CN113642212A

CN113642212A - Design method and system for refined heat treatment process of large ultrahigh-strength steel shell

Info

Publication number: CN113642212A
Application number: CN202110922924.7A
Authority: CN
Inventors: 李敬民; 周文凤; 汪德武; 滕宇; 陈金明; 贺员吉; 黄姝珂; 汤光平; 成丽蓉; 兰成均
Original assignee: 24th Branch Of Pla 96901; Institute of Mechanical Manufacturing Technology of CAEP
Current assignee: 24th Branch Of Pla 96901; Institute of Mechanical Manufacturing Technology of CAEP
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2021-11-12
Anticipated expiration: 2041-08-12
Also published as: CN113642212B

Abstract

The invention discloses a design method and a system for a refined heat treatment process of a large-scale ultrahigh-strength steel shell, wherein the method comprises the following steps: s1: carrying out finite element treatment on the G50 steel shell of the cylindrical rotating body by using simulation software to obtain a G50 steel shell heat treatment finite element model; setting model parameters in the finite element model; s2: setting heat treatment process parameters and simulation parameters of the G50 steel shell according to an optimal parameter interval, and performing process simulation in different process parameter intervals by combining the heat treatment process parameters, the simulation parameters and the model parameters to obtain a plurality of different processes and the integral deformation and microstructure distribution of parts corresponding to the different processes; s3: and comparing the obtained multiple different technological processes according to the integral deformation and the microstructure distribution of the part to obtain the optimal heat treatment technological process. The invention provides technical support for precise control of shell heat treatment process parameters, deformation and microstructure prediction.

Description

Design method and system for refined heat treatment process of large ultrahigh-strength steel shell

Technical Field

The invention relates to the technical field of steel shell heat treatment processes, in particular to a design method and a system for a refined heat treatment process of a large ultrahigh-strength steel shell.

Background

The 28CrMnSiNi4MoNb steel is novel low-alloy ultrahigh-strength steel which is self-developed in China, has the characteristics of low price of common low-alloy ultrahigh-strength steel (30CrMnNi2A, D6AC and the like), has the characteristics of high strength and high toughness of cobalt-containing steel such as 9Ni-5Co steel, belongs to cobalt-free high-strength high-toughness steel, and is a main material of penetration type shells.

As a penetration-type shell subject to high load impact, the stability of toughness matching after heat treatment and the uniformity of the overall mechanical properties of the shell are critical to ensure its success. However, the heat treatment process itself is a special process, and it is necessary to precisely control each factor of the heat treatment of the shell in the heat treatment process to ensure the stability and consistency of the comprehensive mechanical properties of the shell. However, at present, the mechanical properties of the shell after heat treatment have larger fluctuation under the influence of a plurality of factors such as material component fluctuation and the like. Meanwhile, parameters such as heat preservation time and the like in the heat treatment process are mostly based on an empirical estimation algorithm; the mechanical property evaluation of the shell after heat treatment mainly adopts a furnace sample, and an effective method is lacked to establish the relation between the heat treatment process and the mechanical property of the shell.

Disclosure of Invention

In view of the above drawbacks of the prior art, the present invention aims to provide a method and a system for designing a refined heat treatment process for a large ultra-high strength steel shell, so as to solve the problems that the toughness matching of the existing large ultra-high strength steel after heat treatment is unstable, and the parameters of the heat treatment process and the performance evaluation after heat treatment are based on an empirical estimation algorithm.

The invention is realized by the following technical scheme:

in a first aspect, the invention provides a design method for a fine heat treatment process of a large ultra-high strength steel shell, which comprises the following steps:

s1: establishing a G50 steel shell heat treatment finite element model according to the actual heat treatment working condition of the shell by using simulation software; setting model parameters in the G50 steel shell heat treatment finite element model, wherein the model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, a phase change model, boundary conditions and the like of parts;

s2: setting heat treatment process parameters and simulation parameters of the G50 steel shell (reasonably setting simulation software parameters such as the step length of the heat treatment process simulation process and the like to ensure the convergence of the simulation calculation process), and carrying out process simulation in different process parameter intervals by combining the heat treatment process parameters, the simulation parameters and the model parameters to obtain a plurality of different processes and the integral deformation and microstructure distribution of parts corresponding to the different processes;

s3: and (4) comparing the plurality of different technological processes obtained in the step (S2) according to the overall deformation of the part and the distribution of the microstructure, and selecting the technological process with the minimum overall deformation of the part and the optimal distribution of the microstructure to obtain the optimal heat treatment technological process.

