MIL-DTL-1222J
d) When quenched and tempered or solution annealed and aged rod,
bar or wire is used to produce studs, bolts or screws over ½"
in diameter, its nominal diameter may be no more than twice
the nominal diameter of the bolt or screw.
e) Headed fasteners are wedge tensile tested in accordance with
4.5.2.3 and meet the requirements of 3.4. Studs are axial
tensile tested in accordance with 4.5.2.4 and meet the
requirements of 3.4.
4.5.3 Decarburization. Decarburization examination shall be made in
accordance with SAE J121, class B (see 6.2 and 6.3). All decarburization
examinations shall be performed after the final heat treatment. Heading
fasteners, without heating the threaded area, is not, for the purposes of
decarburization examination, a heat treatment. Decarburization examination
may be done on the fastener or the rod, bar or wire used to manufacture the
fastener. Bar, rod or wire, decarburized to a greater extent than permitted
by SAE J121, class B, may be used, without retesting, provided the depth of
total decarburization is removed during a subsequent machining operation.
Headed fasteners machined from heat-treated bar shall not require a
decarburization test.
4.5.4 Magnetic permeability. Determination of magnetic permeability
shall be conducted in accordance with ASTM A 342, method 3 to meet the
requirements of 3.8.
4.5.5 Protective coating thickness. Protective coating thickness may
be determined by one of the following methods: microscopic to ASTM B 487,
coulometric method to ASTM B 504 or x-ray spectrometry to ASTM B 568. No
less than two measurements shall be made on each sample to determine
compliance with 3.6.3. The method used shall produce results that are
precise within 0.4 mils or 10 percent of the specified coating thickness,
whichever is greater. Failure of the coating thickness to meet the minimum
coating thickness requirements shall be cause for rejection.
4.5.6 Hydrogen embrittlement relief. When hydrogen embrittlement
relief is required by 3.7, a stress durability test shall be performed in
accordance with NASM-1312, method 5. The test duration shall not be less
than 48 hours. A wedge in accordance with 4.5.2.3 shall be used under the
heads of bolts and screws or under nuts threaded on studs.
4.6 Invalid Tests. Tests required in 4.5.2 and 4.5.6 may be discarded
and a replacement test done on a specimen selected from the same lot of
fasteners when any one of the following conditions occur:
a) The test specimen was incorrectly machined
b) The test procedure was incorrect
c) There was a malfunction of the testing equipment
d) An external flaw, that is not indicative of an inferior or
defective lot, develops during the test. Test specimens with
internal flaws, such as cracks, ruptures and porosity, are not
invalid.
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