Austenite stainless steel sheet, method for producing same, and sheet spring
An austenitic stainless steel sheet contains, on a mass basis, C: 0.04 to 0.11%, Si: 2.0 to 3.5%, Mn: 1.50% or less, Ni: 6.0 to 10.0%, Cr: 12.0 to 15.0%, Mo: 1.3 to 3.2%, Cu: 1.00% or less, N: 0.03 to 0.15%, and O: 0.0050% or less, the balance being Fe and impurities; wherein the austenitic stainless steel sheet has a value of Md 30 of −30.0 to 0° C., wherein the value of Md 30 is represented by the following equation (1): Md 3 0 = 551 - 462 ( C + N ) - 9.2 Si - 8.1 Mn - 29 ( N i + Cu ) - 13.7 Cr - 18.5 Mo ( 1 ) in which the symbols of the elements each represents a content (% by mass) of each element. The austenitic stainless steel sheet has a metallographic structure having a content of a strain-induced martensite phase of 30% by volume or more, and has a thickness of 0.15 mm or less.
1 . An austenitic stainless steel sheet,
wherein the austenitic stainless steel sheet comprises, on a mass basis, C: 0.04 to 0.11%, Si: 2.0 to 3.5%, Mn: 1.50% or less, Ni: 6.0 to 10.0%, Cr: 12.0 to 15.0%, Mo: 1.3 to 3.2%, Cu: 1.00% or less, N: 0.03 to 0.15%, and O: 0.0050% or less, the balance being Fe and impurities;
wherein the austenitic stainless steel sheet has a value of Md 30 of −30.0 to 0° C., wherein the value of Md 30 is represented by the following equation (1):
Md
3
0
=
551
-
462
(
C
+
N
)
-
9.2
Si
-
8.1
Mn
-
29
(
Ni
+
Cu
)
-
13.7
Cr
-
18.5
Mo
(
1
)
in which the symbols of the elements each represents a content in % by mass of each element;
wherein the austenitic stainless steel sheet has a metallographic structure having a content of a strain-induced martensite phase of 30% by volume or more; and
wherein the austenitic stainless steel sheet has a thickness of 0.15 mm or less,
wherein the austenitic stainless steel sheet has a tensile strength (TS) of 2200 MPa or more,
wherein the austenitic stainless steel sheet has a fold number of 1100 or more, as measured in accordance with JIS P 8115:2001.
2 . The austenitic stainless steel sheet according to claim 1 , further comprising, on a mass basis, one or more selected from Co: 0.05 to 0.50%, Al: 0.15% or less, V: 0.0001 to 0.5000%, Ti: 0.01 to 0.50%, B: 0.0001 to 0.0150%, Nb: 0.001 to 0.100%, Mg: 0.0001 to 0.0030%, Ca: 0.0003 to 0.0100%, Sn: 0.001 to 0.500%, Pb: 0.0001 to 0.0100%, W: 0.0001 to 0.5000%, Zr: 0.0001 to 0.1000%, and REM: 0.0001 to 0.3000%.
3 . The austenitic stainless steel sheet according to claim 1 , wherein the austenitic stainless steel sheet has an average crystal grain size of 15.0 μm or less.
4 . The austenitic stainless steel sheet according to claim 1 , wherein a dislocation density of retained austenite phases is 0.40×10 16 m −2 or more.
5 . The austenitic stainless steel sheet according to claim 1 , wherein the austenitic stainless steel sheet has an elongation at break (EL) of 0.5% or more.
6 . The austenitic stainless steel sheet according to claim 2 , wherein the austenitic stainless steel sheet has an average crystal grain size of 15.0 μm or less.
7 . The austenitic stainless steel sheet according to claim 2 , wherein a dislocation density of retained austenite phases is 0.40×10 16 m −2 or more.
8 . The austenitic stainless steel sheet according to claim 2 , wherein the austenitic stainless steel sheet has an elongation at break (EL) of 0.5% or more.
9 . A sheet spring comprising the austenitic stainless steel plate according to claim 1 .