What is Q345 steel grade equivalent to?
Q345 is a low-alloy high-strength structural steel in the Chinese national standard (GB/T 1591). The international equivalent steel grades are mainly low-alloy structural steels with a yield strength of 345-355MPa, such as European S355, American A572 Gr50, etc.
Are Q345B and Q345 the same thing?
No, the key differences between the two are as follows:
|
Comparison items |
Q345 (basic grade) |
Q345B (high quality grade) |
|
Standard basis |
GB/T 1591 |
GB/T 1591 |
|
Quality grade |
No separate classification |
Class B (-20℃ impact) |
|
Chemical composition |
General control |
Lower phosphorus and sulfur (P≤0.030%, S≤0.025%) |
|
Impact energy requirements |
No low temperature impact requirements |
-20℃ Akv≥34J |
|
Typical uses |
Ordinary structural parts |
Bridges/ships/cryogenic pressure vessels |
Which is better Q345 or Q235 steel?
Q345 has stronger performance but higher cost, suitable for key load-bearing structures, such as bridges, heavy machinery, and high-rise steel structures; Q235 is economical and suitable for general purposes such as fences and small tools
What is the density of Q345 steel?
Q345 is a low-alloy, high-strength structural steel, but its alloy composition has little effect on the overall density, so the density is the same as common steels such as Q235 and Q390, which is 7.85 g/cm³ (or 7850 kg/m³).
Which materials can replace Q345?
When Q345 steel is replaced by other materials, it is necessary to comprehensively consider strength, toughness, weldability, cost and application environment.
|
Alternative Materials |
standard |
Yield Strength |
Advantages |
Applicable scenarios |
|
S355JR |
EN 10025 |
≥355 MPa |
Directly equivalent, universal in Europe |
Buildings, bridges |
|
A572 Grade 50 |
ASTM A572 |
≥345 MPa |
American standard equivalent, export project |
Mechanical equipment, pressure vessels |
|
Q390 |
GB/T 1591 |
≥390 MPa |
Higher strength, weight reduction |
Wind power, heavy machinery |
|
S355NL |
EN 10025 |
≥355 MPa |
Low temperature toughness (-50℃) |
Polar and cold regions |
|
A588 |
ASTM A588 |
≥345 MPa |
Weather resistance, no painting required |
Outdoor bridges, towers |
