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|  MIL-A-12560H (MR)
w/INT. AMENDMENT 4
3. REQUIREMENTS
3.1 First Article. When specified in the contract or purchase order (see 4.1.3, 6.2, 6.9 and 6.11), a
sample or samples of the specified item shall be made available to the contracting officer or his
authorized representative for approval in accordance with 4.1.1. The approval of the first article
samples authorizes the commencement of shipment but does not relieve the supplier of
responsibility for compliance with all applicable provisions of this specification. The first article
samples and test plates shall be manufactured by the process proposed for use on production
armor. The manufacturer's declared chemical analysis shall be submitted to the contracting
agency and to the ballistic test agency. The ballistic test agency shall record the first article
ballistic test plate submitted, showing the dates tested.
3.1.1 First time producer. First time producers wishing to qualify to this specification shall
follow the instructions of 6.8.
3.2 Acceptance requirements.
3.2.1 Materials.
3.2.1.1 Structure. Processes of manufacture shall be such as to produce steel plate having, as
nearly as practicable, a homogeneous structure throughout.
3.2.2 Chemical composition. The product analysis of all plates within a heat shall conform to the
requirement of table I unless otherwise negotiated between the steel supplier and the contractor
(see 6.12). All limits as specified in table I (including any deviations negotiated) shall be
submitted in advance to the procuring activity. The contractor shall establish and submit separate
limits for each thickness of plate to be furnished (see 6.5). A statement showing the product
analysis of each melt and complete details of the heat treatment of each lot shall be furnished
(see 6.5). A statement showing the product analysis of each melt and complete details of the heat
treatment of each lot shall be furnished for the files of the procuring activity at no cost to the
procuring activity. All elements of chemical composition shall be shown in the statement. The
chemical composition range established by the producer and the chemical analysis of the
material submitted shall be reported (see 6.2.2).
3.2.2.1 Hardenability index (class 4 armor plate). An average hardenability indes (DI) shall be
calculated for class 4 armor plate (see 6.1.4). This (DI) calculation method utilizes a series of
hardenability factors for each alloying element in the composition (see SAE J406).
3.2.3 Heat treatment. All plates in each lot, including samples, shall receive the same heat
treatment except for such variations in tempering temperature as shall be necessary to produce
the prescribed hardness. The austenitizing temperature for production plates may vary within a
range of 50 above the temperature used for test plates, but in no case shall it exceed 1700F (see
6.7). Class 4 armor plate shall be heat treated to higher hardness levels than class 1 armor plate to
develop maximum resistance to penetration.
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