3.1 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 (~)
3.2 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.
3.0 TIG welding of materials
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)
1.5
1.5
2
2.5
1.5
2
2.5
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–
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BOC Smootharc TIG 185 AC/DC Operating Manual
Summary of Contents for Smootharc TIG185 AC/DC
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