Project Introduction

Tensile strength test can also be called tensile test for metal mechanical properties. Tensile test can measure a series of strength indexes and plastic indexes of materials. Strength usually refers to the ability of a material to resist elastic deformation, plastic deformation, and fracture under external force. Plasticity refers to the ability of a metal material to deform plastically under load without damage. Commonly used plasticity indicators are elongation and shrinkage.

Guideline

Reference standard for tensile strength test

GB-T228-2002 Metallic materials Tensile test method at room temperature

ASTM E8-04 Metal Tensile Test Method Metal Tensile Strength Test

EN 10002-1:2001 Tensile test of metallic materials, normal temperature test method

JIS Z 2241:1998 Metallic material tensile test method

ISO 6892:1998 Metallic materials, tensile test at ambient temperature

experiment procedure

Elastic zone (from 0 to yield strength YS)

· Less elongation: corresponding percentage.

· Elastic elongation: If the stress stops, the sample will return to its original length.

· Yield strength: when the permanent elongation value reaches 0.2%.

· Yield strength = force at yield (N) / original area of the tensile specimen (mm2) or the same MPA value.

· Longitudinal modulus: ratio of applied force to elongation length (depending on metal).

· Transverse modulus: the ratio of elongation to interface shrinkage (applies to all metals ~ 0.3).

Plastic zone (from tensile strength UTS to yield strength YS)

· Large elongation: a few percent for general metals, up to 50 to 60 percent.

· Inelastic elongation: if the stress stops, the specimen remains permanently strained.

· Breaking force: record of tensile strength (UTS).

· Tensile strength = maximum force (N) before breaking the tensile test / original area of the tensile specimen (mm2) or the same MPA value.

· Due to the cold work effect, the strain will continue to increase with the test.

After breaking

· The overall length needs to be measured to calculate the elongation.

· E% = (Lu – L0) / L0 x 100 (Lu is the final length, L0 is the initial length).

Young's modulus-important parameter

· Modulus of elasticity E: unit N/mm2.

· Yield strength YS 0.2: Unit N/mm2 or MPa.

· Transverse modulus: Poisson coefficient, always around 0.3.

· Breaking force: UTS, unit N/mm2 or MPa, except in special cases.

· Elongation at break E%: ductility, E<5% is brittle (brittleness).

· Executive standards: NF EN 10002 and ASTM E8, the difference between the two is the measurement difference (L0) of different elongation values.