1. i
INTRODUCTION1
MK 1 “BRODIE HELMET” TYPE B....................................................................................................1
Material Composition ...................................................................................................................1
Manufacturing Process................................................................................................................2
Forming the Steel.........................................................................................................................2
Shaping the Helmet .....................................................................................................................2
Material Properties.......................................................................................................................2
Environmental Impact..................................................................................................................3
Causes of in-Service Failure........................................................................................................4
Causes of Early Failure ...............................................................................................................6
ALTERNATIVE MATERIAL SELECTION FOR HELMET DESIGN..................................................6
Requirements of Helmets and Their Materials............................................................................6
Material Choice ............................................................................................................................6
Selection of a New Material.........................................................................................................8
COMPARISON OF MATERIAL PROPERTIES................................................................................10
Carbon Fibre Reinforced Composite (CFRP) ...........................................................................10
Boron Carbide............................................................................................................................10
Processes ..................................................................................................................................12
Conclusion of Alternative Materials ...........................................................................................14
IMPROVEMENTS TO SERVICE LIFE..............................................................................................15
CONCLUSION...................................................................................................................................16

2. ii
Abbreviations/Glossary
BC Boron Carbide
CES Cambridge Engineering Selector
CFRP Carbon Fibre Reinforced Plastic
CO2 Carbon Dioxide
FCC Face Centred Cubic
IED Improvised Explosive Device
ISAF International Security Assistance Force
J Joules. Unit of energy
K Kelvin. Temperature in degrees centigrade + 273
KE Kinetic Energy
MK Mark
UTS Ultimate Tensile Strength

3. 1
INTRODUCTION
1. For this assignment I will be looking at the materials and the processes of military combat
helmets. I will first look at one from the First World War and then use the Cambridge Engineering
Selector (CES) to select an alternative material that helmets could be made from and compare
them against each other.
MK 1 “BRODIE HELMET” TYPE B
2. This helmet was bought into service in 1915, it was brought into service to reduce the
number of casualties caused by shrapnel from enemy artillery. The MK 1 (fig 1) was the first steel
helmet issued to British troops since the early 1700s and its introduction reflected the increase in
firepower and artillery tactics of the WW1. The “soup bowl” shape provided protection from artillery
shells bursting above the trenches, this one piece design allowed for the use of steel that could be
made from a single pressing. A leather liner provided cushioning and a simple strap attached it to
the user. They were finished with a simple coat of paint.
Fig 1. British Army Mk1 Helmet
Material Composition
3. The type B was made out of steel with a manganese content of 12% and carbon content of
1%, this was known as “Hadfields Steel” after its inventor Sir Robert Hadfield. The harder steel
had increased ballistic protection, was non-magnetic and weighed 2.4 lbs or 1.1kg, by the authors
assumption it was required to operate under the following conditions shown below:
Table 1 physical and environmental conditions
Temperature (+/-) 323 Kelvins
Weather
Prolonged exposure to
light and heavy rain
Ballisitc Protection
Shrapnel projectiles (KE up
to 600 Joules)
User Requirements
Potect from general bumps
and impacts, be light and
comfortable enough for
prolonged wearing

