Question

Why is electrode coated with a flux in shielded metal arc welding?

(a) for shiny appearance of electrode

(b) to make welding faster

(c) to increase the melting of electrode

(d) to protect the electrode

I have been asked this question during an internship interview.

Question is from Welding Process in portion Welded Connections of Design of Steel Structures

Answer 1

Correct choice is (d) to protect the electrode

To explain I would say: The electrode is coated with a flux in shielded metal arc welding. Heat from electric current causes the combustion and decomposition of electrode. This creates a gaseous shield to protect the electrode, metal and molten pool from atmospheric contamination due to oxidation.