A nonmetallic product resulting from the mutual dissolution of fluand nonmetallic impurities in some welding and brazing processes.
This term is used to describe the oxides and nonmetallic solids that sometimes are entrapped in weld metal, between adjacent beads, or between the weld metal and the base metal. During deposition and subsequent solidification of the weld metal, many chemical reactions occur. Some of the products of these reactions are solid nonmetallic compounds which are insoluble in the molten metal. Because of their lower specific gravity, these compounds will rise to the surface of the molten metal unless they become entrapped within the weld metal.
In shielded metal arc welding, flux cored arc welding, and submerged arc welding, a slag is also formed over the molten metal, protecting it from the air and slowing down the rate of cooling. By this means, varying in detail with different electrodes and fluxes, the air surrounding the arc is deoxidized and the metal is protected, or shielded, from the oxygen and nitrogen which would otherwise be present. The result is greater tensile strength and ductility of the weld metal.
This term is also applied to the scale blown out of the kerf when cutting with a torch.