What Contributes to Weld Porosity?
Weld porosity results from the entrapment of hydrogen gas. This gas entrapment results in lower weld strength and ductility by reducing the crosssectional area of sound metal and by acting as stress risers which cause premature failure. Several variables can produce gas porosity, one of which is the surface condition of the aluminum filler wire. The qualities relating to the surface characteristics of the filler wire include: · The removal of surface oxides (hydrated oxides). · The absence of any water or water vapor. · The removal of hydrogen-containing compounds(hydrocarbons). Of these three surface conditions, the most common cause of weld porosity is the presence of hydrocarbons. Examples of these compounds include residual wire drawing lubricants, mill dirt or even fingerprints. One relatively quick and inexpensive method of testing aluminum welding wire for freedom from residual hydrocarbons is by means of a “Smoke Test”. What Is A Smoke Test? The “Smoke Test” is a qualitative te
