JPH11156413A - Method for estimating deformation resistance concerning plastic working of metallic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly estimate deformation resistance, i.e., forming load and constitutional change, by introducing residual strain, particle size and effect of chemical composition into expressions of deformation resistance for numerical calculation concerning plastic working of metallic material. SOLUTION: In the method for estimating deformation resistance concerning plastic working of metallic material, the deformation resistance is obtained by applying among the following general expressions in which not less than two items out of residual strain, particle size and chemical composition in addition to working temperature, strain velocity and strain are added as variables. General expressions: Deformation resistance = f(temperature, strain velocity, strain, residual strain, particle size), Deformation resistance = f(temperature, strain velocity, strain, residual strain, chemical composition), Deformation resistance = f(temperature, strain velocity, strain, particle size, chemical composition), Deformation resistance = f(temperature, strain velocity, strain, residual strain, particle size, chemical composition).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting the deformation resistance of plastic working of a metal material, and more particularly, to the determination of the capability of a plastic working machine to be introduced, and whether or not the introduced machine is capable of working. The present invention relates to a method for predicting a deformation resistance, for example, for obtaining a load necessary for determining a load.

[0002]

2. Description of the Related Art Conventionally, it has been indispensable to predict a forming load necessary for a plastic working process such as rolling or forging in determining the capability of a plastic working apparatus to be introduced. Alternatively, it is necessary to accurately predict the forming load in order to determine whether or not it is possible to perform processing with the already introduced plastic working apparatus. Since this forming load greatly depends on the deformation resistance,
Various deformation resistance formulas have been proposed, including theoretical formulas and empirical formulas. Deformation resistance is the resistance per unit area that a material exhibits against external force, and corresponds to the minimum force required for processing. The names include flow stress, flow stress, deformation stress, and the like in addition to the deformation resistance, but these have the same meaning.

[0003] The accuracy of predicting the forming load tends to be lower in a process in which a plurality of processes are applied. This phenomenon is
This occurs because the effect of residual strain on the deformation resistance equation is not taken into account. That is, the reason is that the residual amount of the applied strain is not quantified. FIG. 1 schematically shows this state. An example is given of a process in which the chemical component A is applied twice to the annealed material of the metal material that is the initial grain do. For simplicity, the temperature and strain rate were common in the first and second steps. The conventional deformation resistance formula is generally expressed by the following formula (1). Deformation resistance σ = f (T, dε / dt, ε) ··· Equation (1) where T is the processing temperature, and dε / dt (the black circle on ε in the drawing) is the strain. The velocity, ε, is the strain. Using the equation (1), the deformation resistance in the first step and the second step is given by σ1 = f (T, dε / dt, ε1) σ2 = f (T, dε / dt, ε2). The forming load of each process is σ1 and σ
Calculated from 2.

However, in practice, the deformation resistance in the second step is different from σ2 due to the presence of residual strain εr. Assuming that the deformation resistance actually shown by the material is σ1R and σ2R for the deformation resistances of the first step and the second step, respectively, σ1R = f (T, dε / dt, ε1) σ2R = f (T, dε / dt, εr + ε2). Then, σ1 = σ1R, σ2 ≦ σ
Obviously it is 2R. σ2 = σ2R only when εr is zero, but generally they do not match because distortion remains. As can be inferred from FIG. 1, the value of the calculated value of the deformation resistance and the actual value increases as the number of steps increases. The reason why the prediction accuracy of the molding load is reduced in the process in which the processing is performed a plurality of times is as described above. Naturally, the same phenomenon occurs when the temperature and strain rate of the first step and the second step are different. As described above, it is impossible to accurately predict the load by the conventional deformation resistance formula in which the influence of the residual strain is not introduced.

As described above, the deformation resistance is greatly affected by the residual strain. However, even if the influence of the residual strain is introduced into the deformation resistance formula, it cannot be said that the accuracy alone is sufficient. In order to improve the accuracy of the deformation resistance type, it is necessary to introduce the influence of the particle size. FIG. 2 shows the effect of particle size on deformation resistance. The target is Ni-based heat-resistant alloy Inconel 718 having the chemical components shown in Table 1. Both levels were adjusted by heat treatment to an initial state in which no residual strain was present, the processing temperature was 1253K to 1393K, and the strain rate was 0.0
25S ^-1 . As is apparent from FIG. 3, a difference of up to about 20% is recognized in the range of the particle diameter under the same processing conditions. As described above, it is impossible to accurately predict the load by the conventional deformation resistance formula in which the influence of the particle size is not introduced.

