In arc welding, which arc heats pieces of similar material to a temperature high enough to melt and coalesce?

• A. Electric arc
• B. Gas arc
• C. Laser arc
• D. Plasma arc

Answer: (A)

Arc welding uses an electric arc as the heat source to melt metal so the pieces can fuse together. When current flows between an electrode and the workpiece, an electric arc forms and concentrates a tremendous amount of energy in a small region, heating the metal to its melting point and creating a molten pool. As the metals mix and then solidify, they coalesce into a weld. The other terms describe different heat sources or welding variants that aren’t the general mechanism for melting in arc welding, whereas the electric arc is the defining heat source for this process.