4. 2
Manufacturing Process
Forming the Steel
4. The steel and its alloying elements are heated to an austenitic state at 1050 degrees C, it is
then quenched rapidly. Because the steel contains such a high percentage of manganese, this
has the effect of reducing the transformation temperature to such an extent that austenite is formed
at room temperature, this produces austenitic steel which gives good hardness and ductility
making the steel tough.
Shaping the Helmet
5. The helmet was deep drawn from 20 gauge (0.36in) sheets. Deep drawing is done by
forming flat sheet metal into a shape by pulling it through a die (fig 2). The process depends on
the materials ability to plastically stretch and deform into shape and is limited by the materials draw
ratio.
Fig 2. Drawing process
6. The term deep drawing is mainly used when the depth of draw exceeds the diameter by one
or more, anything less is termed stamping however the operations are the same. Once this
process was complete, the part would’ve been cut out to produce a finished helmet.
7. An alternative method to this could have been to cast the compartment. In this case 2 dies
would be needed to form the shape required when molten metal is poured in and allowed to cool,
using sand casting would’ve been too costly to produce the helmets in the quantity required but a
die cast machine could’ve been used. Casting would’ve offered the benefit that the cast part
would’ve required no further machining and the accuracy of the helmet would’ve been consistent.
The downside of casting would’ve been the fact that the drawing process was key to enhancing the
helmets armour qualities which is explained below.
Material Properties1
8. Hadfield is a steel/manganese alloy, manganese is used in all steels to de-oxidise it, and it
reduces the problems caused by sulphur and improves the strength and wear resistance. Tensile
strength increases up to about 8% manganese before dropping off. Hadfield steel contains 10% or
more manganese and has an austenitic phase with a face centred cubic (FCC) lattice (fig 3), the
austenite structure comprises large grains which allows the material to deform as the grains can
1
http://www.acmealloys.com/Austenitic%20Manganese%20Steels.PDF

5. 3
move a large amount. The steel is strengthened due to the interstitial carbon atoms and the
substitutional manganese atoms (fig 4).
Fig 3: Face Centred Cubic Lattice Fig 4. Alloying arrangements
9. The FCC has 12 equivalent slip systems and deformations and when the material is work
hardened these cause some of the austenite to form into martensite, as martensite is a hard
substance Hadfield steel therefore has a hard outer surface and a tough inner. This hardening of
the outer layer is further beneficial if a crack in the outer layer should occur, the crack propagation
is stopped by the tough inner core.
10. The drawing process was key to the helmets armour qualities, when the metal is drawn it is
work hardened, as mentioned this has the effect of changing the austenitic steel into martensitic
steel on the outer edge (the part that is drawn into the die), the helmet therefore had a hard outer
and tough inner, the hardness gave the helmet a first layer of ballistic resistance and the tough
inner could absorb the energy, it also got harder over time with each successive hit.
11. Helmet attachments. The helmet had internal welded lugs through which a leather strap
was fitted which was in contact with the wearer and allowed a chin strap to be fitted. Leather is a
natural material with good thermal properties but can become slippery when wet and quickly
degrades.
Environmental Impact
12. Due to the number of men in the army at the time well over 1 million helmets were
manufactured, this required about 4000 tonnes of steel, equivalent to around 140 thirty tonne tanks
of the period. As steel at this time was the single most important material for both industry and the
war effort this was clearly a large strain on production.
13. To turn raw steel into a helmet requires a lot of energy, because of that we produce Carbon
dioxide (CO2). The table below demonstrates the cost of energy and CO2 production for
equipping an army of 1 million soldiers with a high carbon steel helmet. Due to lack of information
on the energy and CO2 usage of Hadfield steel I have used CES to find a comparable high carbon
steel.

