CN103729511B - Method for predicating ingredient segregation degrees in casting process of complex-structure casting - Google Patents

Abstract

The invention provides a method for predicating the ingredient segregation degrees in the casting process of a complex-structure casting. The method includes the steps of (1) calculating to obtain thermophysical parameters of alloy through a thermophysical parameter calculating module of commercialized JMatPro software, (2) carrying out analogue simulation on the casting filling and solidifying processes of the complex-structure casting through ProCAST finite element software, and obtaining temperature field data of various parts of the casting, (3) calculating secondary dendrite arm spacing values of the structural parts of the casting through a secondary dendrite arm spacing calculating module built in the ProCAST software, and (4) calculating MSIs of the structural parts of the complex-structure casting, and judging the micro-segregation degrees of the structural parts of the casting according to the MSIs. According to the method, the finite element software and thermodynamic calculation software are used, the casting practice is combined, the micro-segregation degrees of solute elements of the structural parts of the complex-structure casting are effectively predicted, and the application range is wide.

Description

The Forecasting Methodology of component segregation degree in a kind of Complicated structure casting casting process

Technical field

A kind of the present invention relates to steel industry component segregation analysis technical field, in particular it relates to Complicated structure casting casting The Forecasting Methodology of component segregation degree during making.

Background technology

Component segregation is intrinsic characteristic during aluminium alloy solidification.When dissolubility in solid phase for the solute element is less than it in liquid During dissolubility in phase, solid liquid interface will exclude solute in liquid phase；And work as dissolubility in solid phase for the solute element and be more than During dissolubility in liquid phase, solute will lead to solid liquid interface forward position the poor area of solute from liquid phase to solid-state diffusion.This by In alloy graining process, the reallocation of solute leads to the uneven components after alloy graining, as component segregation.Generally, solute Element dissolubility in the liquid phase is higher than in solid phase, and therefore solute has disengaging solidifying phase to be pulled to inclining in the liquid of forward position To the dendritic arm that the liquid rich in solute for the end solidification part is grown is split, forming component segregation zones.Component segregation is foundry goods One of major defect, reduce alloy solid solution strengthening effect, meanwhile, the low melting point precipitated phase that interdendritic is formed, in the weldering of foundry goods Easily become formation of crack in termination process, reduce mechanical property and the welding performance of foundry goods.

According to classical solidification theory, under the conditions of general alloy graining, the solute redistribution behavior of micro-scale And the microsegregation producing depends not only on the physical parameter of alloy (as solid phase diffusion welding d_s, Liquid Diffusion Coefficient d_l, molten Matter partition coefficient k) and external process condition such as freezing rate v (or local solidification time t_f), thermograde g, but also with The factors such as the growth pattern of dendrite, dendrite morphology are closely related.

Simplest analytical model is lever analytical model and scheil analytical model under local equilibrium's curing condition, Other is all correction type analytical model.Based on the consideration of reverse diffusion, lever model and scheil model are two kinds of limiting cases.

Lever model is a kind of equilibrium freezing model it is assumed that solute all fully spreads solid-liquid is biphase, that is,

c_l=c₀[1-(1-k)f_s]^-1①

Formula 1. in, c_lFor liquid phase solute concentration, c₀For initial solute concentration, f_sFor fraction solid, k is solute distribution coefficient.

Scheil model is also referred to as non-equilibrium lever model, wherein assumes that solute fully spreads in the liquid phase and solid phase no expands Dissipate, in model, do not account for that forming core is supercool, the formation of dendritic arm roughening, macroscopic material transmission and pore, that is,

c_l=c₀(1-f_s)^(k-1)②

Obviously, as fraction solid f_sC when=1_lTrend towards infinity, therefore scheil model can not be dense to final solute Degree is accurately calculated.

H.d.brody＆m.c, flemings consider the back-diffusion of solute element in process of setting, that is, have

c_l=c₀[1-(1-2αk)f_s]^{(k-1)/(1-2αk)}③

Formula 3. in, α be the nondimensional solutes accumulation factor, or claim nondimensional diffusion time (fourier number), it represent Diffusion boundary layer thickness δ in solid phase_sWith the proportionate relationship of system dimension l, it is represented by:

When α=0 is no to spread in solid phase, 3. formula is reduced to scheil model；

When α=0.5,3. formula is reduced to lever model.

