Tc 9-524 fundamentals of machine tools

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TC 9-524
GENERAL
PROPERTIES OF METALS
The internal reactions of a metal
known as mechanical properties. The
to external forces are
mechanical properties
are directly related to each other. A change in one property
usually causes a change in one or more additional properties.
For example, if the hardness of a metal is increased, the
brittleness usually increases and the toughness usually
decreases. Following is a brief explanation of the mechanical
properties and how they relate to each other.
TENSILE STRENGTH
Tensile strength is the ability of a metal to resist being pulled
apart by opposing forces acting in a straight line (Figure 2-1).
It is expressed as the number of pounds of force required to
pull apart a bar of the material 1 inch wide and 1 inch thick.
SHEAR STRENGTH
Shear strength is the ability of a metal
fractured by opposing forces not acting in
to resist being
a straight line
(Figure 2-2). Shear strength can be controlled by varying the
hardness of the metal.
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TC 9-524
COMPRESSIVE STRENGTH
Compressive strength is the ability of a metal to withstand
pressures acting on a given plane (Figure 2-3).
ELASTICITY
Elasticity is the ability of metal to return to its original size
and shape after being stretched or pulled out of shape (Figure
2-4).
DUCTILITY
Ductility is the ability of a metal to be drawn or stretched
permanently without rupture or fracture (Figure 2-5). Metals
that lack ductility will crack or break before bending.
MALLEABILITY
Malleability is the ability of a metal to be hammered,
rolled, or pressed into various shapes without rupture or
fracture (Figure 2-6).