Heat treating and inspection of metals Page: 40
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42-43 AIR CORPS
the material is considered too soft for the diamond cone and a 1/ 6-inch
hardened ball should be used. The diamond cone must be used for
all hard materials (those above 100 on the B scale) as the steel ball
may be deformed by the test.
(2) Several anvils are included as regular equipment with each
machine and their selection depends upon the shape of the section to
c. The procedure for making the Rockwell test may be outlined as
(1) Prepare the sample as described for the Brinell test.
(2) Select the proper penetrator and place the corresponding
weight on the weight pan.
(3) Place sample on the anvil and, by turning hand wheel, raise it
slowly until contact is made with the penetrator. Continue turniiig
until the pointer of the indicator has made 3 revolutions and is within
5 divisions (plus or minus) of the upright position. This applies the
10 kilogram or minor load on the sample.
(4) Apply the major load by means of the handle shown at (9),
(5) Release the major load by returning the handle (9) to its origi-
nal position and read the hardness number directly on the indicator
(a) The tensile strength corresponding to the hardness number may
be obtained by referring to table VII.
(b) Identification and condition of temper may be determined by
reference to table VIII.
43. Shore scleroscope hardness test.-a. Testing hardness with
the scleroscope consists of dropping a diamond-tipped hammer upon
the test specimen from a definite height and measuring the rebound
produced. In one type of tester, the height of the rebound must be
measured directly on the scale of the machine, while on another the
amount is indicated on a dial.
b. The tester (fig. 7) consists of the following major parts:
(1) A base, provided with leveling screws, and a clamping arrange-
ment to hold the sample to be tested.
(2) A vertical glass tube, mounted to the base and containing the
cylindrical diamond-point hammer.
(3) A suction head and bulb for lifting and releasing the hammer.
(4) A scale, visible through the glass tube, for determining the
height of the rebound.
(5) A magnifier hammer with a larger contact area is supplied for
use with extremely soft metals.
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United States. War Department. Heat treating and inspection of metals, book, September 10, 1941; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc96657/m1/42/: accessed March 1, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.