Q345D seamless pipe is a kind of low-alloy high-strength structural steel. It is named as low-alloy because of a small amount of alloy elements in the steel. Q345D seamless pipe is mainly used for construction and engineering structures, with carbon content less than or equal to 0.18%. The yield strength of Q345D seamless pipe is 25% - 150% higher than that of carbon structural steel pipe with the same carbon content. Q345D seamless pipe can reduce the weight of steel structure, save steel products and effectively extend the service life of steel structure. Q345D is named after its yield strength and impact temperature. Q stands for yield strength, that is, yield strength is 345 MPa, and D represents impact temperature is minus 20℃.

In addition, Q345D seamless pipe has good toughness and weldability, and has certain corrosion resistance and low temperature resistance. Q345D seamless pipe is also widely used in welding structures, such as bridges, vehicles, ships, pipelines, boilers, large vessels and so on.

The chemical composition of Q345D seamless pipe is as follows: C ≤ 0.18, Si ≤ 0.50, Mn ≤ 1.70, P ≤ 0.030, S ≤ 0.025, Nb ≤ 0.07, V ≤ 0.15, Ti ≤ 0.20, Cr ≤ 0.30, Ni ≤ 0.50, Cu ≤ 0.30, N ≤ 0.012, Mo ≤ 0.10, Al ≥ 0.015. Mechanical properties of Q345D seamless pipe: yield strength ≥ 265 Mpa, tensile strength 450-600 Mpa, elongation after fracture ≥ 17%, impact energy 27J. Q345D seamless pipe has good comprehensive mechanical properties, low-temperature impact toughness, cold stamping, machinability and weldability.