6. 4
Table 2. Energy use and CO2 production
14. This table demonstrates the high levels of energy needed to turn raw materials into useful
objects and the negative effect of doing that in terms of CO2 produced, of interest is the amount of
water required for making the helmets, over 68 million litres which again has a big effect on the
environment and on an island country at war.
15. Due to the pressures placed on the country during a time of war there was a need to reduce
costs wherever possible, the armour qualities of the helmet could’ve been increased with an
increase in thickness, however this would have required more steel and more expense. Another
means of reducing the costs was in the corrosion protection, the finished helmet was painted in
olive drab which was a quick and cheap method but which did not offer the long term corrosion
benefits that could’ve been offered by first galvanising the helmet and then painting it. This led to
the possibility of an increase failure due to corrosion if the paint became damaged.
Causes of in-service failure
16. Impact. For an item that is designed to be worn during combat the biggest threat of failure
is likely to be from impact, typical impacts would have been from shrapnel and bullets but also from
blunt hits such as from a rifle butt or similar objects during trench raids.
17. When a projectile hits the helmet it contains kinetic energy based on its mass and velocity. A
typical fragment of shell is 1.2 grams and travels at 1000 metres per second, this contains kinetic
energy (KE) as calculated by KE=0.5mv², therefore:
KE =
1
2
𝑋 0.0012 𝑋1000² = 600 Joules2
18. As the shrapnel hits the helmet, its material will start to absorb that energy by changing it into
heat and sound. The ability of the material to absorb energy depends on its ultimate tensile
strength and its ability to elastically and plastically distort. Fig 5 shows these regions, as the
2
(Farrar, CL; Leeming, DW; Royal Military College of Science, Shrivenham, 1982)
Energy Ammount
Mass of
Helmet Per unit Per 1 million units
Embodied Energy, Primary Production (MJ/Kg) 34.2 1.1 37.62 37,620,000.00
Drawing Energy (MJ/Kg) 124 1.1 136.40 136,400,000.00
Recycling energy (MJ/Kg) 9.01 1.1 9.91 9,911,000.00
Total 183.93 183,931,000.00
CO2 footprint, primary production (Kg/Kg) 2.34 1.1 2.57 2,574,000.00
C02 footprint, drawing process (Kg/Kg) 9.32 1.1 10.25 10,252,000.00
CO2 footprint, recycling (Kg/Kg 0.708 1.1 0.78 778,800.00
Total 13.60 13,604,800.00
Water Usage (l/Kg) 62.3 1.1 68.53 68,530,000.00
Environmental impact of the Brodie Helmet
(Steel AISI A4 air-hardening cold worked suitable for deep drawing 1.05% carbon and 2.2% manganese)
Energy Usage
Recycling

7. 5
projectile hits the material the stress in it increases disproportionally to the strain (energy is being
absorbed without a change in material shape), it then reaches a point where the material gives up
under the stress and plastically deforms. The area under the curve can be considered work done
or the energy required to break it. If there is enough energy in a projectile it will break the material
it hits. Due to the proximity of the helmet to the head plastic deformation may also cause injury.
Fig 5. Elastic and Plastic deformation
19. Hadfield steel was designed to absorb the energy from relatively small objects like shrapnel
as this was the biggest cause of fatalities in the trenches, however, if the helmet was hit from a
bullet fired by an enemy sniper than the KE could surpass the ability of the helmet.
20. For example, a bullet with a mass of 5g travelling at 920 m/s has KE of 2116 J, this would hit
the helmet, rapidly surpass the tensile strength of the steel and penetrate it killing the soldier, even
if the bullet lost a lot of energy due to the shape of the helmet and failed to penetrate their could
still be enough energy to transmit a shockwave through the material and injure or kill the soldier.
Very few helmets even today can withstand a hit from a high velocity bullet. Other factors can also
affect the point at which the material fractures under impact, these being:
a. Presence of stress concentrations. Either caused during manufacture or by
environmental factors, a small hole or notch can raise the stress
b. Speed with which the projectile hits the material. This may result in the material
not having time to plastically deform and so it fails in a brittle manner instead.
c. Temperature. Metal can behave in a more brittle manner as temperature decreases,
although as Hadfield steel has a Face Centred Cubic structure it is not affected by this
ductile-brittle transition.
21. Other methods of failure such as creep and fatigue were unlikely to cause failure in the Mk1.
Creep will only occur if a continuous force is applied to the helmet and the temperature is within 0.3
to 0.4 of the metals meting temperature, our steel has a melting point of 1773 K which means our
creep value is around 531.9K, the helmets working environment would not have got to that
temperature.
22. Fatigue failures require the constant loading and unloading of a material, again this is not
something that would be expected for a helmet as we would not expect a soldier to either
repeatedly hit his helmet or allow it to be shot over and over again. Furthermore our helmet’s strap
was connected to welded lugs as opposed to drilled holes (which could’ve acted as stress raisers)
so we would not expect fatigue failure to be significant in the Mk1.

