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

 

7 Continued on next page... Figure 10-4 – Examples of Porosity POROSITY Porosity is gas pores found in the solidified weld bead. As seen in Figure 10-4, these pores may vary in size and are generally distributed in a random manner. However, it is possible that porosity can only be found at the weld center. Pores can occur either under or on the weld surface. The most common causes of porosity are atmosphere contamination, excessively oxidized work piece surfaces, inadequate deoxidizing alloys in the wire and the presence of foreign matter. Atmospheric contamination can be caused by: 1)   Inadequate shielding gas flow. 2)   Excessive shielding gas flow. This can cause aspiration of air into the gas stream. 3)   Severely clogged gas nozzle or damaged gas supply system (leaking hoses, fittings, etc.) 4)   An excessive wind in the welding area. This can blow away the gas shield.