US 2026/0226598 A1 · AUSTENITIC STAINLESS STEEL PRODUCT

Abstract

The present invention has as its topic suppressing intergranular cracking (nitriding resistance) and also suppressing Red iron oxide (oxidation resistance) even in a gas atmosphere containing nitrogen and steam such as ammonia combustion gas in a 500 to 700° C. medium/high temperature region and has as its object the provision of such an austenitic stainless steel. The present invention has a predetermined chemical composition giving a nitriding tendency index of 15 or less, polishes the steel product surface to introduce dislocations (strain) and harden the steel sheet surface, and makes the difference of surface hardness and steel product center part hardness 20 Hv or more to thereby form a strong Cr oxide layer and Si oxide layer at a 500° C. or more atmosphere at the surface layer and obtain excellent oxidation resistance and nitriding resistance: Nitriding ⁢ tendency ⁢ index : 0.5 Cr + 10 ⁢ Al + 2 ⁢ Mo + 3 ⁢ Ti + 0.5 Cu - 1.5 Si

Claims20

Dependent claims

An austenitic stainless steel product comprising, by mass %,

C:
0 to 0.150%,
Si:
0.05 to 4.50%,
Mn:
0.05 to 3.00%,
P:
0.050% or less,
S:
0.0050% or less,
Ni:
8.00 to 21.00%,
Cr:
15.00 to 30.00%,
N:
0 to 0.350%,
Nb:
0 to 1.00%
Mo:
0 to 3.00%
Cu:
0 to 3.50%
Al:
0.002 to 0.800%,
Ti:
0 to 0.600%
V:
0 to 1.00%,
B:
0 to 0.0100%,
Ca:
0 to 0.0150%
Sn:
0 to 1.00%,
Hf:
0 to 0.60%,
Zr:
0 to 0.60%,
Sb:
0 to 0.60%,
Co:
0 to 1.50%,
W:
0 to 2.00%,
Ta:
0 to 1.00%,
Ga:
0 to 0.50%,
Mg:
0 to 0.0050%, and
REM:
0 to 0.200% and
having a balance of Fe and impurities,
in which austenitic stainless steel product,
the following formula 1 is satisfied, and
a Vickers hardness of the steel product surface (Hvs) is 20 Hv or more higher than the Vickers hardness of the steel product center part (Hvc):
0.5
Cr
+
10
⁢
Al
+
2
⁢
Mo
+
3
⁢
Ti
+
0.5
Cu
-
1.5
Si
≤
15.
(
formula
⁢
1
)
where, in formula 1, the element symbols indicate the contents (mass %) of the elements, 0 being entered when not contained.

81 more elements

Dependencies are inferred from the claim text.

Austenitic stainless steel product

Life of this patent

Austenitic stainless steel product

Life of this patent

Abstract

Claims20