JPH1161361A - Heat resistant and wear resistant material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material excellent in heat and wear resistance and thermal shock resistance by dispersing Cr carbides having a specified grain size into an Fe-Cr metallic matrix of an alloy having a specified compsn. composed of C, Cr, Nb and Fe. SOLUTION: In an alloy composed of, by weight, 2 to 6.5%, preferably about 3.5 to 6%, more preferably about 4.5 to 5.5% C, 25 to 60%, preferably about 40 to 55%, more preferably 47 to 53% Cr, 0.1 to 10%, preferably about 1 to 5%, more preferably about 1.5 to 3% Nb, and the balance Fe with inevitable impurities, Cr carbides having <=10 μm average grain size are dispersed into Fe-Cr base metallic matrix phases to obtain a heat resistant and wear resistant material. In this alloy components, a part of Fe may be substituted with one or more kinds among 0.1 to 5% V, 0.1 to 5% Mo and 0.1 to 6% W. Furthermore, a part of C can be substituted with one or more kinds of 0.05 to 15 N and 0.05 to 1.5% B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant and abrasion-resistant material suitable for use as a constituent material of a site requiring high-temperature abrasion resistance such as a power plant.

[0002]

2. Description of the Related Art In a coal-fired thermal power plant, there are many parts requiring both heat resistance and abrasion resistance simultaneously, such as a pipe protector and a powder transport pipe. In these parts,
Low alloy steel, SUS310 or the like is used, but depending on the use environment, wear is remarkable, and there is a case where replacement is required at every periodic inspection. In nuclear power plants, stellite-based alloys are used in parts where wear resistance and slidability are required, such as valve seats. Because of this, the adverse effect on the human body and the environment is a problem. Therefore, an alloy that does not contain Co and has properties equivalent to that of a stellite alloy has been eagerly desired. In addition, in the internal combustion engine and aerospace equipment industries, the use environment tends to be harsher with the demand for higher performance of equipment, and conventional wear-resistant materials and heat-resistant materials cannot cope with this. It's getting harder.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a new alloy having both heat resistance and wear resistance to improve the performance of an apparatus, reduce the frequency of replacing parts, or reduce the content of Co in a nuclear power plant. It is an alternative to alloys.

[0004]

Means for Solving the Problems The present inventors have proposed Fe-C
We carefully selected the components of the r-C-Nb alloy system and invented a new heat- and wear-resistant material having excellent high-temperature hardness and thermal shock resistance. That is, the present invention has the following configurations (1) to (3). (1) By weight ratio, C: 2 to 6.5%, Cr: 25 to 60
%, Nb: 0.1 to 10%, and the balance is an alloy consisting of unavoidable impurities and Fe, characterized in that Cr carbide having an average particle size of 10 μm or less is dispersed in the Fe—Cr based metal base phase. A heat and wear resistant material (hereinafter, referred to as a first invention material). (2) In the alloy component of the above (1), a part of Fe is any one of: V: 0.1 to 5%, Mo: 0.1 to 5%, and W: 0.1 to 6% by weight ratio. An alloy substituted with one or more elements and having an average particle size of 10 μm in the Fe—Cr based metal base phase.
A heat-resistant and abrasion-resistant material wherein m or less Cr carbides are dispersed (hereinafter referred to as a second invention material). (3) In the alloy components of the above (1) and (2), a part of C is N: 0.05 to 1%, B: 0.05 to
1.5% of an alloy substituted with one or more elements,
A heat and wear resistant material (hereinafter referred to as a third invention material), characterized in that a Cr carbide having an average particle size of 10 μm or less is dispersed in an Fe—Cr based metal base phase.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reasons for limiting the components in the first invention material of the present invention will be described. In the following description, percent means percent by weight.

C: C forms carbides and secures the hardness of the alloy. In addition, a part thereof is dissolved in the metal base phase and contributes to strengthening of the base. Since the amount of carbide in the alloy can be controlled by the amount of C, it is necessary to change the amount according to the use conditions. If the amount is less than 2%, the amount of carbide is small and sufficient hardness cannot be obtained. If the amount exceeds 6.5%, most of the alloy becomes carbide and the thermal shock resistance decreases,
There is a problem that it is too brittle to make processing into a product shape difficult. Therefore, the suitable range of C is 2% or more and 6.5.
% Or less. Particularly when high-temperature hardness is emphasized, a desirable component range is 3.5% or more and 6% or less, and a more desirable component range is 4.5% or more and 5.5% or less.

