The mechanical property of steel is an important index to ensure the performance of steel body, which depends on the chemical composition of steel and the heat treatment system. In the seamless steel pipe standard, according to the different requirements of use, the provisions of tensile, hardness, toughness, user demand, high and low temperature and other issues.
① Tensile strength (σb) : the ultimate force (Fb) of the specimen during tensile fracture divided by the stress (σ) of the original cross-sectional area (So) of the specimen, unit: N/mm2 (MPa). Represents the ultimate ability of metal material to resist damage under the action of tensile force.
(2) The upper yield point (σ SU) refers to the ultimate pressure before the specimen yields and the force begins to decline.
③ Lower yield point (σ SL) : the lower limit stress in the yield stage when the initial instantaneous effect is not considered.
(4) Elongation after fracture (σ) : in the tensile test, after the specimen is pulled, the percentage of the length increased by the standard distance of seamless steel pipe and the length of the original standard distance is expressed in the unit of %. The calculation formula is σ= (LH-LO) /L0*100%
(5) Brinell hardness (HB) : the use of a certain diameter of seamless steel pipe, hard alloy ball, according to the specified test force (F) pressed into the sample surface, after the specified hold time to remove the test force, measurement of the sample surface indentation diameter (L). Brinell hardness value is the quotient of the test force divided by the surface area of the indentation sphere. HBS (steel ball), unit: N/mm2 (MPa).
Post time: May-12-2022