The choice of material and the condition in which
it is required must depend largely upon design
requirements and the manufacturing processes
within the factory. The alloys most commonly used
in vehicle body work are as shown in Table 4.9.
136 Repair of Vehicle Bodies
Table 4.5 General characteristics of all wrought forms of aluminium alloys
General characteristics
Inert-gas Welding
shielded resistance (spot,
Purity Temper or Cold arc (MIG seam, flash Metal
or alloy condition forming Machining Durability or TIG) butt or stud) b,c Oxy-acetylene d arc
5251 F V G V Ve E Ge Fe
O V G
H22 G G
H24 G V
H28 G V
H39X F V F Ve E Ge Ge
5454 F V V V Ve E Fe N
O V V
H22 G G
H24 G G
5154 F V V Vf E E F N
O V Vf
H22 G Gf
H24 F Gf
H28
5083 F G E Vf E E F N
O G Vf
H22 F Ff
H24 G Ff
6082 F V G G Ve V Fe Ge
O E G G
T4 G V V
T6 F E G
T451
T651
1200 F E F V E V V G
O E F
H12 V F
H14 V F
H16 G G
H18 F G
3103 F E F V E E V G
O E F
H12 V F
H14 V F
H16 G G
H18 F G
(a) Materials are graded thus: E excellent; V very good; F fair; P poor; N not recommended.
(b) The mechanical properties of work hardened or heat-treated materials will be reduced in the vicinity of the weld.
(c) The weld zone is generally discernible after anodic treatment, the degree depending on the material and welding process.
(d) The oxy-acetylene process is normally recommended only for material thinner than 6–4 mm.
(e) Filler or electrode of other than parent metal composition is recommended.
(f) Applicable at temperature of 70 °C and less.
Table 4.6 Chemical composition limits1 and mechanical properties of unalloyed aluminium plate, sheet and strip (BS 1470)
Elongation on 50 mm
Elongation on
Others 2 Thickness Tensile strength
Materials thicker than 5.65 over
Material Tolerance Silicon Iron Copper Manganese Magnesium Chromium Nickel Zinc Gallium Titanium Each Total Aluminium __ Min. Max. 0.5 mm 0.8 mm 1.3 mm 2.6 mm 3.0 mm 12.5 mm thick
designation category (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) min. (%) Temper 4 (mm) (mm) (N/mm 2 ) (N/mm 2 ) min. (%) min. (%) min. (%) min. (%) min. (%) (min.) (%)
1080A A 0.15 0.15 0.03 0.02 0.02 – – 0.06 0.03 0.02 0.02 – 99.80(3) F 3.0 25.0 – – – – – – – –
O 0.2 6.0 – 90 29 29 29 35 35 –
H14 0.2 12.5 90 125 5 6 7 8 8 –
H18 0.2 3.0 125 – 3 4 4 5 – –
1050A A 0.25 0.40 0.05 0.05 0.05 – – 0.07 – 0.05 0.03 – 99.50(3) F 3.0 25.0 – – – – – – – –
O 0.2 6.0 55 95 22 25 30 32 32 –
H12 0.2 6.0 80 115 4 6 8 9 9 –
H14 0.2 12.5 100 135 4 5 6 6 8 –
H18 0.2 3.0 135 – 3 3 4 4 – –
1200 A 1.0 Si _ Fe 0.05 0.05 – – – 0.10 – 0.05 0.05 0.15 99.99(3) F 3.0 25.0 – – – – – – – –
O 0.2 6.0 70 105 20 25 30 30 30
H12 0.2 6.0 90 125 4 6 8 9 9 –
H14 0.2 12.5 105 140 3 4 5 5 6
H16 0.2 6.0 125 160 2 3 4 4 4 –
H18 0.2 3.0 140 – 2 3 4 4 – –
1 Composition in per cent (m/m) maximum unless shown as a range or a minimum.
2 Analysis is regularly made only for the elements for which specific limits are shown. If, however, the presence of other element s is suspected to be, or in the case of routine analysis is
indicated to be, in excess of the specified limits, further analysis should be made to determine that these other elements are not in excess of the amount specified.
3 The aluminium content for unalloyed aluminium not made by a refining process is the difference between 100.00% and the sum of all other metallic elements in amounts of 0.010% or more
each, expressed to the second decimal before determining the sum.
