Monday, August 17, 2015

Porosity in Welding - Causes and Preventions (Part 2)

What are most common causes of porosity in welding and how can be they prevented? You can refer below to find the answers you need.

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6. Excessively long arc length

Weld porosity occurs in case of excessively long arc length (also, high voltage). The shielding magnitude will be reduced, inducing air entrapment if the welding gun is kept away from the joint making longer arc length. Proper arc length is suggested to avert breezes/ draughts.

7. Wrong surface treatments

Weld characteristics can be weakened due to released gases during surface/ painting treatments. Such treatments as galvanizing or zinc coating would create gas and other particles unwelcomed. As a prevention, predict the result of chemical reactions prior to particular surface treatments.

8. Laminated surface

Welding disturbance can also eventuate in case of laminated surface. When welding the laminated work piece, gear up for unlaminated parent metal to ensure the qualified weld procedure.

9. Open surface

Any surface open to the atmospheric air would be prone to contamination. Air introduced from the back side via root opening would be entrapped in the weld puddle. Ensure that your weld joint is safeguarded from such air crevices.

10. Improper welding flux

Welding flux is required to be cautiously treated because of their moisture absorbility. They must be provided in dry conditions. It also should be noted that using low-activity flux induces surface porosity. Then you’re recommended to apply high-activity flux that offers qualified welds without porosity. 


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