Modulus of Elasticity

Metal Properties, Characteristics, Uses, And Codes
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(3) Modulus of Elasticity. The modulus of elasticity is the ratio

of the internal stress to the strain produced.

It expresses the

stiffness of a material.

For steel and most metals, this is a

constant property and is affected very little by heat treatment, hot

or cold working, or the actual ultimate strength of the metal.

According to Hooke's Law: "The degree to which an elastic body bends

or stretches out of shape is in direct proportion to the force

(stress) acting upon it."

But, this law only applies within a

certain range.

(4) Ductility. Ductility is the capacity of a material, such as

copper, to be drawn or stretched under tension loading and

permanently deformed without rupture or fracture. Specifically, the

term denotes the capacity to be drawn from a larger to a smaller

diameter of wire.

This operation involves both elongation and

reduction of area (figure 1, view E, on the following page).

(5) Malleability. Malleability is the property of a metal to be

deformed or compressed permanently without rupture or fracture.

Specifically, it means the capacity to be rolled (figure 1, view F,

on the following page) or hammered into thin sheets. The property of

malleability is similar to but not the same as that of ductility, and

different metals do not possess the two properties in the same

degree.

Lead and tin are relatively high in order of malleability;

however, they lack the necessary tensile strength to be drawn into

fine wire. Most metals have increased malleability and ductility at

higher temperatures. For example, iron and nickel are very malleable

when heated bright-red.

(6) Plasticity.

Plasticity is the ability of a metal, such as

gold, silver, or lead, to be deformed extensively without rupture.

This property, together with strength, are considered to be the two

most important properties that a metal can possess.

(7) Toughness. Toughness is a combination of high strength and

medium ductility. Toughness is the ability of a material or metal

to resist fracture, plus the ability to resist failure after