METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 2
ball of the Brinell.
The impression made by this penetrator is a
dark square on a light background. This type of impression is easier
to measure than the circular impression.
Another advantage lies in
the fact that the diamond point does not deform as is possible with
the steel ball.
With this process, the hardness is measured
by the height of rebound of a diamond-pointed hammer after it has
been dropped through a guiding glass tube onto the test piece and the
rebound checked on a scale.
The harder the material used, the
greater the rebound of the hammer because the rebound is directly
proportional to the resilience or springiness of the test piece. The
height of the rebound is recorded on a gage. Since the scleroscope
is portable, it can be carried to the work enabling tests to be
performed on a large section of metal too heavy to be carried to the
work bench. The indentations made by this test are very slight.
The file test is a method of determining the
hardness of a piece of material by trying to cut into it with the
corner edge of a file.
The hardness is indicated by the bite that
the file will take.
This is the oldest and one of the simplest
methods of checking hardness; it will give results ranging from quite
soft to glass hardness.
The principal objection to the use of the
file test is that no accurate record of results can be maintained as
Other Systems for Identification of Metals
Numerical Index System.
One of the most widely known and
generally used numbering systems for steel specifications and
compositions is the one established by the Society of Automotive
Engineers (SAE), known as SAE designations.
were originally intended for use in the automotive industry;
however, their use has spread into all industries where steel and
As the title implies, this is a numerical
system used to identify the compositions of the SAE steels. With
only a few exceptions, plain steels and steel alloys are
By using this
procedure, it is possible to use numerals on shop drawings and
blueprints to partially describe the composition of the material
referred to. To provide a better understanding of the SAE system,