On the other hand, in the field of plastic working, a technique of predicting a forming load and simultaneously predicting a structural change and a structure distribution inside a workpiece during a working process by numerical calculation has attracted attention. In a plastic working process including a plurality of steps, a mixed structure (a structure in which recrystallized portions and unrecrystallized portions are mixed) may be processed. The grain size and the amount of residual strain are different between the recrystallized portion and the non-recrystallized portion. Therefore, even if the state of the mixed structure immediately before processing is accurately predicted, the deformation resistance of the mixed structure cannot be accurately predicted by the conventional deformation resistance formula in which the influence of the grain size and the residual strain is not introduced. Detailed contents will be described with reference to FIG.

FIG. 3 shows a process in which an annealed material of a metal material which is a chemical component A is subjected to processing twice, in which a recrystallization structure having a grain diameter do is obtained immediately before the first process, Is the particle size
Residual strain εr with ds recrystallization region (no residual strain) and grain size dn
Of a mixed structure (recrystallization rate X) composed of an uncrystallized region. For simplicity, the temperature and strain rate were common in the first and second steps. Since the conventional deformation resistance equation is expressed by the equation (1), the deformation resistance σ1 in the first step and the deformation resistance σ2 in the second step are σ1 = f (T, dε / dt, ε1) σ2 = f (T, dε / dt, ε2). The forming load of each process is σ1 and σ
Calculated from 2.

However, actually, the deformation resistance is affected by the grain size and the residual strain. The deformation resistance actually exhibited by the material is represented by σ1R
If R and σ2RR, σ1RR = f (do, T, dε / dt, ε1) σ2RR = X * f (ds, T, dε / dt, ε2) + (1−
X) * f (dn, T, dε / dt, εr + ε2) where X is the recrystallization rate. Note that * in the formula means x (multiply) (the same applies hereinafter). The magnitude relationship between σ1 and σ1RR differs depending on the particle size. Since the value of the particle size is innumerable, it cannot be expected that the two values agree with each other. The magnitude relationship between σ2 and σ2RR also depends on the recrystallization rate, recrystallized grain size ds, uncrystallized grain size dn, and residual strain. Since these combinations are innumerable, they cannot be expected to match. That is, accurate prediction of the molding load is impossible.
Naturally, the same phenomenon occurs when the temperature and the strain rate are different between the first step and the second step. Further, in tissue prediction by numerical calculation using a computer, temperature, which is one of the most influential factors on tissue, is calculated from deformation resistance. Therefore, if an incorrect deformation resistance is used, the calorific value will be inaccurate, and the accuracy of tissue prediction will decrease. As described above, it is impossible to accurately predict the forming load and the structure by the conventional deformation resistance formula in which the influence of the particle size and the residual strain is not introduced.

Further, even if the effects of the residual strain and the grain size are introduced into the deformation resistance equation, the accuracy is not sufficient. In order to improve the accuracy of the deformation resistance type, it is necessary to introduce the influence of chemical components. FIG. 4 shows the effect of chemical components on deformation resistance. The target is Ni-based heat-resistant alloy Inconel 718 having the chemical components shown in Table 2. The three materials correspond to the upper limit material, the intermediate material, and the lower limit material of the JIS standard for the chemical components. Each level was adjusted to an initial state without residual strain by heat treatment, the initial grain size was 180.2 μm, the processing temperature was 1253K to 1393K, and the strain rate was 0.008.
s-1. As is clear from the figure, a difference of about 20% was recognized between the upper limit material and the lower limit material even under the same processing conditions. That is, the calculated molding load and the calorific value also differ by about 20%. As described above, it is impossible to accurately predict the forming load and the structure by the conventional deformation resistance formula in which the influence of the component is not introduced. As described above, at present, it is impossible to accurately predict the forming load and the structural change by the conventional deformation resistance formula expressed by the formula (1).

