INCH-POUND MIL-A-12560H(MR) 28 November 1990 SUPERSEDING MIL-A-12560G(MR) 15 August 1984 MILITARY sPECIFICATION ARMOR PLATE , STEEL, WROUGHT, HOMOGENEOUS (FOR USE IN COMBAT-VEHICLES AND.FOH AMMUNITION TESTING) This specification is approved for use by the Materials Technology Laboratory, Department of the Army, and is available for use by all Department and Agencies of the Department of Defen$e. 1. SCOPE 1,1 q. This specification covers wrought-steel homogeneous armoc plate in thicknesses from 1/4 to 6 inches inclusive for use in combat-vehicles and 1/4 to 12 inches inclueive for use in.proof and acceptance testin9 of armoz defeating ammunition (see 6,1 and 6.4.3 ]. 1,2 Classification. wrought armor shall be of the following classes as specified (see 6.1). 1,2,1 class 1. wrought armor plate which iS heat treated tO develOp maximum resistance. to penetration. 1.2.2 class 2. Wrought armor plate which is heat treated to develop maximum resistance to shock. 1.2.3 class 3. Wrought armor plate which is heat trea~ed to develop specific hardness and impact values for evaluation of armor defeating ammunition only. ‘I’hisclass armor is not intended for use in combat-vehicles”. To meet the thickness tolerances of this class armor special sUrfaCe finishing may be required. 2. APPLICABLE DOCUMENTS 2.1 Government documents. 2.1.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a Part of this document to the extent specified herein. .Unless otherwise. specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (DODISS) and supplement thereto, cited in the. solicitation (see 6.2). Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this “document shOuld be addressed to: Director, U.S. ArMY Laboratory Command, Materials Technology Laboratory, ATTN : SLCMT-MEE, Watertown, WA U2172-0001 by using the Standardization Document Improvement Proposal (DD FOrm 1426) appearing at the end of this document or’by letter. AMSC N/A FSC 9515 DISTRIBUTION STATEMENT A -. .—
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INCH-POUND
MIL-A-12560H(MR)28 November 1990
SUPERSEDING
MIL-A-12560G(MR)15 August 1984
MILITARY sPECIFICATION
ARMOR PLATE , STEEL, WROUGHT, HOMOGENEOUS
(FOR USE IN COMBAT-VEHICLES AND. FOH AMMUNITION TESTING)
This specification is approved for use by the Materials Technology
Laboratory, Department of the Army, and is available for use by allDepartment and Agencies of the Department of Defen$e.
1. SCOPE
1,1 q. This specification covers wrought-steel homogeneous armoc
plate in thicknesses from 1/4 to 6 inches inclusive for use in combat-vehiclesand 1/4 to 12 inches inclueive for use in.proof and acceptance testin9 ofarmoz defeating ammunition (see 6,1 and 6.4.3 ].
1,2 Classification. wrought armor shall be of the following classes asspecified (see 6.1).
1,2,1 class 1. wrought armor plate which iS heat treated tO develOp
maximum resistance. to penetration.
1.2.2 class 2. Wrought armor plate which is heat treated to develop
maximum resistance to shock.
1.2.3 class 3. Wrought armor plate which is heat trea~ed to develop
specific hardness and impact values for evaluation of armor defeatingammunition only. ‘I’hisclass armor is not intended for use in combat-vehicles”.
To meet the thickness tolerances of this class armor special sUrfaCe finishingmay be required.
2. APPLICABLE DOCUMENTS
2.1 Government documents.
2.1.1 Specifications, standards, and handbooks. The following
specifications, standards, and handbooks form a Part of this document to the
extent specified herein. .Unless otherwise. specified, the issues of thesedocuments are those listed in the issue of the Department of Defense Index ofSpecifications and Standards (DODISS) and supplement thereto, cited in the.solicitation (see 6.2).
Beneficial comments (recommendations, additions, deletions) and any pertinentdata which may be of use in improving this “document shOuld be addressed to:
Director, U.S. ArMY Laboratory Command, Materials Technology Laboratory,ATTN : SLCMT-MEE, Watertown, WA U2172-0001 by using the Standardization
Document Improvement Proposal (DD FOrm 1426) appearing at the end of thisdocument or’by letter.
