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Chemical and mechanical properties of Q345qD grade spiral steel pipe
1、 Chemical composition
The chemical composition of Q345qD spiral steel pipe complies with the national standard GB/T 714-2015 for bridge steel. The core elements and contents are as follows:
Carbon (C): 0.12%~0.20% (upper limit of 0.18% for some data);
Silicon (Si): 0.10%~0.50% (deoxidation and strengthening);
Manganese (Mn): 0.80%~1.60% (core strengthening element, enhancing strength and toughness);
Phosphorus (P) and sulfur (S): ≤ 0.030% and ≤ 0.025% respectively (low impurity ensures weldability);
Alloy elements: Trace additions of niobium (Nb), vanadium (V), titanium (Ti), aluminum (Al), etc. (refine grain size and enhance low-temperature toughness).
2、 Mechanical performance
Basic performance (thickness related):
Yield strength (ReH):
Thickness ≤ 16mm: ≥ 355 MPa；
16~40mm：≥ 335 MPa；
Gradually decrease when the thickness is greater than 40mm, with a minimum of 275 MPa;
Tensile strength (Rm): 450-630 MPa;
Post fracture elongation (A5): ≥ 21%.
Impact toughness:
-20 ℃ impact energy (V-notch): ≥ 27 J (some materials require ≥ 34 J);
Z-direction performance: Z15/Z25/Z35 grades can be selected (with a cross-sectional shrinkage rate of ≥ 15%/25%/35% respectively, to prevent thick plate delamination).
Other performance:
Weldability: Carbon equivalent ≤ 0.3%, supports conventional arc welding and submerged arc welding, thick plates require preheating;
Corrosion resistance: Adding elements such as Cr and Mo to adapt to humid and atmospheric corrosive environments.
3、 Application Fields
Q345qD spiral steel pipe is mainly used in engineering scenarios under high load and low temperature environments:
Bridge engineering: Main beams and supporting structures of highways and railway bridges;
Building structure: load-bearing frame of high-rise buildings, large-span venues;
Marine infrastructure: port machinery, offshore platform connecting pipes;
Energy facilities: Oil and gas transmission pipelines in low-temperature areas.
(Note: Specific parameters may be adjusted due to thickness, delivery status, and additional technical requirements.)
ADD：Chengnan Industrial Development Zone, Yanshan County, Hebei Province
Domestic phone number：0086-317-6689999
International call：0086-317-6165555
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