GRADIENT ARMOR PLATE
A composite armor plate is disclosed. The composite armor plate includes a first layer made from an ultra-high hardness, high strength alloy that is bonded to a second layer made from a high fracture toughness alloy that also may have high strength. The composite armor plate according to the present provides a gradient of strength, hardness, and toughness. The composite armor plate according to the invention may also include third and fourth layers of different alloys that provide combinations of hardness, strength, and fracture toughness that are intermediate of the hardness, strength, and fracture toughness provided by the first and second steel layers. A method of making the composite armor plate is also disclosed.
1 . An armor plate comprising:
a first steel layer made from a first steel alloy having the following composition in weight percent,
C
0.30-0.46
Mn
0.04 max.
Si
0.03 max.
P
0.003 max
S
0.0010 max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.2-3.4
Co
15.4-18.6
Al
0.003 max
Ti
0.015 max.
O
0.0010 max.
N
0.0010 max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen; and
a second steel layer made from a second steel alloy having the following composition in weight percent,
C
0.2-0.33
Mn
0.20 max.
Si
0.1 max.
P
0.008 max.
S
0.0040 max.
Cr
2-4
Ni
10.5-15
Mo
0.75-1.75
Co
8-17
Ti
0.02 max
Al
0.01 max.
Ce
SBE up to 0.030
La
SBE up to 0.01
and the balance is iron and impurities;
wherein said first steel layer has a first planar surface that is bonded to a first planar surface of said second steel layer to form a composite armor plate.
2 . The armor plate as claimed in claim 1 wherein the first steel alloy has the following composition in weight percent
C
0.30-0.46
Mn
0.04 max.
Si
0.03 max.
P
0.003 max
S
0.0010 max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.8-3.4
Co
15.4-18.6
Al
0.003 max
Ti
0.015 max.
O
0.0010 max.
N
0.0010 max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen.
3 . The armor plate as claimed in claim 1 wherein the first steel alloy has the following composition in weight percent
C
0.35-0.46
Mn
0.04 max.
Si
0.03 max.
P
0.003 max
S
0.0010 max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.2-3.4
Co
15.4-18.6
Al
0.003 max
Ti
0.015 max.
O
0.0010 max.
N
0.0010 max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen.
4 . The armor plate as claimed in claim 1 wherein the second steel alloy has the following composition in weight percent
C
0.20-0.31
Mn
0.15 max.
Si
0.1 max.
P
0.008 max.
S
0.0025 max.
Cr
2.25-3.5
Ni
10.75-13.5
Mo
0.75-1.5
Co
10-15
Ti
0.02 max
Al
0.01 max.
Ce
SBE up to 0.030
La
SBE up to 0.01
and the balance is iron and impurities.
5 . The armor plate as claimed in claim 1 wherein the second steel alloy has the following composition in weight percent
C
0.21-0.27
Mn
0.05 max.
Si
0.1 max.
P
0.008 max.
S
0.0020
Cr
2.5-3.3
Ni
11.0-12.0
Mo
1.0-1.3
Co
11-14
Ti
0.02 max
Al
0.01 max.
Ce
0.01 max.
La
0.005 max.
and the balance is iron and impurities.
6 . An armor plate comprising:
a first steel layer made from a first steel alloy having the following composition in weight percent,
C
0.30-0.46
Mn
0.04 max.
Si
0.03 max.
P
0.003 max
S
0.0010 max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.2-3.4
Co
15.4-18.6
Al
0.003 max
Ti
0.015 max.
O
0.0010 max.
N
0.0010 max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen;
a second steel layer made from a second steel alloy having the following composition in weight percent,
C
0.2-0.33
Mn
0.20 max.
Si
0.1 max.
P
0.008 max.
S
0.0040 max.
Cr
2-4
Ni
10.5-15
Mo
0.75-1.75
Co
8-17
Ti
0.02 max
Al
0.01 max.
Ce
SBE up to 0.030
La
SBE up to 0.01
and the balance is iron and impurities; and
a third steel layer made from a third steel alloy having the following composition in weight percent,
C
0.21-0.34
Mn
0.20 max.
Si
0.10 max.
P
0.008 max.
S
0.003 max.
Cr
1.5-2.8
Mo
0.90-1.80
Ni
10-13
Co
14.0-22.0
Al
0.1 max.
Ti
0.05 max.
Ce
0.030 max.
La
0.010 max.
wherein said third steel layer is positioned between the first steel layer and the second steel layer; and
wherein the first steel layer has a first planar surface that is bonded to a first planar surface of said third steel layer and the second steel layer has a first planar surface that is bonded to a second planar surface of said third steel layer.
