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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 greater than the current density of the 1/4" wire at equal welding currents.  The resultant melt-off rate of the solid wire is very high. If we were to increase the current through the 1/4" coated electrode to increase the current density, the resistance heating through the 14" electrode length would be excessive, and the rod would become so hot that the coating would crack, rendering it useless.  The 1/16" wire carries the high current a distance of  less than 3/4", the approximate distance from the end of the contact tip to the arc. 2.4.2 Metal Transfer Modes Spray transfer is a high current density process that rapidly deposits weld metal in droplets smaller than the electrode diameter.  They are propelled in a straight line from the center of the electrode.  A shielding gas mixture of Argon with 1% to 2% Oxygen is used for welding mild and low alloy steel, and pure Argon or Argon-Helium mixtures are used for weld- ing aluminum, magnesium, copper, and nickel alloys.  Welding current at which spray transfer FIGURE 10 AREA = .049 SQ. IN. AREA = .0031 SQ. IN. CORE WIRE FLUX COATING COATED ELECTRODE RELATIVE SIZE OF ELECTRODES FOR WELDING AT 400 AMPS SOLID WIRE 1/4" 1/16" .049 ÷ .0031 = 16 A A × 16 FIGURE 11 SPRAY TRANSFER GLOBULAR TRANSFER PULSE TRANSFER MODES OF METAL TRANSFER 1 2 3 SHORT CIRCUITING ARC METAL TRANSFER takes place is relatively high and will vary with the metal being welded, electrode diameter, and the shielding gas being used.  Deposition rates are high and welding is usually limited to the flat or horizontal fillet position.  See Figure 11.