Cr: Cr combines with C to form a Cr-based carbide and secures the hardness of the alloy. In particular, Cr-based carbides have excellent oxidation resistance, and are therefore selected as the main carbides of the alloy of the present invention. In addition, a part of the matrix dissolves in the metal base phase to improve the oxidation resistance and high temperature strength of the base. When a large amount of Cr is consumed as a carbide, the amount of solid solution in the matrix is reduced and the oxidation resistance and high-temperature strength of the matrix are reduced. Therefore, it is necessary to balance the amount of added Cr with the amount of C and the amount of Nb. . Generally, when the Cr content is less than 25%,
Since the amount decreases and sufficient oxidation resistance cannot be obtained, the lower limit of addition is set to 25%. Further, if the addition exceeds 60%, the metal matrix becomes brittle and the thermal shock resistance is reduced. Therefore, the upper limit of the addition is set to 60%. Particularly when high-temperature hardness is emphasized, a desirable component range is 40% to 55%, and a more desirable component range is 47% to 53%.

Nb: Nb combines with C to form Nb carbide and increases the hardness of the alloy. The main carbide of the invention alloy is Cr
Nb carbide is more stable at high temperatures than Nb carbide, so it suppresses the agglomeration and coarsening of Cr-based carbides during high-temperature heating during alloy production or during long-term use, and reduces thermal shock resistance. Contribute to improvement. If the addition amount is less than 0.1%, there is no substantial effect, and if it exceeds 10%, the Nb carbide itself becomes coarse and adversely affects the thermal shock resistance. Therefore, the addition range is 0.1% or more and 10% or less. And In consideration of material properties and economy, a desirable addition amount is 1% or more and 5% or less, and a more desirable addition amount is 1.5% or more and 3% or less.

Next, the reasons for limiting the components of the second invention material of the present invention will be described, but the description overlapping with the description of the first invention material will be omitted, and only the newly limited reasons for V, Mo, W will be described here. Will be described.

V: V combines with C to form V carbide and increase the hardness of the alloy. The main carbide of the invention alloy is a Cr-based carbide, but the V-carbide is finely dispersed separately therefrom, and thus has the effect of further increasing the high-temperature hardness. If the addition amount is less than 0.1%, there is no substantial effect, and if it exceeds 5%, the V carbide itself becomes coarse and adversely affects the thermal shock resistance. Therefore, the addition range is 0.1% or more and 5% or less. And In consideration of material properties and economy, a desirable addition amount is 1% or more and 3% or less.

Mo: Mo combines with C to form Mo carbides and increases the hardness of the alloy. The main carbide of the invention alloy is Cr
Although Mo carbides are finely dispersed separately from Mo-based carbides, they have the effect of further increasing the high-temperature hardness. In addition, a part of the alloy also forms a solid solution with the metal base phase and the Cr-based carbide, thereby improving the high-temperature thermal stability of the alloy. If the addition amount is less than 0.1%, there is no substantial effect, and if it exceeds 5%, the Mo carbide itself becomes coarse and adversely affects the thermal shock resistance. Therefore, the addition range is 0.1% or more and 5% or less. And In consideration of material properties and economy, a desirable addition amount is 1% or more and 3% or less.

W: W combines with C to form W carbides and increases the hardness of the alloy. The main carbide of the invention alloy is a Cr-based carbide, but the W carbide is finely dispersed separately therefrom, and thus has the effect of further increasing the high-temperature hardness. In addition, a part of the alloy also forms a solid solution with the metal base phase and the Cr-based carbide to improve the high-temperature thermal stability of the alloy. If the addition amount is less than 0.1%, there is no substantial effect, and if it exceeds 6%, the W carbide itself becomes coarse and adversely affects the thermal shock resistance and the oxidation resistance is lowered. .1% or more and 6% or less. Considering the material properties and economy, the desirable addition amount is 2
% Or more and 4% or less.

Further, the reasons for limiting the components in the third invention material of the present invention will be described, but the description overlapping with the description of the first invention material and the second invention material will be omitted, and the limitation of N and B newly limited here will be omitted. Only the reason will be explained.

N: N forms carbonitrides and secures the hardness of the alloy. Carbonitrides have a more complex structure than carbides,
Generally, it has high hardness and good thermal stability. In addition, a part thereof is dissolved in the metal base phase and contributes to strengthening of the base. If the amount is less than 0.05%, the amount of carbide is small and sufficient hardness cannot be obtained, and if it exceeds 1%, the base metal becomes brittle, so the suitable range is 0.05% or more and 1% or less.

B: B forms a boride to secure the hardness of the alloy. The main carbide of the invention alloy is a Cr-based carbide, but the boride is finely dispersed separately therefrom, and since the boride is harder than the carbide, it has the effect of further increasing the high-temperature hardness. If the addition amount is less than 0.05%, there is no substantial effect, and if it exceeds 1.5%, the thermal shock resistance is reduced. Therefore, the suitable range is from 0.05% to 1.5%. I do.

