Cold drawn steel pipes Elongation and reduction of area

Cold drawn is a process material, for the metal material, referring to the drawing in order to achieve a certain shape and a certain mechanical properties, the material is under room temperature conditions for drawing. Cold drawn products compared to thermoforming: high dimensional accuracy and good surface finish advantages.

Drawing large diameter steel pipe Elongation (σ), in the tensile test, The length of the sample after snap its range increased as a percentage of the original gauge length called elongation. With σ expressed in units of %. The formula is: where : L1 – specimen fractured gauge length, mm; L0 – the original specimen gauge length, mm.

Drawing large diameter pipe section shrinkage (ψ) in the tensile test, the specimen largest percentage reduction in the amount of the original cross-sectional area of its cross-sectional area at the necking pull off, known as section shrinkage. To ψ expressed in units of %. Calculated as follows: where: S0 – the original specimen cross-sectional area, mm2; S1 – specimen fractured necking at least cross-sectional area, mm2.

The tensile test specimen into the neck of a plastic deformation process. Then the elongation of the sample showed a steady cross-sectional dimension along the necked section of the specimen continues to expand, until the whole sample becomes necked condition. A sharp decline in the neck occurred in yield stress stage. When the drawing temperature of the metal at points in the drawing below the recrystallization temperature of the drawing, in the drawing above the recrystallization temperature is hot drawing at a temperature higher than the room temperature below the recrystallization temperature of the drawing pull. Drawing a metal wire, wire production drawing the most common way. Thermal pulling the wire to be heated before entering the die orifice, the refractory metal is mainly used for drawing, such as tungsten, molybdenum and other metal wire. When the temperature pull the wire need only be drawn into the die hole by a heater to a specified temperature range, mainly for zinc wire, the wire is difficult to deformation such as high speed steel, bearing steel drawing.