Steel Tig Welding; Copper Tig Welding; Tips For Ac Tig Welding; Gtaw Process - Lincoln Electric INVERTEC V205-T DC Operator's Manual

V205-T DC & V205-T AC/DC

STEEL TIG WELDING

The TIG process is very effective for welding both carbon steel and
alloy steel, especially in applications requiring precision results.
DC Electrode Negative Polarity is required. Since this process does
not include the removal of impurities, proper cleaning and prepa-
ration of the edges is required.
FILLER MATERIAL:
The filler rods must deposit welds with mechanical characteristics
appropriate for the application.

COPPER TIG WELDING

Since TIG welding is a process characterized by high heat concen-
tration, it is particularly suitable for welding materials with high
thermal conductivity, like copper. As with steel, the DC Electrode
Negative Polarity is employed, with argon as protective gas.
Considering the fluidity of molten copper, the use of backup sup-
port may prove useful.
FILLER MATERIAL:
In order to avoid the oxidation of the molten material, filler materi-
als containing phosphorus, silicon or other deoxidating materials
are typically used. The mechanical properties can also be
improved through the use of silver.

TIPS FOR AC TIG WELDING

(AC/DC model only)
AC Inverter TIG power sources offer two significant advantages
over conventional Silicon Controlled Rectifier (SCR) / transformer
power sources:
1. The AC wave balance can be set to a higher percentage elec-
trode negative which minimizes tungsten heating and erosion.
2. The AC frequency can be varied to "focus" the arc. Increasing
the AC frequency above 60Hz will narrow the cone shape arc
from the tungsten's tip. Decreasing the AC frequency below
60Hz will broaden the cone shape arc from the tungsten's tip.
Electrode Polarity
Electrode Tip Preparation
Electrode Type
Electrode Size-in. (mm)
.010 (0.25)
.020 (0.50)
.040 (1.0)
1/16 (1.6)
3/32 (2.4)
1/8 (3.2)
Tungsten electrodes are classified as follows by the American Welding Society (AWS):
+2% Thoria .......................EWTh-2 ...red
+1.5% Lanthana ...............EWLa-1 ...black

GTAW Process

DC-
Sharpened
EWTh-2, EWLa-1
Up to 15 A.
Up to 15 A.
Up to 80 A.
Up to 150 A.
Up to MAX. A.
X
The two above benefits can be used to maintain a tight focus of
the arc for precise heat control and tight joint access. Because of
the AC inverters abilities in these areas the following recommen-
dations are made as a starting point:
• A 2% Thoriated tungsten is recommended instead of the Pure
tungsten that is normally recommended for AC welding.
Thoriated tungstens emit electrons easier and therefore will
improve starting.
• Sharpen the tungsten to a point. Normally it is recommended
to pre-ball a pure tungsten when AC welding with a convention-
al power source. However, the AC inverter with it's extended
AC balance control minimized tungsten heating thus allowing
for a pointed tungsten to be used.
• Set the AC Balance control to maximum 85% electrode nega-
tive. This can be reduced if the material welded is heavily oxi-
dized, however starting at maximum and adjusting to less is
desired.
• Set the AC Frequency in the 100 to 120 Hz range. This is a
"Sweet Spot" for most aluminum applications.
AC
Sharpened
EWTh-2, EWLa-1
Up to 15 A.
Up to 20 A.
Up to 60 A.
Up to 130 A.
Up to MAX. A.
X
B 8
OPERATION
Approximate Argon
Gas Flow Rate
C.F.H. (l/min.)
Stainless
Aluminum Steel
3-8 (2-4) 3-8 (2-4)
5-10 (3-5) 5-10 (3-5)
5-10 (3-5) 5-10 (3-5)
5-10 (3-5) 9-13 (4-6)
13-17 (6-8) 11-15 (5-7)
15-23 (7-11) 11-15 (5-7)