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1
8
Describe what is going to happen to these items; use the verbs:
to bend, to fold, to stretch, to resist, to
deform.
9
First, skim the passage to get an overall understanding, then scan it to answer the following questions.
a
Which two groups can properties be classified into?
b
What is meant by each of the following terms as applied to materials:
strength
,
hardness
,
plasticity
?
c
What is the opposite of elasticity?
d
Explain the meaning of
brittleness
.
e
Find one or more examples of materials for each of the mechanical properties. How many can you and your
class think of for each one?
Properties of materials
M
aterials have various, often very different,
properties that can be classified into two groups:
1
Physical and chemical properties, that include
melting point, electrical and thermal conductivity,
density, expansion, corrosion resistance, magnetism,
etc.
Corrosion resistance is particularly important because
some materials react with the oxygen in the air to form
a new substance more quickly than others. The order
of reactivity of metals is called the metal reactivity
series.
2
Mechanical properties, which include:
strength
the ability of a material to withstand
1
forces;
hardness
the ability of a material to resist abrasion,
scratching;
ductility
the ability of a material to be stretched
without fracture;
malleability
the ability of a material to be extended/
stretched without rupturing
2
;
toughness
the ability of a material to withstand
blows, hammering, without deformation;
elasticity
the ability of a material to be deformed
or strained without fracture and to return to its
original shape;
machinability
the ease (or not) with which a
material can be machined;
plasticity
the opposite of elasticity;
brittleness
the opposite toughness, i.e. easy to
break or shatter.
1
withstand
: resist, offer strong resistance
2
rupturing
: breaking or bursting
TEXT 3
brittleness
fragilità, friabilità
ductility
duttilità
elasticity
elasticità
hardness
durezza
machinability
lavorabilità alla macchina utensile
malleability
malleabilità
plasticity
plasticità
strength
forza
toughness
durezza, tenacità
TECHNICAL ENGLISH
Progetto FOR MECHANICALS_unit_1.indd 19
24/01/