JP2003155536A - HIGH DUCTILE Cr AND PRODUCTION METHOD THEREFOR - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high ductile Cr which has excellent high temperature strength, oxidation resistance and corrosion resistance and has high cold ductility, and to provide a production method therefor. SOLUTION: The high ductile Cr consists of pure Cr or a Cr alloy and has a cold fracture elongation of <=2.5%. The Cr alloy preferably contains one or more elements selected from, by mass, 0.1 to 1.0% V, 0.5 to 5.0% Mg, 0.1 to 2.0% Al2 O3 and 0.1 to 2.0% Y2 O3 , and the balance Cr with inevitable impurities.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Cr high ductility material and a method for producing the same. More specifically, it exhibits ductility at room temperature and can be machined, and has a higher heat resistance and a higher resistance than Ni-base superalloys. The present invention relates to a highly ductile Cr material having excellent high temperature corrosion resistance and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, Ni-base superalloys have been used as materials for members such as jet engines, gas turbines and various chemical plants that are required to have high-temperature strength, high-temperature oxidation resistance and high-temperature corrosion resistance. Generally, Ni-based superalloys are
An alloy based on i, which contains Cr for forming a protective film having oxidation resistance or corrosion resistance, and Al, Ti, Mo, W, etc. for improving strength, the melting point of which is It is 1400 ° C or lower.

[0003]

Recently, in the above-mentioned members and the like, in order to improve the efficiency, for example, in the case of a gas turbine, it is necessary to raise the turbine inlet temperature, and it is used in the relevant portion. For the existing members, materials having higher temperature characteristics than conventional Ni-based superalloys are required.

Further, Ni is expensive, and there is a demand for a substitute material for the Ni-base superalloy from the viewpoint of resource saving. As a result, as a heat-resistant and high-temperature corrosion-resistant material for pure Cr and Cr-based alloys, which has a melting point above 1875 ° C and forms a stable protective film (Cr ₂ O ₃ ) that has self-repairing properties in the atmosphere. The use of is being considered.

However, since pure Cr and Cr-based alloys are not brittle at room temperature and are brittle, there is a problem that they cannot be machined substantially. The present invention is pure C
An object of the present invention is to solve the above-mentioned problems in r- and Cr-based alloys, to provide a Cr high-ductility material having excellent strength, oxidation resistance, and corrosion resistance at high temperatures and good room-temperature ductility, and a method for producing the same. And

[0006]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have found that, in the course of various studies, a Cr-based alloy having a certain chemical component exhibits room temperature ductility, and further The detailed examination of the chemical components has led to the development of the Cr highly ductile material of the present invention.

At the same time, the present inventors investigated not only the chemical composition of the Cr-based alloy but also the effect of the working treatment and / or heat treatment on the room temperature ductility of pure Cr or Cr-based alloy, and as a result, The present invention has led to the development of a method for producing a Cr highly ductile material. That is, the present invention provides a Cr high ductility material comprising pure Cr or a Cr-based alloy and having a breaking elongation at room temperature of 2.5% or more.

In this case, the Cr-based alloy has a V: 0.1
~ 1.0 mass%, MgO: 0.5-5.0 mass%, Al
₂ O ₃ : 0.1-2.0 mass%, Y ₂ O ₃ : 0.1-2.0
It is preferable to contain any one kind or two or more kinds in mass% and the balance is Cr and inevitable impurities.
Further, the Cr-based alloy contains V and Ti: 0.1 to 1.0% by mass in total of both, MgO: 0.5 to 5.0% by mass, Al ₂ O ₃ : 0.1 to ₂ . 0 mass%, Y ₂ O ₃ : 0.1
To 2.0 mass%, any one kind or two or more kinds may be contained, and the balance may be composed of Cr and unavoidable impurities.

The N content in the pure Cr or the Cr-based alloy is preferably 0.05 mass% or less. Further, in the present invention, the sintered material obtained by powder-sintering the raw material powder is subjected to plastic working with a working rate of 50% or more, intermediate annealing with a temperature of 900 to 1100 ° C., and final annealing with a temperature of 1150 to 1250 ° C. There is provided a method for producing the above Cr high ductility material (hereinafter referred to as production method A), which is characterized in that the annealing treatment is performed in this order.

