Austenitic fe-ni-cr alloy having excellent oxidation resistance and method for producing same
Abstract
An austenitic Fe—Ni—Cr alloy has superior oxidation resistance even under extreme high temperatures and includes, in mass %: C: 0.004 to 0.13%, Si: 0.15 to 1.0%, Mn: 0.03 to 2.0%, P:≤0.040%, S:≤0.003%, Ni: 20.0 to 38.0%, Cr: 18.0 to 28.0%, Mo:≤1.0%, Cu:≤1.0%, N:≤0.03%, B:≤0.01%, Al: 0.10 to 1.0%, at least one of Ti: 0.10 to 1.0% and Zr: 0.01 to 0.6%, O: 0.0002 to 0.0030%, Ca:<0.002%, total weight of one or more from La, Ce, and Y: 0.001 to 0.010%, Fe as a remainder and inevitable impurities, and wherein the chemical composition satisfies formulae (1) and (2): 85≥0.3×Si+1.5×Ni+1.3×Cr+5.8×Al+7.7×Zr +2.7×Ti+2173×REM −3582×S ×32.9×Mo -2448×B≥47 . . . (1) 40≥0.6×Si+1.3×Cr +23.53×Al+5.88×Ti+3074×REM −5067×S −0.8×Mn −816×N≥. . . (2), and each element symbols indicates content of each element.
Claims
exact text as granted — not AI-modified1 . An austenitic Fe—Ni—Cr alloy consisting of, in mass %:
C: 0.004 to 0.13%,
Si: 0.15 to 1.0%,
Mn: 0.03 to 2.0%,
P:≤0.040%,
S:≤0.003%,
Ni: 20.0 to 38.0%,
Cr: 18.0 to 28.0%,
Mo:≤1.0%,
Cu:≤1.0%,
N:≤0.03%,
B:≤0.01%,
Al: 0.10 to 1.0%,
at least one of Ti: 0.10 to 1.0% and Zr: 0.01 to 0.6%,
O: 0.0002 to 0.0030%,
Ca:≤0.002%,
total weight of one or more kinds selected from La, Ce, and Y being rare earth metal elements (REMs): 0.001 to 0.010%,
Fe as a remainder and
inevitable impurities, and
wherein the chemical composition satisfies the following formulae (1) and (2):
85
≥
0.3
×
Si
+
1.5
×
Ni
+
1.3
×
Cr
+
5.8
×
Al
+
7.7
×
Zr
+
2.7
×
Ti
+
2173
×
R
E
M
-
3582
×
S
-
32.9
×
Mo
-
2448
×
B
≥
47
(
1
)
40
≥
0.6
×
Si
+
1.3
×
Cr
+
23.53
×
Al
+
5.88
×
Ti
+
3074
×
R
E
M
-
5067
×
S
-
0.8
×
Mn
-
816
×
N
≥
0
,
(
2
)
and
each of element symbols in the formulae indicates content of the each element (mass %).
2 . The austenitic Fe—Ni—Cr alloy according to claim 1 , wherein the total weight in mass % of one or more kinds selected from La, Ce, and Y being rare earth metal elements (REMs) that satisfy the following formula (3):
3.2
≤
R
E
M
(
La
,
Ce
,
Y
)
/
S
(
3
)
3 . The austenitic Fe—Ni—Cr alloy according to claim 1 , wherein composition of surface oxidation scale which is formed in a cycle test in which temperature is repeatedly increased from room temperature to 700 to 900° C. in a mixed gas atmosphere consisting of 7% O 2 -16% H 2 O-10% CO 2 -0.5% CO-0.1% NO2-bal.N 2 consists of, in mass %: Cr: not less than 40%, Fe: 10 to 20%, Ni: 0 to 10%, O:10 to 40%, REM: 0.05 to 0.5%, and remainder Mn, Si, and Ti as an inevitable impurity.
4 . The austenitic Fe—Ni—Cr alloy according to claim 3 , wherein the surface oxidation scale has a thickness of 10 to 100 μm.
5 . The austenitic Fe—Ni—Cr alloy according to claim 3 , wherein an internal oxide layer which is formed immediately below the surface oxidation scale comprises internal oxides containing at least one kind of Cr, Si, Mn, Al, Ti, and REM, and at the same time, an area ratio of the internal oxide layer occupies not less than 30% per 0.005 mm 2 immediately below the surface oxidation scale.
6 . A method for production of the austenitic Fe—Ni—Cr alloy according to claim 1 , wherein
alloy compositions are adjusted by melting alloy raw materials and refining,
in the refining process, decarburizing is performed by blowing a mixed gas of oxygen and argon into melted alloy raw materials (fused alloy) so as to control nitrogen concentration to be not more than 0.03%, Cr reduction is performed, and then, aluminum, limestone and fluorite are added in the fused alloy so as to form CaO—SiO 2 -Al 2 O 3 -MgO—F slag, oxygen concentration in the fused alloy is controlled to 0.0002 to 0.0030 mass %, and after that, raw material containing at least one of La, Ce, and Y is added, the fused alloy is casted so as to obtain a slab, and the slab is subjected to hot-rolling process.Join the waitlist — get patent alerts
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