CN110263406A - The heat treatment method and its optimization method of oversized module gear under low-speed heave-load - Google Patents
The heat treatment method and its optimization method of oversized module gear under low-speed heave-load Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/20—Carburising
- C23C8/22—Carburising of ferrous surfaces
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
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- G06F2119/08—Thermal analysis or thermal optimisation
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Abstract
The invention discloses the heat treatment methods and its optimization method of oversized module gear under a kind of low-speed heave-load.The present invention to stable state and it is metastable balance each other, ermal physics and physical property, mechanical performance, phase transition solve, the relatively accurately heating of prediction alloy material, the physics of cooling stage, thermophysical property, then the heating of prediction 18CrNiMo7-6 low-carbon alloy steel and cooling procedure changes in material properties, reasonable carburizing and quenching process flow is designed, to effectively improve the hardness of gear.
Description
Technical field
This method is related to casting field, and in particular under a kind of low-speed heave-load the heat treatment method of oversized module gear and its
Optimization method.
Background technique
Effect caused by the control and heat treatment of the heat treatment process of high-speed overload gear, is directly related to gear part
Quality, determine its service life.Present industrial generallys use carburizing and quenching Case hardening techniques and improves its mechanical performance, due to
The numerical procedure of carburizing and quenching is relatively complicated, generate this complexity mainly due to heat treatment process by
To the control of a variety of variables, cause entire technology development slower.Heat treatment numerical value, which calculates the main problem faced, correlation
The problems such as foundation of material database, the exploitation of numerical simulation software and proof of analog result, the rate of temperature fall of quenching is to tooth
The hardness influence of wheel is very big, but the component ratio of each gear is different, and optimal rate of temperature fall is also different, and there are currently no bases
The method that heterogeneity ratio controls rate of temperature fall, the present invention is exactly to solve the above-mentioned problems.
DEFORM-3D software: DEFORM is a set of process simulation system based on finite element, for analyze metal forming and
Its relevant various forming technology and heat treatment process.Two industrial practices during the last ten years is confirmed based on FInite Element
DEFORM has brilliant Stability and veracity, and simulation engine is in terms of big flowing, stroke load and product defects
Be consistent with actual production, remain the precision DEFORM-3D for making us acclaiming as the acme of perfection in same the integration environment comprehensive modeling, at
Shape, heat transfer and former characteristic etc. are mainly used for analyzing three-dimensional material mobility status in various complicated METHOD IN METAL FORMING PROCESSESs,
Suitable for hot, cold, warm working, extremely valuable industrial analysis data are provided.
Jmatpro software: a powerful material property simulation softward of Sente Software company exploitation, energy
It is enough to stable state and it is metastable balance each other, solidifiability, ermal physics and physical property, mechanical performance, phase transition solve, compared with
The adequately heating of prediction alloy material, the physics of cooling stage, thermophysical property.
Summary of the invention
In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a kind of heat of oversized module gear under low-speed heave-load
Processing method and its optimization method.The present invention to stable state and it is metastable balance each other, ermal physics and physical property, mechanical performance,
Phase transition is solved, and is relatively accurately predicted alloy material heating, the physics of cooling stage, thermophysical property, is then predicted
The heating of 18CrNiMo7-6 low-carbon alloy steel and cooling procedure changes in material properties, design reasonable carburizing and quenching technique
Process, to effectively improve the hardness of gear.