Further, a sintering material obtained by subjecting the raw material powder to a powder sintering method is subjected to plastic working at a working rate of 50% or more, at a temperature of 9%.
Intermediate annealing treatment at 00 to 1150 ° C, temperature 1150 to 12
A final annealing treatment at 50 ° C., and a plastic working treatment at a working rate of 1% or more at a temperature of 100 to 300 ° C. are performed in this order, and the method for producing a Cr high ductility material (hereinafter,
Manufacturing method B) is provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The Cr high-ductility material of the present invention is pure C
It is characterized by comprising a r- or Cr-based alloy and having a breaking elongation of 2.5% or more at room temperature. In the present invention, the breaking elongation at room temperature is 10 to 35.
The breaking elongation specified in JIS-Z2241 measured at a temperature of ° C.

First, the Cr-based alloy according to the present invention is used,
A highly ductile Cr material having a breaking elongation of 2.5% or more at room temperature will be described. This Cr high ductility material is V, M
gO, Al ₂ O ₃ and Y ₂ O ₃ are contained alone or in combination, and the balance consists of Cr and inevitable impurities. In that case, the content ratio of these chemical components is as follows. Limited to

V: 0.1 to 1.0% by mass V is a component for increasing the ductility and tensile strength of the material at room temperature. If the content is less than 0.1% by mass, the above effects cannot be sufficiently obtained, and if it is more than 1.0% by mass, the above effects are saturated, so the upper limit is made 1.0% by mass. The preferable content rate of V is 0.3 to 0.7 mass%.
Is.

MgO: 0.5 to 5.0 mass% MgO is a component which is dispersed in grain boundaries and is added to enhance the ductility of the material at room temperature. If the content of MgO is less than 0.5% by mass, the above effects cannot be sufficiently obtained, and if it exceeds 5.0% by mass, the above effects are not only saturated, but also the room temperature ductility decreases. Therefore, the content of MgO is set to 0.5 to 5.0 mass%. The preferred content of MgO is 1.5 to 3.5 mass%.

Al ₂ O ₃ : 0.1 to 2.0 mass% Al ₂ O ₃ is dispersed in grain boundaries and is a component added to enhance ductility and tensile strength of the material at room temperature. .
If the content of Al ₂ O ₃ is less than 0.1% by mass, the above effects cannot be sufficiently obtained, and if it exceeds 2.0% by mass, not only the above effects are saturated, but also On the contrary, since ductility and tensile strength at room temperature decrease, Al
The content of ₂ O ₃ is 0.1 to 2.0% by mass. Al ₂ O ₃
The preferred content of is 0.5 to 1.0% by mass.

Y ₂ O ₃ : 0.1 to 2.0 mass% Y ₂ O ₃ is dispersed in grain boundaries and is a component added to enhance the room temperature ductility of the material. The content of Y ₂ O ₃ is 0.
If it is less than 1% by mass, the above-mentioned effect cannot be sufficiently obtained, and if it exceeds 2.0% by mass, not only the above-mentioned effect is saturated, but also the elongation at break is rather lowered, so that Y ₂ The content of O ₃ is 0.1 to 2.0 mass%.
The suitable content of Y ₂ O ₃ is 0.3 to 1.0% by mass.

Further, C composed of the Cr-based alloy according to the present invention
The high ductility material has at least V among the above chemical components.
When it contains, it may further contain Ti,
Its content is limited as follows. Ti: 0.1 to 1.0% by mass in total of V and Ti Ti, like V, is a component for improving ductility and tensile strength of the material at room temperature. The total amount of V and Ti is 0.
If it is less than 1% by mass, the above effects cannot be sufficiently obtained, and if the total amount of both exceeds 1.0% by mass,
Not only are the above effects saturated, but the ductility and tensile strength at room temperature are rather reduced, so the Ti content should be 0.1-1.0 mass% as the total amount of V and Ti. .

In the Cr high ductility material having the above chemical composition, the N content is preferably limited as follows. N: 0.05% by mass or less N is contained in the material as an unavoidable impurity, but it makes the material brittle, so its content is regulated to be 0.05% by mass or less. To control the content rate of N is
It can be performed by electrolyzing and purifying the material.