4 An alternative method of production, designated H2, may be used instead of the H1 routes, subject to agreement between supplier and purchaser and providing that the same specified
properties are achieved.
_ So
Table 4.7 Chemical composition limits1 and mechanical properties of aluminium alloy plate, sheet and strip (non-heat-treatable) (BS 1470)
Elongation on 50 mm
0.2% Elongation on
Other
Others 2 Thickness
proof
Tensile strength
Materials thicker than 5.65 over
Material Tolerance Silicon Iron Copper Manganese Magnesium Chromium Nickel Zinc restrictions Titanium Each Total Aluminium __ stress min. Min. Max. 0.5 mm 0.8 mm 1.3 mm 2.6 mm 3.0 mm 12.5 mm thick
designation category (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Temper 3 (mm) (mm) (N/mm 2 ) (N/mm 2 ) (N/mm 2 ) min. (%) min. (%) min. (%) min. (%) min. (%) (min.)
3103 A 0.50 0.7 0.10 0.9–1.5 0.30 0.10 – 0.20 0.10 – 0.05 0.15 Rem.* F 0.2 25.0 – – – – – – – – –
Zr _ Ti O 0.2 6.0 – 90 130 20 23 24 24 25 –
H12 0.2 6.0 – 120 155 5 6 7 9 9 –
H14 0.2 12.5 – 140 175 3 4 5 6 7 –
H16 0.2 6.0 – 160 195 2 3 4 4 4 –
H18 0.2 3.0 – 175 – 2 3 4 4 – –
3105 A 0.6 0.7 0.30 0.30–0.8 0.20–0.8 0.20 – 0.40 – 0.10 0.05 0.15 Rem. O 0.2 3.0 – 110 155 16 18 20 20 – –
H12 0.2 3.0 115 130 175 2 3 4 5 – –
H14 0.2 3.0 145 160 205 2 2 3 4 – –
H16 0.2 3.0 170 185 230 1 1 2 3 – –
H18 0.2 3.0 190 215 – 1 1 1 2 – –
5005 A 0.30 0.7 0.20 0.20 0.50–1.1 0.10 – 0.25 – – 0.05 0.15 Rem. O 0.2 3.0 – 95 145 18 20 21 22 – –
H12 0.2 3.0 80 125 170 4 5 6 8 – –
H14 0.2 3.0 100 145 185 3 3 5 6 – –
H18 0.2 3.0 165 185 – 1 2 3 3 – –
5083 B 0.40 0.40 0.10 0.40–1.0 4.0–4.9 0.05–0.25 – 0.25 – 0.15 0.05 0.15 Rem. F 3.0 25.0 – – – – – – – – –
O 0.2 80.0 125 275 350 12 14 16 16 16 14
H22 0.2 6.0 235 310 375 5 6 8 10 8 –
H24 0.2 6.0 270 345 405 4 5 6 8 6 –
5154A B 0.50 0.50 1.10 0.50 3.1–3.9 0.25 – 0.20 0.10–0.50 0.20 0.05 0.15 Rem. O 0.2 6.0 85 215 275 12 14 16 18 18 –
Mn _ Cr H22 0.2 6.0 165 245 295 5 6 7 8 8 –
H24 0.2 6.0 225 275 325 4 4 4 6 6 –
5251 A 0.40 0.50 0.15 0.10–0.50 1.7–2.4 0.15 – 0.15 – 0.15 0.05 0.15 Rem. F 3.0 25.0 – – – – – – – – –
O 0.2 6.o 60 160 200 18 18 18 20 20 –
H22 0.2 6.0 130 200 240 4 5 6 8 8 –
H24 0.2 6.0 175 225 275 3 4 5 5 5 –
H28 0.2 3.0 215 255 285 2 3 3 4 4 –
5454 B 0.25 0.40 0.10 0.50–1.0 2.4–3.0 0.05–0.20 – 0.25 – 0.20 0.05 0.15 Rem. F 3.0 25.0 – – – – – – – – –
O 0.2 6.0 80 215 285 12 14 16 18 18 –
H22 0.2 3.0 180 250 305 4 5 7 8 – –
H24 0.2 3.0 200 270 325 3 4 5 6 – –
* Remainder
1 Composition in per cent (m/m) maximum unless shown as a range or a minimum.
2 Analysis is regularly made only for the elements for which specific limits are shown. If, however, the presence of other elements is suspected to be, or in the case of routine analysis is
indicated to be, in excess of the specified limits, further analysis should be made to determine that these other elements are not in excess of the amount specified.
