Which polarity is used where shallow penetration is desired or when increased deposition rate is required?

Which polarity is used where shallow penetration is desired or when increased deposition rate is required?

• A. DCEN
• B. DCEP
• C. AC
• D. Pulsed DC

Answer: (A)

Shallow penetration with a higher filler metal deposition rate comes from directing most of the arc heat into melting the electrode rather than the base metal. When the electrode is the negative terminal (electrode negative), the heat of the arc is concentrated more in the electrode, causing more filler metal to melt and transfer into the weld bead, while less heat goes into the workpiece. This yields a higher deposition rate and a shallower weld profile. If the electrode were positive (electrode positive), more heat goes into the workpiece, increasing penetration depth and often reducing the rate at which filler metal is deposited. Alternating current switches polarity and doesn’t provide the steady balance needed for either maximum deposition or shallow penetration, and pulsed DC controls heat input over time but doesn’t define the polarity itself. So, electrode negative polarity is used when shallow penetration is desired or when a higher deposition rate is required.

Shallow penetration with a higher filler metal deposition rate comes from directing most of the arc heat into melting the electrode rather than the base metal. When the electrode is the negative terminal (electrode negative), the heat of the arc is concentrated more in the electrode, causing more filler metal to melt and transfer into the weld bead, while less heat goes into the workpiece. This yields a higher deposition rate and a shallower weld profile. If the electrode were positive (electrode positive), more heat goes into the workpiece, increasing penetration depth and often reducing the rate at which filler metal is deposited. Alternating current switches polarity and doesn’t provide the steady balance needed for either maximum deposition or shallow penetration, and pulsed DC controls heat input over time but doesn’t define the polarity itself. So, electrode negative polarity is used when shallow penetration is desired or when a higher deposition rate is required.