Next, C which is made of the pure Cr or Cr-based alloy of the present invention and has a breaking elongation of 2.5% or more at room temperature.
r Manufacturing methods A and B of the high ductility material will be described in order. When any one of the production methods A and B of the present invention is applied to a powder in which each raw material powder is mixed so as to have the above-mentioned chemical components to produce the Cr high ductility material of the present invention, the same mixed powder It is possible to improve the room temperature ductility of the obtained Cr high-ductility material as compared with the case where the Cr high-ductility material of the present invention is produced by using the above method.

Further, by applying either of the production methods A and B of the present invention to pure Cr, the high ductility Cr material of the present invention can be produced. In that case, the pure Cr may contain unavoidable impurities, but the obtained Cr
The N content in the highly ductile material is preferably 0.05% by mass or less for the same reason as described above. The production method A of the Cr highly ductile material of the present invention will be described using pure Cr as a raw material.

First, a raw material powder made of pure Cr is filled in a mild steel can by, for example, a conventional powder sintering method.
It is subjected to HIP (high temperature isostatic pressing) and sintered. In this case, prior to HIP, the raw material powder may be placed in a plastic bag, subjected to HP (hydrostatic pressure molding) at room temperature to be preformed, and the preformed body may be subjected to HIP treatment. Then, the obtained sintered material is plastically worked at a working rate of 50% or more at a temperature of 600 to 800 ° C. (hereinafter, referred to as hot working). Then 90 to this processed sintered material
After carrying out an intermediate annealing treatment at a temperature of 0 to 1100 ° C. for 0.5 to 3 hours, 0.5 to 3 at a temperature of 1150 to 1250 ° C.
By applying the final annealing treatment for 3 hours, the target C
r Highly ductile materials can be manufactured.

That is, in the above-mentioned manufacturing method A, the intermediate material is subjected to the intermediate annealing treatment and the final annealing treatment in the temperature range described above, and the working ratio of the hot working is set to 50% or more. It is considered that the normal temperature ductility of the material is expressed because it is possible to remove the minute voids existing in the sintered material and to create sound chromium crystal grains with no sub-grain boundaries and little grain boundary segregation of trace impurities. .

The hot working temperature of the sintered material can be appropriately selected depending on the shape of the intended material, but a temperature of 600 to 800 ° C. is desirable. And
Intermediate annealing temperature is less than 900 ℃ or 1100 ℃
Or / and the temperature of the final annealing treatment is 1
If the temperature is lower than 150 ° C. or higher than 1250 ° C., the above-described effects cannot be obtained, and the elongation at break of the obtained material at room temperature is less than 2.5%.

The suitable temperature ranges for the intermediate annealing treatment and the final annealing treatment in the manufacturing method A are 950 and 950, respectively.
1050 degreeC and 1200-1250 degreeC. Further, in the present invention, since Cr is a refractory metal, the sintered material is manufactured by the powder sintering method, but it is disadvantageous in terms of thermal energy, but pure Cr is melted in place of the sintered material. After being manufactured, it may be made into an ingot and subjected to the treatment under the above-mentioned conditions.

Next, the manufacturing method B will be described. In this manufacturing method B, in the manufacturing method A described above, the temperature range of the intermediate annealing treatment is set to 900 to 1150 ° C., and after the final annealing treatment, the sintered material that has passed through these annealing treatments has a temperature range of 100 to 300 ° C. This is a manufacturing method in which plastic working (hereinafter referred to as prestraining) having a working rate of 1% or more in a temperature range is performed.

That is, in this manufacturing method B, the intermediate annealing in the above-mentioned temperature range for the sintered material,
By carrying out final annealing and pre-straining, a suitable amount of mobile dislocations advantageous for deformation is introduced into sound crystal grains that are free of voids and sub-grain boundaries and have little grain boundary segregation of trace impurities. It is considered that room temperature ductility is exhibited. Then, the temperature of the intermediate annealing treatment is less than 900 ° C. or 11
If the temperature exceeds 50 ℃, the final annealing temperature will be 1150 ℃.
Less than or more than 1250 ° C, the temperature of the prestraining treatment is less than 100 ° C or more than 300 ° C, and / or the processing rate of the prestraining treatment is less than 1%,
The above effects cannot be obtained, and the breaking elongation of the obtained material at room temperature is less than 2.5%.

