US2009004041A1PendingUtilityA1
High Strength, High Toughness Rotating Shaft Material
Est. expiryJun 26, 2027(~0.9 yrs left)· nominal 20-yr term from priority
Inventors:Paul M. NovotnyRobert Wayne KriebleWilliam J. MartinThomas Constantine ZogasMaria Adasczik
C22C 38/44C22C 38/52C22C 33/04
48
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Claims
Abstract
An age hardenable, martensitic steel alloy that provides high strength, high toughness, and good low cycle fatigue life and a method of making same are disclosed. The alloy comprises a matrix having a weight percent composition consisting essentially of about Carbon 0.2-0.36 Manganese 0.20 max. Silicon 0.10 max. Phosphorus 0.01 max. Sulfur 0.004 max. Chromium 1.3-4 Nickel 10-15 Molybdenum 0.75-2.7 Cobalt 8-22 Aluminum 0.01 max. Titanium 0.02 max. Calcium 0.001 max. and the balance being iron and usual impurities. The alloy further contains a plurality of inclusions dispersed in the alloy matrix. The inclusions comprise calcium compounds that are about 0.4 μm to about 7.0 μm in major dimension, they have a median size of at least about 1.6 μm in major dimension, and the inclusions contain essentially no rare earth elements.
Claims
exact text as granted — not AI-modified1 . An age hardenable, martensitic steel alloy that provides high strength, high toughness, and good low cycle fatigue life, said alloy comprising:
a matrix having a weight percent composition consisting essentially of about
Carbon
0.2-0.36
Manganese
0.20 max.
Silicon
0.10 max.
Phosphorus
0.01 max.
Sulfur
0.004 max.
Chromium
1.3-4
Nickel
10-15
Molybdenum
0.75-2.7
Cobalt
8-22
Aluminum
0.01 max.
Titanium
0.02 max.
Calcium
0.001 max.
and the balance being iron and usual impurities; and
a plurality of inclusions dispersed in said matrix, said inclusions comprising calcium compounds that are about 0.4 μm to about 7.0 μm in major dimension and have a median size of at least about 1.6 μm in major dimension, and wherein said inclusions contain essentially no rare earth elements.
2 . An age hardenable, martensitic steel alloy as set forth in claim 1 wherein the matrix composition consists essentially of about
Carbon
0.20-0.33
Manganese
0.15 max.
Phosphorus
0.008 max.
Sulfur
0.0025 max.
Chromium
2-4
Nickel
10.5-15
Molybdenum
0.75-1.75, and
Cobalt
8-17.
3 . An age hardenable, martensitic steel alloy as set forth in claim 1 wherein the matrix composition consists essentially of about
Carbon
0.21-0.27
Manganese
0.10 max.
Phosphorus
0.008 max.
Sulfur
0.0020 max.
Chromium
2.25-3.5
Nickel
11.0-13.0
Molybdenum
1.0-1.5, and
Cobalt
10-15.
4 . An age hardenable, martensitic steel alloy as set forth in claim 1 wherein the matrix composition contains not more than about 0.33% carbon.
5 . An age hardenable, martensitic steel alloy as set forth in claim 1 wherein the matrix composition consists essentially of about
Carbon
0.21-0.34
Phosphorus
0.008 max.
Sulfur
0.003 max.
Chromium
1.5-2.80
Nickel
10-13
Molybdenum
0.9-1.8, and
Cobalt
14-22.
6 . An age hardenable, martensitic steel alloy as set forth in claim 1 wherein the matrix composition consists essentially of about
Carbon
0.30-0.36
Manganese
0.05 max.
Sulfur
0.001 max.
Chromium
1.3-3.2
Nickel
10-13
Molybdenum
1.0-2.7
Cobalt
13.8-17.4, and
Aluminum
0.005 max.
7 . A method of improving the low cycle fatigue life of a high strength, high toughness, martensitic steel alloy comprising the steps of:
melting a martensitic steel alloy having the following composition in weight percent, about
Carbon
0.2-0.36
Manganese
0.20 max.
Silicon
0.10 max.
Phosphorus
0.01 max.
Sulfur
0.004 max.
Chromium
1.3-4
Nickel
10-15
Molybdenum
0.75-2.7
Cobalt
8-22
and the balance being iron and usual impurities;
adding calcium to the alloy while molten such that the calcium combines with available elements to form inclusions dispersed in said alloy;
processing said alloy to remove at least a portion of said inclusions; and then solidifying said alloy;
whereby said alloy is provided with a matrix containing a limited dispersion of said inclusions that are about 0.4 μm to about 7 μm in major dimension and have a median size of at least about 1.6 μm in major dimension, and wherein said inclusions contain essentially no rare earth elements.
8 . The method as set forth in claim 7 wherein the melting step comprises melting the martensitic steel alloy to have the following composition in weight percent, about
Carbon
0.20-0.33
Manganese
0.15 max.
Silicon
0.10 max.
Phosphorus
0.008 max.
Sulfur
0.0025 max.
Chromium
2-4
Nickel
10.5-15
Molybdenum
0.75-1.75
Cobalt
8-17
Aluminum
0.01 max.
Titanium
0.02 max.
and the balance essentially iron and usual impurities.
9 . The method as set forth in claim 7 wherein the melting step comprises melting the martensitic steel alloy to have the following composition in weight percent, about
Carbon
0.21-0.27
Manganese
0.1 max.
Silicon
0.10 max.
Phosphorus
0.008 max.
Sulfur
0.002 max.
Chromium
2.25-3.5
Nickel
11.0-13.0
Molybdenum
1.0-1.5
Cobalt
10-15
Aluminum
0.01 max.
Titanium
0.02 max.
and the balance essentially iron and usual impurities.
10 . A method of making a shaft for a rotating machine comprising the steps of:
melting a martensitic steel alloy having the following composition in weight percent, about
Carbon
0.2-0.36
Manganese
0.20 max.
Silicon
0.10 max.
Phosphorus
0.01 max.
Sulfur
0.004 max.
Chromium
1.3-4
Nickel
10-15
Molybdenum
0.75-2.7
Cobalt
8-22
Aluminum
0.01 max.
Titanium
0.02 max.
and the balance being iron and usual impurities;
adding calcium to the alloy while molten such that the calcium combines with available elements to form inclusions dispersed in said alloy, said inclusions being about 0.4 μm to about 7 μm in major dimension and having a median size of at least about 1.6 μm in major dimension, and wherein said inclusions contain essentially no rare earth elements;
processing said alloy to remove at least a portion of said inclusions;
solidifying said alloy;
mechanically working the solidified alloy to provide an elongated intermediate product; and then
machining the elongated intermediate form to provide a shaft.
11 . A shaft for a rotating machine comprising:
an age hardenable, martensitic steel alloy comprising a matrix having a weight percent composition consisting essentially of about
Carbon
0.2-0.36
Manganese
0.20 max.
Silicon
0.10 max.
Phosphorus
0.01 max.
Sulfur
0.004 max.
Chromium
1.3-4
Nickel
10-15
Molybdenum
0.75-2.7
Cobalt
8-22
Aluminum
0.01 max.
Titanium
0.02 max.
Calcium
0.001 max.
and the balance being iron and usual impurities; and
a plurality of inclusions dispersed in said matrix, said inclusions comprising calcium compounds that are about 0.4 μm to about 7.0 μm in major dimension and have a median size of at least about 1.6 μm in major dimension, and wherein said inclusions contain essentially no rare earth elements.Join the waitlist — get patent alerts
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