This will ensure the weld has similar properties. Dissimilar base metal applications require selection based on mechanical properties, freedom from cracking, and compatibility. DC uses either straight polarity, which is electrode negative or reverse polarity, which is electrode positive. Direct current flows in one direction continuously through the welding circuit. Their key characteristic is fast freezing slag, which make them suitable for out of position welding.
Bead appearance is convex.
The advantages of this current include less chance of arc blow, which is an unbalance of the magnetic field around the arc causing a bend in the arc. It also works well on thick metal with a large diameter electrode. They produce a smooth weld bead, with a flat to slightly convex bead appearance. This current type provides better base metal penetration. Stick out is the distance between the end of the wire and the end of the contact tip.