In the case of the production method B, suitable temperature ranges for the intermediate annealing treatment, the final annealing treatment and the prestraining are 950 to 1050 ° C, 1200 to 1250 ° C and 150 to 250 ° C, respectively. The preferred processing rate for is 1
~ 4%. In addition, in the case of manufacturing the Cr high ductility material by adopting any one of the manufacturing methods A and B of the present invention, the raw material powder contains at least one of MgO, Al ₂ O ₃ , and Y ₂ O _3. At times, it is preferable that the raw material powder is mechanically alloyed by mixing and stirring with an attritor before the HIP treatment.

[0028]

EXAMPLES Examples 1 to 7 and Comparative Examples 1 to 5 of Cr powder having a particle size of 60 mesh or less, V powder, Ti powder, MgO powder, Al ₂ O ₃ powder, and Y ₂ O ₃ powder, respectively. Any one of them or two or more thereof were mixed and mixed so as to have the chemical composition shown in Table 1 to obtain a raw material powder.

When the raw material powder contains at least one of MgO powder, Al ₂ O ₃ powder, and Y ₂ O ₃ powder, each raw material powder is treated with an attritor before HIP treatment. Mechanically alloyed by stirring and mixing under Ar atmosphere. Then, the raw material powder is φ7.
After enclosing it in a 0 mm x L 150 mm mild steel can, temperature 1
HIP treatment was performed at 300 ° C., a pressure of 198 MPa, and an Ar atmosphere for 2 hours. The sintered material obtained from the raw material powder by this HIP treatment was forged at a processing rate of 60% at a temperature of 700 ° C. to form a round bar of φ20 mm, and then a tensile test of a cross section of a parallel part of 3 mm square and a length of 12 mm. Cut out a piece,
A tensile test was performed at a temperature of 30 ° C. to determine tensile strength and elongation at break. The above results are shown in Table 1. From Table 1, the following is clear. 1) V, MgO, Al ₂ O _3, and Y ₂ O containing a predetermined quantity of one or two or more of the _three, Examples 1 to 5 and the balance consisting of Cr and inevitable impurities, temperature 30 ° C. In tensile strength and elongation at break are superior to those of Comparative Example 1 and Comparative Examples 2 to 4 made of pure Cr. In particular, Example 1 containing a predetermined amount of V and the balance Cr and unavoidable impurities
They are better. 2) Example 6 containing V and Ti in a predetermined amount and the balance Cr and inevitable impurities in the balance, and Example 7 further containing a predetermined amount of Al ₂ O ₃ had a pure tensile strength and elongation at break at a temperature of 30 ° C. It is superior to Comparative Example 1 and Comparative Examples 2 to 4 made of Cr. 3) Compared to Example 1, Comparative Example 5 having a chemical composition substantially similar to that of Example 1 except that the nitrogen concentration exceeds 0.05% by mass is inferior in tensile properties at room temperature.

[0030]

[Table 1]

Examples 8 to 14 and Comparative Examples 6 to 10 In manufacturing Examples 8 to 23 and Comparative Examples 6 to 21 described later, round bars commonly used for these were manufactured as follows. . C with a particle size of 60 mesh or less, that is, a maximum particle size of 423 μm or less, and a purity of 99.9%
The r powder was put in a plastic bag and subjected to HP treatment at a pressure of 500 MPa in an Ar atmosphere at room temperature to prepare a preform. Then, the preform is heated to a temperature of 1200.
After HIP treatment for 2 hours in Ar atmosphere at 200 ° C. and 200 MPa pressure, a sintered material made of pure Cr was obtained, and this sintered material was then forged at a processing rate of 55% at a temperature of 700 ° C. and a diameter of 20 mm.
It was a round bar.