3 An alternative method of production, designated H2, may be used instead of the H1 routes, subject to agreement between supplier and purchaser and providing that the same specified
properties are achieved.
_ So
Table 4.8 Chemical composition limits and mechanical properties of aluminium alloy plate, sheet and str ip (heat-treatable) (BS 1470)
0.2%
Elongation on 50 mm
Elongation on
Other
Others 2 Thickness
proof
Tensile strength
Materials thicker than 5.65 over
Material Tolerance Silicon Iron Copper Manganese Magnesium Chromium Nickel Zinc restrictions Titanium Each Total Aluminium __ stress min. Min. Max. 0.5 mm 0.8 mm 1.3 mm 2.6 mm 3.0 mm 12.5 mm thick
designation category (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Temper 3 (mm) (mm) (N/mm 2 ) (N/mm 2 ) (N/mm 2 ) min. (%) min. (%) min. (%) min. (%) min. (%) (min.)
2014A B 0.50–0.9 0.50 3.9–5.0 0.40–1.2 0.20–0.8 0.10 0.10 0.25 0.20 0.15 0.05 0.15 Rem.* 0 0.2 6.0 110 – 235 14 14 16 16 16 –
Zr _ Ti T4 0.2 6.0 225 400 – 13 14 14 14 14 –
T6 0.2 6.0 380 440 – 6 6 7 7 8 –
T451 6.0 25.0 250 400 – – – – – 14 12
25.0 40.0 250 400 – – – – – – 10
40.0 80.0 250 395 – – – – – – 7
Clad B 0.50–0.9 0.50 3.9–5.0 0.40–1.2 0.20–0.8 0.10 0.10 0.25 0.20 0.15 0.05 0.15 Rem. T651 6.0 25.0 410 460 – – – – – – 6
2014A Zr _ Ti 25.0 40.0 400 450 – – – – – – 5
40.0 60.0 390 430 – – – – – – 5
60.0 90.0 390 430 – – – – – – 4
90.0 115.0 370 420 – – – – – – 4
115.0 140.0 350 410 – – – – – – 4
2024 B 0.50 0.50 3.8–4.9 0.30–0.9 1.2–1.8 0.10 – 0.25 – 0.15 0.05 0.15 Rem. O 0.2 6.0 100 – 220 14 14 16 16 16 –
T4 0.2 1.6 240 385 – 13 14 14 – – –
1.6 6.0 245 395 – – – – 14 14 –
T6 0.2 1.6 345 420 – 7 7 8 9 – –
1.6 6.0 355 420 – – – – 9 9 –
O 0.2 6.0 110 – 235 12 12 14 14 14 –
T3 0.2 1.6 290 440 – 11 11 11 – – –
1.6 6.0 290 440 – – – – 12 12 –
T351 6.0 25.0 280 430 – – – – – 10 10
25.0 40.0 280 420 – – – – – – 9
40.0 60.0 270 410 – – – – – – 9
60.0 90.0 270 410 – – – – – – 8
90.0 115.0 270 400 – – – – – – 8
115.0 140.0 260 390 – – – – – – 7
*Remainder
_ So
Table 4.9 Standard aluminium alloys: availability, physical properties, and applications
Nominal
composition:
% alloying Physical properties
elements
Related BS/GE (remainder Coefficient
specification aluminium Standard forms a of linear
Purity or (BS 1470–1475) and normal Melting expansion Typical road transport
alloy (new (old BS alloy impurities) Hollow Density range °C per °C applications
nomenclature) designation) Mg Si Mn Sheet Plate Extrusions extrusions Tube g/cm 3 lb/in 3 (approx.) (20–100°C)
Non-heat-treatable alloys
1200 IC – – – ___ _ _ 2.71 0.098 660 0.000 023 5 Vehicle panelling where panel
beating is required; mouldings
and trim. Tank cladding
3103 N3 – – 1.2 ___b _b _b 2.73 0.099 645–655 0.000 023 5 Flat panelling of vehicles and
general sheet metal work.
Tank cladding
5251 N4 2.25 – 0.4 ___ – _ 2.69 0.097 595–650 0.000 024 Body panelling. Head boards
and drop sides. Truss panels in
buses. Cab panelling. Tanker
shells and divisions
5154A N5 3.5 – 0.4 _ – _ – _ 2.67 0.096 600–640 0.000 024 5 Welded body construction.
