Materials Properties Definitions:

Ductility

Ductility

The ability of a material to deform plasti-cally before fracture.

Elastic iiniit

The greatest stress that a material is capa-ble of sustaining without any pertnanent deformation remaining upon complete release of stress.

Elongation at break or total elongation

The amount of plastic or permanent deformation determined after frac-ture by realigning and fitting together the broken ends of the specimen. •Elongation at fracture or maximum elongation

Engineering strain

A dimensionless value that is the change in length per unit length of the original linear dimension along the loading axis of the specimen. This is frequently expressed in inches per inch or percent.

Engineering stress

"Ille normal stress, expressed in units of applied force per unit of original cross-sectional area. Gage length

Hardness

The resistance of a material to deforma-tions particularly permanent deformation, indentation or scratching.

Hooke's law (Hookean behavior)

Within certain force limits, the stress in a material is proportional to the strain that produced it.

Mechanical properties

Those properties of a material that are associated with the elastic and plastic reaction when force is applied.

Offset yield strength

The engineering stress at which, by convention, it is considered that plastic elongation of the specimen has commenced. Offset yield strength is deter-mined by constructing a line parallel to the linear elastic region of the stress-strain curve and shifting it in the strain direction an amount specified as a percentage of gage length.

Plastic strain ratio

The ratio of the true strain in the width direction to the true strain in the thickness direction of a sheet material loaded beyond yield.

Proportional limit

The greatest stress that a material is capable of sustaining without deviation from a linear relationship of stress to strain. Reduction of area

Ultimate tensile strength or tensile strength

The maximum tensile stress that a material is capable of sus-taining. Tensile strength is the maximum load during a ten-Sion test carried to rupture divided by the original cross-sectional area of the specimen.

Yield by extension under load (EUL)

The engineering stress at which, by conventions it is considered that plastic elongation of the specimen has commenced. EUL is deter-mined by constructing a line perpendicular to the strain axis of a stress-strain curve at a strain value that is specified as a percentage of gage length. e Yield strength