[0010]

SUMMARY OF THE INVENTION The present invention introduces the effects of residual strain, grain size, and chemical composition into a deformation resistance formula for numerical calculation relating to plastic working, and accurately detects deformation resistance, that is, forming load and structural change. The challenge is to predict.

[0011]

In order to solve the above problems, the present invention provides a method for predicting deformation resistance relating to plastic working of a metal material.
It is determined using any one of the following general formulas in which two or more of residual strain, particle size, and chemical component in addition to strain are added as variables. General formula: Deformation resistance = f (temperature, strain rate, strain, residual strain, particle size) Deformation resistance = f (temperature, strain rate, strain, residual strain, chemical component) Deformation resistance = f (temperature, strain rate, strain) , Particle size, chemical component) Deformation resistance = f (temperature, strain rate, strain, residual strain, particle size, chemical component)

Further, in order to solve the above-mentioned problem, in the method of the present invention for predicting deformation resistance related to plastic working of a Ni alloy, the deformation resistance σ is determined by the following equation. Formula: σ = f (particle size, temperature, strain rate, effective strain, component) = σP × ((εEF / εP) × exp (1- (εEF / εP))) ^C, where σP (maximum stress) ) = 5.422E-2 × (do ^5.796E-2 × Z
^2.222E-1 ) ^9.852E-1 εP (strain at σP) = 1.881E-3 × do ^3.049E-1 × Z
^1.087E-1 C (stress index) = 0.7 x (1-exp (-1.821E-3 x (do
^-5.006E-1 × Z ^2.271E-1 ))) Z (parameter) = (dε / dt) × exp (Q / (8.31 *
T)) Q (activation energy) = 389.5 + 3.63 x (Cr-17)
^{0.6664 +} 13.02 × (Mo-2.8) ^0.6004 + 12.94 × (Al-0.2)
^0.6678 + 14.90 × (Ti-0.65) ^{0.5972 +10.8} × (Nb-4.7)
^0.6569 εEF (effective strain) = εr + εεr (residual strain) = (1−0.4 × (1-exp (− (t / t
s) ^2.456 ))) × ε ts (recovery saturation time) = 5.924 × ((T-273) / 1000)
^-12.004 do (particle size) = 10 μm to 800 μm T (temperature) = 1123 K to 1423 K dε / dt (strain rate) = 0.001 S ^{−1 to} 100 S ⁻¹ ε (strain) = 0.05 to 1.50 t ( (Inter-process time) = 0.2 to 4000 sec. In the formula, E-1 is × 10 ⁻¹ , E-2 is × 1
0 ^-2 , E-3 is × 10 ^-3 , and S ^-1 is / s
ec. (same as below)

Hereinafter, the present invention will be described in detail. Residual strain,
It has long been known that the particle size and chemical composition affect the deformation resistance, but there has been no example of quantifying these effects and incorporating them into the deformation resistance formula. The present invention seeks an ideal deformation resistance formula for numerical calculation relating to plastic working,
It is a method to predict the load required for the plastic working process,
This method quantifies the effects of grain size, residual strain, and chemical composition on deformation resistance and predicts the load required for the plastic working process. Hereinafter, the present invention will be described in detail using the Ni-based heat-resistant alloy Inconel 718 as an example. The effect of the particle size on the deformation resistance was investigated for the Ni-based heat-resistant alloy Inconel 718 having the chemical components shown in Table 1 below. In order to accurately evaluate the effect of the grain size, an experiment was performed in which the temperature was adjusted to an initial state in which no residual strain was present, and the strain rate was constant during processing.

