Hebei Shengtian group for you about the mechanical properties of the seamless steel pipe
* 来源 : Hebei Shengtian group Seamless Steel Pipe Company Limited * 作者 : Shengtian group * 发表时间 : 2015-06-13 * 浏览 : 314
The mechanical properties of steel are the important indexes of the final performance (mechanical properties) of the steel, and the chemical composition and heat treatment system of the steel tube are determined by the seamless steel tube.. In the steel tube standard, according to the different requirements, the provisions of the tensile properties (tensile strength, yield strength or yield point elongation) and hardness, toughness index and user requirements of high and low temperature performance.
The tensile strength (b)
Specimen in the tensile process and the rupture under the maximum force (FB) and samples divided by the original cross-sectional area (S0) income should stress (sigma), known as the tensile strength (o b), the unit is n / mm2 (MPA). It indicates the maximum ability of metal material to resist damage under tensile force..
The yield point (s)
A metal material having a yield phenomenon, the stress in the tension process of the specimen is not increasing (holding constant) and can continue to elongate, yielding point. When the force happens to fall, it should be distinguished from the upper and lower yield points. The yield point unit is N/mm2 (MPa)..
Upper yield point (sigma Su): samples yield and force declined for the first time before the maximum stress; yield point (sigma SL): when regardless of the initial transient effect, yield stage in the minimum stress.
The yield point formula is: the tensile strength of Fs-- specimen (Heng Ding), N (Newton) So-- specimen original cross-sectional area, mm2.
The elongation (sigma)
In a tensile test specimen, the percentage of breaking from the standard after the increase in the length of the original gauge length, called elongation. The sigma units for said,%. Formula: L1-- samples were broken after the gauge length, mm; L0-- sample original gauge length, mm.
The contraction ratio of section (I)
In the tensile test, the specimen fractured the shrink diameter cross-sectional area of the biggest shrinkage percentage of reduction and the original cross-sectional area, known as the section shrinkage. The unit is showed,%. The calculation formula is as follows: S0-- samples of the original cross-sectional area, mm2 S1--; the samples were broken after shrinkage minimum cross-sectional area diameter, mm2.
The hardness index
The ability of a metal to resist a hard object indentation, called a hardness.. According to the test method and the range of application, the hardness can be divided into the hardness of the hardness, the hardness of the Vivtorinox, the hardness of the Shaw, the microhardness and the hardness of the high temperature.. For the pipe is commonly used in the three kinds of the hardness of the.
A, HB hardness
With a certain diameter of steel ball of the ball or hard alloy, the provisions of the test force (f) is pressed into the pattern surface, the provisions to keep time after unloading test force, and the measurement of the surface of the sample indentation diameter (L). The value of the hardness of the test is the quotient of the test force divided by the spherical surface area of the indentation.. HBS (ball), the unit is N/mm2 (MPa).
The calculation formula is: the test force of the F-- press into the surface of the metal sample, D--, the diameter of the steel ball, mm, the average diameter of d--, mm, N.
The hardness of the test is more accurate and reliable, but the general HBS is only suitable for the metal materials of 450N/mm2 (MPa), and it is not suitable for the hard steel or the thin plate.. In seamless steel pipe, the most widely used in the steel is the hardness of the material, which is usually D, and it is easy to use..
Example: 120HBS10/1000130: 120N/ () was expressed as the mm2 30s (MPa) with the diameter of 10mm steel ball under the influence of 1000Kgf (9.807KN) test..