Method of Making a High Strength, High Toughness, Fatigue Resistant, Precipitation Hardenable Stainless Steel and Product Made Therefrom
Abstract
A process for making a precipitation hardenable stainless steel alloy is described. The process includes the step of melting a martensitic steel alloy having the following composition in weight percent, about Carbon 0.03 max. Manganese 1.0 max. Silicon 0.75 max. Phosphorus 0.040 max. Sulfur 0.020 max. Chromium 10-13 Nickel 10.5-11.6 Titanium 1.5-1.8 Molybdenum 0.25-1.5 Copper 0.95 max. Aluminum 0.25 max. Niobium 0.3 max. Boron 0.010 max. Nitrogen 0.030 max. and the balance being iron and usual impurities. The process also includes the step of adding calcium to the alloy while molten. The calcium combines with available sulfur and oxygen to form calcium base inclusions selected from the group consisting of calcium sulfides, calcium oxides, calcium oxysulfides, and combinations thereof. In a further step, the alloy is processed to remove at least a portion of the calcium base inclusions. The alloy is then solidified. As a result of the process, the alloy has a matrix containing a sparse dispersion of said calcium-based inclusions and substantially no rare-earth base inclusions.
Claims
exact text as granted — not AI-modified1 . A method of making a precipitation hardenable, high strength, high toughness, stainless steel alloy comprising the steps of:
melting a martensitic steel alloy having the following composition in weight percent, about
Carbon
0.03
max.
Manganese
1.0
max.
Silicon
0.75
max.
Phosphorus
0.040
max.
Sulfur
0.020
max.
Chromium
10-13
Nickel
10.5-11.6
Titanium
1.5-1.8
Molybdenum
0.25-1.5
Copper
0.95
max.
Aluminum
0.25
max.
Niobium
0.3
max.
Boron
0.010
max.
Nitrogen
0.030
max.
and the balance being iron and usual impurities;
adding calcium to the alloy while molten whereby the calcium combines with available sulfur and oxygen to form calcium base inclusions selected from the group consisting of calcium sulfides, calcium oxides, calcium oxysulfides, and combinations thereof;
processing said alloy to remove at least a portion of said inclusions; and then solidifying said alloy;
whereby said alloy has a matrix containing a sparse dispersion of said calcium-based inclusions and substantially no rare-earth base inclusions.
2 . The method as claimed in claim 1 wherein the melting step comprises vacuum melting the martensitic steel alloy and the adding step is performed during said vacuum melting.
3 . The method as claimed in claim 2 wherein the processing step comprises vacuum remelting the alloy.
4 . The method as claimed in claim 1 wherein the processing step comprises vacuum remelting the alloy.
5 . A method of making a precipitation hardenable, high strength, high toughness, stainless steel alloy comprising the steps of:
melting a martensitic steel alloy having the following composition in weight percent, about
Carbon
0.02
max.
Manganese
0.25
max.
Silicon
0.25
max.
Phosphorus
0.015
max.
Sulfur
0.010
max.
Chromium
10.5-12.5
Nickel
10.75-11.25
Titanium
1.5-1.7
Molybdenum
0.75-1.25
Copper
0.50
max.
Aluminum
0.050
max.
Niobium
0.050
max
Boron
0.001-0.005
Nitrogen
0.015
max.
and the balance being iron and usual impurities;
adding calcium to the alloy while molten whereby the calcium combines with available sulfur and oxygen to form calcium base inclusions selected from the group consisting of calcium sulfides, calcium oxides, calcium oxysulfides, and combinations thereof;
processing said alloy to remove at least a portion of said inclusions; and then solidifying said alloy;
whereby said alloy has a matrix containing a sparse dispersion of said calcium-based inclusions and substantially no rare-earth base inclusions.
6 . The method as claimed in claim 5 wherein the melting step comprises vacuum melting the martensitic steel alloy and the adding step is performed during said vacuum melting.
7 . The method as claimed in claim 6 wherein the processing step comprises vacuum remelting the alloy.
8 . The method as claimed in claim 5 wherein the processing step comprises vacuum remelting the alloy.
9 . A method of making a precipitation hardenable, high strength, high toughness, stainless steel alloy comprising the steps of:
melting a martensitic steel alloy having the following composition in weight percent, about
Carbon
0.015
max.
Manganese
0.10
max.
Silicon
0.10
max.
Phosphorus
0.010
max.
Sulfur
0.005
max.
Chromium
11.0-12.0
Nickel
10.85-11.25
Titanium
1.5-1.7
Molybdenum
0.9-1.1
Copper
0.25
max.
Aluminum
0.025
max.
Niobium
0.025
max.
Boron
0.0015-0.0035
Nitrogen
0.010
max.
and the balance being iron and usual impurities;
adding calcium to the alloy while molten whereby the calcium combines with available sulfur and oxygen to form calcium base inclusions selected from the group consisting of calcium sulfides, calcium oxides, calcium oxysulfides, and combinations thereof;
processing said alloy to remove at least a portion of said inclusions; and then solidifying said alloy;
whereby said alloy has a matrix containing a sparse dispersion of said calcium-based inclusions and substantially no rare-earth base inclusions.
10 . The method as claimed in claim 9 wherein the melting step comprises vacuum melting the martensitic steel alloy and the adding step is performed during said vacuum melting.
11 . The method as claimed in claim 10 wherein the processing step comprises vacuum remelting the alloy.
12 . The method as claimed in claim 9 wherein the processing step comprises vacuum remelting the alloy.Join the waitlist — get patent alerts
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