Keikor2139-T84 aluminum alloy armor plate
The application of aluminum alloy as armor plate began in the mid 50s of last century, and has been applied for more than 60 years. It has been applied in wheeled armored vehicle and tracked armored vehicle, and armored vehicle has played an important role in search, reconnaissance, ambulance and infantry transportation. The first Aluminum Alloy armored personnel carrier (Personnel Vehicle) is the United States M113, with a large number of Aluminum Alloy armor, armor will not be enough to slice the bullet breakdown, to ensure the safety of personnel, at the same time than the previous steel armour dray is much lighter, can be transported by plane.
The U.S. Army Research Laboratory (Army Research, Laboratory, ARL) performance and size on the armored car side and front armor plate alloy for quite a long time and a series of firing simulation, screened Aluminum Alloy two best performance, their strength, anti explosion, shrapnel and anti anti bullet breakdown corrosion have been a very good combination, but also has good formability through intermediate heat treatment (Formability). The two alloys are 2139 alloys and 7056 alloys which have been applied in the aviation industry. The armored thick plate is produced by the United States Ken Aluminum Inc (Constellinm). Their registered brands are Keikor 2139TM and Keikor 7056TM.
Keikor 2139 alloy is a structure alloy aerospace industrial development, strength and high fracture toughness, Aluminum Alloy is an excellent comprehensive performance, through a series of standards for the U.S. Army Research Laboratory for long time of shooting test and field test, it is also a kind of armor Aluminum Alloy well, in addition to bulletproof the performance of qualified, have good corrosion resistance and heat resistance, will not soften at high temperatures, the armored vehicles, high corrosion resistance is one of the important technical indicators, because it will operate in the complex environment of extreme and combat, valuable is that 2139 alloy should be low stress corrosion sensitivity.
2139 alloy Al-Cu-Mg-Mn-Ag alloy is a low impurity content, as of December 2016, in the United States Aluminum Association Inc registered common type alloy (Active alloy) 535, is (inactive alloy) alloy type 158, a total of 693, the Aluminum Inc and the special color is not registered, estimated in the Aluminum Alloy model for deformation about 1000. There are 18 silver in the 693 alloy models, of which 16 are 2XXX, 2 of the 7XXX system (7009 alloy and 7047 alloy), and the maximum silver content is 0.7%. The solid solubility of Ag in aluminum is up to 55.6% at 566 degrees, and then changes rapidly with the decrease of temperature. Adding 0.1% to 0.7% Ag to 2XXX and 7XXX systems can improve their mechanical properties and SCC resistance, and 2139 alloy contains 0.15%Ag 0.6%Ag. Ag can form a Ag2Al compound (gamma phase) with Al at 727 C, which contains 88.9%Ag and dense six square lattice.
The first used as armor plate is 2519-T87 alloy thick plate. Later, it is found that it has high stress corrosion cracking sensitivity and is eliminated, because it is not suitable for fighting under complex conditions. The composition of the 2139 alloy (mass%) is as follows: Si0.10, Fe0.15, Cu (4.5 - 5.5), Mn (0.20 - 0.60), Mg (0.20 - 0.80), Cr0.005, Zn0.25, Ti0.15, V0.05, Ag (0.15 0.60), the other impurities are 0.05, total 0.15, and the rest are Al.
According to the American military material standard MIL-DTL32341A, the lowest mechanical properties of the 2139 alloy are shown in the following table. It can be seen from the composition of 2139 alloy that it is a alloy with low impurity content, so it has high fracture toughness and fatigue resistance, and its damage resistance is also good.
The US Army Research Laboratory shows that when the thickness of armor plate is equal, the 2139 alloy plate can resist 2110ft/s's bullet fire, while the safe firing speed of 5083-H131 alloy and 7039-T64 alloy plate is 1780ft/s and 1910ft/s respectively.
The blast resistance of Keikor 2139 alloy is generally better than that of traditional alloy, especially 2139-T84 alloy, because T84 state plate has higher tensile strength and fracture toughness, and they are well combined. In a standardized blasting test, its plastic deformation is much smaller than that of the 5083-H131 alloy thick plate. The permanent deformation of 2139-T84 alloy thick plate is about 50% smaller than that of 5083-H131 alloy. Therefore, when the battlefield explode, the impact of 2139-T84 alloy armored vehicle will be significantly reduced, and the potential damage can be greatly reduced.
The anti explosion plate (T84) is usually used as the lower deck of armored vehicle. All the plates are artificially aged, and the aging temperature is quite high, so they have excellent formability. 2139-T84 alloy armor plate is also protected by patent solution, which has high strength and good formability. The stress in forming parts is low, which is very favorable for later processing.
In the manufacture of armored vehicles, parts of the connection either welded or bolted, structural strength of plate will decrease, therefore, ConnectKentucky Aluminum Inc successfully developed a series of 2138-T84 alloy wire, the welding structure of the weld strength and matrix strength are almost equal, while welding thermal stress is the lowest. The Keikor 2139-T84 alloy armor thick plate is produced by the Aluminum Inc of West Virginia, Vince, Wood (Revenswood, WV), and high-end materials such as aerospace are its leading products.
In September 2016, the United States Army related departments declared that the armored armor of the armored vehicle (TARDEC) will be made with Keikor 2139 alloy plates.