Martensitic oxide dispersion strengthened alloy with enhanced high-temperature strength and creep property, and method of manufacturing the same

a technology of martensitic oxide and dispersions, which is applied in the field of martensitic oxide dispersionstrengthened alloys, can solve the problems of significant low strength, inability to meet design requirements, and inferior high-temperature creep properties of alloys, and achieve enhanced high-temperature strength and creep properties.

Inactive Publication Date: 2014-10-02
KOREA HYDRO & NUCLEAR POWER CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0010]According to an aspect of the present invention, there is provided a martensitic oxide dispersion-strengthened alloy having enhanced high-temperature strength and creep properties, which includes chromium (Cr) of 8 to 12% by weight, yttria (Y2O3) of 0.1 to 0.5% by weight, carbon (C) of 0.02 to 0.2% by weight, molybdenum (Mo) of 0.2 to 2% by weight, titanium (Ti) of 0.01 to 0.3% by weight, zirconium (Zr) of 0.01 to 0.2% by weight, nickel (Ni) of 0.05 to 0.2% by weight, and the balance of iron (Fe).

Problems solved by technology

However, since such an alloy has a problem in that it has a significantly low strength at 650° C. or higher, an oxide dispersion-strengthened alloy manufactured by dispersing an oxide, which is stable at a high temperature, in the structural material has been developed recently.
However, although conventional oxide dispersion-strengthened alloys have an advantage in that they have more excellent strength than other alloys at a high temperature, they have a problem in that they do not satisfy the design requirements.
However, when tungsten (W) is added as the solid-solution hardening element in the proposed method, tungsten (W) forms a Laves phase such as a brittle (Fe, Cr)2W phase when it is used under a high-temperature stress atmosphere for a long period of time.
Accordingly, the proposed method affects the creep strain rate to be accelerated at a high temperature, which results in manufacture of an alloy having inferior high-temperature creep properties.

Method used

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  • Martensitic oxide dispersion strengthened alloy with enhanced high-temperature strength and creep property, and method of manufacturing the same

Examples

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example 1

Manufacture of Martensitic Oxide Dispersion-Strengthened Alloy

[0047]Martensitic oxide dispersion-strengthened alloys having compositions as listed in the following Table 1 were manufactured.

TABLE 1FeCCrWMoNiTiZrY2O3Reference alloy 1Bal.0.151020.250.35Reference alloy 2Bal.0.151120.10.250.35Novel alloyBal.0.151110.10.10.20.35Units: % by weight

[0048]That is, a high-purity source powder (Fe, Cr, Mo, Ti, Zr and Ni: a grain size of 200 mesh or less and a purity of 99% or more) and Y2O3 powder (a particle size of 50 nm or less and a purity of 99.9%) were mixed at respective weight ratios, and then mechanically alloyed at 240 rpm for 48 hours under an ultra-high purity Ar atmosphere using a horizontal ball mill to manufacture an alloy powder. Thereafter, a stainless can was charged with the alloy powder and sealed, and the alloy powder was then degassed at 500° C. for 3 hours under a degree of vacuum of 10−4 torr, or less. The can charged with the manufactured alloy powder was subjected to ...

example 2

Comparison Test of Room-Temperature and High-Temperature Strength Properties

[0049]The three martensitic oxide dispersion-strengthened alloys (i.e., reference alloys 1 and 2 and the novel alloy) manufactured in Example 1 were measured for yield strength (YS), ultimate tensile strength (UTS) and total elongation (TE) at room temperature and 700° C. The results are shown in FIG. 1.

[0050]As shown in FIG. 1, it could be seen that the reference alloy 1 to which tungsten (W) and titanium (Ti) were added had yield strengths of 748 MPa and 195 MPa at room temperature and 700° C., respectively, and the reference alloy 2 to which nickel (Ni) was further added at a content of 0.1% by weight had yield strengths of 1,309 MPa and 162 MPa at room temperature and 700° C., indicating that the reference alloy 2 had enhanced tensile strength, compared with the reference alloy 1. In particular, it could be seen that the alloy (i.e., the novel alloy) according to the present invention in which tungsten ...

example 3

Comparison Test of High-Temperature Creep Property

[0052]A creep test was performed at 700° C. on the three martensitic oxide dispersion-strengthened alloys prepared in Example 1. The results are shown in FIG. 2.

[0053]As shown in FIG. 2, it could be seen that the alloy (i.e., a novel alloy) according to the present invention in which tungsten (W) was replaced with molybdenum (Mo) and to which titanium (Ti), zirconium (Zr) and nickel (Ni) were added together had a significantly increased creep rupture time under stresses of 100 and 120 MPa, compared with the reference alloys 1 and 2 containing tungsten (W) and titanium (Ti).

[0054]From these results, it could be seen that the martensitic oxide dispersion-strengthened alloy according to the present invention had a more excellent high-temperature creep property than the conventional martensitic oxide dispersion-strengthened alloy.

[0055]The martensitic oxide dispersion-strengthened alloy according to the present invention includes chromiu...

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Abstract

The present application discloses a martensitic oxide dispersion-strengthened alloy having enhanced high-temperature strength and creep properties. The alloy includes chromium (Cr) of 8 to 12% by weight, yttria (Y2O3) of 0.1 to 0.5% by weight, carbon (C) of 0.02 to 0.2% by weight, molybdenum (Mo) of 0.2 to 2% by weight, titanium (Ti) of 0.01 to 0.3% by weight, zirconium (Zr) of 0.01 to 0.2% by weight, nickel (Ni) of 0.05 to 0.2% by weight and the balance of iron (Fe). The application also discloses a method of making the alloy.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority to and the benefit of Korean Patent Application No. 2013-0034720 filed on Mar. 29, 2013, and Korean Patent Application No. 2013-0164341, filed on Dec. 26, 2013, the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND[0002]1. Field[0003]The present disclosure relates to a martensitic oxide dispersion-strengthened alloy.[0004]2. Discussion of Related Art[0005]Generally, when a Fe—Cr alloy obtained by adding approximately 12% by weight of chromium to iron is normalized and tempered, a tempered, martensite structure is formed. Therefore, the Fe—Cr alloy is used as a structural material for nuclear energy systems (for example, sodium-cooled fast reactors) or coal-fired power generators since it has excellent neutron irradiation resistance and mechanical properties at a high temperature. However, since such an alloy has a problem in that it has a significantly low strength at 650° C...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C49/08B22F3/15B22F3/12
CPCC22C49/08B22F3/12B22F2998/10B22F2302/25B22F2302/40B22F3/15B22F3/17B22F3/18B22F3/20C22C33/0285C21D6/002C21D7/13C22C38/002C22C38/44C22C38/50C21D2211/004
Inventor KIM, TAE KYUNOH, SANGHOONCHOI, BYOUNG-KWONHAN, CHANG-HEEKIM, KI-BAIKKANG, SUK HOONCHUN, YOUNG-BUMJANG, JINSUNGJEONG, YONG-HWAN
Owner KOREA HYDRO & NUCLEAR POWER CO LTD
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