Difference between Q295A and Q295B Welded Steel Pipe

GB/T 13793 - 2008 standard specifies two kinds of welded steel pipes Q295A and Q295B. Their differences are mainly reflected in the chemical composition and mechanical properties.

In terms of chemical composition, the carbon (C) content of Q295A and Q295B is not more than 0.16%, manganese (Mn) content is not more than 1.50%, and silicon (Si) content is not more than 0.55%. However, Q295B has more stringent requirements for sulphur (S) and phosphorus (P), with sulphur content of not more than 0.040% and phosphorus content of not more than 0.040%, while Q295A has relatively relaxed requirements for the content of these two elements.

Mechanical properties, both yield strength (Rel) are not less than 295MPa, tensile strength (Rm) of 390 - 570MPa, elongation at break (A) is not less than 20%. Overall, their mechanical properties are basically the same, but Q295B may have better toughness and reliability in some cases.

In terms of application, Q295B is more suitable for some occasions with higher material requirements, such as pressure vessels, bridges, ships and other fields, because its chemical composition and mechanical properties are relatively more stable. While Q295A welded steel pipe is suitable for general requirements of structural and mechanical components.

To sum up, Q295B welded steel pipe is stricter than Q295A in terms of chemical composition and performance, which can better meet the needs of some critical occasions. In the actual application, we should choose the appropriate welded steel pipe according to the specific use environment and requirements to ensure the quality and safety of the project.