Q390B is a high-strength low-alloy structural steel defined by the Chinese national standard GB/T 1591-2018. It is widely used in large engineering structures such as bridges, ships, boilers, and pressure vessels due to its high strength and good toughness. Its chemical composition mainly includes carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), and may contain trace alloying elements such as vanadium (V), titanium (Ti), niobium (Nb), etc. The addition of these elements helps improve the overall performance of the material.

In European standards, the performance of Q390B may correspond to S460M or S460ML steel in EN 10025-6. S460 indicates that the material has a minimum yield strength of 460 MPa, and M denotes that the material has good impact energy absorption properties. These steels have high strength and good welding and processing properties similar to Q390B, making them suitable for applications requiring high strength and good toughness.

The mechanical property requirements for Q390B include tensile strength, yield strength, elongation after fracture, and impact energy absorption. For example, for Q390B steel with a thickness less than or equal to 16 mm, the tensile strength ranges from 490 to 650 MPa, the yield strength is not less than 390 MPa, and the elongation after fracture is not less than 21%. These performance indicators ensure that the material can withstand significant loads and impacts in practical applications.

In practical engineering applications, when selecting alternative materials, specific engineering requirements and usage environments must be considered, including chemical composition, mechanical properties, impact test temperature, etc. Engineers and procurement personnel should carefully compare the specific requirements of relevant standards and conduct material testing when necessary to ensure that the selected material meets engineering needs and safety standards.