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| Color
Code and Alloying Elements for Various Tungsten Electrode Alloys |
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AWS
A5.12
Classification |
Color * |
Alloying
Element |
Alloying
Oxide |
Alloying
Oxide % |
Application |
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| EWP |
Green |
Pure tungsten |
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AC & DC |
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| EWCe-2 |
Orange |
Cerium |
CeO2 |
2 |
AC & DC |
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| EWLa-1 |
Black |
Lanthanum |
La2O3 |
1 |
DC |
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| EWLa-1.5 |
Gold |
Lanthanum |
La2O3 |
1.5 |
DC |
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| EWLa-2 |
Blue |
Lanthanum |
La2O3 |
2 |
DC |
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| EWTh-1 |
Yellow |
Thorium |
ThO2 |
1 |
DC |
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| EWTh-2 |
Red |
Thorium |
ThO2 |
2 |
DC |
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| EWZr-1 |
Brown |
Zirconium |
ZrO2 |
0.25 |
AC |
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| EWG |
Gray |
Not Specified |
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Specified by
manufacturer |
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| * Color may be
applied in the form of bands, dots or other at any point on the surface of
the electrode. |
| Reference: AWS
code |
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| Current-carrying
Capabilities of Various Types and Diameters of Tungsten Electrodes |
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Electrode
Diameter
in. (mm) |
DCEN
(A) |
DCEP
(A) |
AC
Unbalanced
Wave (A) |
AC Balanced
Wave (A) |
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| EWX-X |
EWX-X |
EWP |
EWX-X |
EWP |
EWX-X |
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| 1/16 (1.6
mm) |
70-150 |
10 to 20 |
50-100 |
70-150 |
30-80 |
60-120 |
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| 3/32 (2.4
mm) |
150-250 |
15-30 |
100-160 |
140-235 |
60-130 |
100-180 |
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| 1.8 (3.2
mm) |
250-400 |
25-40 |
150-200 |
225-325 |
100-180 |
160-250 |
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| 5/32
(4.0) |
400-500 |
40-55 |
200-275 |
300-400 |
160-240 |
200-320 |
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| 3/16 (4.8
mm) |
500-750 |
55-80 |
250-350 |
400-500 |
190-300 |
290-390 |
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| 1/4 (6.4
mm) |
750-1000 |
80-125 |
325-450 |
500-630 |
250-400 |
340-525 |
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| Reference: GCIL
Module |
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| Current-carrying
Capabilities of Various Types and Diameters of Tungsten Electrodes |
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Electrode
Diameter
in. (mm) |
2% Thoriated
on DC (A) |
Pure
Tungsten
on AC (A) |
Zirconiated
Tungsten
on AC (A) |
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| 0.010
(0.25 mm) |
15 |
15 |
15 |
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| 0.020
(0.5 mm) |
20 |
20 |
20 |
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| 0.040
(1.0 mm) |
80 |
30 |
60 |
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| 1/16 (1.6
mm) |
150 |
80 |
120 |
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| 3/32 (2.4
mm) |
250 |
130 |
180 |
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| 1.8 (3.2
mm) |
400 |
180 |
250 |
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| 5/32
(4.0) |
500 |
240 |
320 |
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| 3/16 (4.8
mm) |
750 |
300 |
390 |
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| 1/4 (6.4
mm) |
1000 |
400 |
525 |
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| Reference:
Article by Mr. Frank Armao (ESAB) |
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| Good to know
tips when welding Steel On The Go |
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| Thungsten
electrode are available with diameters ranging from 0.5 to 6.4 mm |
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| Alloyed
tungsten electrodes have a higher current carrying capacity, provide greater
arc stability, |
| easier arc starting and less weld metal contamination due
to erosion of tungsten electrode. |
| Electrode
size should be chosen that will operate near to its maximum current carrying
capacity |
| without
overheating (electrode should remain shiny after use). |
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| Thoriated
tungsten normally used as sharpend tip (like other electrode on DCEN) |
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| Autogenus means
only fusion with no added filler metal |
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| Application of
TIG is for thin (gauge material) and is clean process |
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| In GTAW, filler
rod metal feed manually similar to oxyacetylen welding |
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| 60-70% of the
time, we use DCEN for TIG |
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| AC is used for
aliminum and magnesium, with bell type electrode |
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| Pointed type electrode are used for DCEN (steel and
stainless steel applications), taper is 2 to 2-1/2 |
| times of diameter in length. |
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| Minimum inside diameter of gas nozzle also equal or above
3 times of diameter of electrode |
| To
make electrode point end type (taper it for DC straight polarity like
EWTh-2), grinding shall be done |
| length wise and
on a stone dedicated for tungsten grinding only. |
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| Filler metal ER
70S-2 is very popularfor on carbon steel-GTAW |
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| ESO (Electrical
Stick Out) is about 1 to 2 times of filler metal diameter |
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| Larger electrode extension (ESO) often used on fillet weld
and it needs higher gas flow rate as well |
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| In
DCEN welding, about 80 percent of the arc energy goes into the work, and the
tungsten electrode has to dissipate |
| only
about 20 percent. Because we don't have to dissipate much heat, we can weld
with relatively small |
| diameter
electrodes. A 3/32 in. diameter electrode can carry up to 250 amps. It also
means we can grind the electrode |
| tip to a sharp,
conical point to concentrate the arc, and it won't deteriorate quickly. |
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| More
heat goes into the tungsten electrode in AC GTAW than in DCEN GTAW. This
means two things. First, you need |
| a
larger diameter tungsten electrode to carry, for example, 200 amps AC than
you would to carry 200 amps DC. |
| Second, if you grind the tungsten to a point and use it in
AC welding, tip rapidly deteriorates. The traditional solution |
| to this is not to grind a point on the
tungsten. Most AC GTAW is performed with a blunt-tip electrode. |
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| This tip
rapidly forms a round ball while welding. |
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| Usually Argon is used for steel and stainless steel;
Helium for aluminum, manganesium, copper |
| Flow rate of
15-20 CFH with argon, 20-25 CFH for Ar/He mix, 15-35 CFH for Helium |
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| In
manual GTAW-Steel, Argon used under and above 3.2 mm (1/8 in.) for better
pool control, Helium |
| over 3.2 mm (1/8 in.) for higher speed than Argon, Ar+He
Mix. for over 3.2 mm (1/8 in.) metal thickness. |
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| In
machine GTAW-Steel, Argon used under and above 3.2 mm (1/8 in.) for better
pool control, Helium |
| over 3.2 mm
for higher speed than Argon, Ar+He Mix. for over 3.2 mm metal thickness. |
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