[0014]

[Table 1]

As a relational expression expressing the deformation resistance σ, CIN
The following equation (2) called GARA equation (Singara equation) was used. .sigma. =. sigma.P * ((. epsilon./.epsilon.P)*exp(1-(.epsilon./.epsilon.P))) ^C Equation (2) where .sigma.P and .epsilon.P are characteristic values, and the relationship on the deformation resistance curve is shown in FIG. As shown in FIG. That is,
σP is the maximum value of the deformation resistance, and εP is the strain at σP. C is a stress index. FIG. 6 shows the effect of the particle size do and the parameter U on .sigma.p. Since the relationship between the parameters U and Z is U = do ^0.05796 * Z ^0.2222 , FIG.
Can be requested. Z is called the temperature compensation strain rate,
It is expressed by the following equation (3). Z = (dε / dt) * exp (Q / (8.31 * T)) (3) where T is the absolute temperature, Q is the activation energy of deformation, and the chemical components shown in Table 1. In the case of Ni-base heat-resistant alloy Inconel 718 having the following formula, it has been confirmed that Q = 427.3 KJ / mol.

As is clear from FIG. 6, the effect of the particle size on the deformation resistance is accurately quantified. The obtained correlation is σP = 5.422E-2 * (do ^5.796E-2 × ^Z2.222E-1 )
^9.852E-1 ... Equation (4) is obtained. On the other hand, FIG. 7 shows the effect of do and parameter S on εP. Since the relationship between the parameters S and Z is S = do ^0.3049 * Z ^0.1087 , the effect of the particle size is accurately quantified as in the case of σP from FIG. The obtained correlation was as follows: ε P = 1.881E-3 * do ^3.049E-1 * Z ^1.87E-1 ... Equation (5)

FIG. 8 shows the influence of do and L on C. The relation between parameter L and Z is L = do ^-5.006E-1 *
Since it is Z ^2.271E-1 , as in the case of σP from FIG.
The effect of particle size has been accurately quantified. The obtained correlation was as follows: C = 0.7 * (1-exp (-1.821E-3 * (do- ^5.006E-1 * ^Z2.271E-1 )))) Equation (6) As described above, the influence of the particle size on the deformation resistance was quantified. It is a feature of the present invention that the characteristic value or coefficient in the deformation resistance formula is a function of the particle diameter, and the same method can be used when another function system such as Shida's equation is used as the deformation resistance. There is no problem.

The residual strain was evaluated based on the change in deformation resistance in the multi-stage processing step. The definition of the residual strain is as shown in FIG. The material has a particle size of 18 with the components in Table 1.
0.2 μm Ni-based heat-resistant alloy Inconel 718.
In order to accurately evaluate the influence of the residual strain, the temperature was adjusted to an initial state in which no residual strain was present, and the temperature and strain rate during processing were constant. Then, processing was performed under the condition that recrystallization does not occur. In general, the residual strain εr in the second step in the case where the material having no residual strain is subjected to two-step processing is expressed by the following equation (7). εr = f (do, T, dε / dt, ε, t) Equation (7) where do is the grain size, T is the processing temperature, dε / dt is the strain rate,
ε is the distortion of the first step, and t is the time between steps. As a result of the investigation, it was found that the expressions can be simply expressed by the following formula groups (8) to (13).

Residual strain εr = f (T, ε1, t) Equation (8) = RR * ε1 Equation (9) Residual rate RR = 1−R Equation (10) Recovery rate R = 0.4 * (1-exp (− (t / ts) ^2.456 )) Equation (11) Recovery saturation time ts = 5.924 * ((T-273) / 1000) ^-12.004 Expression (12) In Expressions (9), (10), and (11), the maximum value of the residual strain is given. 60% of the applied strain, or conversely, the maximum value of the recovery is 40% of the applied strain. Equations (11) and (12) show that the effect of the recovery is saturated and the residual strain is 6
The time to reach 0% means shorter at higher temperatures. As a function system expressing the deformation resistance σ, the above CINGARA
Was used. σ = σP * ((ε / εP) * exp (1− (ε / εP))) ^C Equation (2) σP, εP, and C have already been formulated as functions of temperature, strain rate, and particle size. Have been.

