What is Q345 steel?
Low-alloy high-strength structural steel, formerly GB/T 1591-2008, now replaced by Q355 (GB/T 1591-2018).
2. What does "Q345" mean?
Q: Yield strength (first letter of "屈" in pinyin)
345: Yield strength ≥ 345MPa for thickness ≤ 16mm
3. How many quality grades are there?
Five grades: A, B, C, D, and E, with decreasing impact temperature and increasing toughness in each grade.
4. Impact requirements for each grade?
Q345A: No impact
Q345B: +20℃ impact
Q345C: 0℃ impact
Q345D: -20℃ impact
Q345E: -40℃ impact
5. Core chemical composition (wt%)? C≤0.20; Si≤0.55; Mn: 1.00–1.60; P≤0.035; S≤0.035; Contains trace amounts of Nb/V/Ti to refine the grain size.