7 . The armor plate as claimed in claim 6 wherein the first steel alloy has the following composition in weight percent,
C
0.30-0.46
Mn
0.04 max.
Si
0.03 max.
P
0.003 max
S
0.0010 max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.8-3.4
Co
15.4-18.6
Al
0.003 max
Ti
0.015 max.
O
0.0010 max.
N
0.0010 max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen.
8 . The armor plate as claimed in claim 6 wherein the first steel alloy has the following composition in weight percent
C
0.35-0.46
Mn
0.04 max.
Si
0.03 max.
P
0.003 max
S
0.0010 max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.2-3.4
Co
15.4-18.6
Al
0.003 max
Ti
0.015 max.
O
0.0010 max.
N
0.0010 max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen.
9 . The armor plate as claimed in claim 6 wherein the second steel alloy has the following composition in weight percent
C
0.20-0.31
Mn
0.15 max.
Si
0.1 max.
P
0.008 max.
S
0.0025 max.
Cr
2.25-3.5
Ni
10.75-13.5
Mo
0.75-1.5
Co
10-15
Ti
0.02 max
Al
0.01 max.
Ce
SBE up to 0.030
La
SBE up to 0.01
and the balance is iron and impurities.
10 . The armor plate as claimed in claim 6 wherein the second steel alloy has the following composition in weight percent
C
0.21-0.27
Mn
0.05
max.
Si
0.1
max.
P
0.008
max.
S
0.0020
Cr
2.5-3.3
Ni
11.0-12.0
Mo
1.0-1.3
Co
11-14
Ti
0.02
max
Al
0.01
max.
Ce
0.01
max.
La
0.005
max.
and the balance is iron and impurities.
11 . The armor plate as claimed in claim 6 wherein the third steel alloy has the following composition in weight percent
C
0.22-0.30
Mn
0.05
max.
Si
0.10
max.
P
0.006
max.
S
0.002
max.
Cr
1.80-2.80
Mo
1.10-1.70
Ni
10.5-11.5
Co
14.0-20.0
Al
0.01
max.
Ti
0.02
max.
Ce
0.01
max.
La
0.005
max.
and the balance is iron and impurities.
12 . An armor plate comprising:
a first steel layer made from a first steel alloy having the following composition in weight percent,
C
0.30-0.46
Mn
0.04
max.
Si
0.03
max.
P
0.003
max
S
0.0010
max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.2-3.4
Co
15.4-18.6
Al
0.003
max
Ti
0.015
max.
O
0.0010
max.
N
0.0010
max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen;
a second steel layer made from a second steel alloy having the following composition in weight percent,
C
0.2-0.33
Mn
0.20
max.
Si
0.1
max.
P
0.008
max.
S
0.0040
max.
Cr
2-4
Ni
10.5-15
Mo
0.75-1.75
Co
8-17
Ti
0.02
max
Al
0.01
max.
Ce
SBE up to 0.030
La
SBE up to 0.01
and the balance is iron and impurities;
a third steel layer made from a third steel alloy having the following composition in weight percent,
C
0.21-0.34
Mn
0.20
max.
Si
0.10
max.
P
0.008
max.
S
0.003
max.
Cr
1.5-2.8
Mo
0.90-1.80
Ni
10-13
Co
14.0-22.0
Al
0.1
max.
Ti
0.05
max.
Ce
0.030
max.
La
0.010
max.
and the balance is iron and impurities; and
a fourth steel layer made from a fourth steel alloy having the following composition in weight percent,
C
0.30-0.36
Mn
0.05
max.
Si
0.05
max.
P
0.01
max.
S
0.0010
max.
Cr
1.30-3.2
Ni
10.0-13.0
Mo
1.0-2.7
Co
13.8-17.4
Ti
0.02
max.
Al
0.005
max.
Ce
0.030
max.
La
0.010
max.
and the balance is iron and impurities;
wherein said third steel layer is positioned between the first steel layer and the fourth steel layer and the fourth steel layer is positioned between the second steel layer and the third steel layer;
wherein the first steel layer has a first planar surface that is bonded to a first planar surface of said third steel layer, the fourth steel layer has a first planar surface that is bonded to a second planar surface of said third steel layer, and said second steel layer has a first planar surface that is bonded to a second planar surface of said fourth steel layer.
13 . The armor plate as claimed in claim 12 wherein the first steel alloy has the following composition in weight percent,
C
0.30-0.46
Mn
0.04
max.
Si
0.03
max.
P
0.003
max
S
0.0010
max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.8-3.4
Co
15.4-18.6
Al
0.003
max
Ti
0.015
max.
O
0.0010
max.
N
0.0010
max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen.