W.kurz et al. is corrected to α value, proposes to replace α with α ', that is,

Although scholars have studied the coagulating property of alloying component change of multicomponent alloy, in process of setting energetically in recent years Solid-back diffusion, the limited diffusion of liquid, dendritic arm roughening, dentrite tip is supercool, eutectic interface undercooling and coagulated volume change Affecting it is established that solute concentration parses with the microsegregation that fraction solid increases in some process of setting Deng solute assigning process Model and numerical model.But the microsegregation model of existing solute distribution be built upon during research solidification solute concentration with The change that fraction solid increases, can only represent interfacial concentrationWith fraction solid f_sFunctional relationship, can not determine therefrom that The component distributing of whole solid phase, and must take into this dynamic parameter of fraction solid, and not can determine that large complicated for one Constitutional detail different structure position, by the degree of segregation under many factors collective effect it is impossible to instruct large and complex structure foundry goods Foundry Production.

Content of the invention

For defect of the prior art, it is an object of the invention to provide composition in a kind of Complicated structure casting casting process The Forecasting Methodology of degree of segregation, this Forecasting Methodology can predict parts with complex structures different structure position in different curing conditions Microsegregation degree, has directive significance to the Foundry Production of large and complex structure foundry goods.

For realizing object above, the present invention provides a kind of prediction of component segregation degree in Complicated structure casting casting process Method, the method includes:

(1) obtain calculating thermal physical property parameter

Calculate the thermal physical property parameter obtaining alloy, ginseng using the thermophysical parameter computing module of commercialization jmatpro software Number includes solute balance partition coefficient k, Liquid Diffusion Coefficient d_l, solid phase diffusion welding d_s, alloy initial solidification temperature t_l, eutectic Reaction temperature t_s；

(2) obtain the temperature field data at each position of foundry goods

Application procast finite element software carries out analogue simulation to the casting filling of Complicated structure casting, process of setting, obtains Take the temperature field data at each position of foundry goods, data includes setting rate v of molten metal, local setting time t_f；Or local Setting time t_f, the method that also can be combined with sunykatuib analyses by precision-investment casting of setting rate v obtained.

(3) obtain secondary dendrite arm spacing λ at each structure position of foundry goods₂

Calculate the secondary dendrite of each structure position of foundry goods using the secondary dendrite arm spacing computing module that procast software carries Spacing λ₂；Or, secondary dendrite arm spacing λ₂Also can be obtained by the method that precision-investment casting is combined with sunykatuib analyses.

(4) calculate segregation exponent m si value at each structure position of foundry goods

The Solidification Parameters obtaining from procast: setting rate v of molten metal, local setting time t_f, secondary dendrite arm spacing λ₂, and the thermophysical parameter that jmatpro calculates: solute balance partition coefficient k, Liquid Diffusion Coefficient d_l, solid phase diffusion welding Ds, substitutes in microsegregation deciding degree exponent m si formula, and the viewcast module by procast, calculates labyrinth Segregation exponent m si of each structure position of foundry goods, the size of the segregation exponent m si value according to each structure position of Complicated structure casting is sentenced Determine the microsegregation degree of each structure position of foundry goods: segregation exponent m si is bigger, and microsegregation is more serious, solidification latter stage is formed It is higher that interdendritic separates out phase content；Wherein:

$msi=\frac{{\mathrm{pe}}_l}{{\mathrm{kfo}}_s}=\frac{1}{8}\·\frac{1}{2{\mathrm{kd}}_l{d}_s}\frac{{\mathrm{v\λ}}_2^3}{t_f}=\frac{1}{8}\·a\·\frac{{\mathrm{v\λ}}_2^3}{t_f},a=\frac{1}{2{\mathrm{kd}}_l{d}_s}$

In formula: pe_lFor dimensionless solute p é let number, characterize in the liquid phase of solid liquid interface forward position by solute degree of supersaturation institute really Fixed driving force；fo_sFor dimensionless Fourier number, also referred to as the solid-back diffusion factor；K is solute balance partition coefficient；d_lFor Liquid Diffusion Coefficient；d_sFor solid phase diffusion welding；V is setting rate；L is characterized diffusion length；t_fFor local solidification time；For comprising the physical parameter of alloy material, depending on the selection of material, for the different structure on Same Part Position, a may be considered constant.

