Machining
All three alloys machine well in the aged condition, giving short chips and good finish. Use sharp carbide tools and flood coolant; thick plate is stress relieved by stretching, which limits distortion.
2xxx armour plate
2139, 2195 and 2060 Aluminium Armour Plate
2139, 2195 and 2060 are copper-bearing 2xxx alloys covered by MIL-DTL-32341A for armour plate from 0.500 to 4.000 in thick. 2139 (Class I) is the weldable member of the family, while the aluminium-lithium alloys 2195 and 2060 (Classes II and III) are used as bolt-on appliqué armour. Metline supplies all three to the specification and class your programme calls for, with full mill certification.
- Specification
- MIL-DTL-32341A
- Alloys
- 2139 · 2195 · 2060
- Thickness
- 0.500 – 4.000 in
- Use
- Welded (2139) or appliqué
Why 2xxx alloys are used for vehicle armour
For decades, light armoured vehicles were built almost entirely from 5083 and 7039. The 2xxx armour alloys arrived because designers wanted plate that resisted armour-piercing bullets and fragments better than either, while also coping with underbody blast and keeping good corrosion resistance.
2139 was originally developed as an aircraft wing alloy. Its copper-magnesium-manganese-silver chemistry gives high strength, good toughness and an unusual resistance to softening at moderately elevated temperatures. Trials showed that it outperformed 5083-H131 and 7039-T64 against both fragment-simulating projectiles and armour-piercing rounds at the same thickness, and it was written into MIL-DTL-32341.
2195 and 2060 are third-generation aluminium-lithium alloys. Lithium is the only common alloying element that lowers density and raises stiffness at the same time; each 1 % of lithium reduces density by roughly 3 % and raises the elastic modulus by about 6 %. 2195 was first used for the space shuttle super-lightweight external tank, and 2060 for aircraft fuselage and wing skins. As armour, they give high strength at the lowest weight, but they are not qualified for fusion welding in armour structures and are fitted as bolted appliqué panels.
Classes, types and tempers under MIL-DTL-32341A
The specification groups the plate by alloy class and, within a class, by type. The type identifies the temper and property balance the plate is processed to, and it fixes the ballistic acceptance requirements. Always quote the class, type and thickness together on the order.
| Class | Alloy | Alloy family | Joining | Typical role |
|---|---|---|---|---|
| Class I | 2139 | Al-Cu-Mg-Mn-Ag | Weldable (qualified for Type A at selected thicknesses) | Hull, side and top armour; blast-resistant floors in a blast-optimised temper |
| Class II | 2195 | Al-Cu-Li-Mg-Ag-Zr | Appliqué only (bolted) | Lightweight add-on armour panels |
| Class III | 2060 | Al-Cu-Li-Mg-Zn-Ag-Zr | Appliqué only (bolted) | Lightweight add-on armour panels |
For 2139, industry practice uses two property balances: a high-strength artificially aged condition (T8 family) optimised against armour-piercing and fragment threats, used for appliqué, side and top armour, and a blast-optimised condition (T84) used for vehicle floors, where the plate must bend without tearing. Amendment 1 to the specification added a T84 option for 2139 ballistic plate from 1.500 to 2.600 in. Some T84 plate is supplied in a T3-type condition and aged by the vehicle builder to a supplied thermal cycle after forming.
Chemical composition of 2139, 2195 and 2060 (wt %)
Limits below are the registered Aluminum Association compositions, which the armour specification follows. Single values are maximums.
