Mechanical Properties of Seamless Steel Pipe
Mechanical properties of steel is to ensure that the steel end-use properties (mechanical properties) is an important indicator, it depends on the chemical composition and heat treatment of steel system. In the steel standards, depending on the usage requirements of the tensile properties (tensile strength, yield strength or yield point elongation) and hardness, toughness index, as well as user requirements of high and low temperature properties.
① Tensile strength (σb)
Specimen during stretching, pull off when exposure to the most vigorous (Fb), stress (σ) divided by the original specimen cross-sectional area (So) income, known as the tensile strength (σb), units N / mm2 (MPa). It represents a metal material to resist damage under tension maximum capacity.
② Yield point (σs)
Metallic material having a yield phenomenon specimen during the tensile force does not increase (constant) could continue elongation stress, said yield point. If power down occurs, it should distinguish between the lower yield point. Yield point of the unit N / mm2 (MPa). The yield point (σsu): sample yield and maximum stress occurs force before the first drop; lower yield point (σsl): When excluding the initial transient effects, the yield phases of minimum stress. Yield point is calculated as follows: Where: Fs-- process of tensile yield strength (constant), N (Newton) So-- original specimen cross-sectional area, mm2.
③ Elongation (σ)
In the tensile test, the specimen fractured its gauge of the percentage increase in the length of the original gauge length, called elongation. In σ expressed in units of%. The formula is: where: L1-- specimen fractured gauge length, mm; L0-- original specimen gauge length, mm.
④ Section shrinkage (ψ)
In the tensile test, the specimen fractured its biggest percentage reduction in the amount of the original cross-sectional diameter of the cross-sectional area reduction, known as section shrinkage. In ψ expressed in%. Calculated as follows: where: S0-- original specimen cross-sectional area, mm2; S1-- specimen fractured necking at least cross-sectional area, mm2.
⑤ Hardness index
Metal material to resist indentation capacity hard surface objects, called hardness. Depending on the test methods and scope, it can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, micro hardness and high temperature hardness. Commonly used for pipe Brinell, Rockwell, Vickers hardness of three.
① Tensile strength (σb)
Specimen during stretching, pull off when exposure to the most vigorous (Fb), stress (σ) divided by the original specimen cross-sectional area (So) income, known as the tensile strength (σb), units N / mm2 (MPa). It represents a metal material to resist damage under tension maximum capacity.
② Yield point (σs)
Metallic material having a yield phenomenon specimen during the tensile force does not increase (constant) could continue elongation stress, said yield point. If power down occurs, it should distinguish between the lower yield point. Yield point of the unit N / mm2 (MPa). The yield point (σsu): sample yield and maximum stress occurs force before the first drop; lower yield point (σsl): When excluding the initial transient effects, the yield phases of minimum stress. Yield point is calculated as follows: Where: Fs-- process of tensile yield strength (constant), N (Newton) So-- original specimen cross-sectional area, mm2.
③ Elongation (σ)
In the tensile test, the specimen fractured its gauge of the percentage increase in the length of the original gauge length, called elongation. In σ expressed in units of%. The formula is: where: L1-- specimen fractured gauge length, mm; L0-- original specimen gauge length, mm.
④ Section shrinkage (ψ)
In the tensile test, the specimen fractured its biggest percentage reduction in the amount of the original cross-sectional diameter of the cross-sectional area reduction, known as section shrinkage. In ψ expressed in%. Calculated as follows: where: S0-- original specimen cross-sectional area, mm2; S1-- specimen fractured necking at least cross-sectional area, mm2.
⑤ Hardness index
Metal material to resist indentation capacity hard surface objects, called hardness. Depending on the test methods and scope, it can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, micro hardness and high temperature hardness. Commonly used for pipe Brinell, Rockwell, Vickers hardness of three.
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