Q: What does the designation Q355D steel plate mean?
A: Q represents yield strength, 355 indicates a yield strength value ≥ 355MPa, and D represents the quality grade, requiring a low-temperature impact energy requirement of -20℃.
Q: What material category does Q355D belong to?
A: It belongs to low-alloy high-strength structural steel and is the mainstream low-temperature low-alloy steel plate in the national standard GB/T 3274-2017.
Q: What is the core difference between Q355D and Q355A/B/C?
A: The core difference lies in low-temperature impact performance and sulfur and phosphorus content. Grade D requires an impact energy ≥ 34J at -20℃, with S≤0.015% and P≤0.025%, which is much stricter than grades A/B/C, and grade A has no impact requirements.
Q: What is the execution standard for Q355D steel plate?
A: For general applications, the national standard GB/T 3274-2017 (Hot-rolled steel plates and strips of carbon structural steel and low-alloy structural steel) applies. For engineering applications, GB/T 1591-2018 can be referenced.
Q: What is the old grade of Q355D?
A: The old grade was Q345D. Due to the update of the national standard, the yield strength index was slightly adjusted, and the grade was upgraded to Q355D. The overall performance requirements are the same and slightly improved.