AMSC N/A FSC 9515
DISTRIBUTION STATEMENT A
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“f41L-A-12560H(MR)
STANDARDS
MILITARY
MIL-sTD-367 -MIL-STD-41O -
Armor Test Data ReportingNondestructive Testincl Personnel Qualification andCertification
(Unless otherwise indicated, copies of federal and militaryspecifications, standards, and handbooks are available from ,the
Standardization Documents Order Desk, Sldg. 4D, 700 Robbins Avenue,Philadelphia, PA 19111-5094. )
2.1.2 Other Government documents, drawings, and publications. The
following other Government documents, drawings, and publications form a partof this document to the extent specified herein. Unless otherwise specified,
tbe issues are those cited in tbe solicitation.
USATECO14 TOP 2-2-710 - Ballistic Tests of Armor MaterialsQSTAG 335 - Certification of Personnel for Ultrasonic Inspection
(Application fOK cOPieS should be addressed to the Director, DefenseTechnical Information Center, ATTN: DDR, Cameron Station, Alexandria, VA22314 )
2.2 Non-Government publications. The following documents fOKm a part of
this specification to the extent specified herein. Unless otherwise
specified, the issues of the documents wbicb are DoD adopted are those listedin the issue of the DODISS cited in the elicitation. Unless otherwisespecified, tbe issues of documents not listed in the DODISS are the issues ofthe documents cited in the solicitation (see 6.2) .
AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)
ASTM A578 - Straight-Seam Ultrasonic Examination of Plain and Clad CarbonSteel Plates for Special Application
ASTM A751 - Methods, Practices, and Definitions fOK Chemical Analysis of
Steel Products
ASTM E1O - Srinell Hardness of Metallic MaterialsASTM E18 - Rockwell Hardness and Rockwell Superficial Hardness of
Metallic MaterialsASTM E23 - Notched Bar ImDact Testinq of Metallic MaterialsASTM E11O - Test Method fo> Indentati&r Hardness of Metallic Materials by
Portable Hardness Testers under ASTM E23 - Notched Sar Impace
Testing of Metallic Materials
(Application for copies should be addressed to the American Society forTesting and Materials, 1916 Race Street, Philadelphia, PA 19103. )
(Tachnical aOCietY and technical association specifications and standardsare generally available for reference from libraries. They are also
distributed among technical groups and using Federal agencies. )
2.3 order Df precedence, In the event of a conflict between the text of
this document and the references cited herein, the text of this document takesprecedence. Nothing in this document, however, supersedes applicable laws and
regu~ationsunless a specific exempti On has been ~bta!ned:,
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MIL-A-12560H(wR)
3. REQUIREMENTS
3.1 First article. When specified in the’contract or purchase order (see”
4.2.1.1.2, 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 authOKized representativefor approval in accordance with 4.2.1.1. The approval of the first article
samples authorizes the commencement of shipment but does not relieve thesupplier of responsibility for compliance with all applicable provisions ofthis specification. The.first article samples and test plates shall bemanufactured by the process proposed for use on production armor. The
manufacturer’s declared chemical analysis must be submitted to the contractingagency and to the ballistic test agency. The ballistic test agency will
record tbe first article ballistic test plates submitted, showing the datestasted.
3.1.1 First time producer, First time producers wishing to qualifY to
this specification should 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 producesteel plate having, as nearly as practicable, a homogeneous structurethroughout.
3.2.2 Chemical composition. The product analysis of all plates. within aheat shall conform to tbe requirements .of table I unless otherwise negotiatedbetween the steel supplier and the contractor (see 6.12) . All limits asspecified in table I (including any deviations negotiated) shall be submittedin advance to the procuring activity. The contractor may 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 for the files of the
procuring activity at no cost to the procuring activity. All elements ofchemical composition shall be shown. in the statement. The chemical
composition range established by tbe producer and the chemical analysis of thematerial submitted shall be reported in accordance with MIL-STD-367, (see6.2.2 and 6.7. )
3,2.3 Heat treatment. All plates in each lot, including sample6, shall
receive the same heat tceatment except for such variations in temperingtemperature as may be necessary to produce the prescribed hardness. The
austenitizing temperature for production plates may varY within a ran9e Of
50° above the temperature used for test plates, but in no case shall itexceed 17000F (see 6.13) .
3.2.4 Processing controls.
3.2.4.1 Heating. Stress relieving the plates, local or gi?neral, shall beallowed after final quenching and tempering. at a maximum temperature of 500Fbelow the tempering temperature. Plates shall not be ‘stress relieved in atemperature range of 600-800°F. After stress relieving, the plates shall betested for hardness and shall meet the requirements of table II.