The technical solution adopted by the present invention to solve the technical problems are as follows:
The heat treatment optimization method of oversized module gear, includes the following steps: under a kind of low-speed heave-load
Step 1: finding out at each temperature, the alloying component of ratio and each phase when respectively balancing each other in the gear of non-carburizing；
Step 2: the correlated performance of each phase is calculated；
Step 3: calculating the overall performance of each correlated performance of gear；
Step 4: by the correlated performance and gear correlated performance of the chemical component of non-carburized gears and ratio and each phase
Overall performance input DEFORM-3D Software Create material property model；Setting gear, which heats, carries out austenitizing, at gear thermal
First phase is set as ferrite and pearlite before managing, and in austenitization stage, ferrite and pearlite starts to be changed into austenite, Ovshinsky
The carbon content of body stage gear surface uniforms；
Step 5: Carbon flux C after finding out gear wheel carburization to the carburization process of DEFORM-3D software input settingA；
Step 6: DEFORM-3D software is by Carbon flux CAInput material performance model, it is then defeated to DEFORM-3D software
Enter the corresponding volume ratio that phase transition model simulates to obtain ferrite, martensite, bainite and pearlite at different temperatures；
Step 7: the complex tissue hardness of ferrite, martensite, bainite and pearlite different volumes than under is calculated
HT；
Step 8: obtaining HTEach Phase Proportion when for maximum value or when setting value；
Step 9: selection HTEach Phase Proportion when for maximum value or setting value inputs JmatPro software, obtains each Phase Proportion
So that HTTemperature lowering curve when for maximum value or setting value.
It is further to improve, it is described Step 1: including the following steps: to input the chemical component of manufactured gear and ratio
JmatPro software finds out the alloying component of the ratio and each phase when respectively balancing each other in gear at each temperature.
Further to improve, in the step 2, the correlated performance includes the coefficient of expansion, thermal conductivity, Young's modulus, pool
Loose ratio, specific heat capacity, transformation plasticity coefficient.
It is further to improve, in the step 3, calculate the method for the overall performance of gear each correlated performance such as
Under:
P1=xαPα1+xβPβ1+......+FSPI1 (1.14)
P2=xαPα2+xβPβ2+......+FSPI2 (1.15)
P3=xαPα3+xβPβ3+......+FSPI3 (1.16)
P4=xαPα4+xβPβ4+......+FSPI4 (1.17)
P5=xαPα5+xβPβ5+......+FSPI5 (1.18)
P6=xαPα6+xβPβ6+......+FSPI6(1.19) wherein, α, β ... are 18CrNiMo7-6 material in setting temperature
Phase constitution under degree；xα,xβ... is respectively α, the mass fraction of 18CrNiMo7-6 material shared by β ... phase constitution, the sum of they
It is 1；P1、P2、P3、P4、P5、P6For the overall performance of material, the respectively coefficient of expansion, thermal conductivity, Young's modulus, Poisson's ratio, ratio
Thermal capacitance, density；Pα1、Pβ1It is divided into α, the coefficient of expansion of β phase；Pα2、Pβ2It is divided into α, the thermal conductivity of β phase；Pα3、Pβ3It is divided into α, β phase
Young's modulus；Pα4、Pβ4It is divided into α, the Poisson's ratio of β phase；Pα5、Pβ5It is divided into α, the specific heat capacity of β phase；Pα6、Pβ6Be divided into α, β phase it is close
Degree；FSFor tissue dispersion degree；PI1、PI2、PI3、PI4、PI5、PI6The respectively coefficient of expansion, thermal conductivity, Young's modulus, Poisson's ratio, ratio
Thermal capacitance, density performance relevant to tissue topological structure；PI1、PI2、PI3、PI4、PI5、PI6Calculated by software JmatPro
It arrives.
Further to improve, the step 4 includes the following steps:
The overall performance of each correlated performance is imported into DEFORM-3D software as material property model, gear is set
Heating carries out austenitizing, and first phase is set as ferrite and pearlite before gear heat treatment, and volume fraction is set to 0.75 He
0.25；In austenitization stage, ferrite and pearlite starts to be changed into austenite, the carbon content of austenite phase gear surface
Uniform to turn to carbon content 0.2, phase transition transformation is calculated using formula (1.7)；
In formula: TsFor the lower change point temperature of phase transition, TeFor the upper change point temperature of phase transition, βAFor austenite integral
Number, T is gear temperature.
It is further to improve, in the step 5, Carbon flux CAIt is solved using Fick law:
In formula: s is Carbon Solubility；DeFor the carbon diffusing capacity of carburizing process workpiece surface；φ is carbon spread rate；p
For surface pressing；X is carburizing direction；For unit carbon spread rate in the x-direction；T is temperature；For pressure in the x-direction
Difference；KsIt is temperature to the impact factor of diffusion rate；KpIt is pressure to the impact factor of diffusion rate；
KpAnd KsIt is determined as follows:
In formula: KsIt is temperature to the impact factor of diffusion rate, KpIt is pressure to the impact factor of diffusion rate；C, s distinguishes
For external concentration of carbon, Carbon Solubility；T is carburizing process middle gear surface temperature；Rate is varied with temperature for Carbon Solubility；It is Carbon Solubility with the rate of change of surface pressing.
