST_PATH_IMAGE032
、
Figure 125646DEST_PATH_IMAGE033
、
Figure 298001DEST_PATH_IMAGE034
、
Figure 515356DEST_PATH_IMAGE035
、
Figure 394450DEST_PATH_IMAGE036
、
Figure 39058DEST_PATH_IMAGE010
、
Figure 698710DEST_PATH_IMAGE013
、
Figure 329542DEST_PATH_IMAGE012
、
Figure 453356DEST_PATH_IMAGE011
) To simulate the evolution process of the grain size.
CN202210574104.8A 2022-05-25 2022-05-25 Method for establishing ultra-high strength steel high-temperature forming grain size evolution model Pending CN114864007A (en)

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Publication number Priority date Publication date Assignee Title
CN105373683A (en) * 2015-12-11 2016-03-02 武汉理工大学 Prediction method for microstructure evolution law of 20CrMnTiH steel in thermal deformation process
CN111079309A (en) * 2019-12-30 2020-04-28 湖北汽车工业学院 Multi-pass compression rheological stress model establishment method for coupled recrystallization dynamics

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105373683A (en) * 2015-12-11 2016-03-02 武汉理工大学 Prediction method for microstructure evolution law of 20CrMnTiH steel in thermal deformation process
CN111079309A (en) * 2019-12-30 2020-04-28 湖北汽车工业学院 Multi-pass compression rheological stress model establishment method for coupled recrystallization dynamics

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110245382A (en) * 2019-05-10 2019-09-17 本钢板材股份有限公司 A kind of method of the Avrami mathematical model coefficient of determining metal dynamic recrystallization volume fraction
CN110245382B (en) * 2019-05-10 2023-08-22 本钢板材股份有限公司 Method for determining Avrami mathematical model coefficient of metal dynamic recrystallization volume fraction

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