Common Defects and Causes?
Surface Cracks: Improper continuous casting/rolling process, enrichment of residual elements (Cu)
Welding Cracks: Insufficient preheating, damp welding rods, high sulfur and phosphorus levels
Laminar Tearing: Z-axis deviation in thick plates, excessive welding restraint.
How to Prevent Welding Cracks?
Select low-hydrogen welding rods (J507) and dry them.
Properly preheat thick plates.
Control interpass temperature (100–200℃). Use a reasonable welding sequence to reduce restraint.
How much more expensive is it than Q235?
Usually 10–20% more expensive due to the high cost of alloying elements (Mn) and strict smelting control.
Common Specification Range?
Thickness: 6–200mm
Width: 1500–3000mm
Length: 6000–12000mm (custom length available).
How to quickly distinguish between Q345 and Q235 on-site? EDM (Electrical Discharge Machining): Q345 produces denser and more branched sparks (higher manganese content). Hardness: Q345 has higher hardness (approximately HB 140–180). Spectroscopy: Most accurate for measuring Mn content (Q345 > 1.0%).