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Seamless steel pipe can still continue to stress

浏览: Release time: 2019-11-04 10:20 Times

Seamless steel pipe can still continue to stress

The seamless steel pipe has a yielding metal material. The stress at which the specimen can continue to elongate without increasing the force during tension (keep constant) is called the yield point. If the force drops, the upper and lower yield points should be distinguished. The unit of the yield point is N / mm2 (MPa).

Upper yield point (σsu) of seamless steel pipe: the maximum stress before the first drop of the sample when the yield occurs; lower yield point (σsl): the minimum stress in the yield stage when the initial transient effect is not taken into account.

The formula for calculating the yield point of seamless steel tubes is:

In the formula: Fs--yield force (constant) during the tensile process of the sample, N (Newton) So--the original cross-sectional area of the sample, mm2.

③ Elongation after fracture of seamless steel pipe (σ)

In a tensile test, the percentage of the length of the gauge that is increased after the sample is broken off from the original gauge length is called the elongation. Expressed as σ, the unit is%. The calculation formula is:

In the formula: L1--gage length after the sample is broken, mm; L0--the original gage length of the sample, mm.

④ Sectional shrinkage of seamless steel pipe (ψ)

In the tensile test, the percentage of the maximum reduction of the cross-sectional area at the reduced diameter of the sample after the sample is broken off and the original cross-sectional area is called the reduction of area. Expressed in ψ, the unit is%. Calculated as follows:

In the formula: S0--the original cross-sectional area of the sample, mm2; S1--the minimum cross-sectional area at the reduced diameter of the sample after breaking, mm2.