8. 6
Causes of Early Failure
23. Corrosion. As steel is iron based it can be susceptible to rusting, if unprotected iron is
exposed to oxygen and water then rusting can take place, both these conditions were present on
the western front. The helmet was delivered to troops painted in an olive drab paint, painting
protected the metal by providing a cover over the helmet through which water cannot penetrate.
However, during use the helmet would be dropped and scratched, and this exposed the metal.
24. When steel comes into contact with water and oxygen, the oxygen combines with the steel
atomically and creates a new compound called an oxide which weakens the bonds of it. Rusting is
an electro-chemical process which causes the iron to lose electrons to the oxygen surrounding it
dependant on the presence of water. The chemical process is shown below.
O2 + 4e-
+ 2H2O = 4OH-
25. This problem could’ve been reduced by adding protective measures such as galvanising
which creates another layer of zinc which protects the steel, however this would’ve been too
expensive for so many helmets.
ALTERNATIVE MATERIAL SELECTION FOR HELMET DESIGN
Requirements of helmets and their materials
26. The ability of a projectile to cause damage or injury is determined by its kinetic energy, the
helmet must resist penetration of the projectile and dissipate as much of the kinetic energy as
possible. Additionally, as the helmet is in close contact with the head which can be damaged by
even small amounts of movement, it must also minimise the effects of secondary damage. A
helmet that deforms plastically therefore may still cause injury or death to the wearer even if it
absorbs the energy it was hit with.
27. To absorb energy we require a material that is tough, toughness is defined as a materials
ability to resist crack propagation3
or its ability to absorb energy without fracturing. It requires a
balance of strength and ductility. Toughness is measured in Joules per cubic metre. We could
also use a very hard material to reject all the energy of the projectile.
28. A further requirement of helmet materials is to protect the soldier from everyday knocks and
scrapes when entering or leaving armoured vehicles. Pertinent to today is the need for the helmet
to protect the head against injury from flying projectiles during a vehicle accident/IED strike or from
hitting the ground after a fall as a result of an explosion.
Material Choice
29. Metallic Armour. Metallic armour works by preventing any penetration of the projectile, it
does this by breaking it up and dissipating the energy over a large surface area, this requires
hardness. It is generally successful in withstanding high velocity bullets and multiple hits in the
same area, this is a very strong factor in helmet design and one of the reasons Hadfield steel was
used in the MK1.
30. However, when metallic armour is placed in contact with the body it has the disadvantage
that on impact a shock wave can be transmitted through the material to the body causing cavitation
which then leads to secondary injuries (fig 6).
3
(W.Bolton, 1998)

9. 7
Fig 6 4
31. Metallic armour is normally heavier and this can cause injury when the head is moved rapidly
by impact as well as adding to the weight carried by soldiers, this was a key reason for the
exploration of other materials.
32. Polymer Composite Armour. An interwoven fibre laid into shape and then made hard with
a resin. When the projectile hits, it is trapped by the fibres, each fibre pulls every other fibre
connected to it and so the energy is dissipated across a large surface area, this is similar to a
football being stopped by the goals net.
33. However, this means that each hit weakens the material and so its ability to defeat multiple
hits is reduced. It is not able to resist high velocity bullets but is particularly good at defeating
shrapnel as this presents a larger surface area to get trapped in the fibres. Its low mass (less
mass on the head) and ability to be moulded to shape are its main benefits.
Fig 7. Mk 6 helmet
34. This material is the current common choice for combat helmets such as the British Army Mk
6 helmet (fig 7), this is made from a ballistic nylon fibre hardened with a resin, another common
material is Kevlar which is used to reinforce a plastic material, Kevlar is an aramid with specific
ballistic enhancing properties.
4
(Farrar, CL; Leeming, DW; Royal Military College of Science, Shrivenham, 1982)