Tipper body panelling. Truss
panels in buses
5454 N51 2.7 – 0.8 Tanker shells and divisions
5083 N8 4.5 – 0.5 ___ – _ 2.65 0.096 580–635 0.000 024 5 Pressurized bulk transport at
ambient or low temperature
Heat-treatable alloys
6082 H30 0.7 1.0 0.5 ___ _ _ 2.70 0.098 570–660 0.000 023 5– All structural sections in
0.000 024c riveted vehicle bodies.
Tipper body panelling.
Highly stressed underframe
gussets, truss panels
(a) Other forms may be available by special arrangement.
(b) Not covered by British Standard (general engineering) specification.
(c) Depending on condition.
Metals and non-metals used in vehicle bodies 141
Alloy 5154A is suitable for use in car panels
which are to be pressed into shape; it is supplied in
either annealed condition or H2 condition, which are
the most suitable for press work on vehicle bodies.
Of the other materials, 1200 is a commercial purity
sheet, and is widely used for exterior and interior
panelling where no great strength is required. Types
3103, 5251, 5154A and 5056A are non-heat-treatable
alloys of the aluminium-magnesium range with a
strength of 90–325 N/mm2. They come in sheet
form, and provide a range of mechanical properties
to suit different applications. They are used extensively
in panel work, and also for forming, pressing
and machining, and can be welded without much difficulty.
The plate material 5083 is a medium-strength
non-heat-treatable alloy particularly suitable for
welding. It can be used for parts carrying fairly high
stress loads and is often used in the form of patterned
tread plate for floor sections.
For internal structure members which need to be
stronger than the outer panels, the heat-treatable
alloys usually used are 6063 and 6082, and in
odd cases 2014A. Type 6082 is a heat-treatable
medium-strength alloy which combines good
mechanical properties with high corrosion resistance.
Permissible stresses in this alloy can be as
high as 200 N/mm2 under static loading conditions,
although some reduction below this would
normally be made for transport applications where
there is a considerable element of dynamic loading.
The alloy is weldable by the inert gas arc
process, but there is a considerable loss of strength
near the weld owing to the annealing effect of the
welding process. Type 6063 is also a heat-treatable
alloy but of somewhat lower strength, and is used
mainly in applications requiring good surface finish
or where the parts are required to be anodized.
Alloy 2014A contains a greater percentage of copper
than the others, is more expensive, is more difficult
to form and is less resistant to corrosion, but
has the advantage of a greater tensile strength.
Fastenings and solid rivets can be of commercial
purity material or of aluminium alloy 5154A, and
for smaller sizes 6082 is sometimes used. Rivets
are also available in 5056A material, but should
not be used in cases where high temperatures occur
in service. Bolts used in bodywork are normally of
the 6082 alloy.
The condition in which heat-treatable alloys are
supplied should be related to their application or
use in bodywork. For example, if a section is to
remain straight and is part of a framework which is
to be bolted, riveted or welded in place, it is obvious
that the material used should already be fully
heat treated so that maximum strength is provided
to support the framework or structure of the body.
On the other hand, if the section has to be shaped,
bent or formed in any way the material should be
used in the annealed condition and then heat
treated after the shaping operations have all been
carried out.
Aluminium alloys are now being accepted by the
automobile manufacturers as a standard material
for exterior and interior trim, and are used for all
normal bright trim applications such as radiator
grilles, headlamp bezels, wheel trim, instrument
panels, body mouldings and window and windscreen
surrounds. Alloys used for trimming can be
divided into two groups: high-purity alloys bright
finished on one side only, in which the majority of
the trim components are made; and super-purity
alloys for use when maximum specular reflectivity
is an advantage, such as would be required by light
units.
4.8 Rubber
The value of rubber lies in the fact that it can be
readily moulded or extruded to any desired shape,
and its elastic quality makes it capable of filling
unavoidable and irregular gaps and clearances. It is
an ideal material in door shuts and as the gasket for
window glass, and in both instances it provides the
means for excluding dust and water, although with
windscreens and back-lights additional use has generally
to be made of a sealing material. Rubber
specifications have been built on the basis of the
properties of material which has given satisfaction.