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NIL-A-12560 H(MR)
TABLE I. Chemical composition (product analysis). ~1
MAXIMUM MAXIMUM
RANGE LIMIT
ELEMENT PERCENT PERCENT
cARBON 0,10 0,30 up to 2“ thick, incl.
0.33 over 2“ up to 4“0.35 over 4“
MANGANESE :Up to 1.00% incl. 0.30 -.
Over 1.00% 0.40 --
PHOSPHORUS -- 0.025
sULFER -- O,(I15
SILICON:--
Up to 0.60% incl. 0,20
Over 0.60% to 1.00% incl. 0.30 --
Over 1.00% 0.40 --
NICKEL 0.50 _-
CHROMIUM:Up to 1,25% incl. 0.30 --
Ovec 1.25% 0.4U --
MOLYBDENUM :Up to 0.2U% incl. 0.07 --
Over U.20% 0.15 --
VANAD IUt4: 0.10 --
BORON -- -- y
COPPER -- 0.25 ~/
TITANIUM -- 0.10 y
zIRCONIUM .- 0.10 y
ALUMINUM --
LEAD
0,10 y-- 0.01
TIN -- 0.02 y
ANTIMONY -- 0,02 y
ARSENIC -- 0.02 y
&/ This table lists the maximum range for elements of the manufacturer’s
established chemical composition.
~/ When the amount of boron is specified in the alloy, its content so
determined by heat analysis shall not exceed 0.003 percant.
L33When the amount of an element i6 less than 0.02 percent the analysis may be
reported as 0.02 percent+
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MIL-A-12560H[MR)
I3.2.4.2 Repairing. Unless otherwise approved by the procuring activity,
weld repairs shall not be made on any plates.
3.2.4.3 Forming. Forming after the final quenching and temperingoperations shall not be done except when authorized by the procuri%lg activity.
3.2.4.4 Grinding. Grinding is not ~equi~ed but maY be perfOrmed tOremove minor defects not affecting the serviceability” of the material provided
that,’unless otherwise authorized by the procuring activity, the grinding doesnot result in the reduction of the plate thickness in tbe ground aKea to less
than the tolerances specified in tables III, IV, or V as applicable.
3.2.5 Mechanical properties.
3.2.5.1 surface hardness. The average surface hardness of each plate
including first article samples shall be within tbe SB range shown in table 11
for the applicable class and thickness. . The diameters of Brinell hardnessimpressions on any individual plate “shall not vary by more than 0.15 mm.’
3.2.5.2 u. Tbe Charpy V-notch impact test results of armor platesubmitted shall meet the requirements shown in table VI for the applicable
hardness and thickness. The Charpy V-notch impact specimens shall be obtained
in botb the TL orientation (i.e., transverse to the major direcbion of rollingwith the notch perpendicular to the plate surface so that tbe crack willpropagate in the longitudinal direction) and the LT orientation “(i.e.,parallel to the major direction of Lolling).
3.2.5.3 Bend test. When specified in the contract or order a bend testshall be performed. Bend test criteria shall be agreed upon by tbe supplierand fabricator.
3.2.6 Ballistic requirements. Ballistic requirements for class 1 andclass 3 wrought homogeneous armor shall be in accordance with the Appendixof this specification. class 2 armor shall not be subject to ballistic testrequirements.
3.2.7 Dimensions and tolerances.
3.2.7.1 Dimensions. Classes 1 and 2 armor plate shall. comply with tbedimensions and tolerances specified on applicable drawings or in the contract
(see 6.2). Class 3 armor tolerances on length and width dimensions shall beplug 1 1/2 inches and minus zero.
3.2.7.2 Thickness.
3.2.7 .2.1 Thickness Measurements (ClaSS 1 and ClaSS 2 “AKMOK). Three
thickness measurements will be taken along each side of the length of eachplate (one near each end and one in the middle) and two thickness measurementswill be taken on each end (about 1/3 of the distance from each edge) for a
total of 10 measurements. Measurements will be made in accordance with4.5..2. The acceptance of each plate will be based on these measurementsmeeting the thickness requirements set forth in table III or IV as applicable.
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MIL-A-12560H(MR)
TABLE 11, Hardness requirements.
