FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 4. Metal Structure, Welding, and Brazing | 2. Testing of Metals | 4-19. Vickers Hardness Test
AC 43.13-1B
9/8/98
a. General Precautions. To avoid mis
application of Brinell hardness testing, the
fundamentals and limitations of the test proce
dure must be clearly understood. To avoid in
accuracies, the following rules should be fol
lowed.
(1) Do not make indentations on a
curved surface having a radius of less than
1 inch.
(2) Do make the indentations with the
correct spacing. Indentations should not be
made too close to the edge of the work piece
being tested.
(3) The limit of hardness, 15 HB with
the 500-kg load to 627 HB with the 3,000-kg
load, is generally considered the practical
range.
c. Calibration. A Brinell Hardness Tester
should be calibrated to meet ASTM standard
E10 specifications.
4-19. VICKERS HARDNESS TEST. In
this test, a small pyramidal diamond is pressed
into the metal being tested. The Vickers Hard
ness number (HV) is the ratio of the load ap
plied to the surface area of the indention. This
is done with the following formula.
(3) Apply the load steadily to avoid
overloading caused by inertia of the weights.
(4) Apply the load so the direction of
loading and the test surface are perpendicular
to each other within 2 degrees.
(5) The thickness of the work piece
being tested should be such that no bulge or
mark showing the effect of the load appears on
the side of the work piece opposite the inden
tation.
(6) The indentation diameter should be
clearly outlined.
b. Limitations. The Brinell hardness test
has three principal limitations.
(1) The work piece must be capable of
accommodating the relatively large indenta
tions.
(2) Due to the relatively large indenta
tions, the work piece should not be used after
testing.
HV = P / 0.5393d 2
a. The indenter is made of diamond, and
is in the form of a square-based pyramid hav
ing an angle of 136 degrees between faces.
The facets are highly-polished, free from sur
face imperfections, and the point is sharp. The
loads applied vary from 1 to 120 kg; the stan
dard loads are 5, 10, 20, 30, 50, 100, and
120 kg. For most hardness testing, 50 kg is
maximum.
b. A Vickers hardness tester should be
calibrated to meet ASTM standard E10 speci
fications, acceptable for use over a loading
range.
4-20. MICROHARDNESS TESTING.
This is an indentation hardness test made with
loads not exceeding 1 kg (1,000 g). Such
hardness tests have been made with a load as
light as 1 g, although the majority of micro-
hardness tests are made with loads of 100 to
500 g. In general, the term is related to the
size of the indentation rather than to the load
applied.
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