14 . The armor plate as claimed in claim 12 wherein the first steel alloy has the following composition in weight percent
C
0.35-0.46
Mn
0.04
max.
Si
0.03
max.
P
0.003
max
S
0.0010
max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.2-3.4
Co
15.4-18.6
Al
0.003
max
Ti
0.015
max.
O
0.0010
max.
N
0.0010
max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen.
15 . The armor plate as claimed in claim 12 wherein the second steel alloy has the following composition in weight percent
C
0.20-0.31
Mn
0.15
max.
Si
0.1
max.
P
0.008
max.
S
0.0025
max.
Cr
2.25-3.5
Ni
10.75-13.5
Mo
0.75-1.5
Co
10-15
Ti
0.02
max
Al
0.01
max.
Ce
SBE up to 0.030
La
SBE up to 0.01
and the balance is iron and impurities.
16 . The armor plate as claimed in claim 12 wherein the second steel alloy has the following composition in weight percent
C
0.21-0.27
Mn
0.05
max.
Si
0.1
max.
P
0.008
max.
S
0.0020
Cr
2.5-3.3
Ni
11.0-12.0
Mo
1.0-1.3
Co
11-14
Ti
0.02
max
Al
0.01
max.
Ce
0.01
max.
La
0.005
max.
and the balance is iron and impurities.
17 . The armor plate as claimed in claim 12 wherein the third steel alloy has the following composition in weight percent,
C
0.22-0.30
Mn
0.05
max.
Si
0.10
max.
P
0.006
max.
S
0.002
max.
Cr
1.80-2.80
Mo
1.10-1.70
Ni
10.5-11.5
Co
14.0-20.0
Al
0.01
max.
Ti
0.02
max.
Ce
0.01
max.
La
0.005
max.
and the balance is iron and impurities.
18 . The armor plate as claimed in claim 12 wherein the fourth steel alloy has the following composition in weight percent,
C
0.32-0.35
Mn
0.02
max.
Si
0.05
max.
P
0.005
max.
S
0.0010
max.
Cr
2.0-2.5
Ni
11.0-13.0
Mo
15-2.2
Co
15.0-16.0
Ti
0.015
max.
Al
0.003
max.
Ce
0.020
max.
La
0.010
max.
and the balance is iron and impurities.
19 . The armor plate as claimed in claim 12 wherein the fourth steel alloy has the following composition in weight percent,
C
0.32-0.34
Mn
0.01 max.
Si
0.03 max.
P
0.003 max.
S
0.0005 max.
Cr
2.20-2.30
Ni
11.5-12.5
Mo
1.80-1.90
Co
15.4-15.6
Ti
0.01 max.
Al
0.001 max.
Ce
0.010 max.
La
0.005 max.
and the balance is iron and impurities.
20 . A method of making an armor plate comprising the steps of:
melting a first steel alloy having the following composition in weight percent:
C
0.30-0.46
Mn
0.04
max.
Si
0.03
max.
P
0.003
max
S
0.0010
max.
Cr
1.65-2.90
Ni
10.5-13.0
Mo
1.2-3.4
Co
15.4-18.6
Al
0.003
max
Ti
0.015
max.
O
0.0010
max.
N
0.0010
max.
and the balance is iron and impurities, said impurities including not more than about 0.003% phosphorus, not more than about 0.0010% sulfur, not more than about 0.0010% oxygen, and not more than about 0.0010% nitrogen and casting the first steel alloy into a first ingot;
forming the first ingot into a first billet having a planar surface;
melting a second steel alloy having the following composition in weight percent:
C
0.2-0.33
Mn
0.20
max.
Si
0.1
max.
P
0.008
max.
S
0.0040
max.
Cr
2-4
Ni
10.5-15
Mo
0.75-1.75
Co
8-17
Ti
0.02
max
Al
0.01
max.
Ce
SBE up to 0.030
La
SBE up to 0.01
and the balance is iron and impurities and casting the second steel alloy to form a second ingot;
forming the second ingot into a second billet having a planar surface;
stacking the first and second billets such that the planar surface of the first billet contacts the planar surface of the second billet;
bonding the first and second billets across their respective planar surfaces to form a composite billet;
hot working the composite billet to form a composite plate having a preselected thickness and having a first layer and a second layer; and then heat treating the composite plate under conditions of time and temperature selected to obtain a first preselected combination of strength and toughness in the first layer and a second preselected combination of strength and toughness in the second layer.
21 . The method as set forth in claim 20 wherein the step of bonding the first and second billets comprises the steps of:
encasing the stacked first and second billets in a metallic encasement; and then
hot isostatic pressing the stacked first and second billets in the metallic encasement.