Q: What is the minimum yield strength and tensile strength of Q355 plate?
A: Minimum yield strength: 355 MPa (for plates with thickness ≤16mm; the yield strength decreases slightly with the increase of thickness). Minimum tensile strength: 470-630 MPa. Elongation after fracture: ≥21%.
Q: What is the effect of thickness on the mechanical properties of Q355 plate?
A: With the increase of plate thickness, the cooling rate during rolling slows down, the grain size becomes larger, and the mechanical properties decrease. For example:
Thickness ≤16mm: yield strength ≥355 MPa
Thickness 16-40mm: yield strength ≥345 MPa
Thickness 40-63mm: yield strength ≥335 MPa
Thickness 63-80mm: yield strength ≥325 MPa**
Q: What is the low-temperature impact performance of Q355D and Q355E plates?
A: Q355D plate requires V-notch impact energy ≥34 J at -20℃; Q355E plate requires V-notch impact energy ≥34 J at -40℃. This performance ensures the structural safety of the plate in low-temperature environments.
Q: What are the chemical composition requirements of Q355 plate?
A: Main chemical composition (mass fraction, ≤):
C: 0.20%
Si: 0.55%
Mn: 1.60%
P: 0.035% (0.030% for C/D/E grades)
S: 0.035% (0.030% for C/D/E grades)In addition, micro-alloy elements such as V, Nb, Ti can be added to improve strength and toughness, and the total content of alloy elements shall not exceed 1.5%.
Q: Does Q355 plate have good weldability?
A: Yes. Q355 plate has low carbon equivalent (CEV ≤0.45%), good weldability, and can be welded by common methods such as arc welding, gas welding, and resistance welding. For thick plates or low-temperature welding, preheating measures (preheating temperature 80-150℃) are recommended to prevent welding cracks.