How does oxide formation change due to welding heat?

• A. Slowed down
• B. Remains the same
• C. Sped up
• D. Eliminated

Answer: (C)

Oxide formation is a chemical reaction between the metal surface and oxygen, and as temperature increases, chemical reactions speed up. When welding heats the metal, the surface and molten pool are exposed to air at high temperatures, so oxygen reacts more rapidly with the metal and a thicker oxide layer forms faster. Shielding gas or flux can limit this by reducing oxygen contact, but heat itself makes oxidation occur more quickly, not slower, not the same rate, and not vanish.