Further to improve, in the step 6, phase transition model is as follows:
The volume fraction of ferrite, pearlite and bainite is solved using JMAK equation (1.9).
In formula: βFIndicate ferrite volume fraction；βPIndicate pearlite volume fraction；βBIndicate bainite volume fraction；tF
For the transformation time of ferrite transformation temperature；tBFor the transformation time of bainite transformation temperature；tPIt is pearlite in conversion temperature
Transformation time；kF、nFFor ferrite material parameter；kB、nBFor bainite material parameter；kP、nPFor pearlitic materials parameter, k and n
Material parameter respectively related with phase transition temperature, parent phase ingredient and grain size；The value of cooling stage k and n such as 1.1 institute of table
Show.
The value of table 1.1:k and n
Wherein: table 1.1 and formula (1.9), (1.10), in (1.11), BsStart transition temperature for bainite；CANot change
Carbon content in austenite；Respectively austenite isothermal transformation temperature；AGS is austenite grain size；T is gear temperature
Degree；
Martensite transfor mation is non-diffusing phase transformation, is solely dependent upon temperature change, is solved using formula (1.12).
In formula: MsFor martensite start temperature；βMFor Martensite Volume Fraction；βFFor ferrite mass fraction；
βPFor pearlite volume fraction；βBFor bainite volume fraction；T is gear surface temperature.
Further to improve, the step 7 includes the following steps:
Materials microstructure hardness is calculated according to the mixing rule of composite material, it is assumed that material is isotropism, is calculated first
Then the structural constituent and volume fraction at different temperatures moment are solved using weighted average and calculate hardness values, obtain material
Complex tissue hardness；
HT=HP·ωP+HB·ωB+HA·ωA+HF·ωF+HM·ωM (1.26)
Table 1.2: each phase hardness specific value
In formula (1.14) and table 1.2: HT、HP、HB、HA、HFAnd HMRespectively complex tissue hardness, pearlite hardness, bayesian
Body hardness, anstenite hardness, ferrite hardness and martensite hardness, ωP、ωB、ωA、ωF、ωMRespectively pearlite volume point
Number, bainite volume fraction, austenite volume fraction, ferrite volume fraction and Martensite Volume Fraction；
The heat treatment method of oversized module gear, includes the following steps: under a kind of low-speed heave-load
It is heated Step 1: the gear that 8CrNiMo7-6 low-carbon alloy steel makes is put into continous way gas carbruizing furance, furnace
Temperature was set as 880 DEG C, in heating 1 hour；The size parameter of gear are as follows: modulus 5mm, the number of teeth 25, pressure angle are 20 °, spiral shell
Swing angle is 16 °.
Step 2: being passed through carburizing gas to carburizer, external carbon-potential control is 1%, is kept for 3 hours；880 degree of temperature holdings
3 hours；
Step 3: strong seep: carburizer is warming up to 920 DEG C, and then it is small to keep the temperature 2.5 in the environment of carbon potential 1.15% for gear
When；
Step 4: diffusion: temperature and carbon potential being down to 900 DEG C and 0.9% respectively, keep the temperature 2 hours.
Step 5: using delayed quenching process route: furnace temperature being down to 830-870 DEG C, reduces the internal stress that quenching generates
And distortion, stop being passed through carburizing gas later, and furnace temperature is down to 830-870 DEG C, keeps the temperature 600s；Step 6: primary quenching: will
Gear is immersed in the water, and stirs water, and water and flank of tooth heat convection are cooled to 30 ° of room temperature.
Detailed description of the invention
Fig. 1 is flow chart of the invention；
Fig. 2 a, Fig. 2 b, Fig. 2 c, Fig. 2 d, Fig. 2 e and Fig. 2 f are respectively the coefficient of expansion, thermal conductivity, Young's modulus, the pool of each phase
Pine ratio, specific heat capacity and transformation plasticity coefficient figure；
Fig. 3 is that the TTT of structural transformation schemes；
Fig. 4 is the temperature lowering curve figure originally obtained.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Gear material attribute:
Finite element analysis sets entire gear and meets the equation of heat conduction, by entire spatial domain discretization, is divided into limited list
Member, each unit meet the equation of heat conduction simultaneously.Unit is made of several nodes, and the every bit temperature inside unit is by node temperature
It spends and is obtained with the product of shape function, entire temperature field can also be indicated by node temperature.Model DEFORM-3D software possesses
Dedicated heat treatment module (Heat Treatment), is widely used in the heat treatment of simulation workpiece.
It is 5mm with modulus, the number of teeth 25, pressure angle is 20 °, and the helical gear that helical angle is 16 ° is research object,
Gear material selects 18CrNiMo7-6, and chemical component is shown in Table 9.1.
The chemical component of 9.1 18CrNiMo7-6 low-carbon alloy steel of table
Helical gear is fabricated by low-carbon alloy steel 18CrNiMo7-6, and JMatPro is that English Sente Software company opens
Hair a powerful material property simulation softward, can to stable state and it is metastable balance each other, solidifiability, ermal physics
And physical property, mechanical performance, phase transition are solved, relatively accurately predict alloy material heating, cooling stage physics,
Thermophysical property, therefore herein using JMatPro prediction 18CrNiMo7-6 low-carbon alloy steel heating and cooling procedure material property
Variation.
Dynamics calculation
Heat treatment multi- scenarios method numerical value calculating is related to material phase transformation, different mutually to have this free energy of different jeeps, according to
Thermodynamic principles, system reach the general condition of balance in constant temperature and pressure: (1) total Gibbs free energy G of system reaches minimum
Value Gmin；(2) chemical potential of constituent element i in each phase is equal, so this free energy of the jeep of each phase calculates are as follows:
In formula, XiFor mass fraction shared by constituent element i,For the sum of the Gibbs free energy of pure constituent element, indicate pure
This free energy of the jeep that mechanical mixture obtains；Freely to can increase caused by the ideal entropy of mixing；ΩvIt is mutual
Function coefficient (v 0-1)；To deviate excess free energy caused by perfect solution.
First phase before low-carbon alloy steel heat treatment is mainly ferrite and pearlite, after being heated to austenite transformation temperature,
First phase is gradually converted into austenite.Fig. 1 is the phase constituent of 18CrNiMo7-6 low-carbon alloy steel at different temperatures.
Physics/thermophysical property calculates
Heat treatment multi- scenarios method numerical value calculating is related to material phase transformation, and materials thermophysics performance not only changes with temperature height
Become, phase composition also determines changes in material properties, the Different Effects of structural constituent Material Physics/thermophysical property.
Materials thermophysics performance is determined by composite material mixing rule, i.e., according to the thermophysical property and group of composition phase
Point, the comprehensive thermophysical property of material, the hot object of 18CrNiMo7-6 obtained by JMatPro are calculated by weighted average method
Rationality energy.
The alloying component for obtaining each phase first calculates the public affairs of the correlated performance of the phase based on the alloying component of each phase
Formula is as follows:
In formula, Pα1、Pα2、Pα3、Pα4、Pα5、Pα6Respectively the coefficient of expansion of material, thermal conductivity, Young's modulus, Poisson's ratio,
Specific heat capacity, transformation plasticity coefficient；I is any one out of phase constituent element, XiFor mass fraction shared by i constituent element, Pi 0For i constituent element
Performance,For the sum of the performance of pure constituent element, the purely mechanic performance being mixed to get is indicated；ΩvFor interaction coefficient (v
For 0-1)；To deviate excess performance caused by perfect solution.
See Fig. 2 a by the thermophysical property of the obtained phase of JMatPro), 2b), 2c, 2d, 2e, 2f,
The overall performance of material is calculated using mixing rule according to the performance of the phase composition of material and each phase, following formula is
Calculation formula:
P1=xαPα1+xβPβ1+......+FSPI1
P3=xαPα3+xβPβ3+......+FSPI3
P2=xαPα2+xβPβ2+......+FSPI2
P4=xαPα4+xβPβ4+......+FSPI4
P5=xαPα5+xβPβ5+......+FSPI5
P6=xαPα6+xβPβ6+......+FSPI6
Wherein, α, β ... are the phase constitution of 18CrNiMo7-6 material at such a temperature；xα,xβ... is respectively α, β ... phase
The mass fraction of shared 18CrNiMo7-6 material is organized, the sum of they are 1；P1、P2、P3、P4、P5、P6For the globality of material
Energy, the respectively coefficient of expansion, thermal conductivity, Young's modulus, Poisson's ratio, specific heat capacity, density；Pα1、Pβ1It is divided into α, the expansion system of β phase
Number；Pα2、Pβ2It is divided into α, the thermal conductivity of β phase；Pα3、Pβ3It is divided into α, the Young's modulus of β phase；Pα4、Pβ4It is divided into α, the Poisson's ratio of β phase；
Pα5、Pβ5It is divided into α, the specific heat capacity of β phase；Pα6、Pβ6It is divided into α, the density of β phase；FSFor tissue dispersion degree；PI1、PI2、PI3、PI4、PI5、
PI6The respectively coefficient of expansion, thermal conductivity, Young's modulus, Poisson's ratio, specific heat capacity, density performance relevant to tissue topological structure；
FSPI1......6Reflect influence of the tissue appearance to material property.
Diffusion model:
Workpiece surface Carbon flux depends on temperature and two parameters of pressure, if keeping external condition constant, carburizing process work
Part surface carbon flux numerical value remains unchanged
According to external temperature and pressure, Carbon flux CAIt is solved using Fick law:
In formula: φ, c, p and s are respectively carbon spread rate, external concentration of carbon, surface pressing and Carbon Solubility.
Shown in the influence of carburizing process temperature and pressure to carbon spread such as formula (9.12).
In formula: KsIt is temperature to the impact factor of diffusion rate, KpIt is pressure to the impact factor of diffusion rate.
Through the above steps, the technique of carburizing can be determined.Therefore the Carbon flux that can according to need is back-calculated to obtain carburizing
Technique, specifically: for the Gear Carbonization Process of this patent are as follows: be passed through carburizing gas to carburizer, external carbon-potential control is
1%, it is kept for 3 hours；880 degree of temperature 3 hours of holding.
The volume of each phase passes through following formula respectively and determines under different temperatures:
Structural transformation model (phase transition model)
Before heat treatment starts, reference element distribution, the similar low-carbon alloy steel Tissue distribution of material property will be at the beginning of helical gears
It is mutually set as ferrite and pearlite, volume fraction is set to 0.75 and 0.25.Ferrite, perlitic transformation are austenite and Austria
It is diffusion phase transformation that family name's body, which is changed into bainite, pearlite, ferritic process, in the heating period, when temperature is more than lower critical
Point Ac1When, it is each mutually to start to be changed into austenite.In the heating period, different parts carbon content is equal, therefore ferrite and pearly-lustre
Body be changed into austenite kinetic parameter be only a function relevant to temperature, ferrite, pearlite austenite transformation use with
Lower formula is calculated.
In formula: βAFor austenite volume fraction, TsFor lower change point temperature, TeFor upper change point temperature, T is gear temperature.It is difficult to understand
When family name's body changes, the phase volume of each component is varied with temperature and is changed, the latent heat of phase change discharged under different transition temperatures
It is different.
The structural transformation of cooling stage solves structural transformation point using Jmatpro and following formula is calculated, according to
The structural transformation point that Jmatpro is obtained is as shown in table 9.2.
Table 9.2: the structural transformation point of cooling stage
For being solely dependent upon the non-diffusing phase transformation of temperature change, martensite transfor mation is solved using formula (9.6).
In formula: MsFor martensite start temperature
In cooling stage, due to the inhomogeneous distribution of concentration of carbon, the transformation power of austenite is different compared to formula,
In austenite isothermal transformation, the volume fraction of ferrite, pearlite and bainite uses JMAK equation solution.
