JP3535290B2 - Metals with excellent plastic deformability in the temperature range below the recrystallization temperature - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a metal that exhibits excellent deformability below the recrystallization temperature (pure Fe or Fe -
Cr- based alloy ).

[0002]

2. Description of the Related Art Generally, metals have their own unique characteristics (physical characteristics, chemical characteristics, etc.), but they have common characteristics that they have good processing characteristics such as ductility and malleability. It is used in various fields as an industrial material. And various products and parts using metal are
Generally, by taking advantage of such characteristics inherent to metal, more or less various plastic workings (hereinafter simply referred to as "working"), such as bending, rolling, wire drawing, drawing and overhanging, are carried out. , Or by applying them in combination. Such working is roughly classified into cold working, warm working and hot working depending on the working temperature. Especially, cold working and warm working are hot working in terms of energy saving, surface quality and working accuracy. Advantageous over processing.

However, both cold working and warm working are working in a temperature range below the recrystallization temperature of the metal, so recrystallization at the time of working is not expected, and so-called work hardening phenomenon occurs as the working progresses. Therefore, the deformability is lowered, defects due to processing occur, it is difficult to manufacture a desired product, and there is a problem that an intermediate heat treatment is required until the final product.

By the way, heretofore, the plastic deformability (hereinafter simply referred to as "deformability") in a temperature range below the recrystallization temperature of a metal has been such that the number and quality of slip systems at the time of work deformation and dislocations. It has been shown to depend on mobility and growth morphology, or their interaction with impurity elements. However, regarding the above-mentioned factors governing deformability,
It is hard to say that it has been fully clarified, and many of the factors that have been explained so far have not fallen beyond speculation and expectations. Therefore, it can be said that there was no metal manufacturing technology for universally obtaining excellent deformability in the temperature range of the recrystallization temperature or lower, and it took many trials and errors to obtain desired properties, and many Was spending effort and time. Therefore, the advent of a technique for producing a metal having excellent deformability in a temperature range equal to or lower than the recrystallization temperature has been strongly desired.

On the other hand, with recent advances in industry and industrial technology, there has been an increasing demand for metal materials having high strength at high temperatures. However, Ni-based, Mo-based, and W-based alloys have been mainly used as high-temperature materials that have been conventionally used, so that not only the material price becomes very expensive,
Ni-based alloys and the like also have a practical obstacle such as a large coefficient of thermal expansion. Moreover, these alloys have a problem that cold working and warm working are difficult. Therefore,
As described above, the advent of a technique for producing a metal which has an excellent deformability in a temperature range equal to or lower than the recrystallization temperature, has high strength at high temperature, and is inexpensive has been strongly desired.

[0006]

Therefore, an object of the present invention is to provide a metal having an excellent deformability in a temperature range below the recrystallization temperature so as not to cause the above-mentioned problems of the known art. To establish the manufacturing technology of. Another object of the present invention is to establish a technique for producing a metal which has excellent deformability in a temperature range below the recrystallization temperature, is inexpensive, and has excellent high temperature strength.

[0007]

Means for Solving the Problems Now, as a result of intensive research aimed at realizing the above-mentioned object, the inventors have found that the amount of a gas component in a solid solution state in a metal, the dislocation density, and As a result of diligent research on the mutual relationship between them, it was found that excellent deformability can be obtained by controlling these in an appropriate range, and the present invention has been completed.

The gist of the present invention is the following configuration embodying the above findings. (1) The total amount of gas components in solid solution is 50% by weight.
ppm or less, the balance being Fe and unavoidable impurities, pure having plastic deformability excellent in recrystallization temperature below the temperature range, wherein the dislocation density of ^{1 × 10 10 (1 / cm} 2) or less Fe . (2) the following equation between the total amount and the dislocation density of the gas component in the solid solution _{^{state; ln (d 2 × C gi}} × ρ) + A ≦ -20 However, d: lattice constant (cm) C _gi: Solid Total amount of dissolved gas components (ppm by weight) ρ: Dislocation density (1 / cm ² ) A: Constant determined by crystal structure (body-centered cubic structure and body-centered tetragonal structure: 2, face-centered cubic structure: 0 , Dense hexagonal structure:
1) The pure F described in (1) above, which has the relationship of
e .

