Lesson 1
The Basics of Arc Welding
Lesson 2
Common Electric
Arc Welding Processes
Lesson 3
Covered Electrodes for Welding
Mild Steels
Lesson 4
Covered Electrodes for Welding Low Alloy Steels
Lesson 5
Welding Filler Metals for Stainless Steels
Lesson 6
Carbon & Low Alloy
Steel Filler Metals -
Lesson 7
Flux Cored Arc Electrodes Carbon Low Alloy Steels
Lesson 8
Hardsurfacing Electrodes
Lesson 9
Estimating & Comparing Weld Metal Costs
Lesson 10
Reliability of Welding Filler Metals
© COPYRIGHT 1998 THE ESAB GROUP, INC. LESSON II 2)   1% Thoriated Tungsten (AWS EWTh-1)  Color Code:  Yellow Good current carrying capacity, easy arc starting and provide a stable arc.  Less susceptible to contamination.  Designed for DC applications of nonferrous materials. 3)   2% Thoriated Tungsten (AWS EWTh-2)  Color Code:  Red Longer life than 1% Thoriated electrodes.  Maintain the pointed end longer, used for light gauge critical welds in aircraft work.  Like 1%, designed for DC applications for nonferrous materials. 4)   .5% Thoriated Tungsten (AWS EWTh-3)  Color Code:  Blue Sometimes called "striped" electrode because it has 1.0-2.0% Thoria inserted in a wedge-shaped groove throughout its length.  Combines the good properties of pure and thoriated electrodes.  Can be used on either AC or DC applications. 5)   Zirconia Tungsten (AWS EWZr)  Color Code:  Brown Longer life than pure tungsten.  Better performance when welding with AC.  Melts more easily than thoriam-tungsten when forming rounded or tapered tungsten end.  Ideal for applications where tungsten contamination must be minimized. 2.3.6 Summary - Gas Tungsten Arc Welding is one of the major welding processes today.  The quality of the welds produced and the ability to weld very thin metals are the major features.  The weld metal quality is high since no flux is used, eliminating the problem of slag inclusions in the weld metal.  It is used extensively in the aircraft and aerospace industry, where high quality welds are necessary and also for welding the more expensive metals where the weld defects become very costly.  Metals as thin as .005" can be welded due to the ease of controlling the current. The major disadvantages of the process are that it is slower than welding with consumable electrodes and is little used on thicknesses over 1/4" for this reason.  Shielding gas and tungsten electrode costs make the process relatively expensive. 2.4 GAS METAL ARC WELDING Gas Metal Arc Welding* is an arc welding process that uses the heat of an electric arc established between a consumable metal electrode and the work to be welded.  The electrode is a bare metal wire that is transferred across the arc and into the molten weld puddle.  The * Gas Metal Arc Welding (GMAW) is the current technology approved by the American Welding Society. Formerly known as "MIG" (Metal Inert Gas) Welding.
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