The deformation resistance σ1 when a strain of ε1 is applied in the first step is as follows: σ1 = σP * ((ε1 / εP) * exp (1- (ε1 / ε
P))) given by ^C. On the other hand, when the strain of ε2 is applied in the second step, the deformation resistance σ2 is σ2 = σP * ((εEF / εP) * exp (1- (εEF / εP))) ^C effective strain εEF = εr + ε2 · ... It can be expressed by equation (13). Further, the residual strain immediately before the third step is given by RR * εEF as estimated from the equation (9).
The deformation resistance σ3 when a strain of ε3 is applied in the process is as follows: σ3 = σP * (((RR * εEF + ε3 / εP) * exp ((1-
(RR + ε3) / εP))) ^C RR * εEF + ε3 is the effective strain in the third step, which is expressed by the equation (1)
It is the same as 3).

In the fourth and subsequent steps, the effective strain can be taken into account by the same method, and the deformation resistance in the presence of residual strain can be accurately evaluated. The introduction of the influence of the grain size and the strain rate depending on the processing conditions and the material is effective for improving the accuracy. Also, when the temperature is different between the first step and the second step, there is no problem because the residual strain can be expressed by introducing the effect of the temperature change into the recovery saturation time. Even when the temperature and the strain rate are different between the first step and the second step, there is no problem in calculation because the deformation resistance equation includes the temperature and the strain rate as variables. It is a feature of the present invention that the distortion term in the deformation resistance equation is replaced with an effective strain. In the case where another function system such as Shida's equation is used as the deformation resistance, the effect of the residual strain is obtained by the same method. There is no problem. Further, there is no problem even if another function system is used as the residual strain or the effective strain.

The influence of the chemical components on the deformation resistance was investigated for the Ni-base heat-resistant alloy Inconel 718 having the chemical components shown in Table 2 below. In order to accurately evaluate the influence of the chemical components, the particle size was adjusted to an initial state in which no residual strain was present, and the particle size was set to 180.2 μm. Further, the temperature and the strain rate during processing were constant. As the function system expressing the deformation resistance σ, the above-mentioned CINGARA equation was used. σ = σP * ((ε / εP) * exp (1- (ε / εP))) ^C Equation (2) σP, εP, and C have already been formulated as a function of Z and particle size. , Ε by the effective strain, the influence of the residual strain can be considered. As shown in equation (3), since Z includes the activation energy Q, the influence of chemical components on deformation resistance can be introduced by making Q a function of components.

[0023]

[Table 2]

The activation energies calculated by a general method are 389.5 KJ / mol for the lower limit material, 418.3 KJ / mol for the intermediate material, and 435.2 KJ / mol for the upper limit material in Table 2. The activation energy of the Ni-based heat-resistant alloy Inconel 718 was used as a function of the component as a standard for the activation energy of the lower limit material by using an appropriate method. The resulting correlation, Q = 389.5 + 3.63 * ( Cr-17) 0.6664 +13.02 * (Mo-2.8) 0.6004 +12.94 * (Al-0.2) 0.6678 +14.90 * (Ti-0.65) 0.5972 +10 .8 * (Nb-4.7) ^0.6569 Expression (14) Here, each element such as Cr means the weight% contained in the material. As described above, the effect of the component on the deformation resistance was quantified. If the same processing is performed on a plurality of Ni-based heat-resistant alloys, the influence of the components can be considered in a wider range, and the deformation resistance of all Ni-based heat-resistant alloys can be accurately evaluated. Further, even in steel materials, it is possible to accurately evaluate the deformation resistance of a wide range of steel types by using the activation energy as a function of the component. Even when a function system that does not include the term of the activation energy is used as the deformation resistance equation, the influence of the component can be introduced by making the characteristic value or coefficient a function of the component by the same method.
There is no problem at all.

As shown in Table 3, the deformation resistance is classified into four types depending on the temperature and strain rate during processing. Groups 1 and 3 also include cases where the temperature change during processing is corrected by calculation. Groups 1 and 2 also include cases where the strain rate during processing is corrected by calculation. Many functional systems have been proposed as deformation resistance equations belonging to each group. The present invention is to make the characteristic values and coefficients in the deformation resistance equation a function of the particle diameter, replace the strain term in the deformation resistance equation with effective strain, and convert the characteristic values and coefficients in the deformation resistance equation to components. Since it is characterized by being a function, it can be applied to all these functional systems.

