Ballistic Studies of Lightweight Alloys A Review [607443]

Ballistic Studies of Lightweight Alloys– A Review
S.Balajia, S.Dharani Kumarb, K.Chandra Moorthyc, M.Mohamed Javeedd, D.Dharanidharane

a,b,c,d,e Department of Mechanical Engineering, Sri Eshwar College of Engineering, Coimbatore,
Affiliated to Anna Unive rsity, Tamil Nadu, India .

Email: [anonimizat]
Abstract:
A recent development in the material studies provides beneficial application of
lightweight alloys such as aluminium, magnesium alloys. The alloys are experimentally
improved by increasing hardness in the ballistics testing using projectiles, makes them viable
for the areas such as aerospace, military, defence, automobiles and so on. So the study is
made on different approaches. First, by co mparing different types of non -ferrous alloys and
projectiles regarding sizes, structures. Second, the materials with heat treatment are also
studied for investigating the hardness property by overcoming successful penetrati on on non –
ferrous alloys. Finall y, the aim of this paper is to review the recent progress ballistic studies of
lightweight materials and to provide a best choice of material for further on-going research.
Keywords: lightweight alloys , ballistics, heat treatment, hardness.

Introduction:
Ballistic testing is a field of science which deals with the study of impact objects such
as a bullet, bombs, projectiles, etc. Ballistic research had been carried out in the lightweight
material to utilize these materials in the defence industr ies. Technological improvisations had
paved solution on constructing the lightweight and compact defence tankers for military
applications. Many of the non -ferrous alloys dominated their role in the application of fields
such as aerospace and military espe cially in the con struction of defence tankers . Few
lightweight materials such as aluminium, magnesium are substitution material for steel and
rolled homogenous steel (RHS) because of its less density compared to steels. The impact
strength of the material is analysed from the ballistic behaviours, failure mechanisms such as
hole growth and crack which are important to study The hardness is an essential property to
determine the ballistic performance. The study is carried out in non -ferrous alloys of desirab le
compositions for withstanding various projectiles of cross -sections. Ballistic experiments
involve the loading of the work piece in the target area and striking the projecti le of required
velocity and obtain readings, result out of it.
This paper revie ws the published journals in the field of ballistic studies of lightweight
alloys . It includes the few non -ferrous in their ballistic perfo rmances and failure mechanisms
agains t the different projectile velocities.

Ballistic Experimental details:
Study o f ballistics was done for various lightweight materials on predicting their limits
on different projectiles. The experiments involve the study of the characterisation of the
materials on strength, hardness, energy absorption before and after the ballistic impact. While
the size and structure of the projectile material vary accordingly and to be tested on the targets
for impact energy generated on them. The experimental test involves series of procedure that
is to be carried out with visual inspections and i nvestigations, however carrying out ballistic
test with precaution such as the remote location of the test area, noise cancellation devices are

used in preventing from hearing impairments. The lightweight material such as aluminium
alloys, magnesium alloys are reviewed on the type of alloys tested against the projectiles. The
various projectile equipped in the ballistic operations are double nose projectile structure,
conical, hemispherical and blunt projectile are shown in Figure 1i.

Figure 1 : The specification of the (a) conical (b) hemisph erical and (c) blunt projectile i

Parabellum and NATO projectile , 7.62 mm calibre – ogival -nose – steel jacketed with
hard tungsten core armour piercing (AP) projectile, 5.56 mm FMJ NATO projectile, flat
projectile, the flat -ended steel projectile, 15CDV6 steel, 50 calibre projectile, C30 steel, M80
of 7.62 mm × 51 mm. Reviewing among the articles, there are experimental se tup made out of
which some are tested using gas guns and some with impact testing machines. The schematic
diagram of the gas gun setup is illustrated in Figure 2 .

Figure 2 : Schematic Representation of Gas Gun Triggering Experiment ii

Studies of Bal listic test on Aluminium Alloys
Prince Sharma et al. i conducted a test on AA2014 -T652 which results in providing the
perforation of target by hard steel projectile with a velocity of 834 m/s whereas soft iron
projectiles do not perforate with the velocities less than 937 m/s. It results in extensive
fragmentation and conical crater formation on the rear side of the work piece. Senthil et al.ii
worked on the AA2024 target on blunt nose projectile which shows a grad ual increase in
ballistic resistance in increase with target thickness. The numerical and experimental values
are almost the same for 1.27 mm thickness and slightly change of 29% from the numerical
values to the experimental test on 3.18 mm target thicknes s. The values become insignificant
for increasing thickness up to 19.05 mm respectively. Charles E. Anderson et al.iii done the
comparison of two aluminium alloys such as Al -7075 -T6 and Al -6061 -T6 and found out the
difference in strength is 85%. The deformat ion changes slightly according to the thickness
level. But the crack appears different in failure process results in comparative ballistic
velocities of 366 m/s and 330 m/s on 7075 -T6 and 6061 -T6. J.K. Holmen et al.iv investigated
the heat -treated aluminium alloys and its effect on the ballistic properties where projectile
limit is based on the thickness of the target and independent of the material and perforation in
aluminium is compared with the steel and found to be better than steel where areal mass is
taken in account, so the presence of scale effect provide such increased perforation resistance
than steel plates. The target plates of 20 mm thickness are tested with APM2 bullets at
different velocities as shown in Figure 3 . Iqbal et al.v studied the bal listic behavior of
aluminium alloy using different projectiles. It is noted that the petal formation is found only
on the conical -blunt projectiles and not on other projectiles such as single -nose blunt, single –
nose conical. The highest penetration limit f or 0.82 mm is observed against blunt -blunt