Further, model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, a phase transformation model and boundary conditions of the part, wherein:

the material parameters of the part are various parameters under different temperatures and different phases, and the material parameters of the part comprise thermophysical parameters and mechanical parameters; the thermophysical parameters comprise specific heat, density, heat exchange coefficient and the like, and the mechanical parameters comprise yield strength, Young modulus, strain strengthening value and the like;

the phase transformation model comprises pearlite- > austenite, martensite- > austenite, bainite- > austenite, austenite- > bainite, austenite- > pearlite, austenite- > martensite, austenite- > ferrite and other phase transformation models;

the boundary conditions include heat transfer coefficients, which are heat transfer coefficients of heating and quenching processes of the actual measurement shell or the scaled sample.

Further, the boundary condition comprises a heat exchange coefficient, wherein the heat exchange coefficient is the heat exchange coefficient of the heating and quenching process of the actual measurement shell or the scaled sample; the heat exchange coefficient is an important boundary condition which is used as a precondition for the simulation; it includes:

characteristics of G50 steel shell body or shrinkage sampleDrilling a hole in a characteristic area, arranging a plurality of thermocouples, and acquiring data of temperature change along with time in the heating and quenching processes by using corresponding data acquisition devices; quenching cooling data are led into a reverse solving module, and a heat exchange coefficient is calculated; the calculation formula of the heat exchange coefficient in the heating process is as follows: h ═ H_k+H_sCoefficient of convective heat transfer, H_sIs the radiant heat transfer coefficient;

the convective heat transfer coefficient calculation process is as follows:

in the formula, λ₀Is the medium thermal conductivity; h is the size (m) of the workpiece, taking a shaft as an example, taking the shaft length in the vertical case and the diameter in the horizontal case; n is a radical of_uIs the number of Nusselt;

heat transfer coefficient of radiation H_sThe calculation process is as follows:

where ε is calculated by the following equation:

and epsilon₀The emissivity of the furnace hearth refractory material is generally 0.82; epsilon_wIs determined by the following formula

Wherein A is_W，A₀The surface areas of the workpiece and the hearth correspondingly.

Further, performing finite element modeling on the G50 steel shell by using simulation software in the step S1 to obtain a G50 steel shell heat treatment finite element model; wherein:

the G50 steel shell heat treatment finite element model is a finite element model which is established according to the state of the part before heat treatment and can reflect the structural characteristics of the actual part; for the convenience of calculation, the size and the number of the model meshes need to be reasonably set.

Further, the process in step S2 is divided into two stages to perform a process treatment process, wherein the pre-rough-machining stage is performed with normalizing and high-temperature tempering heat treatment, and the post-rough-machining stage is performed with quenching and tempering heat treatment.

The chemical composition of the G50 steel is shown in Table 1:

table 1. main chemical composition of G50 steel, wt.%

C

Si

Mn

S

P

Ni

Cr

Mo

Nb

0.26～0.3

1.70～2.10

0.40～0.75

≤0.005

≤0.010

4.30～4.60

0.90～1.20

0.50～0.70

0.02～0.04

Furthermore, the manual selection of the process parameter interval is time-consuming and labor-consuming; the design of the invention is realized by selecting a process interval passing the sample verification; specifically, the method comprises the following steps: in the step S2, carrying out technological process simulation in different technological parameter intervals to obtain different technological processes and the integral deformation and microstructure distribution of parts corresponding to the different technological processes; the process simulation is carried out by selecting different simulation value combinations of normalizing, high-temperature tempering, quenching and tempering to obtain a plurality of different processes; the simulation value combination is that the heat treatment parameters of the normalizing, high-temperature tempering, quenching and tempering procedures are selected by adopting an orthogonal experiment method according to the following rules in advance to obtain a plurality of different technological processes, wherein:

