What type of current should be used for welding mild steel?

• A. AC
• B. DCEN
• C. DCEP
• D. DCSP

Answer: (B)

Polarity in shielded metal arc welding controls where most of the arc heat goes and how the bead behaves on mild steel. For common carbon-steel electrodes, using direct current with the electrode as the negative terminal (DCEN) gives a stable arc, good fusion into the base metal, and easier slag removal. This setup reduces the tendency to burn through thinner plates and produces a dependable, controllable weld on mild steel. In contrast, using the electrode positive (DCEP) tends to alter heat distribution and arc characteristics in ways that aren’t as favorable for typical carbon-steel welds, and straight-polarity (DCSP) is not the usual choice for this application. So the best choice for welding mild steel with standard SMAW electrodes is DCEN.