projectile. While single -nose is highest penetration limit for 1.82 mm respectively. Rodriguez –
Millan et al.vi compared the ballistic limit of AA 5754 -H111 and AA6082 -T6 plates and
found out the AA5754 is efficient than AA6082 -T6, when the conical and hemispherical
projectiles while the behavior is opposite for blunt p rojectiles. Evren Ozsahin et al.vii
researched the application of coatings on the aluminium for better ballistic performances.
Penetration depth is foun d to appear on the coated alloy with bulging on the rear side making
it ballistic efficient than the uncoated alloy especially at the higher impacts such as 390 m/s
and higher due to presence of Co -Mo-Cr coatings rather than the Zirconium. LIANG Xiao –
Peng et al.viii discussed the micro structural evolution of 2519 -T87 aluminium alloys with
different stages in projectile penetration. The entering stage, stable -running stage and leaving
stage which discusses adiabatic shear band and micro bands which are a large r amount in
leaving the stage with the less adiabatic shear band while the micro hardness is increased.
Bendarma et al.ix study found that temperature plays a significant role in the mechanical
behavior also the projectile nose is closely associated with th e ballistic limit and failure mode
evaluation. For conical projectile, the energy produced due to residual stress at room
temperature is 26J and decreased to 18J of energy which is shown in Figure 4 .

Figure 3: Target Plates of 20 mm tested with APM2 Bullets at Different Velocities iv

Figure 4 : Experimental observation of failure patterns on aluminium alloy,
= 85.3 m/s &
132.3 m/s ix

Studies of Ballistic test on Magnesium Alloys:
Mohamed Faizal Abdullah et al.x tested the AZ31B alloy by addition of the lead
content with varied percentage while the target is impacted with parabellum and NATO
projectile. The magnesium can be feasibly used in ballistic applications with the dependence
of hardness of the alloy. The hardness of the alloys with different lead content is compared
with their hardness and the optimum amount that can be added to the AZ31B alloy is 1 % Pb
as it is shown in F igure 5.

Figure 5 : Different work piece tested with 9 mm* 19mm Parabellum projectile x

HE Huan -ju et al.xi done test on AZ91 with impact situations where two types of the
alloy are used cast and the other one is by solid solution and age -treatment. The result
discusses the strain rate in both alloys where the casted AZ91 had less failure stress than
solution ageing state and the fracture is occurred due to different strain rates. M. F. Abdullah
et al.xii implemented the usage of Carbon -Nano Tube (CNT) for improving impact resistance
on AZ31B magnesium alloy together with lead (Pb) addition. Ballistic performance is
improved when tested with 5.56 mm FMJ NATO projectile. Therefore the addition of lead
provides increased protection on military and defence. Tyrone L. Jones et al.xiii updated the
ballistic performance of various non -ferrous alloys includes aluminium and magnesium
alloys. It mainly compared AZ31B and AA5083 alloys tested with APM2 projectile. The
proje ctile is tested on the target plate at 0 and 30 where the magnesium fails at initial and
initially has higher ballistic resistance than AA5083 alloy at 30. But AMX602 fail to meet the
ballistic resistance on APM2 projectile. Therefore AZ31B provides better ballistic
performance at 26.6 mm thickness.

Summary and Conclusions:
The outcome of this literature review paper and other papers related to ballistic studies
depicts the subsequent observation aspects which relate to lightweight materials for their
defence applications. The study mainly involves discussion of the projectile perforation to the
targets and the examinations are done on the effect of projectile by measuring velocity
through the infra -red spectroscopy and chronograph. The further examinations are done to
find the failure modes in light weight alloys such as microstructure evaluation and impact
study . The aluminium is compared with the steel and found to be better than steel based on
projectile perforation resistance . While coating provides bet ter resistance to the impact
projectile thus ductile hole is reduced . For magnesium alloy AZ31B , it is light weight and has
more resistance to projectile impact than the other magnesium alloy; hence it is suited for
ballistic operation. The dynamic recryst allization in magnesium alloy allows the material
structure to be refined and gives more resistance to penetration. The magnesium alloys can
also be used as armor . Thus magnesium acts as a substitute for aluminium due to its less
density and can be applica ble in defense industries such as constructing of defense tankers.
By concluding the review made on various manuscripts, the following main points are to
be highlighted with remarks are discussed below:
1. The overview of ballistic research is focussed on alu minium alloys which has high
ballistic performances and dominated the chart by impact resistance. The future research

can be focussed on the welded joints and their behaviour associated with the ballistic
impacts.
2. The usage of magnesium alloys are increas es consistently on the improved performances
of ballistic test. The magnesium has the property of low density which makes the future
research focussed on application of it in the field of defence. Many researchers have
contributed the improvement of this a lloy by various techniques to improve its hardness
on withstanding high velocity impact projectiles.

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xiii T. L. Jones, “Update on ballistic characterization of the scalability of magnesium alloy AMX602,” in
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