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SECTION 1
15
Read the passage and do the exercises below.
16
Answer the following questions.
a
What is an alloy?
b
Name four non-ferrous pure metals.
c
Name three non-ferrous alloys.
17
Identify two examples of each material type listed below that is in your school workshop.
Materials in engineering
T
here are two basic types of materials used in engineering, metals and non-metals.
They both have properties suitable
1
for tooling and manufacturing.
A metal is a raw material usually extracted from the Earth in the form of an
ore
.
Metals are often mixed together to form
alloys
.
Metals can be divided into two categories:
ferrous
and non-ferrous, the former contain
the element,
iron
.
Steel
is perhaps the most common alloy used in engineering. There are many different
grades (qualities) of steel. Steel is an alloy of iron and small amounts of other elements, the most widely used
being carbon and manganese, but there are many others: for example high-speed steel, stainless steel, which are
produced by adding various elements such as chromium, tungsten, nickel or manganese to the steel.
Cast iron
is iron mixed with much larger amounts of carbon than are used in plain carbon steels.
It is useful because it is very fluid when molten.
2
Non-ferrous materials and alloys are those which do not contain iron. For example: aluminium,
copper
,
tin
,
lead
and zinc are pure non-ferrous metals. They are also used to form alloys.
The most common alloys used in engineering are:
duralumin = aluminium 96%, copper 4%
cast
brass
= copper 60%, zinc 40%
coin
bronze
= copper 97%, zinc 2.5%, tin 0.5%
phosphor bronze = copper 94%, tin 5%,
phosphorus
1%
tinmans = tin 30%, lead 70%
electrical solder = tin 60%, lead 40%
Some are: plastics, organic substances (
rubber
,
wood
), minerals (oil, glass, silicon), or synthetic materials.
1
suitable
: right or appropriate for a particular purpose
2
molten
: heated to a very high temperature so that it becomes liquid
TEXT 5
Ferrous
Non-ferrous
Non-metal
A
B
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alloy
lega
brass
ottone
bronze
bronzo
cast iron
ghisa
copper
rame
ferrous
ferroso
iron
ferro
lead
piombo
ore
minerale metallifero
phosphorus
fosforo
rubber
gomma
steel
acciaio
tin
latta
wood
legno
TECHNICAL ENGLISH
Progetto FOR MECHANICALS_unit_1.indd 22
24/01/