(3) The total amount of gas components in solid solution is heavy.
The amount ratio is 50 ppm or less, Cr is 16 to 60 wt %, or
Furthermore. 1 to 15 wt% containing substitutional solid solution strengthening elements other than Cr
However, the balance consists of Fe and unavoidable impurities.
Is less than 1 × 10 ¹⁰ (1 / cm ² )
It has excellent plastic deformability in the temperature range below the crystallization temperature.
Fe-Cr alloy used. (4) Between the total amount of gas components in solid solution and the dislocation density
Following _{^{formula; ln (d 2 × C gi}} × ρ) + A ≦ - 20 However, d: lattice constant (cm) C _gi: the total amount of gas component in the solid solution state (weight ratio ppm) [rho: the dislocation density ( 1 / cm ² ) A: constant determined by crystal structure (body-centered cubic structure and
Body-centered tetragonal structure: 2, face-centered cubic structure: 0, dense hexagonal structure:
Fe-Cr according to (3) above, which has the relationship of 1).
Series alloy.

[0010]

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION First, an experiment that triggered the present invention will be described, and the configuration of the present invention will be clarified.

Experiment 1 Pure iron having different total amounts of gas components in a solid solution state (hereinafter, simply referred to as “amount of solid solution gas components”) was melted by changing the purity of raw materials and the melting conditions. And plate thickness 4 mm
After hot-rolling to 80 ° C., it was annealed (830 ° C.) and then cold-rolled to a sheet thickness of 0.2 mm without intermediate annealing. Hot
The dislocation density of the rolled and annealed plate is 1.7 to 2.9 × 10 ⁸ / c
It was in the m ² range. Observe the surface of the obtained cold rolled sheet,
The deformability was evaluated by the degree of cracking. FIG. 1 shows the relationship between the degree of cracking and the amount of solid solution gas components. It can be seen from FIG. 1 that when the amount of the solute gas component is 50 ppm by weight or less, no cracks are observed and good deformability is exhibited. Here, the amount of solid solution gas component was determined by subtracting the amount of extracted gas components such as carbides, nitrides, sulfides and oxides obtained by inclusion extraction analysis from the total amount of gas components contained in the sample. That is, the total amount of solid solution gas components = total (C + N + S + O) − (C + N + S +) as inclusions.
O). The dislocation density was obtained by observing 100 fields with a transmission electron microscope and using the average value of the number of dislocations per unit area.

Experiment 2 An Fe-16 wt% Cr alloy having a solid solution gas content of 35 ppm by weight was melted, hot-rolled to a plate thickness of 5 mm, and then annealed (850 ° C.).
And, then up and to adjust the dislocation density by changing the pressure under rate,
Cold rolling with a total reduction of 95% was performed without intermediate annealing. The surface of the obtained cold-rolled sheet was observed and the deformability was evaluated by the degree of cracking. The relationship between the degree of cracking and the dislocation density is shown in FIG. From Fig. 2, the dislocation density is 1 × 10 ¹⁰
It can be seen that when the ratio is (1 / cm ² ) or less, no cracks occur and good deformability is exhibited. The amount of the solid solution gas component and the dislocation density were determined in the same manner as in Experiment 1.

Experiment 3 Pure Fe, Fe-, in which the amount of solid solution gas components was adjusted to various levels (7 to 43 weight ppm) by the same method as in Experiment 1
30 wt% Cr, Fe-50 wt% Cr, Fe-50 wt% C
With respect to r-8 wt% W, Fe-42 wt% Ni and Cu, the dislocation density was adjusted (6.2 × 10 ^{7 to} 3.5 × 10 ⁹ / cm) from a 5 mmφ round bar by the same method as in Experiment 2.
² ) and cold drawing was performed up to 0.4 mmφ.
The amounts of solid solution gas components and dislocation densities were determined in the same manner as in Experiment 1 and Experiment 2. Deformability was evaluated by observing cracks by observing the surface of the processed wire rod thus obtained. In this experiment, various investigations were made on the method of organizing the data, and by organizing the constants determined by the crystal structure and the lattice constants by the newly introduced parameters, the deformability was evaluated and good correspondence was obtained regardless of the type of metal. It was found that FIG. 3 shows cracking scores and ln (d ² × C _gi × ρ) + based on such knowledge.
It shows the relationship with A. Where d, C _gi , ρ
And A are d: Lattice constant (cm) C _gi : Solid solution gas content (ppm by weight) ρ: Dislocation density (1 / cm ² ) A: Constant determined by crystal structure (body-centered cubic structure and body-centered tetragonal structure) Structure: 2, face-centered cubic structure: 0, dense hexagonal structure:
1) is represented. From FIG. 3, the amount of solid solution gas component is 50 ppm by weight or less, the dislocation density is 1 × 10 ¹⁰ (1 / cm ² ) or less, and ln (d ² × It can be seen that when the relationship of C _gi × ρ) + A ≦ −20, good deformability is exhibited regardless of the type of metal.