[0016]

EXAMPLES The effects of the present invention will be clarified by giving specific examples of the heat and wear resistant material of the present invention.

(Example 1) Hereinafter, specific experimental examples relating to the first invention material will be described. Table 1 summarizes the chemical components of the materials subjected to the test. The method for producing the first invention material is not particularly limited, but the raw powder of the constituent element or the alloy powder of the constituent element is used as a starting material, and these are strongly mixed using a mechanical alloying method. After the powder is manufactured, it is hot pressed or H
The most common method is to obtain a structure having high heat resistance and abrasion resistance by heating and solidifying and forming into a bulk material by using IP, hot extrusion, or the like, and by precipitating carbide. The procedure for producing the test alloy is shown below. First, industrial Fe powder, Cr powder,
After weighing a predetermined amount of Nb powder and graphite powder, milling was performed for 150 hours using a vibration type ball mill. In milling, steel balls were used as a grinding medium, and the weight ratio between the steel balls and the powder was set to 10: 1. The obtained powder was pressed at 1000 ° C. by a hot press to form a dense compact.

The test alloy prepared according to the above procedure was measured for Vickers hardness at room temperature, 500 ° C. and 900 ° C. Further, in order to easily evaluate the thermal shock resistance, 20
A × 20 × 20 mm cubic test specimen was placed in a furnace set at 1000 ° C., heated, held for one hour, pulled out of the furnace, forced-cooled to room temperature, and observed for cracks. Four test pieces were prepared for each test alloy, and the thermal shock resistance was evaluated based on the crack occurrence rate. In addition, the average particle size of Cr carbide was measured. Table 2 shows the test results. It is apparent that the alloy of the present invention has a high hardness of 600 HV or more even at 900 ° C. and has good characteristics in which no crack is generated even by rapid heating and rapid cooling.

Next, the characteristics when the size of Cr carbide was changed using the component of alloy number 2 were investigated. The size of the Cr carbide was adjusted by changing the mechanical alloying time and the heating temperature during hot pressing. Table 3 shows the results. The hardness tends to decrease as the Cr carbide coarsens, and the average Cr carbide particle size is 19.
In the case of 3 μm, the hardness at 900 ° C. is lower than 600 HV. A particular problem is that if the average particle size of the Cr carbide exceeds 10 μm, cracking occurs due to rapid heating and rapid cooling, and the thermal shock characteristics deteriorate. In order to secure thermal shock characteristics, the average particle size of Cr carbide should be 1
It can be seen that it is necessary to control the thickness to 0 μm or less.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

As described above, the first invention material of the present invention has both excellent heat resistance and abrasion resistance and thermal shock resistance, and by using this, it is possible to improve the performance of a device mainly for a thermal power plant, It is possible to reduce the frequency of replacing parts or to replace the Co-containing alloy in the electronic power plant.

(Example 2) Hereinafter, a specific experimental example regarding the second invention material will be described. Table 4 summarizes the chemical components of the materials subjected to the test. Alloy No. 4 shown as a comparative material in this table is the invention material of Example 1, and is the same as the material number of Table 1. Second example in the present embodiment
The invention material is obtained by adding V, Mo, and W based on alloy number 4. Also in this test, test materials were prepared and subjected to each test in the same manner as in Example 1. That is, first,
Industrial Fe powder, Cr powder, Nb powder, graphite powder and V powder,
After a predetermined amount of Mo powder and W powder were weighed, milling was performed for 150 hours using a vibration type ball mill. In milling, steel balls were used as a grinding medium, and the weight ratio between the steel balls and the powder was set to 10: 1. The obtained powder was pressed at 1000 ° C. by a hot press to form a dense compact.

The test alloys prepared according to the above procedure were measured for Vickers hardness at room temperature, 500 ° C. and 900 ° C. Further, in order to easily evaluate the thermal shock resistance, 20
A × 20 × 20 mm cubic test specimen was placed in a furnace set at 1000 ° C., heated, held for one hour, pulled out of the furnace, forced-cooled to room temperature, and observed for cracks. Four test pieces were prepared for each test alloy, and the thermal shock resistance was evaluated based on the crack occurrence rate. In addition, the average particle size of Cr carbide was measured. Table 5 shows the test results. Second
It is clear that the inventive material has improved hardness as compared with the first inventive material which is a comparative material, and has good characteristics in which cracks do not occur even by rapid heating and rapid cooling.

Next, using the component of alloy number 15, Cr
The characteristics when the size of the carbide was changed were investigated. The size of the Cr carbide was adjusted by changing the mechanical alloying time and the heating temperature during hot pressing. Table 6 shows the results. The hardness tends to decrease with the coarsening of the Cr carbide. However, what is particularly problematic here is that, when the average particle size of Cr carbide exceeds 10 μm, cracking is caused by rapid heating and rapid cooling. It can be clearly understood that it is necessary to control the average particle size of Cr carbide to 10 μm or less in order to secure the thermal shock characteristics.

