During stress testing of a material sample, the stress–strain curve is a graphical representation of the relationship between stress, obtained from measuring the load applied on the sample, and strain, derived from measuring the deformation of the sample. The nature of the curve varies from material to material.

# Category Archives: Stress-Strain

# True Stress – True Strain Curve: Part Four

This article describes strain-hardening exponent and strength coefficient, materials constants which are used in calculations for stress-strain behaviour in work hardening, and their application in some of the most commonly used formulas, such as Ludwig equation.

# True Stress – True Strain Curve: Part Three

The parameters that are usually determined from the true stress – true strain curve include true stress at maximum load, true fracture stress, true fracture strain, true uniform strain, true local necking strain, strain-hardening exponent and strength coefficient.

# Engineering Stress-strain Curve: Part Three

The engineering tension test is widely used to provide basic design information on the strength of materials and as an acceptance test for the specification of materials. In the tension test a specimen is subjected to a continually increasing uniaxial tensile force while simultaneous observations are made of the elongation of the specimen. The parameters, which are used to describe the stress-strain curve of a metal, are the tensile strength, yield strength or yield point, percent elongation, and reduction of area. The first two are strength parameters; the last two indicate ductility.

# True Stress – True Strain Curve: Part Two

Generally, the metal continues to strain-harden all the way up to fracture, so that the stress required to produce further deformation should also increase. If the true stress, based on the actual cross-sectional area of the specimen, is used, it is found that the stress-strain curve increases continuously up to fracture. If the strain measurement is also based on instantaneous measurements, the curve, which is obtained, is known as a true-stress-true-strain curve.

# Engineering Stress-strain Curve: Part Two

The engineering tension test is widely used to provide basic design information on the strength of materials and as an acceptance test for the specification of materials. The parameters, which are used to describe the engineering stress-strain curve of a metal, are the tensile strength, yield strength or yield point, percent elongation, and reduction of area.

# High Strengths Steels: TRIP Steels

TRIP-aided multiphase steels are a new generation of low-alloy steels that exhibit an enhanced combination of strength and ductility, thus satisfying the requirements of automotive industry for good formable high-strength steels.

After the thermal treatment of TRIP steels, a triple-phase microstructure is obtained, consisting of ferrite, bainite and retained austenite. TRIP steels are essentially composite materials with evolving volume fractions of the individual phases.

# True Stress – True Strain Curve: Part One

During stress testing of a material sample, the stress–strain curve is a graphical representation of the relationship between stress, obtained from measuring the load applied on the sample, and strain, derived from measuring the deformation of the sample. The nature of the curve varies from material to material.

# Engineering Stress-strain Curve: Part One

The shape and magnitude of the stress-strain curve of a metal will depend on its composition, heat treatment, prior history of plastic deformation, and the strain rate, temperature, and state of stress imposed during the testing. The parameters, which are used to describe the stress-strain curve of a metal, are the **tensile strength, yield strength or yield point, percent elongation, and reduction of area**. The first two are strength parameters; the last two indicate ductility.