Brinell Brinell
Specified nominal hardness indentation Rockwell C
thickness of plate Armor range (BHN) diameters hardness (HNC)
(inches) class (3000-Kq load) (millimeters) range~ To and
3.2.7 .2.2 Thickness Measurements (Class 3 Armor). The thickness of all
Class 3 plates shall be determined by measurements made one foot on centersover the entire surface of each plate. The measurements will be to theneatest thousarrdtb of an inch. The acceptance of each plate will be based onthese measurements meeting tbe thickness requirements of table v for Class 3armor,
3.2.7 .2.3 Thickness Tolerances. The thickness tolerances of each plate,after final treatment, shall be in accordance with tables XII and IV forClasses 1 and 2 armor or with table V fOr Class 3 armor.
3.2. 7.3 FldtneSS. Unless otherwise specified in the contract or order,
(see 6.2) the flatness tolerance of each plate shall be within therequirements specified in table VII. Tighter tolerance requirements may bespecified in the contract or order and shall be as agreed upon between thecontractor and the procuring activity.
3.2.7.4 Waviness. Unless otherwise specified in the contract or order,(see 6.2) the waviness tolerance of each plate shall be within tberequirements of table VIII for the applicable. thickness.
3.2.8 Identification marking. Identification marking and records shallbe such as to ensure positive identification of all plates, including testsamples and specimens, with the lot and corresponding heat fIom which theywere produced. First article and acceptance ballistic test plates shall alSO
be marked with the manufacturer ‘a name or trademark, the number of thisspecification; and tbe ordered plate thickness in inches. First azticleplates shall be marked ‘PRE”, acceptance plates ‘ACCW and retest plates will
be marked “RI” and ‘R2*. If a second set of retest plates are submitted theyshall be marked “RR1” and ‘RR2n. Tbe marking shall be approximately 1/16 inch
deep and approximately 1/2 inch high and located along the edge with the
lifting hole, if present, and shall be stamped into tbe surface unless the
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MIL-A-12560H(MR)
plate hardness makes painting necessary: All plate markings shall be
highlighted with a highly visible yellow or orange border such as fluorescentpaint or highlighted with a special white paint intended to delineate and
highlight stamping. The primary plate rolling direction shall be identified.
Manufacturers supplying armor to be used for proving ground testing of
ammunition are required to:
a. Mark each class 3 plate with one foot square blocks showing thickness
at the center of each block. The acceptance of each plate will be based onthese measurements meeting the thickness requirements set forth in table V.
b. stamp each plate ‘HOMO, CLASS 3, MIL-A-12560, plate No. _, heat
No,._. m Stamping shall be approximately 1/2 inch bigb letters to a depth
approximately 1/16 i.ncb. Location of stamping for all plates will be in tbeupper right hand corner.
3.2.9 Information required. A statement showing the product analYSiS 0<
each melt and complete details of the heat treatment of each lot shall be
furnished for the files of the procuring activity. All elements of thechemical composition ehall be shown in the statement, including special
additives or hardening agents, whether shown in table I or not.
3.2.10 Workmanship.
3.2.10.1 Surface imperfections. Tbe top and bottom surface of each plate
shall be free from the following surface defects: slivers, laps, checks,
seams, blisters, snakes,” cold shuts, cracks, burning, and laminations (see6.4). The surface of each plate shall be such that mill scale or oxidation
product shall not. interfere with determination of acceptability.Imperfections listed above which are of such a nature as to affeCt thefabrication of the material, are rejectable.
3.2.10 .1.1 Depth of imperfections. ‘lbe depth of rolled-in scale, scalepitting, mechanical gouges, or snakes shall not exceed 0.015 inch.and shall
not reduce tbe steel thickness below the allowable minimum. Isolated
individual pits over 0.015 inch deep but not over 0.03 inch deep and notwithin 6 inches of each other and which do not violate tbe minimum allowable
thickness, as specified in the applicable drawings and fabrication documents,are acceptable.
3.2.10.2 Edqe preparation. Thermal cutting shall be permitted afterfinal heat treatment provided the procedure, which may include grinding afterthermal cutting, is such that no cracks develop on any thermally cut edgewhether detected by nondestructive inspection, or as agreed upon in thecontract. Tbe heat affected zone of thermally cut plates (uP to and inclrrdingl/2-inch in thickness) shall not exceed 152 times the plateS thickness froio
the cut edge. FrJrplates OVeI. l/2-inch thick, the heat affected zone shall
not exceed 5/8-inch from” tbe cut edge. In order to have the heat affectsdzone exceed these limits approval shall be obtained from the procuring
~/ ASTM E140 shall be UBed to convert HRC readings to HS equivalents.
