Welding Defects

Welding Defects 
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Welding Defects 

Welding defects
Explanation and causes
1. Cracks
Cracks occur when localized stresses exceed the ultimate tensile strength of material. These stresses are developed due to shrinkage during solidification of weld metal. Cracks may be developed due to poor ductility of base metal, high sulpher and carbon contents, high arc travel speeds i.e. fast cooling rates, too concave or convex weld bead and high hydrogen contents in the weld metal.
2. Porosity
Porosity results when the gases are entrapped in the solidifying weld metal. These gases are generated from the flux or coating constituents of the electrode or shielding gases used during welding or from absorbed moisture in the coating. Rust, dust, oil and grease present on the surface of work pieces or on electrodes are also source of gases during welding.
3. Lack of Fusion
Too fast a travel, Incorrect welding technique, Insufficient heat 
4.Slag Inclusion
Slag from previous runs not being cleaned away, Insufficient cleaning and preparation of the base metal before welding commences.
5. Undercuts
Too fast a travel, Bad welding technique, Too great a heat build-up.
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