Does Q345 require heat treatment?
A: Generally, it can be used in the hot-rolled state; for thick plates (>50mm) or low-temperature environments, normalizing or stress-relieving annealing is recommended.
Can Q345B be used in low-temperature environments?
A: No; use C below 0℃, D below -20℃, and E at -40℃.
How is the corrosion resistance of Q345?
A: It's at the level of ordinary carbon steel, requiring anti-corrosion measures (painting, galvanizing, rust removal); adding Cu/Cr/Ni can improve weather resistance.
Will hot-dip galvanizing cause pitting?
A: Q345 contains Si, making it an active steel, prone to pitting; controlling the zinc temperature to 450–460℃ and adding a trace amount of Ni can improve this.
How to distinguish between Q345 and Q235?
A: Check the warranty certificate: composition (Q345 has higher Mn content), mechanical properties.
Check the stamp: Q345B/C/D/E. A simple estimate: for the same thickness, Q345 is harder and more difficult to bend.