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MIL-A-12560 H(MR)
TABLE VI 1. Permissible variations for flatness, in.
~Specified Variations from a flat surface for specified widths, in.thickness, i!. Under 48 to 60 to 72 to 84 to 96 to
48 60 excl. 72 excl. 84 excl. 96 excl. 108 excl.
1/4 to 3/8 excl. 3/4
3/8 to 1/2 e%cl. 1/21/2 to 3/4 excl. 1/23/4 to 1-1/4 excl. 1/21-1/4 to 1-5/8 excl. 3/81-5/8 to 3 excl. 3/83 to 4 excl. 3/84 to 6 excl. 1/2
6 to 8 excl. 9/168 to 10 excl. 5/8
10 to 12 excl. 11/16
15/169/169/169/161/23/81/2
5/811/163/4
13/16
1-1/85/85/85/81/27/161;25/8
11/163/4
13/16
1-3/4
3/4
3/43/45/81/25/8
3/413/167/8
15;16
1-7/87/8
7/87/83/45/83/4
7/815/161
1-1/8
3/43/4
7/815/161
1-1/8
NOTE : The above variations apply to plates up to 12 feet in length, or to any12 feet or longer plates.
3.2.10.3 Edge condition. Plate, edge on plates delivered after heattreatment shall be free of cracks. The supplier shall PraCtiCe such necessarYprocess controls to prevent this condition.
3.2.10.4 Internal soundness. All plates l/2-inch and greater in thicknessshall be ultrasonically examined for internal soundness in accordance with4.6.5, The steel supplier shall institute process Controls such that any edgeof any cut part shall comply with the requirements of 3.2.10.4.1.
3.2 ,10.4.1 Acceptance criteria.
3.2.10 .4.1.1 Single linear indications. In any four inches of length a
single linear indication shall not exceed twice the plate thickness.
3 ,2.10.4.1.2 Multiple linear indications. Multiple linear indicationsshall not,exceed 1-1/2 times the plate thickness’ if,two or more lie in the same
plane. The total length of indications in one plane, in any four inch length,shall not exceed twice the plate thickness. No more than ten indications,
whether in one plane or ‘multiple planes, are permitted in any four inch length.
3.2.10 .4.1.3 _. All cracks are rejectable.
3.2.10 .4.1;4 Removal of large indications. Large indications shall bere”moved by the manufacturer nr processor by grinding, provided the resultingcavity does not exceed l/4-inch.
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MIL-A-12560HIMR)
TABLE VIII. Waviness tolerances for Plates.
Flatnesstolerance When number of waves in 12 ft is:
NoTE 1. Waviness denotes the deviation of the top or bottom surface from ahorizontal line, when the plate is resting on a flat surface, as measured inan increment of.less than 12 ft of length. Tbe waviness tolerance is a
function of tbe flatness tolerance as obtained from table VII.
NOTE 2, When the flatneSs tolerance is l/2-inch or less for plates l/2-inchor less in thickness, the waviness tolerance shall not apply.
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‘MIL-A-12560H(MR)
4. QUALITY ASSURANCE PROVISIONS
4.1 Responsibility for inspection. Unless otherwise ‘specified in the
contract or purchase order, the contractor is responsible fo~ the performance
of all inspection requirements (examinations and tests ) as specified herein.
Except as otherwise specified in the contract or purchase order, thecontractor may use his own or any other facilities suitable for theperformance of the inspection requirements specified herein, unlessdisapproved by the Government. The Government reserves the right to performany of tbe inspections set forth in this specification where such inspectionsare deemed necessary to ensure supplies and services. conform to prescribedrequirements.
4.1.1 Responsibility for compliance. All items shall meet all
requirements of sections 3 and 5. The inspection set forth in thisspecification shall become a part of the co,ntractoc’s overall inspectionsystem or quality program. .The absence of any inspectio? requirements in tbespecification shall not relieve the contractor of the responsibility ofensuring that all products or supplies submitted to the Government for
acceptance comply with all requirements of the contract. Sampling inspection,
as part of manufacturing operations, is an acceptable practice to ascectainconformance Eo requirements, however, this does not authorize submission of
known defective material, eitber indicated or actual, nor does it commit tbeGovernment to accept defective material.