The 12 round bars were subjected to intermediate annealing treatment at the temperature and time shown in Table 2 and then air-cooled. After that, apply 1 to each of these rods at the temperature and time shown in Table 2.
After the final annealing treatment for a period of time, air cooling is performed, and for each round bar that has been subjected to these annealing treatments, a tensile test piece having a cross section of parallel part and a length of 3 mm square and 12 mm is cut out and stretched at a temperature of 30 ° C. The test was conducted. The results are shown in Table 2.

For Examples 10 and 14 in which the intermediate annealing treatment temperatures were 1000 ° C. and 1100 ° C., respectively, and Comparative Example 6 in which the intermediate annealing treatment was not performed,
A plurality of the same test pieces as described above were prepared, and the elongation at break was obtained over the temperature range of 30 to 400 ° C. The result is shown in FIG. From Table 2 and FIG. 1, the following two points are clear. 4) Examples 8 to 14, which were subjected to the intermediate annealing in the temperature range of 980 to 1100 ° C, were Comparative Example 6 in which the intermediate annealing was not performed, and Comparative Example 7 in which the intermediate annealing was performed at 700 ° C and 1150 ° C, respectively. Compared with No. 8, the tensile strength and the elongation at break at a temperature of 30 ° C. are large. 5) Examples 11 to 13 which were subjected to the final annealing treatment in the temperature range of 1180 to 1220 ° C. were 1050 ° C. and 130, respectively.
The tensile strength and the elongation at break at a temperature of 30 ° C. are larger than those of Comparative Examples 9 and 10 which were subjected to the final annealing treatment at 0 ° C. 6) From the relationship between temperature and elongation at break shown in FIG.
The DBTT (ductile-brittle transition temperature) of 0 and 14 is 70 ° C. and 80 ° C., respectively, which is extremely low compared to that of Comparative Example 6 which is 275 ° C. That is, subjecting the material to the intermediate annealing treatment at a predetermined temperature has the effect of not only exhibiting room temperature ductility but also lowering the DBTT. The material with the lowered DBTT becomes easier to machine.

[0034]

[Table 2]

Examples 15 to 20 and Comparative Examples 11 to 18 14 round bars were subjected to intermediate annealing treatment at the temperature and time shown in Table 3 and then air-cooled. After that, these round bars were also subjected to final annealing at the temperature and time shown in Table 3 and then air-cooled, and rolled at the temperature and working rate also shown in Table 3 to each of the round bars that have undergone these annealing treatments. After processing, the parallel section and length are 3mm square and 12mm, respectively.
A tensile test piece having a size of mm was cut out and the tensile strength and the elongation at break at a temperature of 30 ° C. were obtained. The results are shown in Table 3.

[0036]

[Table 3]

From Table 3, the following points are clear. 7) Examples 15 to 20, which were subjected to the intermediate annealing treatment at a temperature of 900 to 1150 ° C., had higher tensile strength and elongation at room temperature than Comparative Examples 12 and 13 which were subjected to the intermediate annealing treatment at a temperature of 700 ° C. and 1150 ° C. Is excellent. 8) Examples 15 to 20, which were subjected to the final annealing treatment at a temperature of 1150 to 1250 ° C, had 1050 ° C and 1300, respectively.
The tensile strength and elongation at break at room temperature are superior to those of Comparative Examples 14 and 15 which were subjected to the final annealing treatment at a temperature of ° C. 9) Tensile strength and rupture at room temperature of Examples 15 to 20 subjected to the rolling process at a temperature of 100 to 300 ° C were higher than those of Comparative Examples 16 and 17 subjected to the rolling process at a temperature of 50 ° C and 600 ° C, respectively. Excellent elongation. 10) Tensile strength and break elongation at room temperature of Examples 15 to 20 subjected to the rolling processing at a working rate of 1% or more are superior to those of Comparative Example 18 subjected to the rolling processing at a working rate of 0.5%. ing.

Examples 21 and 22 As Example 21, tensile test pieces were produced under the same conditions as in Example 8 except that Cr powder and V powder each having a grain size of 60 mesh or less were used as raw material powders. Create
The tensile strength and breaking elongation at a temperature of 30 ° C. were obtained. Further, as Example 22, a tensile test piece was prepared under the same conditions as in Example 15, except that Cr powder and V powder each having a particle size of 60 mesh or less were used as raw material powders, and the temperature was 30 The tensile strength and the elongation at break at ℃ were obtained.

