Standard: TB/T 1979-2014
Grade: Q345NQR3
Category: weathering steel, atmospheric corrosion resistant steel
Application: containers, power plant chimneys, railway projects
Q345NQR3 steel composition (%)
|
C |
Si |
Mn |
P |
S |
Cu |
Ti |
RE |
|
≤0.12 |
0.20-0.50 |
0.25-0.70 |
0.060-0.12 |
≤0.020 |
0.25-0.50 |
≤0.030 |
0.010-0.040 |
Q345NQR3 steel tensile requirement
|
Grade |
Thick mm |
Yield strength MPa |
Tensile strength MPa |
Flexion ratio |
Elongation, A% |
180° cold bending test |
|
Q345NQR3 |
≤6 |
≥345 |
≥480 |
≤0.75 |
≥24 |
D=a |
|
>6 |
D=2a |
Corrosion resistance
After adding phosphorus, copper, chromium, nickel and other trace elements to Q345NQR3 steel, a dense and highly adherent protective film is formed on the surface of the steel, which hinders the spread and development of rust, and protects the substrate under the rust layer to slow down its corrosion rate. The amorphous spinel-type oxide layer with a thickness of about 50μm-100μm formed between the rust layer and the substrate is dense and has good adhesion to the substrate metal. Due to the existence of this dense oxide film, it prevents oxygen and oxygen in the atmosphere. The penetration of water into the steel matrix slows down the in-depth development of corroded steel materials and greatly improves the atmospheric corrosion resistance of steel materials.
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