What element is added to the core of FCAW-SS wires to deoxidize/denitrify the weld?

• A. Aluminum
• B. Silicon
• C. Magnesium
• D. Titanium

Answer: (A)

Deoxidation and denitrification in a stainless-steel weld come from scavenging oxygen and nitrogen from the molten metal so porosity and nitride-related defects don’t form. Aluminum in the flux core does this effectively because aluminum readily bonds with oxygen to form aluminum oxide and with nitrogen to form aluminum nitride. Those compounds are stable and move to the slag or become part of the protective inclusions, keeping the weld metal cleaner and reducing porosity, which is especially important with stainless steels that are prone to nitrogen-related porosity.

Silicon can help remove oxygen but isn’t as strong for denitrification. Magnesium isn’t typically used for this purpose in FCAW-SS, and titanium can deoxidize and stabilize alloys but isn’t the standard denitrification agent in these wires. Aluminum is the common, effective choice for deoxidizing/denitrifying the weld in FCAW-SS.