METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 1
(c) The yield strength is the number of pounds per square inch
required to produce deformation to the yield point.
(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
6
Previous Page