Preferably, in step (2), secondary dendrite arm spacing λ₂Computing formula be

λ₂=(mt_f)^1/3

Wherein:

$m=166\·\frac{{\mathrm{\γd}}_{l}ln(c_{eut}/c_0)}{m(1-k)(c_0-c_{eut})}$

In formula, γ is gibbs thomson coefficient, c₀For initial solute concentration, c_eutThere is eutectic reaction for solidification latter stage When liquid phase solute concentration, m is alloy liquid phase line slope, and m is with the related parameter of material.

It is highly preferred that m value calculates with each parameter from Thermodynamic Calculation Software jmatpro or list of references l.nastac.numerical modeling of solidification morphologies and segregation Patterns in cast dendritic alloys [j] .acta mater.vol.17.pp:4253-4262.1999. obtains ?.

Preferably, calculate in panel in procast, corresponding initial solidification temperature t is inputted according to different alloys_l, eutectic Reaction temperature t_sAnd the m value calculating, secondary dendrite arm spacing value λ of each structure position of foundry goods can be calculated₂.

Compared with prior art, the present invention has a following beneficial effect:

The present invention, by finite element software procast and Thermodynamic Calculation Software jmatpro, can effectively predict labyrinth The microsegregation degree of the solute element of each structure position of foundry goods；By the application of the inventive method, not only can be without dissection Foundry goods can predict the degree of segregation of a certain solute element of each structure position of foundry goods, for optimizing and revising at casting technique and heat Science and engineering skill provides foundation, and the method can be to the prediction of other solute element degree of segregation of multicomponent alloy, range of application Extensively.

Brief description

The detailed description with reference to the following drawings, non-limiting example made by reading, the further feature of the present invention, Objects and advantages will become more apparent upon:

Fig. 1 is one embodiment of the invention Casting Three-dimensional illustraton of model；

Fig. 2 is one embodiment of the invention foundry goods pictorial diagram；

Fig. 3 is one embodiment of the invention msi segregation exponential forecasting result and laves phase content experimental result comparison diagram.

Specific embodiment

With reference to specific embodiment, the present invention is described in detail.Following examples will be helpful to the technology of this area Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill to this area For personnel, without departing from the inventive concept of the premise, some deformation can also be made and improve.These broadly fall into the present invention Protection domain.

In the present embodiment, the determination of microsegregation deciding degree exponent m si (micro-segregation index) is based on Considered below.

Theoretical by means of buckingham π non-dimension analysis widely used in mathematical physics, to solute in process of setting Distribution carries out non-dimension analysis.Diffusion flux research based on solid liquid interface both sides liquid phase and solid phase solute atoms, the present invention is comprehensive Close the back-diffusion considering the limited diffusion of solid liquid interface forward position liquid phase solute and solid phase solute to alloy graining solute redistribution Behavior is studied.The employing p é let number of solid liquid interface forward position solutes accumulation represents, p é let number is dendrite end radius of curvature r With liquid phase solute Equivalent boundary layer thickness δ_cRatio, liquid phase solute Equivalent boundary layer thickness δ_c(δ_c=2d_l/ v) represent diffusion length In degree, contained whole solutes are equal to the solute total amount contained by infinite boundary layer.Due to the solute concentration gradient of dendrite end, The solute concentration gradient in the spheroid forward position being to grow up can approx be look at, according to the asking of diffusion field around the globular crystal growing Solution method, if only considering radial diffusion, the boundary layer thickness around globular crystal growing is equal to the radius of ball, i.e. dendrite end Solutes accumulation length l in portion is approximately equal to the radius r of ball.Therefore, p é let number is represented by

${\mathrm{pe}}_l=\frac{vl}{2d_l}---\left(7\right)$

P é let number characterizes in the liquid phase of solid liquid interface forward position driving force determined by solute degree of supersaturation.

Due to eutectic usually occurring in actual process of setting and liquid concentration can not possibly continue to increase, in order to truly The component distributing of description solidification end is it is necessary to consider the back-diffusion of solute atoms in solid phase.According to the principle of mass conservation, in solid phase The speed degree of solute atoms back-diffusion depends on dimensionless group α, also referred to as fo_s, it is anti-that it characterizes solute atoms in solid phase The ability of diffusion.

