GTAW Flashcards
The word ‘TUNGSTEN’ refers to what?
The pure element
Tungsten’s melting point is…
6170 degrees Fahrenheit
All GTAW electrodes start with the letters…
EW
The ‘E’ stands for…
Electrode
The ‘W’ stands for…
include the German name as well
Tungsten
From Wolfram, which is German for tungsten
Electrodes are further identified by the element with which they are alloyed. Identify the following by what they stand for…
Th... La... Ce... Zr... P...
Th…Thoriated
La…Lanthanated
Ce…Ceriated
Zr…Zirconiated
P…pure
EWla-1.5%
In the electrode classification above what does the 1.5% stand for?
Indicated the percentage of element that is in the electrode…
1.5% lanthanated
The key material GTAW electrodes are comprised of…
Tungsten
GTAW electrodes with a red color code indicate:
A. Pure tungsten
B. 1.7% - 2.2% Thoriated
C. 1.3% Lanthanated
D. 1.8% -2.2% ceriated
B. 1.7% - 2.2% Thoriated
GTAW electrodes come in diameters of:
1/8”
0.040”
5/32”
All of the above
All of the above
What type of electrode is EWP?
Color code?
Current?
Perfect for welding on what kind of material?
Pure
Green
AC
Aluminum
What electrode type is EWCe-2?
Color code?
Current?
2% Ceriated
Orange
DCEN, AC
What electrode type is EWLa-1?
Color code?
Current?
1% Lanthanated
Black
DCEN, AC
What electrode type is EWLa-1.5%?
Color code?
Current?
1.5% Lanthanated
Gold
DCEN, AC
What electrode type is EWLa-2%?
Color code?
Current?
2% Lanthanated
Blue
DCEN, AC
What electrode type is EWZr-1?
Color code?
Current?
1% Zirconiated
Brown
AC
What electrode type is EWTh-1?
Color code?
Current?
1% Thoriated
Yellow
DCEN, Inverter AC
What electrode type is EWTh-2?
Color code?
Current?
2% Thoriated
Red
DCEN, Inverter AC
What electrode type is EWG?
Color code?
Current?
General
Gray
Manufacturer Specified
GTAW electrodes with a green color code indicate:
Pure tungsten
EWP electrodes contain a minimum of _____ tungsten, with no additional __________ ___________.
99.5%
Alloying elements
EWP (pure tungsten) provides good _____ __________ when used with _________ current.
Arc stability
AC current either balanced-wave or continuous high frequency
The tip of the EWP electrode maintains…
A clean, balled end that promotes good arc stability
EWP electrodes are usually used with AC but may also be used with ______ but doesn’t provide the arc initiation and arc stability characteristics
DC
EWP electrodes are generally used for welding what?
Aluminum and Magnesium alloys
EWTh electrode characteristics include
Easy are starting
Excellent arc performance
Long service life
Withstands high amps
Note: contains Thoria which is radioactive.
EWLa electrode characteristics include:
Easy arc start
Arc stability
Good service life
What is the best non-radioactive alternative to EWTh-2 electrodes?
EWLa-1.5
ELa-2 is better suited for ________ ________ __________ and numerous _____________.
Short weld cycles
Re-ignitions
GTAW electrode that offers the best performance and longevity for welding higher current mild steel in DC - polarity
1.7% - 2.2% Thoriated
If the amount of current used exceeds the capability of the electrode (diameter), tungsten inclusions in the weld may result. This can be identified with radiographic inspection and is known as:
Tungsten spitting
As a general rule, the inside diameter of the gas nozzle should be a minimum of:`
3x the diameter of the electrode
Tungsten boasts the highest melting point of any metal:
6191 degrees Fahrenheit
The AWS standard that guides GTAW electrodes is:
A5.12
AWS GTAW electrode classification EWG:
A. Zirconiated
B. Rare earth tungsten(varies per manufacturer)
C. Ceriated
D. Pure tungsten
Rare earth tungsten
AWS GTAW electrode color classification EWP:
Green
EWTh electrodes are superior to EWP electrodes in several ways:
Higher current capacity Longer life Greater resistance to contamination of the weld Arc starting is easier More stable arc
EWTh electrodes maintain what kind of tip?
Sharpened
Sharpened tips are desired for __________ welding operations
DCEN
Electrode tip preferred for AC welding:
Balled end
Compared to EWP electrodes, the EWCe electrode advantages are:
Facilitate arc starting
Improve arc stability
Reduce rate of vaporization or burn-off
Work well with either AC/DC polarity
AWS GTAW electrode classification with excellent low amperage arc staring:
EWP
Electrodes that can be used as a non-radioactive substitute for EWTh-2
EWLa-1
EWLa-1.5
EWLa-2
EWZr electrode advantages v.s pure tungsten
Arc stability and starting
Recommended over EWP for radiographic-quality weld on aluminum and magnesium
Balls up easier
Higher resistance to contamination
With AC welding, EWP or EWZr electrodes form a _______ ______.
Balled end
With DC welding, EWTh, EWCe and EWLa electrodes are usually used, and the electrode end is usually ground to a specific included angle and is often __________.
Truncated
Small-diameter electrodes can be used with a _________ ____________ preparation for _______ welding
Square end
DCEN
Tungsten tips are generally prepared by:
Grinding
Balling
Chemical sharpening
What are the 3 main advantages of GTAW electrodes
One of the highest melting points of all metals @ 6170’ F
Low electrical resistance
Good heat conductivity
If tungsten spitting occurs:
Change the type of electrode
Use a larger diameter electrode
Decrease the welding current
GTAW-P is usually applied with electrode negative(DCEN)
TRUE OR FALSE
TRUE
Generally, the GTAW-P adjustments are pre-set in the power source with the minimal adjustability from the operator.
True of false
False
PPS stands for:
Pulses per second
In pulsed DC welding, the pulse current level is usually set at:
2-10x the background current
Advantages of pulsed current include:
Greater penetration
Minimizes distortion
Equal penetration to joints with dissimilar metal thicknesses
Ceriated tungsten requires special precautions due to radioactive dust concerns
True or false
False