β=1-exp (- ktn)
Table 9.3: the value of cooling stage k and n
In table 9.3, CA、Carbon content and austenite isothermal transformation temperature, B in austenite are not changed respectivelys,
AGS, T are respectively that bainite starts transition temperature, austenite grain size and temperature.
Tissue hardness reference composite material mixing rule is calculated, and firmness change is set as isotropism, according to each phase body
Fraction and its hardness values are weighted and averaged value and solve calculating.On the other hand, according to previous studies, martensite hardness and its
Carbon content is related, and the mathematical formulae of martensite hardness HB determines under the conditions of different carbon contents；When carbon content is 0.25,0.85,
Martensite hardness is respectively 44.87 and 65.25, and other tissues are set as stable constant value, each phase hardness specific value such as table 9.5.
HT=HP·ωP+HB·ωB+HA·ωA+HF·ωF+HM·ωM (1.1)
In formula (9.10) and table 9.4: HT、HP、HB、HA、HFAnd HMRespectively complex tissue hardness, pearlite hardness, bayesian
Body hardness, anstenite hardness, ferrite hardness and martensite hardness, ωP、ωB、ωA、ωF、ωMRespectively pearlite volume point
Number, bainite volume fraction, austenite volume fraction, ferrite volume fraction and Martensite Volume Fraction.
Table 9.4: each phase hardness specific value
Obtain HTEach Phase Proportion when for maximum value or when setting value；
Select HTEach Phase Proportion when for maximum value or setting value inputs JmatPro software, obtains each Phase Proportion and makes HTFor
Temperature lowering curve when maximum value or setting value, as shown in Figure 4.
Above-described embodiment is only the specific embodiment of the present invention, restriction of the invention is not intended as, to this hair
The bright simple replacement made is within the scope of the invention.
Claims (9)
1. the heat treatment optimization method of oversized module gear under a kind of low-speed heave-load, which comprises the steps of:
Step 1: finding out at each temperature, the alloying component of ratio and each phase when respectively balancing each other in the gear of non-carburizing；
Step 2: the correlated performance of each phase is calculated；
Step 3: calculating the overall performance of each correlated performance of gear；
Step 4: by the whole of the correlated performance and gear correlated performance of the chemical component of non-carburized gears and ratio and each phase
Body performance inputs DEFORM-3D Software Create material property model；Setting gear, which heats, carries out austenitizing, before gear heat treatment
First phase is set as ferrite and pearlite, and in austenitization stage, ferrite and pearlite starts to be changed into austenite, austenite rank
The carbon content homogenization of section gear surface；
Step 5: Carbon flux C after finding out gear wheel carburization to the carburization process of DEFORM-3D software input settingA；
Step 6: DEFORM-3D software is by Carbon flux CAThen input material performance model inputs phase transformation to DEFORM-3D software
Modeling obtains the corresponding volume ratio of ferrite, martensite, bainite and pearlite at different temperatures；
Step 7: the complex tissue hardness H of ferrite, martensite, bainite and pearlite different volumes than under is calculatedT；
Step 8: obtaining HTEach Phase Proportion when for maximum value or when setting value；
Step 9: selection HTEach Phase Proportion when for maximum value or setting value inputs JmatPro software, obtains each Phase Proportion and makes
HTTemperature lowering curve when for maximum value or setting value.
2. the heat treatment optimization method of oversized module gear under low-speed heave-load as described in claim 1, which is characterized in that described
Step 1: including the following steps: to find out the chemical component of manufactured gear and ratio input JmatPro software at each temperature
The alloying component of ratio and each phase when respectively balancing each other in gear.
3. the heat treatment optimization method of oversized module gear under low-speed heave-load as described in claim 1, which is characterized in that described
In step 2, the correlated performance includes the coefficient of expansion, thermal conductivity, Young's modulus, Poisson's ratio, specific heat capacity, transformation plasticity coefficient.
