| Color Code and Alloying Elements for Various Tungsten Electrode Alloys | ||||||||
| AWS
A5.12 Classification |
Color * | Alloying
Element |
Alloying
Oxide |
Alloying
Oxide % |
Application | |||
| EWP | Green | Pure tungsten | AC & DC | |||||
| EWCe-2 | Orange | Cerium | CeO2 | 2 | AC & DC | |||
| EWLa-1 | Black | Lanthanum | La2O3 | 1 | DC | |||
| EWLa-1.5 | Gold | Lanthanum | La2O3 | 1.5 | DC | |||
| EWLa-2 | Blue | Lanthanum | La2O3 | 2 | DC | |||
| EWTh-1 | Yellow | Thorium | ThO2 | 1 | DC | |||
| EWTh-2 | Red | Thorium | ThO2 | 2 | DC | |||
| EWZr-1 | Brown | Zirconium | ZrO2 | 0.25 | AC | |||
| EWG | Gray | Not Specified | 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 | ||||||||
| Current-carrying Capabilities of Various Types and Diameters of Tungsten Electrodes | ||||||||
| 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 | |||
| 1/16 (1.6 mm) | 70-150 | 10 to 20 | 50-100 | 70-150 | 30-80 | 60-120 | ||
| 3/32 (2.4 mm) | 150-250 | 15-30 | 100-160 | 140-235 | 60-130 | 100-180 | ||
| 1.8 (3.2 mm) | 250-400 | 25-40 | 150-200 | 225-325 | 100-180 | 160-250 | ||
| 5/32 (4.0) | 400-500 | 40-55 | 200-275 | 300-400 | 160-240 | 200-320 | ||
| 3/16 (4.8 mm) | 500-750 | 55-80 | 250-350 | 400-500 | 190-300 | 290-390 | ||
| 1/4 (6.4 mm) | 750-1000 | 80-125 | 325-450 | 500-630 | 250-400 | 340-525 | ||
| Reference: GCIL Module | ||||||||
| Current-carrying Capabilities of Various Types and Diameters of Tungsten Electrodes | ||||||||
| 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 | |||||
| 0.020 (0.5 mm) | 20 | 20 | 20 | |||||
| 0.040 (1.0 mm) | 80 | 30 | 60 | |||||
| 1/16 (1.6 mm) | 150 | 80 | 120 | |||||
| 3/32 (2.4 mm) | 250 | 130 | 180 | |||||
| 1.8 (3.2 mm) | 400 | 180 | 250 | |||||
| 5/32 (4.0) | 500 | 240 | 320 | |||||
| 3/16 (4.8 mm) | 750 | 300 | 390 | |||||
| 1/4 (6.4 mm) | 1000 | 400 | 525 | |||||
| Reference: Article by Mr. Frank Armao (ESAB) | ||||||||
| Good to know tips when welding Steel On The Go | ||||||||
| Thungsten electrode are available with diameters ranging from 0.5 to 6.4 mm | ||||||||
| 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). | ||||||||
| Thoriated tungsten normally used as sharpend tip (like other electrode on DCEN) | ||||||||
| Autogenus means only fusion with no added filler metal | ||||||||
| Application of TIG is for thin (gauge material) and is clean process | ||||||||
| In GTAW, filler rod metal feed manually similar to oxyacetylen welding | ||||||||
| 60-70% of the time, we use DCEN for TIG | ||||||||
| AC is used for aliminum and magnesium, with bell type electrode | ||||||||
| Pointed type electrode are used for DCEN (steel and stainless steel applications), taper is 2 to 2-1/2 | ||||||||
| times of diameter in length. | ||||||||
| 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. | ||||||||
| Filler metal ER 70S-2 is very popularfor on carbon steel-GTAW | ||||||||
| ESO (Electrical Stick Out) is about 1 to 2 times of filler metal diameter | ||||||||
| Larger electrode extension (ESO) often used on fillet weld and it needs higher gas flow rate as well | ||||||||
| 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. | ||||||||
| 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. | ||||||||
| This tip rapidly forms a round ball while welding. | ||||||||
| 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 | ||||||||
| 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. | ||||||||
| 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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