Corrosion-resistant, cold-formable, machinable, high strength, martensitic stainless steel
A corrosion resistant, martensitic steel alloy having very good cold formability is described. The alloy has the following weight percent composition. Carbon 0.10-0.40 Manganese 0.01-2.0 Silicon 2.0 max. Phosphorus 0.2 max. Sulfur 0.030 max. Chromium 10-15 Nickel 0.5 max. Molybdenum 0.75-4.0 Nitrogen 0.02-0.15 Copper 1.5-4.0 Titanium 0.01 max. Aluminum 0.01 max. Niobium + Tantalum 0.10 max. Vanadium 0.20 max. Zirconium less than 0.001 Calcium less than 0.001 The balance of the alloy is essentially iron. Nickel and copper are balanced in the alloy such that the ratio Ni/Cu is less than 0.2. A second embodiment of the alloy contains at least about 0.005% sulfur, selenium, or a combination thereof to provide good machinability.
1. A corrosion resistant, martensitic steel alloy consisting essentially of, in weight percent, about
Carbon
0.10-0.40
Manganese
0.01-0.3
Silicon
1.0 max
Phosphorus
0.2 max
Chromium
10-15
Nickel
0.25 max
Molybdenum
0.75-4.0
Nitrogen
0.02-0.15
Copper
1.75-3.0
Titanium
0.01 max
Aluminum
0.01 max
Niobium + Tantalum
0.10 max
Vanadium
0.20 max
Zirconium
less than 0.001
Calcium
less than 0.001,
0.007-0.030% of sulfur, selenium, or a combination thereof, and the balance is essentially iron, wherein Ni/Cu is not more than about 0.10.
2. A corrosion resistant, martensitic steel alloy as set forth in claim 1 containing not more than about 14.3% chromium.
3. A corrosion resistant, martensitic steel alloy as set forth in claim 1 containing not more than about 3.0% molybdenum.
4. A corrosion resistant, martensitic steel alloy as set forth in claim 1 containing at least about 0.04% nitrogen.
5. A corrosion resistant, martensitic steel alloy as set forth in claim 2 containing at least about 11.5% chromium.
6. A corrosion resistant, martensitic steel alloy as set forth in claim 1 containing at least about 2.0% copper.
7. A corrosion resistant, martensitic steel alloy consisting essentially of, in weight percent, about
Carbon
0.15-0.30
Manganese
0.01-0.3
Silicon
1.0 max
Phosphorus
0.1 max
Chromium
11.5-14.3
Nickel
0.25 max
Molybdenum
1.25-3.0
Nitrogen
0.04-0.10
Copper
1.75-3.0
Titanium
0.01 max
Aluminum
0.01 max
Niobium + Tantalum
0.10 max
Vanadium
0.20 max
Zirconium
less than 0.001
Calcium
less than 0.001,
0.007-0.020% of sulfur, selenium, or a combination thereof, and the balance is essentially iron, wherein Ni/Cu is not more than about 0.10.
8. A corrosion resistant, martensitic steel alloy as set forth in claim 7 containing not more than about 13.8% chromium.
9. A corrosion resistant, martensitic steel alloy as set forth in claim 7 containing at least about 2.0% copper.
10. A corrosion resistant, martensitic steel alloy as set forth in claim 7 containing not more than about 2.5% molybdenum.
11. A corrosion resistant, martensitic steel alloy as set forth in claim 7 containing at least about 0.05% nitrogen.
12. A corrosion resistant, martensitic steel alloy as set forth in claim 9 containing at least about 13.0% chromium.
13. A corrosion resistant, martensitic steel alloy consisting essentially of, in weight percent, about
Carbon
0.20-0.25
Manganese
0.01-0.3
Silicon
0.75 max
Phosphorus
0.05 max
Chromium
13.0-13.8
Nickel
0.25 max
Molybdenum
1.75-2.5
Nitrogen
0.05-0.08
Copper
2.0-3.0
Titanium
0.01 max
Aluminum
0.01 max
Niobium + Tantalum
0.10 max
Vanadium
0.20 max
Zirconium
less than 0.001
Calcium
less than 0.001,
0.007-0.015% sulfur, selenium, or a combination thereof, and the balance is essentially iron, wherein Ni/Cu is not more than 0.10.