4. the heat treatment optimization method of oversized module gear under low-speed heave-load as described in claim 1, which is characterized in that described
In step 3, the method for calculating the overall performance of gear each correlated performance is as follows:
P1=xαPα1+xβPβ1+......+FSPI1 (1.1)
P2=xαPα2+xβPβ2+......+FSPI2 (1.2)
P3=xαPα3+xβPβ3+......+FSPI3 (1.3)
P4=xαPα4+xβPβ4+......+FSPI4 (1.4)
P5=xαPα5+xβPβ5+......+FSPI5 (1.5)
P6=xαPα6+xβPβ6+......+FSPI6 (1.6)
Wherein, α, β ... are the phase constitution of 18CrNiMo7-6 material at a set temperature；xα,xβ... is respectively α, β ... phase group
The mass fraction of shared 18CrNiMo7-6 material is knitted, the sum of they are 1；P1、P2、P3、P4、P5、P6For the overall performance of material,
The respectively coefficient of expansion, thermal conductivity, Young's modulus, Poisson's ratio, specific heat capacity, density；Pα1、Pβ1It is divided into α, the coefficient of expansion of β phase；
Pα2、Pβ2It is divided into α, the thermal conductivity of β phase；Pα3、Pβ3It is divided into α, the Young's modulus of β phase；Pα4、Pβ4It is divided into α, the Poisson's ratio of β phase；Pα5、
Pβ5It is divided into α, the specific heat capacity of β phase；Pα6、Pβ6It is divided into α, the density of β phase；FSFor tissue dispersion degree；PI1、PI2、PI3、PI4、PI5、PI6
The respectively coefficient of expansion, thermal conductivity, Young's modulus, Poisson's ratio, specific heat capacity, density performance relevant to tissue topological structure；PI1、
PI2、PI3、PI4、PI5、PI6It is calculated by software JmatPro.
5. the heat treatment optimization method of oversized module gear under low-speed heave-load as described in claim 1, which is characterized in that described
Step 4 includes the following steps:
The overall performance of each correlated performance is imported into DEFORM-3D software as material property model, gear is set and is heated
Austenitizing is carried out, first phase is set as ferrite and pearlite before gear heat treatment, and volume fraction is set to 0.75 and 0.25；?
Austenitization stage, ferrite and pearlite start to be changed into austenite, the carbon content homogenization of austenite phase gear surface
For carbon content 0.2, phase transition transformation is calculated using formula (1.7)；
In formula: TsFor the lower change point temperature of phase transition, TeFor the upper change point temperature of phase transition, βAFor austenite volume fraction, T
For gear temperature.
6. the heat treatment optimization method of oversized module gear under low-speed heave-load as described in claim 1, which is characterized in that described
In step 5, Carbon flux CAIt is solved using Fick law:
In formula: s is Carbon Solubility；DeFor the carbon diffusing capacity of carburizing process workpiece surface；φ is carbon spread rate；P is surface
Pressure；X is carburizing direction；For unit carbon spread rate in the x-direction；T is temperature；For pressure difference in the x-direction；KsFor
Impact factor of the temperature to diffusion rate；KpIt is pressure to the impact factor of diffusion rate；
KpAnd KsIt is determined as follows:
In formula: KsIt is temperature to the impact factor of diffusion rate, KpIt is pressure to the impact factor of diffusion rate；C, s is respectively outer
Portion's concentration of carbon, Carbon Solubility；T is carburizing process middle gear surface temperature；Rate is varied with temperature for Carbon Solubility；For
Carbon Solubility with surface pressing rate of change.
7. the heat treatment optimization method of oversized module gear under low-speed heave-load as described in claim 1, which is characterized in that described
In step 6, phase transition model is as follows:
The volume fraction of ferrite, pearlite and bainite is solved using JMAK equation (1.9).
In formula: βFIndicate ferrite volume fraction；βPIndicate pearlite volume fraction；βBIndicate bainite volume fraction；tFFor iron
The transformation time of ferritic conversion temperature；tBFor the transformation time of bainite transformation temperature；tPFor pearlite conversion temperature conversion
Time；kF、nFFor ferrite material parameter；kB、nBFor bainite material parameter；kP、nPFor pearlitic materials parameter, k and n difference
For material parameter related with phase transition temperature, parent phase ingredient and grain size；The value of cooling stage k and n are as shown in table 1.1.
