What are the special features of Q345 for bridge applications?
A: Bridge-specific Q345qB/C/D/E conforms to GB/T 714-2015 and has higher requirements for toughness and fatigue resistance.
What are Z-direction properties (Z15/Z25/Z35)?
A: Z35 has the best resistance to lamellar tearing and is used for thick plates, welded joints, and heavy-load structures.
How is the weldability of Q345?
A: With a carbon equivalent of ≈0.49%, it has good weldability. Preheating (100–150℃) is required for thick plates or low-temperature applications.
What are the commonly used welding materials?
A: Electrodes E50 series (E5015/E5016); welding wire ER50-6; submerged arc welding H08MnA+HJ431.
What welding defects are prone to occur?
A: Thick plates are prone to cold cracking and heat-affected zone hardening; these can be avoided by controlling preheating, layer temperature, and post-heating.