One major difficulty has been to ensure and measure
resistance to weathering; rubber is subject to oxidation
by ozone in the atmosphere, and this results in
cracking. In addition to natural rubber, a variety of
types of synthetic rubbers are used by the motor
industry; these vary in price and characteristics, and
all are more expensive than natural rubber. For complete
ozone resistance, it is necessary to use either
butyl or neoprene rubber; both satisfy atmospheric
and ozone ageing tests. Butyl rubber, however, is
‘dead’ to handle and contains no wax, and so whilst
neoprene is costly its use is essential for some parts.
142 Repair of Vehicle Bodies
Sponge sealing rubbers can be provided with
built-in ozone resistance by giving them a live skin
of neoprene, and a further way of providing ozone
resistance is to coat the rubber components with
Hypalon; more recently, continuously extruded
neoprene sponge has been adopted. Apart from
weather resistance, the important requirement of
door and boot lid seals is that their compression
characteristics should ensure that they are capable
of accommodating wide variations in clearance,
without giving undue resistance to door closing.
Various types of foam rubber have been evolved
to suit the different parts of the car seating, and the
designer’s choice of material is governed by cost,
comfort, durability, the type of base, the type of
car, and whether it is a cushion or a squab, a rear or
front seat. When considering the foams available, it
is apparent that the number of permutations is
large. The types of foam available today fall into
seven broad categories. These are:
Moulded latex foam
Low-grade fabricated polyether
Fabricated polyether
Moulded polyether
Fabricated polyester
Polyvinyl chloride foam
Reconstituted polyether.
Latex foam today utilizes a mixture of natural and
synthetic latexes to obtain the best qualities of
both. After being stabilized with ammonia, natural
latex is shipped in liquid form to this country from
Malaysia, Indonesia and other rubber producing
countries. Synthetic latex, styrene butadiene rubber,
is made as a byproduct of the oil cracker plants.
Polyether foam can now be made in different grades,
and the physical properties of the best grades
approach those of latex foam. As a general guide,
service life and physical properties improve as
the density increases for any given hardness. As the
cost is proportional to weight, it follows that the
higher-performance foams are more costly.
Flexible polyurethane foam seats are replacing
heavy and complicated padded metal spring structures.
Moulded seats simplify assembly, reduce
weight and give good long-term performance.
A major innovation here has been the cold cure
systems. These produce foams of superb quality,
particularly in terms of strength, comfort and longterm
ageing. The systems are particularly suitable for
the newer seat technologies such as dual hardness,
where the wings are firm to give lateral support,
leaving the seat pad softer and more comfortable.
4.9 Sealers
The history of sealers is longer than that of the
motor car. Mastic, bitumen compounds and putties
of various kinds have been used since the invention
of the horseless carriage. It is likely that early
coach builders used putties of some kind – possibly
paint fillers – to bridge joints in various applications
on motor bodies, but it is generally conceded
that the first use of specialized sealers on a large
scale was in the early 1920s when, in America, the
pressed steel body became popular. In this country
it was 1927 before one of the first truly effective
sealers was introduced. It was known as Dum Dum
and is still in use. It was a modified roof sealer, and
proved to have many applications in body production.
It was not until the late 1930s, when all-steel
bodies and unitary construction became a common
feature of mass produced cars, that more thought
was given to the points that required the use of
sealing compounds, and to the nature of these
products. Amongst the first developed was interweld
sealing compound, primarily to prevent corrosion.
Since then, particularly in the post-war years, there
have been remarkable developments, probably
accelerated by criticisms from overseas markets
that British cars were susceptible to dust and water
entry. Companies specializing in the manufacture
of mastic compounds have developed a range of
materials which are now used not only for welding
and for general putty application but also for floor
pans, drip rails, body joints, exterior trim and many
other points, leading to well sealed car bodies
equal to any produced elsewhere in the world
(Figure 4.2, Table 4.10).
The term ‘sealer’ covers a wide variety of materials
used in the motor industry for sealing against
water and dust, from products which remain virtually
mastic throughout their life to others which
harden up but still retain some measure of elasticity.
They range from mixtures of inert fillers and semidrying
oils to heat curing plastisols which may be
applied in a thin paste form as an interweld sealer
or as extruded beads. Sealing compounds can be
categorized into the following general groups: oilbased
compositions, rubber-based compositions and
Metals and non-metals used in vehicle bodies 143
Figure 4.2 Problem areas requiring body sealing