normalizing: normalizing at 910-930 deg.c, maintaining for 1 hr after heat penetration (generally 1.2-2.5) D min, and air cooling to below 200 deg.c after maintaining;

high-temperature tempering: the high-temperature tempering temperature is 660-690 ℃, the heat is preserved for not less than 2 hours (generally (1.8-3) D minutes, wherein the effective thickness of the shell D) after the heat is thoroughly conducted, and an air cooling or furnace cooling mode is adopted after the heat preservation is finished.

Quenching: the quenching temperature is 840-900 ℃, the temperature is kept for 1 hour (generally (1-2.5) × D minutes, wherein the effective thickness of the shell D) after the heat is thoroughly conducted, and oil cooling is adopted after the temperature is kept; cooling the oil to below 100 deg.c, and air cooling;

tempering: the tempering temperature is 200-300 ℃, the heat is preserved for not less than 2 hours (generally (1.8-3) D minutes, wherein the effective thickness of the shell D) after the heat is thoroughly conducted, and an air cooling or oil cooling mode can be adopted after the heat preservation is finished.

During specific implementation, the normalizing temperature in the normalizing range is selected to be unchanged to adjust the temperature range of high-temperature tempering, and the quenching temperature in the quenching temperature range is selected to be unchanged to adjust the temperature range of tempering.

Further, in step S3, based on the overall deformation of the part and the microstructure distribution, comparing the plurality of different processes obtained in step S2, and selecting a process with the minimum overall deformation of the part and the optimal microstructure distribution to obtain an optimal heat treatment process; wherein, the optimal heat treatment process comprises the following steps:

and (3) normalizing process: normalizing at 920 +/-10 ℃, preserving the temperature for 880 minutes, and cooling the air to below 200 ℃ after the heat preservation is finished;

and (3) high-temperature tempering process: the high-temperature tempering temperature is 680 +/-10 ℃, the temperature is kept for 960 minutes, and an air cooling or furnace cooling mode is adopted after the temperature is kept;

quenching process: the quenching temperature is 880 +/-10 ℃, the temperature is kept for 580 minutes, and oil cooling is adopted after the temperature is kept; cooling the oil to below 100 deg.c and air cooling;

and (3) tempering process: tempering temperature is 280 ℃, heat preservation is carried out for 700 minutes, and air cooling is carried out after the heat preservation is finished.

In a second aspect, the present invention further provides a system for designing a fine heat treatment process for a large ultra-high strength steel shell, the system comprising:

establishing a finite element model unit for establishing a G50 steel shell heat treatment finite element model according to the actual heat treatment working condition of the shell by using simulation software;

the model parameter setting unit is used for setting model parameters in the G50 steel shell heat treatment finite element model, and the model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, a phase change model and boundary conditions of parts;

the heat treatment process parameter setting unit is used for setting heat treatment process parameters of the G50 steel shell;

the simulation software parameter setting unit is used for setting simulation parameters;

the simulation unit is used for carrying out process simulation in different process parameter intervals by combining the heat treatment process parameters, the simulation parameters and the model parameters to obtain a plurality of different processes and the integral deformation and microstructure distribution of parts corresponding to the different processes;

and the optimal result unit is used for comparing a plurality of obtained different technological processes according to the integral deformation and the microstructure distribution of the part, and selecting the technological process with the minimum integral deformation and the optimal microstructure distribution of the part to obtain the optimal heat treatment technological process.

the material parameters of the part are various parameters under different temperatures and different phases, and the material parameters of the part comprise thermophysical parameters and mechanical parameters; the thermophysical parameters comprise specific heat, density and heat exchange coefficient, and the mechanical parameters comprise yield strength, Young modulus and strain strengthening value;

the phase transformation model comprises pearlite- > austenite, martensite- > austenite, bainite- > austenite, austenite- > bainite, austenite- > pearlite, austenite- > martensite, austenite- > ferrite phase transformation model;

