What is the difference between Q355D and Q355ND?
A: Q355ND = Normalized Q355D, with a more stable microstructure and superior low-temperature toughness, used for important low-temperature thick plates.
What are the preheating requirements for Q355D welding?
A: General thickness: Preheating not required.
>40mm or low-temperature environment: Preheat 80～120℃. Control the layer temperature ≤150℃ to prevent cold cracking.
Common welding methods?
A: Arc welding, gas shielded welding (CO₂/MAG), submerged arc welding; mature processes.
Welding material selection?
A: Match E50 series (E5015, E501T-1, etc.), -20℃ impact matching.
Precautions for thick plate welding?
A: ≥40mm: Layered multi-pass welding. Full penetration, UT inspection. Slow cooling after welding, necessary stress relief.