tungsten electrode

Research and Development:

 

Traditional pure tungsten electrode has low emission efficiency, sagging and broken at high temperature. To overcome those shortcomings, new techniques to adapt to modern industry is developed. Rare earth metal oxides have excellent thermal electron emission ability. So now the development directions is to look for rare earth tungsten electrode to replace traditional pure tungsten electrode.

 

Application:

 

Tungsten Inert Gas (TIG) welding and Plasma Arc Welding (PAW).

 

Characteristics:

 

Starting arc, arc stability and weld quality have played an important role in TIG or PAW welding.

 

Classification:

 

2.0% Ceriated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWCe-2	CeO2	1.8-2.2%	Grey

 

This ceriated tungsten electrode is an replacement of EWT-2 lamp and welding electrode. Doping with 2.0% cerium oxide reduces the electron work function and improves  the ignition behaviour and the lifetime by reducing the rate of arc erosion

 

2.0% Thoriated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWTh-2	ThO2	1.8-2.2%	Red

 

The thoriated tungsten electrode was development specially for lamp and welding electrode. Doping with 2.0% thorium oxide can reduce the electron work function and improvethe recrystallization temperature strength. In addition the WT20 can be readily machined.

 

Pure Tungsten tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWP			Green

 

 Pure tungsten electrode contain a minimum of 99.95%wt tungsten,with no international alloying elements. pure tungsten electrode has a very high work function. and thus it is more difficult to start and produce a stable arc than other materials. Also,because of its high work function, the temperature at the tip is higher and grain growth occurs. This leads to an unstable arc, starting difficulty and a shorter service life. pure tungsten electrode is only used for AC welding.

 

1.0% lanthanated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWLa-1	La2O3	0.8-1.2%

 

By doping with 1.0% lanthanum oxide, 1.0% lanthanated tungsten electrode can increase the creep strength and recrystallization temperature compared to pure tungsten electrode. Additionally the oxide particles help to eliminate the poor machine ability  associated with pure tungsten electrode. 1.0% lanthanated tungsten electrode is preferred for machined components in a wide variety of application whereas 1.5% lanthanated tungsten electrode is used for welding electrode.

 

1.5% lanthanated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWLa-1.5	La2O3	1.3-1.7%

 

By doping with 1.5% lanthanum oxide, WL15 can increase the creep strength and recrystallization temperature compared to pure tungsten electrode. Additionally the oxide particles help to eliminate the poor machine ability  associated with pure tungsten electrode.

 

2.0% lanthanated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWLa-2	La2O3	1.8-2.2%

 

The most common lanthanated tungsten electrode contains 2 percent  lanthanum oxide (La2O3), referred to as lanthanum. In Europe and Japan, Lanthanated tungsten electrode has been the most popular alternative to 2% thoriated tungsten for most applications. it is available as 2%,1.5% and 1% lanthanated tungsten electrode.lanthanum Trioxide has the lowest work function

 

2.0% Yttriated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWY-2	YO2	1.8-2.2%

 

2% yttriated tungsten electrode (AWS classification EWY) ,which contain a minimum of 97.30% tungsten and .15 to .40%yttrium, is sometimes used for AC welding. it applies in military industry with narrow arc beam and high compressing strength.

 

0.3% Zirconiated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWZr-3	ZrO2	0.2-0.4%

 

0.3% Zirconiated tungsten electrodes (AWS classification EWZr-1) ,which contain a minimum of 99.10% tungsten and .15 to .40% zirconium, is most commonly used for AC welding because it balls up well in AC welding and has a more stable arc compared to EWP or Pure Tungsten. Its current carrying capability is equal to or greater than 2% thoriated tungsten electrodes.

 

0.8% Zirconiated tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWZr-8	Zr2O3	0.6-1.0%

 

Zirconiated tungsten electrode contain a small amount of zirconium oxide. Zirconiated tungsten electrode have welding characteristics that generally fall between those of pure and thoriated tungsten electrode.Zirconiated tungsten electrode  is most commonly used for AC welding because it balls up well in AC welding and has a more stable arc than pure tungsten electrode. it also resists contamination well in AC welding.

 

Tri-mix tungsten electrode:

 

 

Type	Oxide	Percentage	Tip color
EWX	La2O3,Y2O3,CeO2	1.8-2.2%	Sky blue

 

Tri-mix tungsten electrode combines three non-radioactive materials into one tungsten. The goal was to make the best possible tungsten electrode by balancing the migration and evaporation rates, while keeping the work function down. It starts and re-ignites very well, and it offers a particularly excellent service life in welding situations where welding cycles of at least 15 minutes are used.