Further, the boundary condition comprises a heat exchange coefficient, wherein the heat exchange coefficient is the heat exchange coefficient of the heating and quenching process of the actual measurement shell or the scaled sample; it includes:

drilling holes in a G50 steel shell body or a characteristic region of a scaled sample, arranging a plurality of thermocouples, and acquiring data of temperature change along with time in the heating and quenching processes by using corresponding data acquisition devices; introducing quenching cooling data into a Deform-inverse module or other reverse modules, and calculating a heat exchange coefficient; the calculation formula of the heat exchange coefficient is as follows: h ═ H_k+H_sCoefficient of convective heat transfer, H_sIs the radiant heat transfer coefficient.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the technological parameters listed in S2 are reasonably selected, the G50 steel shell is stable in mechanical property and good in toughness after heat treatment, and the mechanical properties of the shell with different yield ratios can be obtained by adjusting tempering temperature parameters and the like.

2. According to the invention, a large-scale shell quenching and tempering simulation method is established, and the authenticity of a simulation effect and the accuracy of a simulation result are improved.

3. The invention considers the problems of time and labor consumption of manual selection of process parameters and verification, and reduces the test times by means of a numerical simulation method; specifically, the method comprises the following steps: in the step S2, carrying out technological process simulation in different technological parameter intervals to obtain different technological processes and the integral deformation and microstructure distribution of parts corresponding to the different technological processes; different simulation value combinations of normalizing, high-temperature tempering, quenching and tempering are selected for the process simulation, and a plurality of different processes are obtained; therefore, the problems of time and labor consumption caused by manual selection of process parameters are solved.

4. The invention provides technical support for precise control of shell heat treatment process parameters, deformation and microstructure prediction.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 is a flow chart of a design method of a refining heat treatment process for a large ultra-high-strength steel shell.

FIG. 2 is a schematic diagram of the heat transfer coefficient of the heating process of the present invention.

Fig. 3 is a schematic view of the arrangement of the heat exchange surface of the shell of the present invention.

FIG. 4 is a schematic diagram of the calculation result of the heat transfer coefficient according to the present invention (two-point difference method).

FIG. 5 is a schematic diagram of the heat transfer coefficient calculation results (optimized heat transfer coefficient) of the present invention.

FIG. 6 is a heat treatment model of the shell of the present invention.

FIG. 7 is a graph of TTT and CCT of G50 steel of the present invention.

FIG. 8 shows the fitting result (b) of the curve (a) of the total radial strain of the sample with the temperature change and the transformation plasticity parameter K under each load according to the invention.

Fig. 9 is a graph of G50 mechanical properties (for process parameter interval setting) under different process conditions.

Detailed Description

Hereinafter, the term "comprising" or "may include" used in various embodiments of the present invention indicates the presence of the invented function, operation or element, and does not limit the addition of one or more functions, operations or elements. Furthermore, as used in various embodiments of the present invention, the terms "comprises," "comprising," "includes," "including," "has," "having" and their derivatives are intended to mean that the specified features, numbers, steps, operations, elements, components, or combinations of the foregoing, are only meant to indicate that a particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as first excluding the existence of, or adding to the possibility of, one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.

In various embodiments of the invention, the expression "or" at least one of a or/and B "includes any or all combinations of the words listed simultaneously. For example, the expression "a or B" or "at least one of a or/and B" may include a, may include B, or may include both a and B.

Expressions (such as "first", "second", and the like) used in various embodiments of the present invention may modify various constituent elements in various embodiments, but may not limit the respective constituent elements. For example, the above description does not limit the order and/or importance of the elements described. The foregoing description is for the purpose of distinguishing one element from another. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of various embodiments of the present invention.

It should be noted that: if it is described that one constituent element is "connected" to another constituent element, the first constituent element may be directly connected to the second constituent element, and a third constituent element may be "connected" between the first constituent element and the second constituent element. In contrast, when one constituent element is "directly connected" to another constituent element, it is understood that there is no third constituent element between the first constituent element and the second constituent element.

