MIL-DTL-14538D
4.3.2 Separate specimens. When the plated articles are not readily adaptable to the test specified
in 4.4.1 the test may be made by the use of separate specimens plated concurrently with the articles
represented. The separate specimens shall be of a basis metal equivalent to that of the articles
represented, and should be at least 6 square inches on a side and 1/16 inch thick. The specimens shall
be introduced into a lot at regular intervals prior to the cleaning operations preliminary to plating and
shall not be separated therefrom until after completion of the processing.
4.4 Acceptance tests.
4.4.1 Corrosion resistance. The test for corrosion resistance shall be performed on the specimens
selected in accordance with paragraph 4.3.1. The specimens shall be subjected to a continuous test of
four hours in 5% salt spray fog in accordance with ASTM B117 (see 3.5.4). Any failure from a lot
shall reject the lot.
4.4.2 Samples for corrosion resistance test. Samples used for test in 4.4.1 shall be discarded
except as the procuring agency may permit replating and reinspection.
4.5 Hydrogen embrittlement relief treatment. All steel parts shall be baked at 375°F ± 25°F
(191°C ± 14°C) for three hours or more after plating to provide hydrogen embrittlement relief. The
baking shall begin within four hours after plating.
4.6 Hydrogen embrittlement relief test. Type 1a test specimens described in annex A1 of ASTM
F519 (4340 steel at HRC 51-54) shall be plated and hydrogen embrittlement relief treated similar to the
parts. Within one hour after baking, the specimens shall be loaded per ASTM F519. After testing, the
specimens shall be examined for cracks. If failure occurs, the embrittlement relief time shall be extended
until the specimens pass the test.
5. PACKAGING
5.1 Packaging. Packaging requirements are not applicable for this specification.
6. NOTES
(This section contains information of a general or explanatory nature that may be helpful, but is not
mandatory.)
6.1 Intended use. The black chromium plate covered by this specification is military unique.
Black chromium plate is hard, adherent, heat resistant, and free of light reflection. Black chromium plate
is suitable for military applications such as rocket launcher rails, interior surfaces of optical parts, and
small arms applications where a non-reflecting black coating is desirable. This coating provides limited
corrosion protection, but added protection can be obtained by specifying a corrosion resistant
underplate such as nickel.
6.2 Acquisition requirements. Acquisition documents should specify the following:
(a) Title, number and date of this specification.
(b) Issue of DoDISS to be cited in the solicitation, and if required, the specific issue of
individual documents referenced (see 2.2.1 and 2.3).
(c) Operations to be performed on the items after plating or further processed, if different (see
3.2.1).
(d) Evidence of stress relief, if required (see 3.2.2).
(e) When hydrogen embrittlement relief treatment is not required (see 3.4.2).
(f) Sample of color to be duplicated, if required (see 3.5.3).
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