Quench and temper corrosion resistant steel alloy and method for producing the alloy
A quench and temper steel alloy is disclosed having the following composition in weight percent. C 0.1-0.4 Mn 0.1-1.0 Si 0.1-1.2 Cr 9.0-12.5 Ni 3.0-4.3 Mo 1-2 Cu 0.1-1.0 Co 1-4 W 0.2 max. V 0.1-0.6 Ti 0.1 max. Nb up to 0.01 Ta up to 0.01 Al 0-0.25 N 0.1-0.35 Ce 0.006 max. La 0.006 max. The balance of the alloy is iron and the usual impurities found in similar grades of quench and temper steels intended for similar use or service, including not more than about 0.01% phosphorus and not more than about 0.010% sulfur. A quenched and tempered steel article made from this alloy is also disclosed. Further disclosed is a method of making the alloy.
1. A steel alloy consisting essentially of, in weight percent, about:
C
0.15-0.3
Mn
0.1-1.0
Si
0.1-1.2
Cr
9.0-12.5
Ni
3.0-4.3
Mo
1-2
Cu
0.1-1.0
Co
1-4
W
0.02 max.
V
0.1-0.6
Ti
0.02 max.
Al
0-0.25
Nb
0-0.01
Ta
0-0.01
N
0.15-0.35
Ce
0.006 max.
La
0.006 max.
the balance of the alloy is iron and impurities, wherein the impurities include not more than about 0.01% phosphorus and not more than about 0.001% sulfur.
2. The alloy as set forth in claim 1 in which titanium is not more than about 0.01%.
3. The alloy as set forth in claim 1 in which nitrogen is not more than about 0.30%.
4. The alloy set forth in claim 1 in which chromium is at least about 9.5%.
5. The alloy set forth in claim 1 in which molybdenum is about 1.25-1.75%.
6. The alloy set forth in claim 1 in which cobalt is about 2-3%.
7. The alloy set forth in claim 1 in which nickel is at least about 3.2%.
8. The alloy as set forth in claim 1 in which vanadium is not more than about 0.5%.
9. The alloy as set forth in claim 1 wherein C+N is about 0.3-0.6%.
10. The alloy as set forth in claim 1 in which copper is not more than about 0.7%.
11. A steel alloy consisting essentially of, in weight percent, about
C
0.15-0.3
Mn
0.1-0.7
Si
0.5-1.2
Cr
9.5-12.5
Ni
3.2-4.3
Mo
1.25-1.75
Cu
0.1-0.7
Co
2-3
W
0.1 max.
V
0.1-0.5
Ti
0.01 max.
Nb
up to 0.01
Ta
up to 0.01
Al
0.25 max.
N
0.15-0.30
Ce
0-0.006
La
0-0.005
and the balance is iron and impurities, wherein the impurities include not more than about 0.005% phosphorus and not more than about 0.001% sulfur.
12. The alloy as set forth in claim 11 in which copper is at least about 0.3% copper.
13. A quenched and tempered steel article made from the alloy set forth in claim 1 which has a tensile strength of at least 280 ksi.
14. The steel article set forth in claim 13 which has a fracture toughness (K Ic ) of at least about 65 ksi√in when tested in accordance with ASTM Standard Test Procedure E1290.
15. The steel article set forth in claim 14 which has general corrosion resistance characterized by the article not having rust after 200 hours when tested in accordance with ASTM Standard Test Procedure B 117.
16. The steel article as set forth in claim 14 which has pitting corrosion resistance characterized by the article having a pitting potential of at least 90 mV when tested in accordance with ASTM Standard Test procedure G61 modified by using round bar samples.
17. A structural component for an aerospace vehicle wherein the component is made from an alloy consisting essentially of, in weight percent, about
C
0.15-0.3
Mn
0.1-0.7
Si
0.5-1.2
Cr
9.5-12.5
Ni
3.2-4.3
Mo
1.25-1.75
Cu
0.1-0.7
Co
2-3
W
0.1 max.
V
0.1-0.5
Ti
0.01 max.
Nb
0.01 max.
Ta
0.01 max.
Al
0.25 max.
N
0.15-0.30
Ce
0-0.006
La
0-0.005
and the balance is iron and impurities, wherein the impurities include not more than 0.005% phosphorus and not more than 0.0005% sulfur.
18. The aerospace structural component as set forth in claim 17 wherein the component is selected from the group consisting of one or more of landing gear, a rotatable shaft, an actuator, flap tracks, and slat tracks.