${\mathrm{fo}}_s=\mathrm{\α}=\frac{d_s{t}_f}{l^2}---\left(8\right)$

According to Solute mass conservation, characterize the segregation exponent m si (micro- of the solute segregation degree in process of setting Segregation index) it is represented by

$msi=\frac{{\mathrm{pe}}_l}{{\mathrm{kfo}}_s}---\left(9\right)$

WhereinSubstitute into (9)

$msi=\frac{{\mathrm{pe}}_l}{{\mathrm{kfo}}_s}=\frac{1}{2{\mathrm{kd}}_l{d}_s}\frac{{\mathrm{vl}}^3}{t_f}=a\·\frac{{\mathrm{vl}}^3}{t_f}---\left(10\right)$

WhereinIt is the physical parameter comprising alloy material, depending on the selection of material.For Same Part On different structure position, a may be considered constant.Knowable to formula (10), judgement microsegregation degree proposed by the present invention Segregation exponent m si value size, not only with the thermal physical property parameter solute balance partition coefficient k of alloy, Liquid Diffusion Coefficient d_l, solid phase Diffusion coefficient d_sCorrelation, and also local solidification condition setting rate v of alloy, feature diffusion length l and local solidification when Between t_fRelated.

For general casting process, dendrite is grown with isometry branch crystal type.Now, secondary dendrite arm spacing λ₂It is solute The characteristic length of diffusion.Therefore, the half taking secondary dendrite arm spacing is diffusion length, that is,

Substitution formula (10)

$msi=\frac{{\mathrm{pe}}_l}{{\mathrm{kfo}}_s}=\frac{1}{8}\·\frac{1}{2{\mathrm{kd}}_l{d}_s}\frac{{\mathrm{v\λ}}_2^3}{t_f}=\frac{1}{8}\·a\·\frac{{\mathrm{v\λ}}_2^3}{t_f},a=\frac{1}{2{\mathrm{kd}}_l{d}_s}---\left(11\right)$

It is below the present invention one application the present embodiment:

The present embodiment provides a kind of Forecasting Methodology of component segregation degree in Complicated structure casting casting process, to being cast as The k4169 nickel base superalloy large-scale complex thin-wall foundry goods of type carries out the prediction of microsegregation degree.The design of this foundry goods is not containing The large-area thin plate of stack pile, variable cross-section, the structure such as cylinder.Casting Three-dimensional illustraton of model is as shown in figure 1, the foundry goods of cast acquisition is real Thing figure is as shown in Figure 2.Because the alloying element that k4169 nickel base superalloy adds is many, alloying level is high, solidification temperature range Width, the solidifying segregation of alloying element is serious.Microsegregation is one of major defect of k4169 nickel base superalloy foundry goods, to casting The mechanical property of part, welding performance and processing characteristics have important impact.K4169 nickel base superalloy casting solidification process Middle nb solute atoms dissolubility in the base is little, and in process of setting, solid liquid interface will exclude a large amount of nb solute atoms to liquid phase, When being cooled to 1180 DEG C, there is γ+laves eutectic reaction, form laves phase in interdendritic.If due to alloy graining process Component segregation, the laves phase amount that solidification latter stage is formed is more, regardless of their form and distribution, because solid in laves phase The intensified elements such as a large amount of nb are determined, thus reducing solid solution strengthening effect.Meanwhile, decrease hardening constituent γ ' or γ " quantity, Reduce precipitation strengthening effect, cause alloy mechanical property to deteriorate.Therefore, solute element nb segregation and laves phase are eliminated always It is the key technology difficulty of k4169 nickel base superalloy castings production.