10. 8
35. Ceramic Armour. Ceramics (specifically engineered ceramics) are hard materials with low
density, they defeat projectiles by being harder than the projectile which is forced to distort itself on
impact with the ceramic thereby reducing its kinetic energy by itself (fig 8), and although they fail in
a brittle manner they are still justifiable due to the extremely high hardness levels.
Fig 8. Impact of projectile on ceramic5
36. For this reason it is able to resist penetration from high velocity projectiles. However it does
need an additional material such as a composite to hold it together if it shatters after the projectile
hits, this actually allows the armour to continue to defeat the projectile as the ceramic dust will
wear away at the bullet. The additional material then dissipates the remaining energy to an
acceptable level.
Selection of a new material
Based on this ballistics information of materials, I will look for a composite and a ceramic material
that can offer similar ballistic protection to that offered by steel but that is also lighter. A lighter
helmet will mean less weight for the soldier to carry and will minimise the damage caused by
injuries such as whiplash during an IED explosion or vehicle roll-over.
37. To do this I will use CES to compare yield strength versus density for a composite material
and hardness verses density for a ceramic option. I will use yield strength as a guide of a
materials ability to elastically deform, the ultimate yield point being an indicator of the point to
which the material will elastically deform. Hadfield steel is not included in CES so for comparisons
I shall use high carbon steel.
5
(Fundus, 2013)
Composite
Ceramic
Ceramic

11. 9
Graph 1 Material selection based on elastic limit
Graph 2 Material selection based on Hardness

12. 10
38. By using CES I have established that two suitable materials for helmets might be Carbon
Fibre Reinforced Plastic (CFRP) and Boron Carbide (BC). CFRP is a material from the
plastic/composite category and BC is a material from the ceramic category, these both differ from
Hadfield steel which is of the metal category.
39. These two materials should match my requirements of finding a new material with
comparable ballistic qualities of steel but with a reduced weight. CFRP has a comparable yield
strength to steel, and BC has a much higher hardness value to steel so I am justified in choosing
these materials.
COMPARISON OF MATERIAL PROPERTIES
Carbon Fibre Reinforced Composite (CFRP)
40. This composite material consists of fibres of carbon added to a polyester or epoxy resin, the
epoxy holds the materials in the desired shape and transfers the loads to the carbon fibres which
do all of the work, the resin allows for ductility and toughness and protects the fibres, the epoxy
also keeps the fibres apart which helps to reduce crack propagation.
41. Carbon fibre is first spun into filament yarns, this yarn is then heated to get rid of any non-
carbon atoms and then wound onto bobbins. Unidirectional sheets can then be made. The
sheets are laid into a mould pre-coated with resin, after each layer is aligned it is coated with more
resin and rolled to distribute the resin fully throughout the fibres in a hand layup technique (fig 9),
this is then repeated until the required thickness is reached. Once complete it is either air-cured or
put into an autoclave to heat and set the epoxy.
Fig 9. Hand layup technique.
42. Much of the strength depends on the orientation and type of the fibres. Aligning the fibres in
a continuous length will give the highest strength against a force applied in line with the fibres but
reduces performance when it is placed against them, randomly arranging them will give less
performance than continuous but the performance is achieved in all directions.
43. This material offers reduced weight but comparable tensile strength when compared to steel,
it is more likely to fail in a brittle manner than steel but the reduced weight is such a big factor that
this could still be acceptable. A more common material added to plastic helmets is Kevlar which is
a poly-aramid fibre with increased ballistic properties but this was not shown on CES. However,
CFRP helmets are used by Special Forces teams were its lightweight is more beneficial than its
outright ballistic protection. The big downside with CFRP is the difficulty of manufacture due to the
lengthy hand layup technique
Boron Carbide
44. Boron Carbide (BC) is a very hard material that exceeds the hardness offered by steel.
Graph 2 shows BC having a Vickers hardness level of 1300 HV and a density of 1200 kg/m3. BC

