Shielding in arc welding — electrode size choice without protective flux or gas The statement “A large electrode is used in un-shielded arc welding” is being evaluated. Considering arc stability, spatter, and metallurgical protection, is this statement correct?

Introduction / Context:
Arc welding processes rely on either flux coverings (SMAW), shielding gases (GMAW/GTAW), or self-shielding flux cores (FCAW) to protect the molten pool from atmospheric contamination. The legacy term “un-shielded arc welding” describes an arc without adequate flux or gas protection, which is poor practice for structural-quality welds.

Given Data / Assumptions:

• Scenario: arc welding attempted without flux coating or shielding gas.
• Question addresses choice of electrode diameter/size.
• Focus is on arc stability and weld quality.

Concept / Approach:
Merely increasing electrode size in the absence of shielding does not solve metallurgical problems such as oxidation and nitrogen absorption. Larger electrodes generally require higher current, which aggravates spatter and oxidation in an unprotected arc. Quality welding necessitates adequate shielding; electrode size is selected according to joint thickness, position, and current range within a correctly shielded process.

Step-by-Step Solution:

Verification / Alternative check:
Standard welding procedures (WPS) always specify shielding method. None endorse increasing electrode diameter to replace shielding effectiveness.

Why Other Options Are Wrong:

• “Correct”: contradicts welding science; porosity and brittleness result without shielding.
• “Correct only for stainless” or “only with high current”: alloy or current does not negate the need for protection.
• “Small electrodes are always mandatory”: size is application-specific, but shielding remains non-negotiable.

Common Pitfalls:
Attempting arc welds without proper flux or gas; confusing electrode size effects with shielding effects; ignoring preheat/interpass requirements.

Final Answer: