US2019226065A1PendingUtilityA1
Low-cost cast creep-resistant austenitic stainless steels that form alumina for high temperature oxidation resistance
Est. expiryJan 25, 2038(~11.5 yrs left)· nominal 20-yr term from priority
C22C 38/52C22C 38/001C22C 38/58C22C 30/02C22C 38/06C22C 38/44C22C 38/48C22C 38/04C22C 38/02C22C 38/42
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Claims
Abstract
An air castable Fe-based stainless steel alloy comprises in weight % based on the total weight of the alloy 18-22% Cr, 15-22% Ni, 3-6% Al, 0.5-5% Mn, 0-3.5% W, 0-5% Cu, 0-2% Si, 1-2.5% Nb, 0.3-0.5% C balance Fe wherein, Cu+W+Si=0.5-10.5, and the alloy provides an oxidation resistance of 0.5<specific mass change <+2 mg/cm2 after 400 one hour cycles at 900° C. in 10% water vapor.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . An air castable Fe-based stainless steel alloy comprising in weight % based on the total weight of the alloy:
18-22% Cr 15-22% Ni 3-6% Al 0.5-5% Mn 0-3.5% W 0-5% Cu 0-2% Si 1-2.5% Nb 0.3-0.5% C balance Fe wherein, Cu+W+Si=0.5-10.5, and the alloy provides an oxidation resistance oxidation resistance of −0.5<mass change <+2 mg/cm 2 after 400 one hour cycles at 900° C. in 10% water vapor.
2 . The alloy of claim 1 , further comprising 0-2% Ta.
3 . The alloy of claim 2 , wherein Ta+Nb<4.0.
4 . The alloy of claim 2 , wherein Ta/Nb=0-0.75.
5 . The alloy of claim 1 , further comprising 0.1-5.0% Co.
6 . The alloy of claim 1 , wherein the alloy is non-magnetic and free of alpha or delta ferrite phases, and does not form a thermal or strain induced martensite phase.
7 . The alloy of claim 1 , wherein the Cu/W ratio is 0.75-1.67.
8 . The alloy of claim 1 , wherein Nb/C is from 2-5.
9 . The alloy of claim 1 , wherein N is less than 0.1.
10 . The alloy of claim 1 , wherein Cr/Al 4.7-8.
11 . The alloy of claim 1 wherein the Cr/(Al+Si) ratio can be 2.25 to 6.15.
12 . The alloy of claim 1 , wherein the alloy provides anof −2<mass change <+2 mg/cm 2 after 300 one hour cycles at 950° C. in 10% water vapor.
13 . The alloy of claim 1 , wherein the alloy provides creep rupture resistance of 863 hrs at 950° C., 35 MPa and 469 hours at 1050° C., 10 MPa.
14 . The alloy of claim 1 , wherein the alloy provides a yield strength of 41.6 Ksi and tensile strength of 84.1 Ksi at room temperature.
15 . The alloy of claim 1 , wherein the alloy provides an elongation of 11.1 at room temperature and 39% at 1000° C.Join the waitlist — get patent alerts
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