13. 11
has strong covalent bonds (atoms sharing electrons) which means they require a lot of energy to
break them. It consist of a complex crystal structure of boron and carbon atoms (fig 10).
Fig 10. Boron-carbide
45. It is formed by pressing BC powder into the desired shape, a polymer binder is added to hold
its shape and then the whole thing is fired at a high temperature which burns off the polymer and
causes the powder particles to coalesce and fuse together in a process known as sintering (fig 11),
the temperature is typically around 1550 -1700 o
C and continues for up to 20 hours, this process
has the negative effect of causing the shape to shrink by around 20%, this means the initial
shaping must be done above the desired end shape. The process and in particular the
temperature and time need to be sufficiently high in order to reduce the porosity of the material.
Fig 11. Sintering and pressing technique.
46. The ability of this material to defeat projectiles depends on it having a very low porosity,
porosity (holes) in ceramics is what gives them the ability to shatter easily, the pressing and
sintering process reduces the porosity but, if this is not done correctly or isn’t successful than a
very porous material will be produced which could shatter easily when hit. Because of the constant
equal pressure needed to form a non-porous material it is difficult to form anything other than
simple shapes such as squares or rectangles.
47. With research this is not often used for helmet manufacture due to the difficulties in forming it
into a single curved shape, however it is being investigated and is a potential future technology.
Also, due to the relatively poor ability of this armour to survive multiple hits without cracking it is
perhaps not ideally suited for use by soldiers as replacement of the damaged helmet on the
Boron
atom
Carbon
atom

14. 12
battlefield may be problematic. However, it could be justified based on its ability to defeat high
kinetic energy projectiles such as those from a high velocity sniper rifle.
48. Another alternative could be for this type of material to be fitted as a temporary removable
extra piece of armour on a composite helmet as and when the threat level requires it, such as on
static guard duty in a Sanger with the main threat coming from sniper fire. If the BC was formed
into small square or diamond shapes they could be added to a helmet in a similar fashion to how
ceramic armour is fitted to armoured vehicles currently. Being small they could be easily replaced
when hit.
49. This material offers reduced weight but increased protection compared to steel, the downside
is the difficulty in manufacture and it’s potential for brittle failure. It could however be combined
with CFRP to provide protection from cracking, this would be a much better solution.
Processes
50. To compare these materials with meaningful comparisons I will design a basic helmet shape
based on the circumference of my own head. I can then use these measurements to compare
cost, weight and environmental conditions by comparing the materials like for like.
51. Circumference of head plus air gap is 62cm, therefore diameter = 62 / 3.14 =19.7cm.
Simplified helmet shape is a hollowed out half sphere (Volume outer (Vo) – Volume Inner (Vi)) with
thickness of 0.9cm (based on the thickness of current combat helmets such as the Mk 6) therefore
volume of helmet is:
Vo
1
2
(
4
3
𝜋𝑟3) – Vi
1
2
(
4
3
𝜋𝑟3) = 500cm3
or 0.0005m3
Fig 12. Example helmet design for material comparison
52. I will base the cost on equipping an army of 100,000 soldiers with the new helmet. Figures
taken from CES are the highest ones given. As before, in place of Hadfield steel I have used Steel
AISI A4 air-hardening cold worked suitable for deep drawing with 1.05% carbon and 2.2%
manganese. I would expect Hadfield steel to have a higher cost than plain high carbon steel due
to the extra manganese in it.
53. It should be noted that these dimensions and figures serve to illustrate the difference in costs
only, they do not reflect the actual dimensions required of a helmet, the MK1 steel helmet had a
much thinner dimension of .09cm as opposed to .9cm and a mass of 2.2kg as opposed to 4kg, this
means our figures our accounting for more material than may be necessary. The reason for this is
that making accurate figures for ballistic protection is very complicated and out of the scope of this
assignment, however, they are still justifiable for comparing the costs of materials. We would
expect that a steel helmet could be made thinner than its CFRP or BC counterpart.