[0026]

[Table 3]

One example of the deformation resistance formula group of the present invention is shown below as Formula Group A. The material is Ni-based heat-resistant alloy Inconel 718
It is. Equation group A Deformation resistance σ = f (particle size, temperature, strain rate, effective strain, component) = σP * ((εEF / εP) * exp (1- (εEF / εP))) ^C σP (maximum stress) = 5.422E-2 * (do ^5.796E-2 * Z
^2.222E-1 ) ^9.852E-1 εP (strain at σP) = 1.881E-3 * do ^3.049E-1 * Z
^1.087E-1 C (stress index) = 0.7 * (1-exp (-1.821E-3 * (do
^-5.006E-1 * Z ^2.271E-1 ))) Z (parameter) = (dε / dt) * exp (Q / (8.31 *
T)) Q (activation energy) = 389.5 + 3.63 * (Cr-17)
^{0.6664 +13.02 * (Mo-2.8)} 0.6004 +12.94 * (Al-0.2) 0.6678 +
14.90 * (Ti-0.65) ^{0.5972 +10.8} * (Nb-4.7) ^0.6569 εEF (effective strain) = εr + εr (residual strain) = (1-0.4 * (1-exp (-(t / t
s) ^2.456 ))) * ε ts (recovery saturation time) = 5.924 * ((T-273) / 1000)
^-12.004

The domain is as follows. do (particle size) = 10 μm to 800 μm T (temperature) = 1123 K to 1423 K dε / dt (strain rate) = 0.001 S ^{−1 to} 100 S ⁻¹ ε (strain) = 0.05 to 1.50 t (interprocess Time) = 0.2-4000sec

On the other hand, an example of a group of deformation resistance formulas obtained by a conventional formulation method is shown below as a formula group B. The material is Ni-based heat-resistant alloy Inconel 718 having the components shown in Table 1. Formula group B Deformation resistance σ = f (temperature, strain rate, strain) = σP * ((ε / εP) * exp (1- (ε / εP))) ^C σP (maximum stress) = 5.422E-2 * Z ^2.222E-1 εP (strain at σP) = 1.818E-3 * Z ^1.087E-1 C (stress index) = 0.7 * (1-exp (-1.821E-1 *
Z ^2.271E-1 )) Z (parameter) = (dε / dt) * exp (Q / (8.31 *
T)) Q (activation energy) = 427300 As Q, the value confirmed for the Ni-based heat-resistant alloy Inconel 718 having the chemical components shown in Table 1 was used. The domain is common to the case of the formula group A.

[0030]

Embodiments of the present invention will be described below. Example 1 Molding load of particles having different particle diameters The load in the case of upsetting and forging a columnar material of Ni-base heat-resistant alloy Inconel 718 having the chemical components shown in Table 1 above was measured, and a value predicted from the calculation was obtained. Compared. The material was adjusted to an initial state without residual strain. Initial particle size is 4
The range was changed from 9.6 μm to 655.1 μm. The initial shape of the material is 300 mm in diameter × 400 mm in height.
It is compressed to a height of 200 mm by processing. Processing temperature is 1123K and 1393K, strain rate is 0.01S
^-1 (0.01 / sec). As the deformation resistance, the above formula group A
(Used in the present invention) and Group B (conventional deformation resistance type) are used. The results are shown in Table 4 below.

[0031]

[Table 4]

When a conventional formula that has not been quantified is used, the predicted molding load is, of course, the same regardless of the particle size. However, as shown in FIG. 2, since the deformation resistance is actually affected by the particle size, the forming load also changes according to the particle size. With the conventional deformation resistance formula, it is not possible to accurately predict the forming load. When the deformation resistance formula used in the present invention is applied,
Since such actual phenomena can be accurately expressed, the molding load can be predicted with high accuracy.