Although all the workings in the above experiments were cold working, it was confirmed that the same tendency was observed in the case of warm working. From this, it was found that the present invention is effective in improving the deformability in the working in the temperature range below the so-called recrystallization temperature range, including the cold working and the warm working.

From the above experimental results, in order to improve the deformability in the temperature range below the recrystallization temperature range, the amount of solid solution gas component is 50 wtppm or less and the dislocation density is 1 × 10 ^10.
(1 / cm ² ) or less is required, and further, the relationship of ln (d ² × C _gi × ρ) + A ≦ −20 is satisfied between the total amount of gas components in a solid solution state and the dislocation density. It was shown that more favorable results can be obtained by performing the above.

From the experimental results obtained above, the deformability of a metal depends on the ease with which dislocations move, and the dislocations move with solid solution gas components such as C, N, S and O, which are obstacles. Relatedly, the higher the dislocation density and the amount of solid solution gas components, the higher the probability of interaction between dislocations and solid solution elements such as C, N, S and O, resulting in a decrease in deformability. To be done. In addition to such solid solution gas components, precipitates such as carbides and nitrides may also hinder the movement of dislocations, so it is preferable that the amount of these precipitates is also small. As is clear from the above experimental results, the deformability can be applied irrespective of the type of metal, since it can be uniformly organized by taking the crystal structure and the lattice constant into consideration.
Al-based, Au-based, Fe-Cr-based, Fe-Ni-based, Fe-
Al-based, Fe-Cr-Al-based, Fe-Cr-Cu-based, F
e-Ni-Cu system, Fe-Cr-W system, Fe-Cr-M
o type, Fe-Cr-Nb type, Al-Cu type, Au-Ag
It is applicable to all metals that are usually used as industrial materials such as systems.

Of the above-mentioned metals to which the present invention is applicable, when further good high temperature strength is required, Cr is 16 to 60.
1% by weight of substitutional solid solution strengthening elements other than wt% or Cr
It is particularly preferable that it contains 15 wt% and the balance is Fe and inevitable impurities both in terms of characteristics and economically. This is because in order to maintain the oxidation resistance as a high temperature material, it is necessary to add at least 16 wt% Cr, but even if added in excess of 60 wt%, the effect is saturated. This is economically disadvantageous. In addition, in order to increase the high temperature strength, Mo, W, N
It is extremely effective to add substitutional solid solution strengthening elements such as b, Ta and Zr. This high-temperature strength can be obtained by adding 1 wt% or more of these substitutional solid solution strengthening elements, but if added in excess of 15 wt%, an intermetallic compound between these elements and Fe will be formed, and sufficient high temperature ductility will be obtained. Will not be obtained. Therefore, the substitutional solid solution strengthening element may be added alone or in the range of 1 to 15 wt%.

In producing the metal according to the present invention, in order to suppress the amount of the solute gas component to a desired amount or less, in particular,
It is necessary to pay attention to the purity of the raw materials and the prevention of contamination during melting, and for example, a method such as skull vacuum melting using a water-cooled copper crucible may be adopted. Further, in order to suppress the dislocation density to a desired amount or less, it is necessary to pay particular attention to the temperature and time of annealing. For example, in the case of Fe type, a method of performing high temperature annealing of 700 ° C. or higher may be adopted. Good.

When processing the metal according to the present invention, the shape of the object to be processed does not have to be specified in particular, and it can be applied to any shape such as plate, sphere, tube, rod, wire and powder. it can.

[0021]

EXAMPLES Pure Fe, Fe-Cr alloy, Fe-Ni alloy, Fe-Cr-W alloy, Fe-Cr having the chemical compositions shown in Table 1
-Mo alloy and Fe-Cr-Nb alloy were melted. Ultra-high purity electrolytic iron (purity 9
9.998 wt%), high-purity chromium (purity 99.95 wt%
%), High-purity Ni (purity 99.95 wt%), high-purity Mo
(Purity 99.95 wt%), high purity W (Purity 99.95 wt%)
%) And high-purity Nb (purity 99.95 wt%), and a skull melting method was adopted using a water-cooled copper crucible. In addition, the amount of the solid solution gas component is adjusted by adjusting the atmosphere during melting to 10
-Ar of 500 mmtorr under high vacuum of ^-6 torr or less
It was carried out by using a gas, using CrN as the N source, using a Fe—C alloy as the C source, and using a reagent S agent as the S source. After heating this ingot, plate thickness 15
hot-rolled to mm, then split the hot-rolled sheet in two,
By cold working, one plate is 8 mm thick and the other is 8 mm thick.
It was made into a φ rod, annealed, and then subjected to a deformability test. Also,
For some of the test materials, a round bar tensile test piece with a parallel portion of 3 mmφ was sampled from the 8 mmφ round bar, and the high temperature strength was measured.

