Performance comparison of structural seamless steel tubes

Structural performance comparison of seamless steel tubes. Carbon structural steel pipe: This kind of structural steel pipe is generally smelted by converter or open hearth furnace. Its main raw material is molten iron and scrap steel. The content of sulfur and phosphorus in steel is higher than that of high quality carbon structural steel pipe. Generally, sulfur is ≤0.050% and phosphorus is ≤0.045%.
The content of other alloying elements brought into the steel by the raw materials, such as chromium, nickel and copper, generally does not exceed 0.30%. According to the composition and performance requirements, the grades of such structural steel pipes are Q195, Q215A, B, Q235A, B, C, D. , Q255A, B, Q275 and other steel grades.
Note: “Q” is the Chinese Pinyin uppercase head of the yielded “Qu” character, after which the number is the minimum yield point (σs) of the grade, and the subsequent sign is based on the content of the impurity element (sulfur, phosphorus) of the steel. High to low and divided into A, B, C, D and so on with changes in carbon and manganese.
Such structural steel pipes have the largest output and are widely used, and are rolled into sheets, profiles (round, square, flat, work, grooves, corners, etc.) and profiles and welded steel pipes. It is mainly used for building structures such as factories, bridges, ships, etc. and pipes for general conveying fluids. Such steels are generally used directly without heat treatment.
Low alloy high strength structural steel pipe
In addition to a certain amount of basic elements of silicon or manganese, such structural steel pipes contain other elements suitable for the resources of China. Such as vanadium (V), niobium (Nb), titanium (Ti), aluminum (Al), molybdenum (Mo), nitrogen (N), and rare earth (RE) and other trace elements. According to chemical composition and performance requirements, its grades are Q295A, B, Q345A, B, C, D, E, Q390A, B, C, D, E, Q420A, B, C, D, E, Q460C, D, E, etc. The steel grade indicates that it has the same meaning as a carbon structural steel pipe.
V, Nb, Ti, Al and other refined grain trace elements, in addition to A, B grade steel in such structural steel pipes, at least one of C, D, E grade steel should be included; in order to improve steel Performance, one of the A and B grade steels can also be added. In addition, the residual element content of Cr, Ni, and Cu of such steel is not more than 0.30%. Q345A, B, C, D, E are the representative grades of such steels, of which A and B grade steels are usually called 16Mn; more than one trace elements are required for structural steel grades above C grade, and one low temperature impact property is added to the mechanical properties.
This type of structural steel pipe is compared with carbon structural steel. It has the advantages of high strength, good comprehensive performance, long service life, wide application range and economical. The steel is rolled into sheets, profiles, seamless steel tubes, etc., and is widely used in bridges, ships, boilers, vehicles and important building structures.