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10.0 TIG welding of materials
10.1 Application summary
Material
Type of current
Polarity
C-Mn steel
Direct current (-)
DC negative
Alloyed steel
Direct current (-)
DC negative
Copper and Cu alloys
Direct current (-)
DC negative
Nickel and Ni alloys
Direct current (-)
DC negative
Titanium and Ti alloys
Direct current (-)
DC negative
Aluminum and Al alloys
Alternating current (~)
Direct current (-) with Helium
DC negative
Magesium and Mg alloys
Alternating current (~)
10.2 C-Mn steel
TIG welding may be used for welding carbon steel
but because deposition rates are low, it is usually
only used for welding sheet and thin sections for
high quality applications, small components, and
root passes of multipass butt joints in plate and
pipe.
Standard DC TIG equipment is normally suitable and
DCEN polarity is usually chosen to provide good
workpiece heating.
Only inert or reducing gases should be used for TIG
welding and pure argon is normally recommended
as the shielding gas for steel.
Filler rods are usually selected to match the
chemical composition and the mechanical
properties of the parent plate. The weldability of
the steel may impose restrictions on the choice of
filler rod.
Steels with carbon contents above about 0.3%
are hardenable, and fast cooling will produce a
hard HAZ and this is liable to result in hydrogen
cracking. This form of cracking can be prevented by
use of preheat and suitable welding procedures.
C-Mn steel welding parameters
Plate thickness (mm)
0.8
1
1.5
2
1
1.5
2
Joint type
Fillet
Fillet
Fillet
Fillet
Butt
Butt
Butt
Number of passes
1
1
1
1
1
1
1
Tungsten electrode (mm)
1.6
1.6
1.6
2.4
1.6
1.6
2.4
Consumable size (mm)
1.6
1.6
2
2.4
1.6
2
2.4
Current (A)
70
90
110
130
80
120
140
Welding speed (cm/min)
30
30
30
25
20
20
20
Gasflow (l/min)
5
5
6
6
6
7
7
Shielding gas: Argon, Consumable ER70S-6, Position: Downhand, Polarity: DC–
Summary of Contents for BOC RAPTOR
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