(1) obtain calculating thermal physical property parameter

By jmatpro software, PHASE DIAGRAM CALCULATION is carried out to k4169 alloy, and combine list of references l.nastac.numerical modeling of solidification morphologies and segregation Patterns in cast dendritic alloys [j] .acta mater.vol.17.pp:4253-4262.1999. obtains Each thermophysical parameter used by calculating, each parameter is as follows:

γ=3.65 × 10^-7(km), k_nb=0.48, d_l,nb=3 × 10^-9(m²s^-1), d_s,nb=2.82 × 10^-13(m²s^-1), c_0,nb=4.316 (wt.pct), c_eut,nb=19.1 (wt.pct), m_l=-10.9, t_l=1360 DEG C, t_s=1180 DEG C；

(2) obtain the temperature field data at each position of foundry goods

Application procast finite element software carries out emulating mould to the casting filling of foundry goods as shown in Figure 1, process of setting Intend, obtain the temperature field data at each position of foundry goods, such as local setting time t of molten metal_f, setting rate v；

Or local setting time t_f, the side that also can be combined with sunykatuib analyses by precision-investment casting of setting rate v Method obtains.For fixing k4169 alloy, based on fixing cast model and full form casting process condition, carry out actual fusible pattern Casting obtains foundry goods.In casting process, it is pre-placed high temperature resistance tungsten-rhenium thermal couple in casting features structure position, in real time measurement casting Make the cooling curve of process molten metal.On the one hand, carry out PHASE DIAGRAM CALCULATION acquisition in conjunction with jmatpro software to k4169 alloy to open Beginning solidification temperature t_lAnd solidification end temp t_s, you can obtain local setting time t_fWith rate of cooling r, local setting time t_f It is molten metal to start to solidify to solidification end the experienced time, and rate of cooling r passes through formula r=- (t_s-t_l)/t_fObtain ?.On the other hand, in conjunction with the position of the branched thermocouple of equidistant layout, you can obtain thermograde g of appointed part, then root According to formula r=-gv, you can obtain setting rate v of appointed part molten metal.Finally by the actual measured value of thermocouple and simulation Value is compared, if both identical then it is assumed that this simulation obtain local setting time t_f, setting rate v be foundry goods office Domain setting time t_f, setting rate v, if instead then two; would differ, adjust model boundary condition setting, then be simulated, directly Identical to both.

(3) obtain secondary dendrite arm spacing λ at each structure position of foundry goods₂

Calculate the λ of each structure position of foundry goods using the secondary dendrite arm spacing computing module that procast software carries₂Value.Warp The m value calculating acquisition k4169 alloy is 19.43 (um³s^‐1)；Secondary dendrite arm spacing λ₂Computing formula be

λ₂=(mt_f)^1/3(12)

Wherein:

$m=166\·\frac{{\mathrm{\γd}}_{l}ln(c_{eut}/c_0)}{m(1-k)(c_0-c_{eut})}---\left(13\right)$

In formula (13), γ is gibbs thomson coefficient, c₀For initial solute concentration, c_eutThere is eutectic for solidification latter stage Liquid phase solute concentration during reaction, m is alloy liquid phase line slope, and m is with the related parameter of material.Calculate in panel in procast, Corresponding initial solidification temperature t is inputted according to different alloys_l, eutectic reaction temperature t_s, and the m value being calculated according to formula (13), The secondary dendrite arm spacing λ of each structure position of foundry goods can be calculated₂Value.

Or, secondary dendrite arm spacing λ₂Also can be obtained by the method that precision-investment casting is combined with sunykatuib analyses.Pin To fixing k4169 alloy, based on fixing cast model and full form casting process condition, carry out actual model casting and cast Part, carries out subdivision to foundry goods, each structure position is intercepted metallographic specimen, using 10gcucl₂+ 100 ethanol+100ml hydrochloric acid Mix reagent carries out slight erosion, then carries out metallographic observation statistics secondary dendrite arm spacing λ₂Meansigma methodss, finally subdivision is cast The actual secondary dendrite arm spacing λ that part obtains₂Value is contrasted with the analogue value, if within both identical or errors are 5%, recognizing It is the secondary dendrite arm spacing λ of foundry goods for this analog result₂Value, if instead then two, differ, adjustment model boundary condition sets Put, then be simulated, until both are identical or in range of error.