| Element | 2139 (Class I) | 2195 (Class II) | 2060 (Class III) |
|---|---|---|---|
| Silicon (Si) | 0.10 | 0.12 | 0.07 |
| Iron (Fe) | 0.15 | 0.15 | 0.07 |
| Copper (Cu) | 4.5 – 5.5 | 3.7 – 4.3 | 3.4 – 4.5 |
| Manganese (Mn) | 0.20 – 0.6 | 0.25 | 0.10 – 0.50 |
| Magnesium (Mg) | 0.20 – 0.8 | 0.25 – 0.8 | 0.6 – 1.1 |
| Chromium (Cr) | 0.05 | — | — |
| Zinc (Zn) | 0.25 | 0.25 | 0.30 – 0.50 |
| Titanium (Ti) | 0.15 | 0.10 | 0.10 |
| Vanadium (V) | 0.05 | — | — |
| Zirconium (Zr) | — | 0.08 – 0.16 | 0.05 – 0.15 |
| Lithium (Li) | — | 0.8 – 1.2 | 0.6 – 0.9 |
| Silver (Ag) | 0.15 – 0.6 | 0.25 – 0.6 | 0.05 – 0.50 |
| Others, each / total | 0.05 / 0.15 | 0.05 / 0.15 | 0.05 / 0.15 |
| Aluminium | Remainder | Remainder | Remainder |
Silver in all three alloys promotes a fine, uniform strengthening precipitate (the Ω phase in 2139, T1 in the Al-Li alloys), which is a large part of their strength and toughness.
Ballistic and blast performance compared with 5083 and 7039
Published producer data for 2139 at about 1.28 in thickness show clear gains over the traditional armour alloys. The V50 ballistic limit is the striking velocity at which half the shots are expected to perforate the plate; a higher V50 at the same thickness means better protection or lower weight for the same protection.
| Plate (about 1.28 in) | 20 mm FSP V50 | .50 cal AP V50 |
|---|---|---|
| 2139 (AP/FSP temper) | about 3,050 ft/s | about 2,110 ft/s |
| 7039-T64 | about 2,650 ft/s | about 1,910 ft/s |
| 5083-H131 | about 2,550 ft/s | about 1,780 ft/s |
Indicative published values for comparison only. Acceptance limits for your plate are the minimum V50 figures in the specification for the ordered class, type and thickness.
In blast testing, the blast-optimised 2139 temper has been reported to deform plastically about half as much as 5083-H131 of the same thickness. That matters for floor plates under a mine or IED, where large deflection injures occupants even if the plate is not breached.
Density is the other half of the comparison. 2139 has a density of about 2.80 g/cm³, slightly above 5083 (2.66 g/cm³), while 2195 (about 2.71 g/cm³) and 2060 (about 2.72 g/cm³) are lighter than other copper-bearing alloys of similar strength. The armour designer compares alloys on areal density, kilograms per square metre needed to defeat a given threat, rather than on thickness.
Sizes, tolerances and inspection
Supply range
- Alloys
- 2139, 2195, 2060
- Specification
- MIL-DTL-32341A (with amendments); producer or AMS specifications for non-armour orders
- Thickness
- 0.500 – 4.000 in (12.7 – 101.6 mm)
- Width / length
- Up to about 100 in wide and 236 in long, depending on alloy and thickness
- Processing
- Saw cutting, waterjet profiling and machining to drawing
- Testing
- Chemistry, tensile tests per ASTM B557, ultrasonic inspection, ballistic V50 per MIL-STD-662 when specified
Final dimensions and test scope are confirmed against the specification revision on your order.
Thickness tolerances for armour plate are tighter on the minus side than for commercial plate, because a thin plate may fail ballistic acceptance. Tolerances are based on ANSI H35.2 values for the ordered width, with the specification moving part of the tolerance to the plus side. Flatness is important for appliqué panels, which must sit tight against the hull behind them; ask for flatness limits if your panel design is sensitive to gaps.
Machining, joining and finishing
Welding 2139
Can be fusion welded with commonly available 2xxx and 4xxx filler wires in the qualified class, type and thicknesses. Weld procedures and ballistic tests of welded joints should follow the specification and the vehicle programme.
Appliqué fixing (2195, 2060)
Fixed with bolts or studs to the base hull. Detail the bolt pattern so that a hit near a fastener does not tear the panel, and isolate dissimilar metals.
Forming
Aged plate has limited ductility. Where floors need bends, form in the softer condition and age afterwards, following the supplied heat-treatment cycle.
Corrosion protection
Copper-bearing alloys are less corrosion resistant than 5xxx. Use a chemical conversion coat, primer and military paint system, and seal cut edges.
Heat exposure
Keep paint curing and any other heating within the limits of the temper, since over-ageing lowers strength and ballistic performance.