Table 1 shows the amount of solid solution gas component, dislocation density, lattice constant, and values such as ln (d ² × C _gi × ρ) + A of the test material. The amount of solid solution gas component was determined by subtracting the amount of extracted gas components such as carbides, nitrides, sulfides and oxides obtained by inclusion extraction analysis from the total amount of gas components contained in the sample. That is, the total amount of solid solution gas components = total (C + N + S + O) − (C + N +) as inclusions.
S + O). The dislocation density was obtained by observing 100 fields with a transmission electron microscope and using the average value of the number of dislocations per unit area. Furthermore, Fe-Cr, Fe-C
The value of α-Fe as the lattice constant of each alloy of r-W, Fe-Cr-Mo and Fe-Cr-Nb, and Fe-Ni
As the lattice constant of the alloy, the value of γ-Fe was used for convenience.

[0023]

[Table 1]

The deformability test was carried out by the following two methods and the more severe processing conditions. 0.2 mm without intermediate annealing of a plate with a thickness of 8 mm
Cold plate rolling until. Using a mineral oil as a lubricating oil, a round rod of 8 mmφ was used.
Cold draw up to 4 mm. Further, the high temperature strength was obtained from a tensile test at 800 ° C. and 900 ° C. using a round bar tensile test piece having a parallel portion of 3 mmφ. The results of the above deformability test and high temperature tensile test,
It shows collectively in Table 2.

[0025]

[Table 2]

From Table 2, in the invention examples, no crack was observed on the surface of the test material after processing in any deformability test, and good deformability was obtained. Moreover, Fe-Cr-W, Fe
It can be seen that excellent high temperature strength can be obtained by adding an appropriate amount of the substitutional solid solution strengthening element to the Fe-Cr system such as -Cr-Mo and Fe-Cr-Nb. On the other hand, in the comparative examples, although there are some differences, cracks are generated in all of them and it is understood that the deformability is inferior.

[0027]

As described above, according to the present invention, the deformability of metals, particularly the plastic deformability in the temperature range below the recrystallization temperature, is remarkably improved. This makes it possible to broaden the application of metals to difficult-to-process products and to save energy by omitting intermediate annealing, which greatly contributes to industry. Further, according to the present invention, in addition to the plastic deformability in the temperature range equal to or lower than the recrystallization temperature, the high temperature strength is economically improved, so that the metal can be applied to difficult-to-process products requiring high temperature and high strength. Becomes

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a solid solution gas component amount and plastic deformability.

FIG. 2 is a graph showing the relationship between transition density and plastic deformability.

FIG. 3 is a graph showing the relationship between ln (d ² × C _gi × ρ) + A and plastic deformability.

Claims (4)

(57) [Claims] 1. The total amount of gas components in a solid solution is 50 ppm or less in weight ratio, and the balance is Fe and inevitable impurities.
Therefore, pure Fe 3 having excellent plastic deformability in the temperature range below the recrystallization temperature, which is characterized in that the dislocation density is 1 × 10 ¹⁰ (1 / cm ² ) or less. Formula between the wherein the total amount of gas component in the solid solution state and the dislocation _{^{density; ln (d 2 × C gi}} × ρ) + A ≦ -20 However, d: lattice constant (cm) C _gi : Total amount of solid solution gas components (ppm by weight) ρ: Dislocation density (1 / cm ² ) A: Constant determined by crystal structure (body-centered cubic structure and body-centered cubic structure: 2, face-centered cubic structure) : 0, dense hexagonal structure:
The pure F according to claim 1, having the relationship of 1).
e . 3. The total amount of gas components in a solid solution is the weight ratio.
Then 50ppm Is Cr To 16 ~ 60wt %, Or even
To Cr Substitution type solid solution strengthening elements other than 15wt % Content, balance
Department Fe And unavoidable impurities with a dislocation density of 1 ×
Ten ^Ten (1 / cm ² ) Recrystallization temperature characterized by
Has excellent plastic deformability in the temperature range below 40 degrees Fe
-Cr Series alloy. 4. The total amount of gas components in a solid solution state and the dislocation density.
The following formula between the degree and; ln (d ² × C _gi × ρ) + A ≦ − 20 However, d: lattice constant ( cm ) C _gi : Total amount of gas components in solid solution (weight ratio ppm ) ρ: dislocation density (1 / cm ² ) A: A constant determined by the crystal structure (body-centered cubic structure and
Body-centered tetragonal structure: 2, face-centered cubic structure: 0, dense hexagonal structure:
1) The relationship according to claim 3, characterized in that Fe-C
r Series alloy.