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TIG All positions One side only 0.8 < t <1.5 A slight peak formed by
the edges limits
deformation
TIG Horizontal One side only 0.8 < t < 5 Chamfered card, stainless
steel support, clamped weld
TIG All positions One side only 1.5 < t < 5 Tack-welded free edges
back-weld
possible
Tack-welded free edges.
TIG All positions One side only 4 < t < 6 Angle same principle but
with offset bevel
MIG All positions One side only 2.5 < t < 6 Back-weld necessary after
with back-weld gouging to base of
first pass
MIG All positions One side only 2.5 < t < 6 Stainless steel support
MIG All positions One side only 2.5 < t < 6
MIG Horizontal One side only 6 < t < 25 Back-weld necessary after
and overhead* with back-weld gouging to base of first
pass.
Clearance: 1.5 mm max.
MIG Horizontal One side only 4 < t < 25 Ribbed stainless
and vertical* steel support
ALUMINIUM IN COMMERCIAL VEHICULES CHAPTER VIII WELDING 114 | 115
3.7. Edge preparation for
MIG welding
Just the most frequent examples
are given in the Table VIII.1
For more details please consult
EN ISO 9692-3.
* X-shaped bevels are preferred for components 6 mm > t > 25 mm to restrict deformation due to welding.
TABLE VIII.1
EDGE PREPARATION
80°
2 mm 1 mm
1 mm
1 mm
1 mm
2 mm
e
e
80°
80°
115
EUROPEAN ALUMINIUM ASSOCIATION
CHOICE OF FILLER METALS AS A FUNCTION OF THE ALLOY COMBINATION
TABLE VIII.2
(a) 5000 series alloys with more than 3.5% Mg are sensitive to intergranular corrosion when exposed to temperatures over 65°C
and when used in certain aggressive environments (see section 2.2.6 in Chapter XI).
(b) 5000 series alloys with less than 3% Mg and 3000 series alloys that contain magnesium may be sensitive to hot cracking.
(c) The mechanical performance of the weld depends on the internal soundness of the castings. Gassed materials and injection
mouldings are considered to be non-weldable.
(d) The percentage of silicon in the filler wire must be as near as possible to that in the casting.
(e) The welding of aluminium-silicon castings (40000 series) to 5000 series alloys should be avoided where possible as Mg2Si intermetallics
form in the weldment and weaken the joint.
Each combination has three possible choices - indicated where the lines intersect - depending on the selected criterion:
Optimum mechanical properties: top line – Optimum resistance to corrosion: middle line – Optimum weldability:
bottom line
The filler metal indicated is: 4 : series 4xxx 4043A, 4045, 4047A – 5 : series 5xxx 5356, 5183, 5556A
Alloy A
Wrought 5
5000 Series 5 (a)
Mg < 3% 4 - 5 (b)
Wrought 5 5
5000 Series 5 5
Mg > 3% (a) 5 5
Wrought 5 - 4 5 - 4 5 - 4
6000 Series 5 5 5
4 4 4
Wrought 5 - 4 5 - 4 5 - 4 5 - 4
7000 Series 5 5 5
without copper 4 4 4
Cast 4 (e) 5 - 4 (e) 4 4 4 (d)
Si > 7% 4 5 4 4
(c) 4 4 4 4
Wrought Wrought Wrought Wrought Cast
Alloy B 5000 Series 5000 Series 6000 Series 7000 Series Si > 7%
Mg < 3% Mg > 3% without copper (c)
116
ALUMINIUM IN COMMERCIAL VEHICULES CHAPTER VIII WELDING 116 | 117
Most of the alloys listed in
Chapter V are weldable and also
combinations of these alloys are
possible. Welding consumables
are not available in exactly the
same chemical composition as
the base metal to be joined.
There are wires and rods in the
4XXX and 5XXX series, namely
4043A, 4045, 4047A, 5183,
5356 and 5556A in the market
(see also ISO 18273). In the Table
VIII.2 , with the recommendation
of the best suited weld consumable,
we distinguish between different
requirements for the weld:
optimal strength, good corrosion
resistance and weldability. A
choice must be made according
to the relative importance of
these three requirements.
The weld consumables should be
stored in their sealed package
and once a package is open, it
should be kept in a dry atmosphere,
because humidity on the
surface of the wire or rod causes
porosity in the weld. If open reels
of filler wire are exposed to
ambient climatic conditions for a
longer period (months), it is recommended
to dry them in a
warming box at approx. 80° C for
one night before use.
SELECTION OF WELDING PROCESS
TABLE VIII.3
Process TIG MIG
Atmosphere Inert Inert
Electrode Refractory Consumable
Current A.C. D.C. Smooth Pulsed Pulsed Pulsed
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