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

As described above, the material of the second invention of the present invention has both excellent heat and abrasion resistance and thermal shock resistance, and by using this, it is possible to improve the performance of a device mainly for a thermal power plant. In addition, it is possible to reduce the frequency of replacing parts or to replace a Co-containing alloy in a nuclear power plant.

(Example 3) A specific experimental example relating to the third invention material will be described below. Table 7 summarizes the chemical components of the materials subjected to the test. The alloy number 4 shown as a comparative material in this table is the first invention material of Example 1, alloy number 1
Reference numerals 3 and 14 denote second invention materials of Example 2, which are the same as those of the material numbers in Tables 1 and 4. The third invention materials 16 and 17 in this embodiment are obtained by adding N and B based on alloy number 4, and the third invention materials 18 and 19 are alloy number 13
With addition of N and B on the basis of the third invention material 2C
Is obtained by adding B based on alloy number 14. Also in this test, test materials were prepared and subjected to each test in the same manner as in Examples 1 and 2. That is, first, industrial Fe powder, Cr powder, Nb powder, graphite powder, V powder, Mo powder, W powder
After weighing a predetermined amount of the powder, Fe-N powder, and Fe-B powder, milling was performed for 150 hours using a vibration-type ball mill.
In milling, steel balls were used as a grinding medium, and the weight ratio between the steel balls and the powder was set to 10: 1. The obtained powder was pressed at 1000 ° C. by a hot press to form a dense compact.

With respect to the test alloy prepared by the above procedure, Vickers hardness was measured at room temperature, 500 ° C. and 900 ° C. Further, in order to easily evaluate the thermal shock resistance, 20
A × 20 × 20 mm cubic test specimen was placed in a furnace set at 1000 ° C., heated, held for one hour, pulled out of the furnace, forced-cooled to room temperature, and observed for cracks. Four test pieces were prepared for each test alloy, and the thermal shock resistance was evaluated based on the crack occurrence rate. In addition, the average particle size of Cr carbide was measured. Table 8 shows the test results. Third
It is clear that the invented material has improved hardness as compared with the first and second invented materials, which are comparative materials, and has good characteristics in which cracks do not occur even by rapid heating and rapid cooling. It is.

Next, using the component of alloy number 19,
The characteristics when the size of the carbide was changed were investigated. The size of the Cr carbide was adjusted by changing the mechanical alloying time and the heating temperature during hot pressing. Table 9 shows the results. The hardness tends to decrease with the coarsening of the Cr carbide. However, what is particularly problematic here is that, when the average particle size of Cr carbide exceeds 10 μm, cracking is caused by rapid heating and rapid cooling. It can be seen that it is necessary to control the Cr carbide average particle size to 10 μm or less in order to secure the thermal shock characteristics.

[0034]

[Table 7]

[0035]

[Table 8]

[0036]

[Table 9]

As described above, the third invention material of the present invention has excellent heat resistance, abrasion resistance, and thermal shock resistance, and by using this, the performance of a device mainly for a thermal power plant can be improved. In addition, it is possible to reduce the frequency of replacing parts or to replace a Co-containing alloy in a nuclear power plant.

[0038]

As described in detail above, the heat and wear resistant material of the present invention has both excellent heat and wear resistance and thermal shock resistance. By using this material, a thermal power plant can be made a medium product. It is possible to improve the performance of the apparatus, reduce the frequency of replacing parts, or replace a Co-containing alloy in a nuclear power plant.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Toshimitsu Tetsui 5-717-1 Fukahori-cho, Nagasaki City, Nagasaki Pref.

Claims (3)

[Claims] 1. C: 2 to 6.5% by weight, Cr: 2 by weight
5 to 60%, Nb: 0.1 to 10%, and the balance is an alloy consisting of unavoidable impurities and Fe, and Cr carbide having an average particle size of 10 μm or less is dispersed in the Fe—Cr based metal base phase. Characterized heat and wear resistant material. 2. The alloy composition according to claim 1, wherein a part of Fe is expressed by weight ratio: V: 0.1 to 5%, Mo: 0.1 to 5%.
And W: an alloy substituted with any one or more elements of 0.1 to 6%, and an average particle size in the Fe-Cr-based metal base phase: 1
A heat- and wear-resistant material, characterized in that Cr carbide of 0 μm or less is dispersed. 3. The alloy according to claim 1, wherein
Are partly by weight: N: 0.05 to 1%, B: 0.05
An alloy substituted with at least one element of at least 1.5%, wherein a Cr carbide having an average particle size of 10 μm or less is dispersed in an Fe—Cr based metal base phase. material.