15. 13
54. The figures below are calculated from the information on CES, manufacture costs are then
calculated by CES which gives a high and low relative cost index per batch size, the average
between high and low was then taken.
Table 3. Cost comparison
55. These figures show the cost of manufacture of up to 100,000 helmets, at this stage the price
per helmet is relatively fixed and no further reduction in cost per unit can be made. Of interest is
the difference in price per single helmet and price per 100,000 helmets, this shows the expense
incurred in starting up a new business such as the cost of the machinery.
56. Another interesting point is that despite CFRP having the lowest overall mass and the lowest
cost per single unit of all three it remains by far the highest cost per unit, this is due to the complex
manufacturing process which is difficult to automate.
57. We can now look at how our materials compare against in each other in terms of energy use
and CO2 levels. Due to the difficulties in obtaining accurate figures for BC we will look at the
energy and CO2 levels for primary production only.
HIGH CARBON
STEEL
CFRP Boron Carbide
Density (KG/m3) 7999 1600 2550
Volume of
example helmet
(m3)
0.0005 0.0005 0.0005
Mass of example
helmet (kg)
4.00 0.80 1.28
Price (kg/m3) 0.39 26.20 56.20
Type of
manufacture
Deep Drawing Lay-up
Pressing and
Sintering
Cost with
manufacture
(per unit) (£)
7250.00 2705.00 5250.00
Cost with
manufacture
(per 100,000
units) (£)
6.25 395.00 55.00

16. 14
Table 4. Comparison of energy use and CO2 production
58. Of interest is the high numbers for CFRP, they show how much energy is required for
producing the material coupled with the high amount of CO2 produced as a result, although the
figures aren’t shown we would also expect high figures for manufacturing energy and CO2 footprint
from CFRP, again this is due to the complex nature of making the CFRP sheets and the lengthy
time required in the “hand layup” techniques.
59. The other interesting point is the lack of ability to re-cycle CFRP or BC, this is because once
formed the energy required to try and convert them back into their base components would be far
too excessive, steel on the other hand can be melted back.
Conclusion of alternative materials
60. The two materials I have chosen offer the benefits of reduced helmet mass compared to
steel, for this reason both materials are justified in their selection if mass is our only consideration.
However, steel offers a more versatile material to work with, and pertinent to today, can be
recycled with relative ease.
61. If we were selecting a material based on its ballistic protection then Boron Carbide would be
the best selection as this offers a higher hardness value then steel but at a reduced mass, this
makes it very attractive for armour but, the ability to form it into a complex shape and its brittleness
makes it a possibility for future or specialised helmets only.
62. If cost, energy consumption and CO2 levels were of less concern than protection then
combining a BC core with inner and outer layers of CFRP would offer a lightweight, high tensile
strength and extremely hard helmet that could offer greatly increased ballistic protection compared
to steel.
Energy Ammount Mass of Helmet Per unit Per 100,000
Embodied Energy, Primary Production (MJ/Kg) 34.2 3.95 135.09 13,509,000.00
CO2 footprint, primary production (Kg/Kg) 2.34 1.28 3.00 299,520.00
RECYCLE YES
Embodied Energy, Primary Production (MJ/Kg) 500 0.8 400.00 40,000,000.00
CO2 footprint, primary production (Kg/Kg) 36.4 0.8 29.12 2,912,000.00
RECYCLE NO
Embodied Energy, Primary Production (MJ/Kg) 169 1.28 216.32 21,632,000.00
CO2 footprint, primary production (Kg/Kg) 9.1 1.28 11.65 1,164,800.00
RECYCLE NO
STEEL
CFRP
BORON CARBIDE