The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present invention belong. The terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their contextual meaning in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in various embodiments of the present invention.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Example 1

As shown in fig. 1 to 9, the simulation method of the invention for designing a refining heat treatment process of a large ultra-high strength steel shell, as shown in fig. 1, includes the following steps:

s1: carrying out finite element processing on the G50 steel shell of the cylindrical rotating body by using simulation software according to the actual heat treatment working condition of the shell to obtain a G50 steel shell heat treatment finite element model; setting model parameters in the G50 steel shell heat treatment finite element model, wherein the model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, a phase change model, boundary conditions and the like of parts;

Specifically, model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, a phase change model and boundary conditions of the part, wherein:

Specifically, the boundary condition includes a heat exchange coefficient, which is a heat exchange coefficient in the heating and quenching process of the actual measurement shell or the scaled sample; the heat exchange coefficient is an important boundary condition which is used as a precondition for the simulation; it includes:

drilling holes in characteristic areas of a G50 steel shell body or a scale sample, arranging a plurality of thermocouples, and acquiring the time-varying temperature of the heating and quenching process by using corresponding data acquisition devicesAccordingly; introducing quenching cooling data into a Deform-inverse module or other reverse modules, and calculating a heat exchange coefficient; the calculation formula of the heat exchange coefficient is as follows: h ═ H_k+H_sCoefficient of convective heat transfer, H_sIs the radiant heat transfer coefficient;

the convective heat transfer coefficient calculation process is as follows:

where ε is calculated by the following equation:

Specifically, in step S1, performing finite element processing on the G50 steel shell of the cylindrical rotating body by using simulation software to obtain a G50 steel shell heat treatment finite element model; wherein:

Specifically, the process in step S2 is a process of performing a process treatment in two stages, a pre-roughing stage and a post-roughing stage, according to the chemical composition of the G50 steel, wherein the pre-roughing stage is subjected to normalizing and high temperature tempering heat treatment, and the post-roughing stage is subjected to quenching and tempering heat treatment.

Specifically, the manual selection of process parameters is time-consuming and labor-consuming; the design of the invention is realized by randomly selecting and combining a selection plug-in simulation software; specifically, the method comprises the following steps: in the step S2, carrying out technological process simulation in different technological parameter intervals to obtain different technological processes and the integral deformation and microstructure distribution of parts corresponding to the different technological processes; the technological process simulation is carried out by selecting different simulation value combinations of normalizing, high-temperature tempering, quenching and tempering through a selection plug-in unit to obtain a plurality of different technological processes; the simulation value combination is that the heat treatment parameters of the normalizing, high-temperature tempering, quenching and tempering procedures are selected by adopting an orthogonal experiment method according to the following rules to obtain a plurality of different technological processes, wherein:

Note that: during specific implementation, the normalizing temperature in the normalizing range is selected to be unchanged to adjust the temperature range of high-temperature tempering, and the quenching temperature in the quenching temperature range is selected to be unchanged to adjust the temperature range of tempering.

Specifically, in step S3, based on the overall deformation of the part and the microstructure distribution, comparing the plurality of different processes obtained in step S2, and selecting a process with the minimum overall deformation of the part and the optimal microstructure distribution to obtain an optimal heat treatment process; wherein, the optimal heat treatment process comprises the following steps:

The technological parameters listed in S2 are reasonably selected, the G50 steel shell is stable in mechanical property and good in toughness after heat treatment, and the mechanical properties of the shell with different yield ratios can be obtained by adjusting tempering temperature parameters and the like; according to the invention, a large-scale shell quenching and tempering simulation method is established, so that the authenticity of a simulation effect and the accuracy of a simulation result are improved; the invention provides technical support for precise control of shell heat treatment process parameters, deformation and microstructure prediction.