(4) calculate segregation exponent m si value at each structure position of foundry goods

Temperature field data obtaining from procast: setting rate v of molten metal, local setting time t_f, secondary dendrite Spacing λ₂, and the thermophysical parameter of the calculating of jmatpro: solute balance partition coefficient k, Liquid Diffusion Coefficient d_l, solid-state diffusion Coefficient d_s, substitute in formula (11), and the viewcast module by procast, calculate each structure position of Complicated structure casting Msi segregation index；According to the size of each structure position msi segregation index, judge the microsegregation of each structure position of foundry goods Degree；Wherein:

$msi=\frac{{\mathrm{pe}}_l}{{\mathrm{kfo}}_s}=\frac{1}{8}\·\frac{1}{2{\mathrm{kd}}_l{d}_s}\frac{{\mathrm{v\λ}}_2^3}{t_f}=\frac{1}{8}\·a\·\frac{{\mathrm{v\λ}}_2^3}{t_f},a=\frac{1}{2{\mathrm{kd}}_l{d}_s}---\left(11\right)$

In formula (11): pe_lFor dimensionless solute p é let number, characterize in the liquid phase of solid liquid interface forward position by solute degree of supersaturation Determined by driving force；fo_sFor dimensionless Fourier number, also referred to as the solid-back diffusion factor；K distributes system for solute balance Number；d_lFor Liquid Diffusion Coefficient；d_sFor solid phase diffusion welding；V is setting rate；L is characterized diffusion length；t_fFor local solidification Time.

Predict the outcome and model casting obtains the subdivision Comparative result (comparing result is as shown in Figure 3) of foundry goods it is seen then that predicting Result and subdivision result are coincide, and segregation index is bigger, and microsegregation is more serious, and the interdendritic laves phase that solidification latter stage is formed contains Amount is higher.

The present invention, by finite element software procast and Thermodynamic Calculation Software jmatpro, in conjunction with foundry practice, can have The microsegregation degree of the solute element of the effect prediction each structure position of Complicated structure casting；By the application of the inventive method, no Only can be without dissecting the degree of segregation that foundry goods can predict a certain solute element of each structure position of foundry goods, for optimizing and revising casting Make technique and Technology for Heating Processing provides foundation, and the method can be to other solute element degree of segregation of multicomponent alloy Prediction, applied range.

Above the specific embodiment of the present invention is described.It is to be appreciated that the invention is not limited in above-mentioned Particular implementation, those skilled in the art can make various modifications or modification within the scope of the claims, this not shadow Ring the flesh and blood of the present invention.

Claims (3)

1. in a kind of Complicated structure casting casting process the Forecasting Methodology of component segregation degree it is characterised in that the method includes Following steps:

(1) obtain calculating thermal physical property parameter

Thermophysical parameter computing module using commercialization jmatpro software obtains the thermal physical property parameter of alloy, and parameter includes molten Matter equilibrium distribution coefficient k, Liquid Diffusion Coefficient d_l, solid phase diffusion welding d_s, alloy initial solidification temperature t_l, eutectic reaction temperature t_s；

(2) obtain the temperature field data at each position of foundry goods

Application procast finite element software carries out analogue simulation to the casting filling of Complicated structure casting, process of setting, obtains casting The temperature field data at each position of part, data includes setting rate v of molten metal, local setting time t_f；Or local solidifies Time t_f, the method that combined with sunykatuib analyses by precision-investment casting of setting rate v obtained；

(3) obtain secondary dendrite arm spacing λ at each structure position of foundry goods₂

Calculate the Secondary Branch of each structure position of foundry goods using the secondary dendrite arm spacing computing module that procast finite element software carries Intergranular is away from λ₂；Or secondary dendrite arm spacing λ₂Obtained by the method that precision-investment casting is combined with sunykatuib analyses；

(4) calculate segregation exponent m si value at each structure position of foundry goods

Solidification Parameters obtaining from procast finite element software: setting rate v of molten metal, local setting time t_f, secondary Dendrite interval λ₂, and the thermophysical parameter that jmatpro software obtains: solute balance partition coefficient k, Liquid Diffusion Coefficient d_l, solid Phase diffusion coefficient d_s, substitute in microsegregation deciding degree exponent m si formula, and by procast finite element software Viewcast module, calculates segregation exponent m si of each structure position of Complicated structure casting, according to each structure of Complicated structure casting The size of the segregation exponent m si value at position judges the microsegregation degree of each structure position of foundry goods: segregation exponent m si is bigger, micro- Sight segregation is more serious, and it is higher that the interdendritic that solidification latter stage is formed separates out phase content；Wherein:

