The objective of the present work is to evaluate the fundamentals properties of an air granulated slag and his use during the automatic submerged arc welding process, confront it to a water granulated fused flux. For it the manufacturing procedure influence of air granulated slag on its physical properties and this relation with its performance during the solder and mechanical properties of welding join obtained is considered. Is demonstrated that the characteristics of the types of evaluated grains (slag and fused flux) are different; however, this does not conduce to variations among its operating behaviors during the welding process, neither on the welding joint mechanical properties obtained; but makes to be noticeable than the granulating process of slag with air is more economic than the of granulation with water.