Mechanical properties of galvanized steel pipe

① Tensile strength (σb) : During the tensile process of the sample, the maximum force (Fb) it is subjected to when it breaks, divided by the original cross-sectional area of the sample (So), the stress (σ) is called the tensile strength (σb), and the unit is N/mm2 (MPa). It represents the maximum ability of a metal material to resist damage under tensile force. Where: Fb-- the maximum force borne by the specimen when it breaks, N (Newton); So-- original cross-sectional area of sample, mm2.
② Yield point (σs) : a metal material with yield phenomenon, the stress when the specimen can continue to extend without increasing the force during the tensile process (remaining constant), called the yield point. If the force drops, the upper and lower yield points should be distinguished. The unit of the yield point is N/mm2 (MPa). Upper yield point (σsu) : the maximum stress of the specimen before the first drop in force occurs. Lower yield point (σsl) : The minimum stress in the yield stage when initial transient effects are not considered. Where: Fs-- yield force (constant) of the specimen during tensile process, N (Newton) So-- original cross-sectional area of the specimen, mm2.
③ Elongation after breaking: (σ) In the tensile test, the percentage of the length increased by the standard distance of the specimen after breaking and the length of the original standard distance is called the elongation. The unit is %, expressed as σ. Where: L1-- the standard distance length of the specimen after pulling off, mm; L0-- original gauge length of sample, mm.
④ Section shrinkage: (ψ) In the tensile test, the percentage of the maximum reduction of the cross-sectional area at the reduced diameter and the original cross-sectional area after the specimen is pulled is called the section shrinkage. It is expressed in ψ and the unit is %. Where: S0-- the original cross-sectional area of the sample, mm2; S1-- The minimum cross-sectional area at the reduced diameter of the specimen after tensile break, mm2.
⑤ Hardness index: The ability of metal materials to resist hard objects to compress the surface, called hardness. According to the different test methods and application scope, the hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. There are three kinds of Brinell, Rockwell and Vickers hardness commonly used for pipes.