JPH08188844A - Oxide dispersion reinforced type heat resistant alloy - Google Patents

Abstract

PURPOSE: To improve oxidation resistance, nitriding resistance and strength at high temp. by incorporating specific amounts of Zr, La, Ce, Nd, and Y into an oxide dispersion reinforced type heat resistant alloy consisting of Fe, refractory metal oxide, and Cr. CONSTITUTION: This oxide dispersion reinforced type heat resistant alloy has a composition consisting of, by weight, <=20% Fe, 0.2-2.0% refractory metal oxide, 0.5-5%, in total of one or >=2 elements among Zr, La, Ce, Nd, and Y, and the balance essentially Cr. Further, 0.5-10%, in total of Mo and/or W and <=3% Si are incorporated, at need. As the refractory metal oxide, Y2 O3 , ZrO2 , Al2 O3 , Gd2 O3 , etc., are used, and it is preferable to regulate their size to <=0.1μm. By using this alloy, Zr, La, Ce, Nd, or Y is nitrided first and Cr is not nitrided even if repeated load and repeated heating are applied at temps. as high as >=about 1450 deg.C. As a result, embrittlement due to the precipitation of Cr2 N can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an oxide dispersion strengthened heat-resistant alloy containing Cr as a main component, which is excellent in oxidation resistance and high-temperature strength, and in particular, C containing Ni and the like to improve nitriding resistance.
The present invention relates to an oxide dispersion strengthened heat resistant alloy containing r as a main component.

[0002]

2. Description of the Related Art Heretofore, there has been no metal material which can be used for applications where it is subjected to repeated load for a long time at a high temperature of 1450 ° C. or higher and in the atmosphere. Therefore, in the skid rail and skid button of the heating furnace which receives the repeated load of the heated steel material at high temperature, a ceramic sintered material, a composite material of a heat-resistant alloy and ceramics, and an oxide described in JP-A-2-38516. Dispersion strengthened heat resistant alloy (18-4
0% Cr, 5% or less Fe, 5% or less Al, 5% or less Ti, fine refractory metal oxide: 0.1 to 2%, the balance being substantially Ni), etc. are used. It was

[0003]

However, although the ceramic sintered material has high high temperature strength, it cannot be used as a structural material. Also, heat-resistant alloys are strong against impact, but 130
At high temperatures above 0 ° C, it lacks strength and acid resistance. The high temperature strength of the composite material of heat resistant alloy and ceramics has been improved to some extent, but the strength and acid resistance were still insufficient at high temperatures of 1300 ° C. or higher. Further, the above oxide dispersion strengthened heat-resistant alloy is effective in a furnace heated to 1400 ° C., but could not be used in a furnace heated to a temperature higher than that. Further, the conventional oxide dispersion strengthened heat-resistant alloy containing Cr as the main component, when used under the condition of being heated at high temperature, causes Cr ₂ N to precipitate and becomes brittle.
It could not be used for a long time at the above temperature. An object of the present invention is to provide an oxide dispersion strengthened heat-resistant alloy containing Cr as a main component, which does not become brittle due to nitriding even when subjected to repeated load and repeated heating at a high temperature of 1450 ° C. or higher.

[0004]

In order to achieve the above object, in the oxide dispersion strengthened heat-resistant alloy of the present invention, Fe: 20% or less by weight%, refractory metal oxide: 0.2
˜2.0% and the balance is substantially Cr, and the oxide dispersion strengthened heat-resistant alloy contains 1 of Zr, La, Ce, Nd and Y.
That is, 0.5 to 5% in total is contained. Further, in weight%, Fe: 20% or less, 0.5 to 10% in total of one or two kinds of Mo and W, and 0.2 to 2.0% of refractory metal oxide, and the balance. Substantially C
Zr, La, C in the oxide dispersion strengthened heat resistant alloy which is r
One or two or more of e, Nd, and Y in a total amount of 0.5 to
That is, 5% was included. Furthermore, S as an impurity
i: 3% or less and Mn: 3% or less, each of the above oxide dispersion strengthened heat-resistant alloys contains one or more of Zr, La, Ce, Nd, and Y in a total amount of 0.5 to That is, 5% was included.

To further explain the above invention, refractory metal oxides include Y ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ and Gd ₂ O _3.
Etc., and the size is preferably 0.1 μm or less. Applications of the alloy of the present invention include skid rails and skid buttons of the above heating furnace, and hypersonic aircraft materials.
The oxide dispersion strengthened heat resistant alloy of the present invention is Fe-
Alloy powder of Cr, or Fe, Cr simple metal powder, Z
A close and uniform mixture of fine powders of each component by mechanical alloying of r, La, Ce, Nd and Y metal powders and refractory metal oxide powders or powders obtained by adding Mo and W powders to these powders. It can be produced by making a powder, pressing and sintering the mixture by hot extrusion or hot isostatic pressing.

[0006]

According to the present invention, an oxide dispersion strengthened heat resistant alloy containing, by weight, Fe: 20% or less, refractory metal oxide: 0.2 to 2.0%, and the balance being substantially Cr, or This alloy contains one or two of Mo and W in a total amount of 0.5 to 10%.
Zr, La, C in the oxide dispersion strengthened heat resistant alloy contained
One or two or more of e, Nd, and Y in a total amount of 0.5 to
By containing 5%, Zr, La,
Since Ce, Nd, or Y is nitrided first and Cr is not nitrided, as a result, embrittlement due to precipitation of Cr ₂ N can be prevented.

