The mechanical properties of the seamless steel tube is a important indicator that ensure seamless pipe end-use properties (mechanical properties), which depends on the chemical composition and heat treatment of steel. In steel standards, according to different requirements, it provide the tensile properties (tensile strength, yield strength or yield point elongation) and hardness.
① Tensile strength (σb)
During stretching, when pull off the bear most strongly (Fb), divided by the original cross-sectional area (So) from the stress (σ), known as the tensile strength (σb), units of N/mm2 (MPa). It said the maximum capacity resist destruction of metallic materials under tension.
② Yield point (σs)
Yield the phenomenon of metal materials, the sample does not increase during the tensile force (remains constant) and continue elongation stress is known as the yield point. If the force drop occurred, you should distinguish between upper and lower yield point. The yield point of the unit is in N/mm2 (MPa). On yield point (σsu):Sample to yield the maximum stress and force the first drop; lower yield point (σsl): yield minimum stress in the stage when excluding the initial transient effect.
③ Elongation (σ)
In the tensile test, the specimen fractured a percentage of the gauge to increase the length of the original gauge length, called elongation. Σ, said the unit is%.
(4) Cross-section contraction rate (ψ)
In the tensile test, the percentage of the specimen fractured its shrink the diameter at the cross-sectional area of the maximum reduction and the original cross-sectional area is known as section shrinkage. Ψ expressed in%.
⑤ Hardness testing
Metallic materials against hard objects indentation of the surface, known as hardness. accoring to the test method and scope of application, the hardness can be divided into brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, hardness and high temperature hardness. Commonly used for pipe, Brinell, Rockwell, Vickers hardness of three kinds.
Post time: Oct-21-2019