Example 2

As shown in fig. 1 to 9, the difference between this embodiment and embodiment 1 is that the phase change model of the material established in the present invention has versatility, and the shells made of the same material can be used subsequently. The heat exchange coefficient of the heating and cooling process obtained by the invention is a shrinkage ratio test piece with a structure similar to that of a processed shell.

The specific implementation is as follows:

the G50 steel shell has a length of about 2600mm, a diameter of 450mm and an effective thickness of 300 mm. Performing heat treatment after rough machining of a bar stock. The quenching medium for heat treatment is N32 quenching oil. The implementation is detailed below according to the steps provided in example 1.

1. Actually measured heat exchange coefficient of shell or shrinkage sample in heating and quenching processes

1) Heating process

The heat exchange coefficient in the heating process is calculated by adopting the calculation formula in the implementation 1, and the calculation result is shown in figure 2.

2) Quenching process

The G50 steel shell heat exchange surface arrangement is schematically shown in figure 3,

fig. 3 is a schematic diagram of the arrangement of the heat exchange surface of the shell, and since the shell adopts a relatively complex protection, in order to reduce the complexity of modeling, the method shown in fig. 3 is simplified, that is, the method of setting the heat exchange coefficient in sections is adopted for simplification. The heat exchange coefficient is obtained by calculating a shrinkage sample by a near-surface double-point difference method and optimizing the calculation, and is shown in fig. 4 and 5. Wherein the heat exchange surface 6 can be processed as an insulating surface by calculation.

2. Establishing a G50 steel shell heat treatment finite element model

FIG. 6 is a heat treatment model diagram of a shell, wherein the shell belongs to a cylindrical rotating body, and in order to reduce the calculation workload, the shell is modeled by a rotating section and a 2D finite element model is adopted.

3. Setting parameters such as material parameters, phase change models, boundary conditions and the like of parts in a G50 steel shell heat treatment finite element model

The solid-state phase transformation of the G50 steel under the action of no external stress is researched by a thermal expansion method, and the CCT curve and the TTT curve of the G50 steel are measured. The results are shown in FIG. 7. The martensite phase transformation dynamics is described by using a K-M formula, and a martensite phase transformation dynamics equation is fitted by a thermal expansion curve of a small sample: ξ (T) ═ 1-exp [ -0.03342 × (290-T)]The martensite transformation start point was 290 ℃. The transformation kinetics of isothermal bainite transformation is expressed by the JMAK formula: 1-exp [ -b (t-t)_s)ⁿ]. Obtaining the incubation time of bainite phase transformation from the thermal expansion curve of isothermal bainite phase transformation, and fitting the transformation dynamicsThe parameters b and n in the formula are shown in Table 2.

TABLE 2 parameters of isothermal bainite transformation kinetics of G50 steels

Temperature/. degree.C	310	330	350
				B	6.8316E-11	1.0010E-9	1.0411E-8
n	3.003	2.683	2.178
				Inoculation period/(t)_s/S)	272.5	271.9	344.4

The general expression for phase change plasticity is: epsilon^tpK σ f (ξ) when ξ is 1, f (ξ) is 1, epsilon^tpMeasured at different stress levels

Can obtain epsilon^tp _maxIn relation to σ, fromAnd fitting a phase change plasticity parameter K:

FIG. 8 shows the fitting results (b) of the curve (a) of the total radial strain of the sample with the temperature change and the transformation plasticity parameter K under each load.

The K values measured under different stresses are shown in FIG. 8(b), and the phase change plasticity parameter K can be constant within the applied stress range, wherein K is 4.7212 × 10-⁵MPa^-1。

4. Setting a thermal processing process interval

From the prior research process, the influence of normalizing on the subsequent comprehensive mechanical properties is limited, and the mechanical properties of the shell are mainly determined by the quenching and tempering processes. FIG. 7 shows the mechanical properties under different quenching process conditions. The heat treatment process of the case was set as follows according to the method of fig. 9 and example 1:

and (3) normalizing process: normalizing at 920 +/-10 deg.c for 880 min, and air cooling to below 200 deg.c.