Next, the reason for limiting each component will be described. Fe: 20% or less Fe is an element effective for reducing fine voids in the alloy and increasing strength and toughness, but if it exceeds 20%, the melting point is lowered and the oxidation resistance is deteriorated. Therefore, the content is set to 20% or less. One or two kinds of Mo and W: 0.5 to 10% Mo and W are elements that solid-solution strengthen the matrix. Therefore, its content is set to 0.5 to 10% because it deteriorates the chemical conversion property. High-melting point metal oxide: 0.2 to 2.0% The high-melting point metal oxide is a component dispersed in a matrix to increase its high temperature strength. This effect is obtained at 0.2% or more and saturated at 2.0%, so the content is 0.2%.
~ 2.0%.

One or more of Zr, La, Ce, Nd and Y: 0.5 to 5% Zr, La, Ce, Nd and Y are Cr ₂ N in which Cr is bonded to nitrogen as described above. This is to prevent the precipitation and embrittlement of Cr, but if the content is less than 0.5%, the effect of addition is slight, and if it exceeds 5%, the excellent oxidation resistance of Cr is impaired. Therefore, its content is 0.5-5%
And Si: 3% or less, Mn: 3% or less Si and Mn are impurities, and the smaller the amount, the better.
%, The high temperature strength and the oxidation resistance are less likely to decrease, so the content is set to 3% or less.

[0009]

Embodiments of the present invention will be described below. F
e, Cr, W, Mo, Zr, La, Ce, Nd and Y powders having an average particle size of about 100 μ and about 1% of a refractory metal oxide.
The powder of μ was put in a ball mill so that the ratio was as shown in Table 1 and Table 2, mechanical alloying treatment was performed, and the resulting powder was filled in a metal capsule, deaerated, and sealed. This was molded by hot extrusion at 1250 ° C., and further heated at 1550 ° C. for 2 hours to adjust the crystal grain to 500 μm or more by secondary recrystallization to make various test materials. Test pieces were cut out from these test materials and subjected to various tests.

(1) Creep rupture test A test piece with a diameter of 6 mm was cut out from the test material, and 1400
A creep rupture test was performed under the conditions of 3 ° C. and 3 kgf / mm ² . The results are shown in the creep rupture time column of Tables 1 and 2. (2) Repeated Oxidation Test A cylindrical test piece having a diameter of 10 mm and a length of 50 mm was cut out from the test material and heated and cooled as shown in FIG. 1 three times in the atmosphere, and the scale remaining on the test piece was treated with an alkaline solution and The acid solution was removed, and the change in weight was determined from the change in the weight of the test piece before and after the removal. The results are shown in the weight loss column of Table 1.

[0011]

[Table 1]

[0012]

[Table 2]

As is clear from Tables 1 and 2, Zr,
The oxide dispersion strengthened heat-resistant alloy with La, Ce, Nd and Y added has significantly improved creep rupture time and significantly reduced weight loss due to oxidation, as compared with the alloys of Comparative Examples in which these are not added. You can see that it is done.
In addition, when a test piece subjected to repeated oxidation test was cut and the cross section was measured by EPMA, Zr, La, Ce,
In the oxide dispersion strengthened heat-resistant alloy of the comparative example in which Nd and Y were not added, Cr ₂ N was precipitated at the grain boundaries, whereas the present invention in which Zr, La, Ce, Nd and Y were added was used. It was confirmed that in the example, the nitride such as ZrN was uniformly dispersed throughout the crystal grains.

The present invention is not limited to the embodiments in points other than the above, and it is needless to say that various modifications can be made without departing from the scope of the invention.

[0015]

EFFECTS OF THE INVENTION The present invention has the excellent effects of improving the oxidation resistance, nitriding resistance and high temperature strength at a high temperature of 1450 ° C. or higher by virtue of the above composition.
Further, as a result, it can be used for slabs used at high temperatures of 1450 ° C. or higher, skid rails of walking beam conveyor type heating furnaces for heating steel materials such as billets, various members such as skid buttons, and hypersonic aircraft materials. Became.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining heating and cooling conditions in a repeated oxidation test for testing the oxidation resistance of oxide dispersion strengthened heat resistant alloys of the present invention and a comparative example.

Claims (4)

[Claims] 1. By weight%, Fe: 20% or less, refractory metal oxide: 0.2 to 2.0%, Zr, La, Ce, Nd.
And 1 or 2 or more of Y in a total amount of 0.5 to 5%, and the balance being substantially Cr. 2. By weight%, Fe: 20% or less, refractory metal oxide: 0.2 to 2.0%, one or two of Mo and W in a total amount of 0.5 to 10%, Zr, La, Ce, N
An oxide dispersion-strengthened heat-resistant alloy, containing one or more of d and Y in a total amount of 0.5 to 5%, and the balance being substantially Cr. 3. By weight%, Fe: 20% or less, refractory metal oxide: 0.2 to 2.0%, Si: 3% or less, Mn:
3% or less, one or two of Zr, La, Ce, Nd and Y
An oxide dispersion-strengthened heat-resistant alloy, characterized in that it contains 0.5 to 5% in total of at least one species, and the balance is substantially Cr. 4. By weight%, Fe: 20% or less, refractory metal oxide: 0.2 to 2.0%, one or two kinds of Mo and W in a total amount of 0.5 to 10%, Si: 3% or less, M
n: 3% or less, one or two or more of Zr, La, Ce, Nd and Y in a total amount of 0.5 to 5%, and the balance being substantially Cr. Dispersion strengthened heat resistant alloy.