Q345 steel is a Chinese GB Standard Low Alloy High Strength Structural Steel, material density is 7.85 g/cm3, tensile strength is 470-630 Mpa, and yield strength is 345 MPa. According to GB/T 1591-2018, Q345 material has 5 quality grades: Q345A, Q345B, Q345C, Q345D, and Q345E.

Here are some additional details about Q345 steel:

Chemical composition (%, max):
- C: 0.20
- Si: 0.55
- Mn: 1.70
- P: 0.045
- S: 0.045

Mechanical properties:
- Tensile strength (Mpa): 470-630
- Yield strength (Mpa): 345
- Elongation (%): 21
- Impact test: -20℃, AKV≥34J

Q345 steel is commonly used in the following applications:
- Bridges
- Vehicles
- Pressure vessels
- Cranes
- Mining machinery
- Power plants
- Offshore structures
- Petrochemical industry

It is worth noting that Q345 steel is similar to ASTM A572 Gr 50, EN S355JR, ST 52-3, and GB Q345B steel.