The value of table 1.1:k and n
Wherein: table 1.1 and formula (1.9), (1.10), in (1.11), BsStart transition temperature for bainite；CANot change Ovshinsky
Carbon content in body；Respectively austenite isothermal transformation temperature；AGS is austenite grain size；T is gear temperature；
Martensite transfor mation is non-diffusing phase transformation, is solely dependent upon temperature change, is solved using formula (1.12).
In formula: MsFor martensite start temperature；βMFor Martensite Volume Fraction；βFFor ferrite mass fraction；βPFor
Pearlite volume fraction；βBFor bainite volume fraction；T is gear surface temperature.
8. the heat treatment optimization method of oversized module gear under low-speed heave-load as described in claim 1, which is characterized in that described
Step 7 includes the following steps:
Materials microstructure hardness is calculated according to the mixing rule of composite material, it is assumed that material is isotropism, is calculated first different
Then the structural constituent and volume fraction at temperature moment are solved using weighted average and calculate hardness values, obtain answering for material
Close tissue hardness；
HT=HP·ωP+HB·ωB+HA·ωA+HF·ωF+HM·ωM (1.13)
Wherein, HT、HP、HB、HA、HFAnd HMRespectively complex tissue hardness, pearlite hardness, bainite hardness, anstenite hardness,
Ferrite hardness and martensite hardness, ωP、ωB、ωA、ωF、ωMRespectively pearlite volume fraction, bainite volume fraction,
Austenite volume fraction, ferrite volume fraction and Martensite Volume Fraction.
9. the heat treatment method of oversized module gear under a kind of low-speed heave-load, which comprises the steps of:
It is heated Step 1: the gear that 8CrNiMo7-6 low-carbon alloy steel makes is put into continous way gas carbruizing furance, furnace temperature is set
880 DEG C are set to, in heating 1 hour；The size parameter of gear are as follows: modulus 5mm, the number of teeth 25, pressure angle are 20 °, helical angle
It is 16 °.
Step 2: being passed through carburizing gas to carburizer, external carbon-potential control is 1%, is kept for 3 hours；880 degree of temperature are kept for 3
Hour；
Step 3: strong seep: carburizer is warming up to 920 DEG C, and then gear keeps the temperature 2.5 hours in the environment of carbon potential 1.15%；
Step 4: diffusion: temperature and carbon potential being down to 900 DEG C and 0.9% respectively, keep the temperature 2 hours.
Step 5: using delayed quenching process route: furnace temperature being down to 830-870 DEG C, reduces internal stress that quenching generates and abnormal
Become, stops being passed through carburizing gas later, and furnace temperature is down to 830-870 DEG C, keep the temperature 600s；
Step 6: primary quenching: gear being immersed in the water, and stirs water, water and flank of tooth heat convection are cooled to 30 ° of room temperature.
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| JP2005315703A (en) * | 2004-04-28 | 2005-11-10 | Nippon Steel Corp | Method for predicting material in steel material |
| CN104060081A (en) * | 2014-07-05 | 2014-09-24 | 扬州大学 | Method for preventing heat treatment deformation of carburized gear from being out of tolerance |
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| CN1431060A (en) * | 2002-01-11 | 2003-07-23 | 中国科学院金属研究所 | Method for predicting evolvement and performances of structure of strip steels in hot rolled proces |
| JP2005315703A (en) * | 2004-04-28 | 2005-11-10 | Nippon Steel Corp | Method for predicting material in steel material |
| CN104060081A (en) * | 2014-07-05 | 2014-09-24 | 扬州大学 | Method for preventing heat treatment deformation of carburized gear from being out of tolerance |
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| CN114438288A (en) * | 2022-01-13 | 2022-05-06 | 中车福伊特传动技术(北京)有限公司 | Quenching method for material defect gear |
| CN114438288B (en) * | 2022-01-13 | 2024-04-26 | 中车福伊特传动技术(北京)有限公司 | Material defect gear quenching method |
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