Example 2 Molding load in multi-stage processing A Ni-base heat-resistant alloy Inconel 718 having the chemical components shown in Table 1 above was used as a columnar body having a diameter of 300 mm and a height of 400 mm, and was adjusted to an initial state without residual strain. did. The initial particle size is 97.8 μm. The process is the following 4 of cylindrical material
It is a step upset forging, and the processing conditions in each step are processing temperature 1
123K, a strain rate of 0.01 S ⁻¹ , a strain of 0.2, and a time between processes of 10 seconds are common. The distortion of each process is given by the following equation (15).
Defined by ε = In (the height of the material before processing / the height of the material after processing) Expression (15) As the deformation resistance, the above-mentioned expression group A (used in the present invention)
And group B (conventional deformation resistance type). The results are shown in Table 5 below.
Shown in

[0034]

[Table 5]

When a conventional equation in which the effect of residual strain is not quantified is used, the predicted forming load is the same regardless of the process. However, as shown in FIG. 1, since the deformation resistance is actually affected by the residual strain, the forming load also changes depending on the process. Therefore, accurate prediction of the forming load cannot be performed by the conventional deformation resistance method. When the deformation resistance formula used in the present invention is applied, such actual phenomena can be accurately expressed, so that the forming load can be predicted with extremely high accuracy.

Example 3 Load when a mixed structure was processed The thickness of the Ni-based heat-resistant alloy Inconel 718 having the chemical components shown in Table 1 above was 50 mm in thickness, 200 mm in width, and 40 in length.
A 0 mm plate was used as a raw material and adjusted to an initial state without residual strain. The initial particle size is 275.4 μm. The process is a two-stage rolling of a plate-shaped material, and the processing conditions in each process are a processing temperature of 1
273 K, a strain rate of 0.1 S ⁻¹ , a strain of 0.2, and a time between processes of 5 seconds are common. The distortion in each step is defined by the above equation (15). The microstructure immediately before the second step obtained from the microstructure prediction formula has a recrystallization ratio of 28% and a particle size of 37 μm in the recrystallization region.
m, the grain size of the amorphous region is 222.3 μm, and the residual strain of the amorphous region is 0.136. As the deformation resistance, the above formula group A (used in the present invention) and group B (conventional deformation resistance formula) are used. The results are shown in Table 6 below.

[0037]

[Table 6]

When a conventional deformation resistance formula in which the effects of the residual strain and the particle size are not quantified is used, the predicted forming load is the same regardless of the process. However, as shown in FIG. 3, since the deformation resistance is actually affected by the residual strain and the particle size, the forming load also changes depending on the process. The conventional deformation resistance method cannot accurately predict the forming load. When the deformation resistance formula used in the present invention is applied, the area of 28% is 37 μm.
a recrystallized portion having a particle size of m (no residual strain);
% Region can accurately represent the deformation resistance of the structure state of an amorphous portion having a particle size of 222.3 μm and a residual strain of 0.136, so that the prediction could be made very accurately.

Example 4 Recrystallization rate A Ni-based heat-resistant alloy having the chemical components shown in Table 1 and having a thickness of 50 mm × 200 mm × 400 mm was adjusted to an initial state without residual strain. The process was a two-stage rolling of a plate-shaped material, and the structure of the material quenched immediately after the second process was investigated. The processing conditions are shown in Tables 7 and 8. For the calculation, the above formula group A (used in the present invention) and group B (conventional deformation resistance formula) are used. The results are shown in Tables 7 and 8 below.

[0040]

[Table 7]

[0041]

[Table 8]

The accuracy of tissue prediction when the deformation resistance formula used in the present invention is applied is very high. This is probably because the deformation resistance can be accurately expressed, and the heat generated during processing is also accurately calculated.

Example 5 Load, Recrystallization Ratio and Particle Size in Multi-stage Processing The initial shape of the Ni-base heat-resistant alloy having the chemical components shown in Table 2 was 50 mm thick × 200 mm wide × 400 m long.
m was used as a material and adjusted to an initial state without residual strain. The initial particle size is 275.4 μm. The process is four-stage rolling of a plate-like material, and the processing conditions in each process are a processing temperature of 127.
3K, strain rate 0.1S ^-1 , strain 0.2, time between processes 10
Common in seconds. The distortion in each step is defined by the above equation (15). Regarding the recrystallization rate and the recrystallized grain size, the structure of the material quenched immediately after the fourth step was used. As the deformation resistance, the above formula group A (used in the present invention) and group B (conventional deformation resistance formula) are used. The results are shown in Table 9 below (load),
The results are shown in 10 (recrystallization rate) and 11 (recrystallized particle size).

