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The Power Of Seamless Steel Pipe

Author: Suli Lee
by Suli Lee
Posted: Nov 16, 2018
yield point

Seamless steel pipe has become an essential part of people's lives. It is related to people's quality of life and promotes national finance.

The mechanical properties of steel are an important indicator to ensure the end-use performance (mechanical properties) of the steel. It depends on the chemical composition of the steel and the heat treatment system. In the steel pipe standard, tensile properties (tensile strength, yield strength or yield point, elongation), and hardness and toughness indexes, as well as high and low temperature performance required by users, are stipulated in accordance with different application requirements.

  1. Tensile strength (?b)The maximum force (Fb) at which the specimen is subjected to tensile breaking during the drawing process is divided by the stress (?) obtained from the original cross-sectional area (So) of the specimen and is called the tensile strength (?b) in units of N/mm2 (MPa). It represents the maximum ability of a metal material to resist damage under the action of a tensile force.
  2. Yield point (?s)Metal material with a yield phenomenon, the specimen does not increase (hold constant) in the tensile process can still continue to stretch the stress, known as the yield point. If the force drops, the upper and lower yield points should be distinguished. The unit of yield point is N/mm2 (MPa).

The upper yield point (?su): the maximum stress before the specimen first drops after yielding; the lower yield point (?sl): the minimum stress in the yield phase when the initial transient effect is not taken into account.The formula for yield point is:In the formula: Fs - the yield force (constant) during the tensile of the specimen, N (Newton) So - the original cross-sectional area of??the specimen, mm2.

  1. Elongation after breaking (?)In the tensile test, the percentage of the gauge length and the original gauge length after the specimen is pulled off is called the elongation rate. Expressed in?, the unit is %. The formula is:? = (Lh - Lo) / L0 * 100% where: Lh - specimen gauge length after pull off, mm; L0 - the original gauge length, mm.
  2. Section shrinkage (?)In a tensile test, the percentage of the reduction in the cross-sectional area at the reduced diameter of the specimen after it is broken and the percentage of the original cross-sectional area is called the reduction of area. Expressed in?, the unit is %. Calculated as follows:Where: S0 - the original cross-sectional area of??the sample, mm2; S1 - the smallest cross-sectional area at the reduced diameter after the sample is broken, mm2.
  3. Hardness indexThe ability of a metal material to resist the collapse of a hard object is called hardness. According to the test method and application range, the hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. For the pipe commonly used are Brinell, Rockwell, Vickers hardness three.
  4. Brinell hardness (HB)With a certain diameter of steel ball or cemented carbide ball, with the specified test force (F) pressed into the surface of the model, after the specified retention time to remove the test force, measure the indentation diameter (L) of the sample surface. The Brinell hardness value is the quotient obtained by dividing the test force by the ball surface area of??the indentation. Expressed in HBS (steel ball), the unit is N/mm2 (MPa).
About the Author

A worker from a steel pipe company, which is located in China.

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Author: Suli Lee

Suli Lee

Member since: May 29, 2017
Published articles: 158

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