What are the cold working properties of Q355?
Good; suitable for cold bending, stamping, and shearing; no cracks were observed in the 180° cold bending test (d=2a), making it suitable for structural forming.
Does Q355 welding require preheating?
For plates **≤25mm**: room temperature welding, generally no preheating is required;
>25mm: preheating to 80–120℃ is recommended to prevent cold cracking;
For ambient temperatures < 0℃ or high-constraint structures, the preheating temperature needs to be increased.
What are the commonly used welding methods and welding materials for Q355?
Methods: submerged arc welding, gas shielded welding (CO₂/MAG), manual arc welding;
Welding materials: J507 (E5015) low-hydrogen welding rods, H10Mn2 welding wire, matching strength and toughness.
Does Q355 welding require heat treatment after welding? For thick plates (>50mm) or high-restraint joints, it is recommended to hold at 200–250℃ for 1–2 hours to eliminate welding stress and reduce the risk of cold cracking.
What are the cutting methods for Q355? What are the precautions?
Flame cutting: Most commonly used; thick plates require preheating to 100–150℃ to avoid cracking.
Laser/plasma cutting: Suitable for thin plates, high precision, and a small heat-affected zone.
Waterjet cutting: No thermal deformation; suitable for irregularly shaped parts.
After cutting, grind the bevel to remove the hardened layer.