Q345D steel comprehensive analysis

Q345D is a kind of low-alloy high-strength structural steel, belonging to the Q345 series of steel, widely used in Bridges, buildings, vehicles, ships and pressure vessels and other engineering fields. The "Q" in its name represents the yield point, the "345" refers to its minimum yield strength of 345 MPa, and the "D" represents its quality grade, which is especially suitable for use in low temperature environments. Compared with Q345B, Q345D has lower sulfur (S) and phosphorus (P) content, as well as better low-temperature impact toughness, and usually requires impact tests at -20 ° C, so it is considered a high-performance steel.

Q345D dimensions are flexible and diverse, can be made into steel plate, section steel (such as H-section steel, Angle steel), steel pipe and other forms. The thickness of the steel plate is wide, ranging from a few millimeters to hundreds of millimeters, and the section size of the section steel and steel pipe is customized according to the design requirements to adapt to the processing requirements of different structural parts. Its chemical composition is strictly controlled, mainly including carbon (C≤0.18%), silicon (Si≤0.55%), manganese (Mn≤1.70%), sulfur (S≤0.030%), phosphorus (P≤0.030%), and may be micro-added niobium (Nb), vanadium (V) or titanium (Ti) and other alloying elements to enhance strength and toughness. Low sulfur and phosphorus content is the key to its excellent low temperature performance.

The Q345D is usually delivered in hot rolled, normalized or normalized rolling condition. Hot rolled is suitable for conventional processing, and normalizing optimizes the internal grain structure of the steel by heating and cooling, improving low temperature toughness and uniformity. The surface can be sandblasted, galvanized or coated as needed to improve weather resistance. In practical applications, Q345D is often used for engineering projects in cold climates, such as northern Bridges and steel structures in high latitudes, because of its excellent comprehensive performance and adaptability to high cold areas. Its cost is relatively reasonable, taking into account strength and durability, is one of the indispensable high-end structural materials in modern industry.