Quantcast Tests Used to Identify Metals

 
  
 


METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 2
until they are learned.
These tests are described in the following
paragraphs.
2.
Tests Used to Identify Metals
a.
General.  Simple tests can be conducted in the shop to identify
the different metals.
Since the ability to judge can be developed
only through personal experience, practice these tests with known
metals until you are familiar with the reactions of each metal to
each  type  of  test.
The  tests  are  described  in  the  following
subparagraphs.
b.
Appearance/Chemical Analysis.
Appearance/chemical analysis, as
the name implies, is based on the general appearance of the metal,
which includes such general features as the color and texture of
machined and unmachined surfaces.  It is obvious that the appearance
portion  of  this  type  test  is  not  an  extremely  accurate  method;
however,  the  experienced  metalworker  can  make  a  reasonably  good
determination
based
on
experience
and
the
above
mentioned
characteristics.  The chemical analysis procedure referred to in the
following paragraphs is confined to the analysis used to distinguish
between aluminum and magnesium, and between steel and aluminum or
lead.
c.
Fracture.
The  fracture  of  many  metals  may  be  used  for
identification through the appearance of the fracture and study of
metal chips.
This test is made by simply notching a specimen and
then  breaking  it.
Although  no  measurable  indications  of  the
properties of a metal are obtained from this test, many metals can,
through experience, be quickly identified by examining the surface of
the  break,  or  by  studying  the  chips  produced  with  a  hammer  and
chisel.  The fracture test is probably the oldest of the methods used
in the inspection and testing of metals.
d.
Sparks.  When the exact type of material is unknown, a spark test
may be used to determine its identity.
The test is conducted by a
study of the sparks formed when the material is held against a high-
speed grinding wheel.
A grinding wheel may be used on the various
types of iron and steel because they produce sparks which vary in
length, shape, and color when held lightly against a grinding wheel.
When any form of iron or steel is held against a grinding wheel, small
particles, heated to a red or yellow heat, are released from the metal
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