Where 2xxx armour plate is used
- Light and medium combat vehicles: side, top and appliqué armour where 2139 gives better AP and fragment resistance than 5083
- Vehicle floors and belly plates: blast-optimised 2139 that limits deflection under mine and IED blast
- Add-on armour kits: bolt-on 2195 or 2060 panels that raise protection with minimum added weight
- Helicopter and aircraft protection: crew-seat and floor panels where weight is the main constraint
- Naval craft: appliqué protection on patrol boats and superstructures, with suitable corrosion protection
A typical design uses a welded 5083 or 2139 hull as the base structure, then adds bolt-on panels in a higher-strength alloy over the most exposed faces. This keeps the welded structure in a well-understood alloy while the appliqué carries the ballistic load.
2139, 2195 and 2060 compared with other armour alloys
| Alloy | Specification | Weldable in armour structures | Strength | Corrosion resistance | Best use |
|---|---|---|---|---|---|
| 5083 / 5456 / 5059 | MIL-DTL-46027 | Yes | Moderate | Excellent | Welded hulls, marine |
| 7039 | MIL-DTL-46063 | With care; SCC risk | High | Fair | AP-resistant plate |
| 2139 | MIL-DTL-32341A Class I | Yes, in qualified type and thickness | High | Good for a 2xxx alloy | Hulls, floors, side armour |
| 2195 / 2060 | MIL-DTL-32341A Class II / III | No, appliqué | High, low density | Moderate | Lightweight appliqué |
| 7085 / 7056 | MIL-DTL-32375 | No, appliqué | Very high | Fair | High-threat appliqué |
See the 7085 and 7056 appliqué plate page for the highest-strength 7xxx option, and the 5083, 5456 and 5059 armour plate page for the weldable 5xxx baseline.
How to order 2xxx armour plate
- SpecifyAlloy, class and type, specification revision, thickness, plate size or cut drawing, and quantity.
- Define testingState whether ballistic acceptance, ultrasonic class and witness inspection are required, and any export documentation.
- QuoteWe confirm availability, test scope, certification and delivery terms (EXW, FOB, CIF or DAP).
- DocumentEach lot ships with an EN 10204 3.1 mill certificate and test reports; third-party inspection on request.
- ShipPlates are interleaved, packed in seaworthy wooden cases and shipped subject to applicable export controls.
References and standards
- MIL-DTL-32341A – Armor Plate, Aluminum Alloy, 2139, 2195 and 2060, Weldable and Unweldable Applique
- MIL-STD-662F – V50 Ballistic Test for Armor
- ASTM B557 – Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
- Light Metal Age – Advanced Aluminum Armor Alloys
2139, 2195 and 2060 armour plate: frequently asked questions
Which of these alloys can be welded?
2139 is the weldable alloy in MIL-DTL-32341A, with weldability established for Class I Type A at specific thicknesses. 2195 and 2060 have not been qualified for fusion welding in armour and are used as bolted appliqué.
Why use aluminium-lithium for armour?
Lithium lowers density and raises stiffness. 2195 and 2060 give high strength at low weight, so a bolt-on panel adds less mass for the protection it provides.
How does 2139 compare with 5083 armour?
At the same thickness, published data show 2139 with a markedly higher V50 against 20 mm fragment simulators and .50 calibre AP rounds than 5083-H131, and less deformation under blast. 5083 remains easier to weld and more corrosion resistant.
What is the thickness range under MIL-DTL-32341A?
The specification covers plate from 0.500 to 4.000 in nominal thickness. Amendment 1 added a T84 option for 2139 ballistic plate from 1.500 to 2.600 in.
Do you supply ballistic test reports?
When the order calls for MIL-DTL-32341A ballistic acceptance, plate is supplied with the lot test results required by the specification, together with the EN 10204 3.1 mill certificate.
Can 2139 aluminum plate be used outside defence?
Yes. 2139 was first developed for aircraft structures and is also used in aerospace plate where damage tolerance and elevated-temperature stability matter. Order to the relevant aerospace specification in that case.
Specifying 2xxx armour plate?
Send the alloy, class, type, thickness and quantity. We will reply with availability, test scope and a delivered price.