[0044]

[Table 9]

[0045]

[Table 10]

[0046]

[Table 11]

From these results, when the deformation resistance equation used in the present invention is applied, the deformation resistance can be more accurately predicted than that obtained by using the conventional deformation resistance equation. It can be seen that can also be accurately predicted.

[0048]

According to the method of the present invention for predicting the deformation resistance relating to plastic working of a metal material, since the deformation resistance is obtained as a function of all the physical properties of the material and the physical conditions applied to the material, the deformation resistance can be accurately predicted. As a result, an excellent effect of being able to accurately predict the recrystallization rate, the recrystallized grain size, and the processing power is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the effect of residual strain on deformation resistance, where a is a schematic diagram of two-stage rolling, b is a diagram for explaining a conventional concept, and c is an actual phenomenon. FIG.

FIG. 2 is a graph for explaining the effect of the particle size on the deformation resistance.

FIG. 3 is a diagram for explaining deformation resistance in the processing of a mixed structure, where a is a schematic diagram of two-stage rolling, b is a diagram for explaining a conventional concept, and c is an actual phenomenon. It is a figure for explaining.

FIG. 4 is a graph for explaining the effect of a chemical component on deformation resistance.

Fig. 5 Stress (STRESS) and strain (STRAI) of Ni-base heat-resistant alloy
9 is a graph showing the relationship of N).

FIG. 6 is a graph showing the influence of grain size, strain rate and temperature on σP (peak stress) of a Ni-base heat-resistant alloy.

FIG. 7 is a graph showing the effects of grain size, strain rate, and temperature on εP (strain at σP) of a Ni-base heat-resistant alloy.

FIG. 8 is a graph showing the influence of grain size, strain rate and temperature on C (stress index) of a Ni-base heat-resistant alloy.

Claims (2)

[Claims] In a method for predicting deformation resistance related to plastic working of a metal material, the deformation resistance is determined by a processing temperature, a strain rate,
The deformation resistance related to plastic working of a metal material, which is obtained by using one of the following general formulas in which two or more items of residual strain, particle size, and chemical component in addition to strain are added as variables, is predicted. Method. General formula: Deformation resistance = f (temperature, strain rate, strain, residual strain, particle size) Deformation resistance = f (temperature, strain rate, strain, residual strain, chemical component) Deformation resistance = f (temperature, strain rate, strain) , Particle size, chemical component) Deformation resistance = f (temperature, strain rate, strain, residual strain, particle size, chemical component) 2. A method for predicting the deformation resistance of a Ni alloy according to the plastic working, wherein the deformation resistance is determined by the following equation. Formula: σ = σP × ((εEF / εP) × exp (1- (εEF / ε
P))) ^C where σP (maximum stress) in the formula = 5.422 E-2 × (do ^5.796E-2 × Z
^2.222E-1 ) ^9.852E-1 εP (strain at σP) = 1.881E-3 × do ^3.049E-1 × Z
^1.087E-1 C (stress index) = 0.7 x (1-exp (-1.821E-3 x (do
^-5.006E-1 × Z ^2.271E-1 ))) Z (parameter) = (dε / dt) × exp (Q / (8.31 ×
T)) Q (activation energy) = 389.5 + 3.63 x (Cr-17)
^{0.6664 +13.02 × (Mo-2.8)} 0.6004 +12.94 × (Al-0.2) 0.6678 +14.90 × (Ti-0.65) 0.5972 + 10.8 × (Nb-4.7) 0.6569 εEF ( effective strain) = εr + ε εr (Residual strain) = (1-0.4 × (1-exp (-(t / t
s) ^2.456 ))) × ε ts (recovery saturation time) = 5.924 × ((T-273) / 1000)
^-12.004 do (particle size) = 10 μm to 800 μm T (temperature) = 1123 K to 1423 K dε / dt (strain rate) = 0.001 S ^{−1 to} 100 S ⁻¹ ε (strain) = 0.05 to 1.50 t ( (Inter-process time) = 0.2 to 4000 sec. In the formula, E-1 is × 10 ⁻¹ , E-2 is × 1
0 ⁻² and E−3 are × 10 ⁻³ .