The results are shown in Table 4 together with the results of Example 1 described above. From Table 4, the following is clear.

[0040]

[Table 4]

13) A Cr-based alloy containing a predetermined amount of V and the balance Cr and unavoidable impurities is produced by the production method A of the present invention.
And B, the tensile strength and the breaking elongation at a temperature of 30 ° C. are improved as compared with the case where the Cr-based alloy having the same composition is manufactured by the conventional method. From this,
C consisting of a Cr-based alloy having the predetermined chemical composition of the present invention
It can be seen that, when the r high ductility material is manufactured by any of the manufacturing methods A and B of the present invention, the tensile properties at room temperature are further improved as compared with the case of manufacturing by the conventional method.

[0042]

As is clear from the above description, the Cr high ductility material of the present invention and the manufacturing method thereof have the following effects. 1) The Cr high ductility material of the present invention composed of a Cr-based alloy having a predetermined chemical composition has excellent room temperature tensile properties even when manufactured by the conventional manufacturing method, but when manufactured by the manufacturing method of the present invention, Further, the room temperature tensile properties are improved. 2) By applying the production method of the present invention to pure Cr,
The normal temperature tensile properties of pure Cr can be improved.

The C of the present invention that achieves the above-mentioned effects
The high ductility material can be used not only as a heat and high temperature corrosion resistant material used in jet engines, gas turbines, various chemical plants, etc., but also processed into a predetermined shape, for example, a functional thin film. It is also useful as a sputter target material used in the manufacturing process such as, and the industrial effect of the present invention is great.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between temperature and elongation at break in Examples and Comparative Examples.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22F 1/00 630 C22F 1/00 630A 630B 640 640A 640B 650 650A 651 651B 682 682 683 683 684 685A 685C 687 691 691B 694 694A 694B 1/11 1/11 (72) Inventor Yasunori Harada 25 Hamaike, Nishiyuki-cho, Toyohashi-shi, Aichi Apuerumiyuki No. 302 (72) Inventor Michihiko Fujine, Miyoshi-cho, Nishikamo-gun, Aichi Kita Yashiki 55 F term (reference) 4K018 AA40 AB01 AC01 BA03 BA20 BC16 EA13 FA03 FA09 KA07 KA12 KA58

Claims (6)

[Claims] 1. A highly ductile Cr material, which is made of pure Cr or a Cr-based alloy and has a breaking elongation of 2.5% or more at room temperature. 2. The Cr-based alloy has V: 0.1 to 1.0.
% By mass, MgO: 0.5 to 5.0% by mass, Al ₂ O ₃ :
0.1 to 2.0% by mass, Y ₂ O ₃ : 0.1 to 2.0% by mass
The highly ductile Cr material according to claim 1, comprising any one or more of the above and the balance consisting of Cr and inevitable impurities. 3. The Cr-based alloy comprises V and Ti: both
0.1 to 1.0% by mass, MgO: 0.5 to 5.
0 mass%, Al₂O₃: 0.1 to 2.0 mass%, Y ₂O₃:
Any one or more of 0.1 to 2.0 mass%
Including the above, the balance consists of Cr and unavoidable impurities
The Cr high ductility material according to claim 1. 4. The highly ductile Cr material according to claim 1, wherein the N content in the pure Cr or the Cr-based alloy is 0.05% by mass or less. 5. A sintered material obtained by powder-sintering a raw material powder is subjected to plastic working at a working rate of 50% or more, at a temperature of 900 to 900.
Intermediate annealing treatment at 1100 ° C, and temperature 1150-12
The final annealing treatment at 50 ° C. is performed in this order, and the method for producing a Cr high ductility material according to claim 1. 6. A sintered material obtained by powder-sintering raw material powder, is subjected to plastic working at a working rate of 50% or more, and a temperature of 900 to 900.
Intermediate annealing treatment at 1150 ° C, temperature 1150 to 1250 ° C
The final annealing treatment and the plastic working treatment at a working rate of 1% or more at a temperature of 100 to 300 ° C. are performed in this order, and the method for producing a Cr high ductility material according to claim 1.