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|  MIL-W-50985A
of extreme furnace conditions. When a continuous type furnace is
used for final heat treatment, a sample shall be 1.5% of the
castings completing heat treatment. If boxes or baskets are used
which contain approximately 70 castings, one casting from each box
shall be tested. A heat treat batch will be considered a quantity
of castings not to exceed 8 hours production. If any specimen is
outside of the hardness limits, the lot shall be rejected. The
lot may be re-heat treated to attain specification requirements.
4.5.3 Tension Test. Two tension test specimens or specimen
conforming to a standard "R" type specimen as prescribed by
Federal Test Method Standard No. 151 shall be taken longitudinally
from each sample. Samples shall be taken 1800 apart. The
criteria for determining yield strength and elongation shall be as
prescribed by Federal Test Method Standard No. 151, Method 211.1.
4.5.3.1 Warhead (malleable iron). The hardest and softest
casting representing the day's heat treat production shall be
subjected to this test. Failure of any test specimen to comply
with the applicable physical properties requirements on referenced
specification of dwg 9258180 shall be cause for rejection of the
day's heat treat production represented by the specimens.
4.5.3.2 Warhead (ductile iron). To qualify the heat
treatment, one type keel block representative of each heat treat
lot shall be subjected to this test. In the case of the
continuous heat treat oven, one specimen shall be tested for each
(8) hours of oven operating time. If any specimen fails the
specification requirements listed on the body drawing, the lot
represented by the sample shall be rejected.
4.5.4 Continuity and open circuit test. This test shall be
performed 100% on all subassemblies and 100% on all complete metal
parts warhead assemblies. Continuity of each conductor circuit
shall be checked with an ohmmeter. Insulation resistance between
the two fuze attachment contacts shall be checked with a megohm
meter. Any assembly that fails to comply with the requirement
shall be classed defective and removed from the lot.
4.5.5 Air tightness test. Each warhead assembly in the
sample shall be subjected to ten (10) PSIG pressure internally for
a period of ten (10) seconds. Observations shall be made by a dry
test method with equipment capable of detecting a pressure drop of
0.5 psig. Any warhead assembly that indicates a pressure drop in
excess of the requirement shall be classed defective.
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