Question

Nitrogen pickup by liquid steel is low in:

• A. LD process
• B. Bessemer process
• C. Open-hearth process
• D. Twin hearth process

Hint:

Oxygen steelmaking reduces nitrogen contamination compared to air-based processes.

Answer 1

The Correct Option is A

Concept: Nitrogen pickup in steel depends on:
• contact time with atmosphere
• partial pressure of nitrogen
• oxygen environment in furnace Dissolved nitrogen in steel leads to: \[ \text{embrittlement, strain aging} \]

Step 1: LD process characteristics.
LD (Linz–Donawitz) process:
• uses pure oxygen jet
• avoids direct air contact
• creates CO-rich protective atmosphere Thus nitrogen absorption is minimized.

Step 2: Comparison with other processes.

• Bessemer process → air blown → high nitrogen pickup
• Open-hearth → prolonged air exposure → moderate/high pickup
• Twin hearth → more exposure compared to LD Final Answer: \[ \boxed{\text{LD process}} \]