$msi=\frac{{\mathrm{pe}}_l}{{\mathrm{kfo}}_s}=\frac{1}{8}\·\frac{1}{2{\mathrm{kd}}_l{d}_s}\frac{{\mathrm{v\λ}}_2^3}{t_f}=\frac{1}{8}\·a\·\frac{{\mathrm{v\λ}}_2^3}{t_f},a=\frac{1}{2{\mathrm{kd}}_l{d}_s}$

In formula: pe_lFor dimensionless solute p é let number, characterize in the liquid phase of solid liquid interface forward position and expand determined by solute degree of supersaturation Scattered driving force；fo_sFor dimensionless Fourier number, also referred to as the solid-back diffusion factor；K is solute balance partition coefficient；d_lExpand for liquid phase Scattered coefficient；d_sFor solid phase diffusion welding；V is setting rate；t_fFor local setting time；For comprising alloy material Physical parameter, depending on the selection of material, for the different structure position on Same Part, a is considered constant；

Described local setting time t_f, the method that combined with sunykatuib analyses by precision-investment casting of setting rate v obtain, tool Body is: for fixing k4169 alloy, based on fixing cast model and casting technique condition, carries out actual casting and is cast Part, in casting process, is pre-placed high temperature resisting thermocouple in casting features structure position, measures casting process molten metal in real time Cooling curve, on the one hand, with reference to jmatpro software, k4169 alloy is carried out with phasor and obtain beginning solidification temperature t_lAnd solidification knot Shu Wendu t_s, you can obtain local setting time t_fWith rate of cooling r, wherein: local setting time t_fIt is molten metal to start to coagulate Gu terminating the experienced time to solidification, and rate of cooling r passes through formula r=- (t_s-t_l)/t_fObtain；On the other hand, in conjunction with many Prop up the position of thermocouple, obtain thermograde g of appointed part, obtain the solidifying of appointed part molten metal further according to formula r=-gv Gu speed v；

Finally the actual measured value of thermocouple and the analogue value are compared, if both identical then it is assumed that this simulation obtain office Domain setting time t_f, setting rate v be foundry goods local setting time t_f, setting rate v, if both differ, adjust mould Type boundary condition is arranged, then is simulated, until both are identical；

Described secondary dendrite arm spacing λ₂Obtained by the method that precision-investment casting is combined with sunykatuib analyses, particularly as follows: for solid Fixed k4169 alloy, based on fixing cast model and full form casting process condition, carries out actual model casting and obtains foundry goods, Subdivision is carried out to foundry goods, each structure position is intercepted metallographic specimen, using 10gcucl₂+ 100ml ethanol+100ml hydrochloric acid Mix reagent carries out slight erosion, then carries out metallographic observation statistics secondary dendrite arm spacing λ₂Meansigma methodss, finally subdivision is cast The actual secondary dendrite arm spacing λ that part obtains₂Value is contrasted with the analogue value, if within both identical or errors are 5%, recognizing It is the secondary dendrite arm spacing λ of foundry goods for this analog result₂Value, if both differ, adjusts model boundary condition setting, then It is simulated, until both are identical or in range of error.

2. in a kind of Complicated structure casting casting process according to claim 1 component segregation degree Forecasting Methodology, its It is characterised by, in step (3), secondary dendrite arm spacing λ₂Computing formula be

λ₂=(mt_f)^1/3

Wherein:

$m=166\·\frac{{\mathrm{\γd}}_{l}ln(c_{eut}/c_0)}{m(1-k)(c_0-c_{eut})}$

In formula, γ is gibbs-thomson coefficient, c₀For initial solute concentration, c_eutThere is liquid during eutectic reaction for solidification latter stage Phase solute concentration, m is alloy liquid phase line slope, and m is with the related parameter of material.

3. in a kind of Complicated structure casting casting process according to claim 2 component segregation degree Forecasting Methodology, its It is characterised by, m value calculates with each parameter from Thermodynamic Calculation Software jmatpro or list of references l.nastac.numerical modeling of solidification morphologies and segregation patterns in cast Dendritic alloys [j] .acta mater.vol.17.pp:4253-4262.1999. obtains.