And (3) high-temperature tempering process: the high-temperature tempering temperature is 680 +/-10 ℃, the heat preservation is carried out for 960 minutes, and an air cooling or furnace cooling mode is adopted after the heat preservation is finished.

Quenching process: quenching temperature is 860-900 ℃, heat preservation is carried out for 300-750 minutes, and oil cooling is adopted after heat preservation is finished. The oil is cooled to below 100 ℃ and then discharged and cooled by air.

And (3) tempering process: the tempering temperature is 200-300 ℃, the heat preservation is carried out for 540-900 minutes, and an air cooling or oil cooling mode can be adopted after the heat preservation is finished.

5. Performing thermal process simulation and tuning optimization

And respectively carrying out corresponding heat treatment process numerical simulation technologies aiming at the set process interval. Finally determining an optimized heat treatment process based on the deformation and the obtained microstructure.

And (3) finally optimizing the heat treatment process:

Quenching process: the quenching temperature is 880 +/-10 ℃, the temperature is kept for 580 minutes, and oil cooling is adopted after the temperature is kept. Cooling the oil to below 100 deg.c, discharging oil and air cooling.

The shell deformation simulation results are compared with the actual measurement results, and the mechanical properties of the shell are respectively shown in tables 3 and 4.

TABLE 3 optimal Process simulation results and actual measurement results

TABLE 4 Shell mechanics Performance Table

	R_p0.2(MPa)	R_m(MPa)	R_p0.2/R_m	α_ku2(J/cm²)	A(％)	Z(％)
							Require that	≥1330	≥1660	≤0.86	65	10	45
Measured in fact	1400.6	1763.9	0.79	84.8	11.4	49.0

Aiming at the G50 material applied to the penetration shell, the invention provides the method for obtaining the combination with better toughness and better mechanical property stability; and the mechanical property combinations with different yield ratios can be obtained by applying the listed process interval combinations.

The invention obtains the change rules of key thermophysical parameters such as specific thermal melting, TTT curves, CCT curves and the like, and a G50 steel phase change plasticity mechanism, establishes a temperature-structure-stress three-field coupling model in the quenching process of a G50 steel shell by adopting a method for setting heat exchange coefficients in a segmented manner, and provides a method for realizing the accurate control of heat treatment process parameters.

Example 3

As shown in fig. 1 to 9, the present embodiment is different from embodiment 1 in that the present embodiment provides a system for refining heat treatment process design for a large ultra-high strength steel shell, the system comprising:

The execution process of each unit in the system is executed according to the design method for the refined heat treatment process of the large ultra-high-strength steel shell described in embodiment 1, and details are not repeated in this embodiment.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A design method for a refined heat treatment process of a large-scale ultrahigh-strength steel shell is characterized by comprising the following steps:

s1: establishing a G50 steel shell heat treatment finite element model according to the actual heat treatment working condition of the shell by using simulation software; setting model parameters in the G50 steel shell heat treatment finite element model, wherein the model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, a phase change model and boundary conditions of parts;

s2: setting heat treatment process parameters and simulation parameters of the G50 steel shell, and carrying out process simulation in different process parameter intervals by combining the heat treatment process parameters, the simulation parameters and the model parameters to obtain a plurality of different processes and corresponding part deformation and microstructure distribution;

2. The design method for the refining heat treatment process of the large-scale ultrahigh-strength steel shell according to claim 1, wherein the model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, a phase transformation model and boundary conditions of a part, wherein:

3. The design method for the refining heat treatment process of the large-scale ultrahigh-strength steel shell according to claim 2, wherein the boundary conditions comprise a heat exchange coefficient, and the heat exchange coefficient is a heat exchange coefficient obtained by a heating and quenching process of an actually measured shell or a scaled sample; it includes:

drilling holes in a G50 steel shell body or a characteristic region of a scaled sample, arranging a plurality of thermocouples, and acquiring data of temperature change along with time in the heating and quenching processes by using corresponding data acquisition devices; quenching cooling data are led into a reverse solving module, and a heat exchange coefficient is calculated; the calculation formula of the heating heat exchange coefficient is as follows: h ═ H_k+H_sCoefficient of convective heat transfer, H_sIs the radiant heat transfer coefficient;

the convective heat transfer coefficient calculation process is as follows:

in the formula, λ₀Is the medium thermal conductivity; h is the size of the workpiece; n is a radical of_uIs the number of Nusselt;

where ε is calculated by the following equation:

and epsilon₀Emissivity of the furnace hearth refractory material; epsilon_wIs determined by the following formula

