Introduction
Incomplete
Penetration
Lack of
Longitudinal
Undercutting
Fusion
Porosity
Cracking

 

 

 

Variations-
Metal
Transfer
Equipment
Power
Supply
Shielding
Gases
Wire
Electrodes
Safety
Welding
Techniques
Welding
Conditions
Economics
Weld
Defects
Mig Spot
Welding
Tables

 

6 However, as the arc voltage is raised to excessive levels, undercutting may again appear. This is particularly true in spray arc welding. When the arc becomes very long, it also becomes too wide. This results in an increased amount of base material being melted. However, the heat transfer of a long arc is relatively poor, so actually the arc is supplying no more total heat to the weld zone. The outermost areas are very quickly cooled and again proper wetting is prevented. The arc length should be kept short, not only to avoid undercutting but to increase penetration and weld soundness. Excessive welding currents can also cause undercutting. The arc force, arc heat and penetration are so great that the base plate under the arc is actually ”blown” away. Again, the outermost areas of the base material are melted but solidify quickly. Puddle turbulence and surface tension prevent the puddle from wetting properly. It is always advisable to remain within the current ranges specified for each wire size.