17. 15
IMPROVEMENTS TO SERVICE LIFE
63. The MK1 steel helmet was a critical part of a soldier’s equipment when in the trenches,
however, it was not without criticisms. If we were to improve the service life of it we could look at
the following improvements.
64. Materials Composition. Hadfield steel proved to be very efficient at protecting the soldiers
from enemy shrapnel, however it was not as good at protecting them from rifle rounds, as these
projectiles carry so much kinetic energy the only way to improve the helmet with the technology of
the time is to add more steel to vulnerable areas.
Fig 13. Increased ballistic protection6
65. Figure 13 shows this concept as used by the German army, an extra steel plate which could
be added to the front of the helmet to protect men when on sentry duty, this increased the ballistic
protection against frontal attack. However, the extra weight meant it was tiresome to wear for
anything but short periods.
66. Design. The design of the Mk 1 helmet was designed to protect against shrapnel, for this
reason a large rim was added to cover not just the head but also part of the shoulders from artillery
rounds exploding overhead.
67. An improvement could have been made by adding a neck shield at the back, this would
protect the extremely vulnerable area around the spine and could have reduced the number of
spinal injury to troops. However, due to the material technology at the time this could only have
been done with an extra steel plate, this would’ve been very inflexible and could have hindered
movement when taking up a firing position.
68. One key improvement that was made was to redesign the chin strap attachment with a brass
screw attachment on the helmet, this meant that a damaged liner could be changed far easier and
quicker in the field.
69. Corrosion Protection. The materials were only painted in standard army olive drab due to
costs. This meant that if the helmet was dropped or hit then some paint could flake off which
would result in corrosion through rusting. A better method would have been to galvanise the metal.
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Fig 14. Galvanising process
70. Galvanising involves degreasing the metal and then dipping it into liquid zinc, it is then
cooled in air. The process allows the molten zinc to alloy itself with the steel which forms a thin
coat around it (fig 14). Then if the helmet is scratched it the zinc that is scratched rather than the
steel underneath.
71. Working conditions/environment. The working conditions of the mk1 would be difficult to
alter, however a big problem with a helmets lifespan is due to user error, this could be soldiers
throwing it around and causing dents and scratches. The only way to improve the working
conditions is to better educate the user.
CONCLUSION
72. The mk1 helmet was the first ballistic helmet issued to the British Army since medieval ages,
it was rushed into service as what would today be termed an “urgent operational requirement” in
response to the increase in injuries from overhead artillery fire. Many soldiers and officers were
initially dubious about it and failed to understand its abilities, this led to misuse or over confidence
in it, coupled to this was the fact that injuries actually increased after it was introduced (due to the
reduction in deaths which would’ve occurred) meant that its issue required a change in thinking for
the British Army.
73. This was mirrored nearly 60 years later with the issue of the MK6 helmet, the first plastic
helmet issued to British soldiers was problematic as again a change in thinking was required to
accept plastic helmets after so many years with steel ones, the heavy weight of steel was more
reassuring than plastic and as everyone “knows” steel is hard and plastic is weak.
74. So, despite the increased benefits that material technology can bring, the most important
aspect to remember is what the customer wants or is willing to accept. Without trust or
understanding of the material in question, the customer is unlikely to use it, perhaps this is the
biggest problem armour manufacturers will face as they introduce ever lighter and different armour
materials.
75. As someone who has used helmets repeatedly on operations but never really thought about
how it works or what it is capable of, I found this assignment very interesting. I think there is a real
need for the development of helmets with increased ballistic protection. The use of single shot
attacks on ISAF troops in Afghanistan demonstrates the need for head protection from high
velocity, high kinetic energy rounds.

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Bibliography
Farrar, CL; Leeming, DW; Royal Military College of Science, Shrivenham. (1982). Military
Ballistics-A basic manual. Oxford: BRASSEYS.
Fundus, M. (2013). Ballistic Protection-Trends in Body Armour and Helmets. Berlin: ESK Ceramics
Gmbh and Co. KG.
http://eandt.theiet.org/magazine/2014/06/putting-a-lid-on-it.cfm. (2014, November 12). Retrieved
from the IET.
W.Bolton. (1998). Engineering Materials Technology (Third ed.). Oxford: Butterworth-Heinemann.
Materials Précis, Blocks 1-4. ESD DSEME Bordon.