4. The design method of the refining heat treatment process for the large ultra-high strength steel shell according to claim 1, wherein in step S1, finite element processing is performed on the G50 steel shell of the cylindrical rotating body by using simulation software, so as to obtain a G50 steel shell heat treatment finite element model; wherein:

the G50 steel shell heat treatment finite element model is a finite element model which is established according to the state of the part before heat treatment and can reflect the structural characteristics of the actual part; and sets the model mesh size and number.

5. The design method of the refining heat treatment process for the large ultra-high strength steel shell according to claim 1, wherein the process in the step S2 is divided into two stages, wherein the first stage is subjected to normalizing and high-temperature tempering heat treatment, and the second stage is subjected to quenching and tempering heat treatment.

6. The design method for the refined heat treatment process of the large-scale ultrahigh-strength steel shell according to claim 5, wherein in step S2, a process simulation is performed in a given process parameter interval to obtain the overall deformation and microstructure distribution of different processes and corresponding parts; the process simulation is carried out by selecting different simulation value combinations of normalizing, high-temperature tempering, quenching and tempering to obtain a plurality of different processes; wherein the given process parameters are process intervals preferred by using the samples:

normalizing: normalizing at 910-930 deg.c, maintaining for 1.2-2.5 hr after heat penetration, i.e. (1.2-2.5) × D min, wherein the effective thickness of the shell D is air cooled to below 200 deg.c after heat preservation;

high-temperature tempering: the high-temperature tempering temperature is 660-690 ℃, and the heat is preserved for not less than 2 hours (1.8-3) D minutes after the heat is thoroughly conducted, wherein the effective thickness of the shell body D is the effective thickness of the shell body D, and an air cooling or furnace cooling mode is adopted after the heat preservation is finished;

quenching: the quenching temperature is 840-900 ℃, the temperature is kept for 1-2.5 hours (1-2.5) D minutes after the heat is thoroughly conducted, wherein the effective thickness of the shell body D is oil cooling after the temperature keeping is finished; cooling the oil to below 100 deg.c and air cooling;

tempering: and (3) tempering at the temperature of 200-300 ℃, and preserving heat for not less than 2 hours (1.8-3) D minutes after heat penetration, wherein the effective thickness of the shell D is in an air cooling or oil cooling mode after heat preservation is finished.

7. The design method of the refining heat treatment process for the large-scale ultrahigh-strength steel shell according to claim 6, wherein in step S3, based on the overall deformation of the part and the microstructure distribution, the multiple different processes obtained in step S2 are compared, and the process with the minimum overall deformation of the part and the optimal microstructure distribution is selected to obtain the optimal heat treatment process; wherein, the optimal heat treatment process comprises the following steps:

8. A system for designing a refining heat treatment process for a large ultra-high strength steel shell according to any one of claims 1 to 7, wherein the system comprises:

9. The system of claim 8, wherein the model parameters of the G50 steel shell heat treatment finite element model comprise material parameters, transformation model, boundary conditions of the part, wherein:

10. The system of claim 9, wherein the boundary conditions include a heat transfer coefficient of a heating and quenching process through a measured shell or scaled sample; it includes:

drilling holes in characteristic areas of G50 steel shell body or scaling sample, arranging a plurality of thermocouples, and utilizing phasesA corresponding data acquisition device acquires data of temperature change along with time in the heating and quenching processes; introducing quenching cooling data into a Deform-inverse module or other reverse modules, and calculating a heat exchange coefficient; the calculation formula of the heat exchange coefficient is as follows: h ═ H_k+H_sCoefficient of convective heat transfer, H_sIs the radiant heat transfer coefficient.