4.2 classification,
4.2.1 Classification of inspection. Tbe inspection requirements
specified herein are classified as follows:
a. First article inspection.b. QualitY cOnfOrmance in?PectiOn (acceptance) ?
4.2.1.1 First article inspection. When required, the first article
samples submitted in accordance with 3.1, shall be examined for ail theprovisions of this specification applicable to end item examination.
4.2.1 .1.1 First article tests. First article tests (see 6.2) shall consist
of all the tests specified in 4.6.
4.2.1,1.2 First article ballistic test. Unless otherwise specified (see
3.1, 6;2, and 6.11), the first article ballistic test shall not be requiredprovided (a) the manufacturer, within 37 months, has produced acceptableplatee within the sama nominal thickness ranges of table IX, and (b) his
production conditions are the same as’for previously accepted plates. Asupplier wbo has previously met the first article requirements w“ill furnish
tbe procuring activity the firing record of the ballistic test plate abd otherpertinent data relative to complaince with first article. Neither firstarticle nor acceptance ballistic tests will be required for plates ordered to’thicknesses of mor,e than 6.25 inches. Acceptance of these tbir!ker plates will
be based on meeting the other requirements of the specification.
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MIL-A-12560H(MR)
4.2.1,2 Quality conformance (acceptance) inspection. The acceptance
examination under 4.5 and the tests under 4.6 shall serve as a basis for theacceptance of individual production lots.
4,3 Lot. A lot shall consist of all production and ballistic test plates—of the same melt of steel, of the same thickness, having the mme treatment,and heat-treated with the same thermal cycle in the same productionfurnace in the seinefacility. When Specified by the procuring activity(see 4.3.1), production and ballistic test plates may be allowed to beheat-treated separately. The test plate shall be heat-treated in a production
furnace.
4,3.1 Separately heat treated ballistic test plate. When the procuringactivity allows a ballistic test plate to be heat-treated separately from theproduction plates it represents, (see 6.2) it will be so stated in the data tobe supplied in accordance with MIL-STD-367 (see 6.13).
4.4 SamplinQ.
4.4,1 First article sampling.
4.4.1.1 Chemical composition. Samples for chemical analysis shall betaken from each plate selected for the ballistic tests.
4.4.1.2 Impact samples. At least one impact test sample Ghan he taken
from each submitted test plate in accordance with 4.6.3.1 or 4.6.3.2 and eachehall consist of enough material for four impact specimens.
4,4.1.3 Ultrasonic examination. Each submitted test plate 3/8 inch in
thickness and thicker, shall be ultrasonically examined in accordance with4.6,5.
4.4.1.4 Ballistic test plates. Three ballistic test plates for each
nOIIIiflalthickness ranoe (see table Ix) shall be randomly selected andsubmittedrepresentbe of the
thicknessagency as
4.4.2
for ballistic test. Any thickness within the range may be chosen to
any other thickness in the range but the three plates submitted mustsame ordered thickness. Unless otherwise sPecified, the average
of each test plate shall be determined at the teat site by the testindicated in 4.4.2.5,
Sampling for quality conformance inspection.
4.4.2.1 For chemical analysis. At least One sample for chemical analysisshall be taken from each heat in accordance with the applicable IIethodspecified in ASTM A751 (Bee 6.6).
4.4,2,2 For hardness test. The Brinell hardness of each plate as heat
treated in each lot up to 1 1/2” thick shall be measured in two places, one ateach end of a diagnal on one plate surface. The Brinell hardness of each
plate as beat-tzeated in each lot over 1 1/2” thick shall be measured in four
places, one at each end of a diagonal on both plate surfaces.
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MIL-A-12560H(MR)
4.4.2.3 For Charpy V-notch impact tests. At least one sample shall be
taken from a plate representing each lot for Charpy V-notch impact tests. The
sample shall be the same thickness as the plate they represent and largeenough to obtain at least two specimens, in each direction, from each sample
in accordance with 4.6.3.
4.4,2.4 Ultrasonic examination. All plates over 1/2 inch in thickness
shall be examined ultrasonically. Tbe ultrasonic examination shall be
performed in accordance with 4.6.5.
4,4.2.5 For ballistic acceptance SamPleS. Unless otherwise specified in
the contract or order, one test plate shall be submitted from each lot. Tbeminimum plate size shall be as shown in table IX.for the applicablethickness. unless otherwise specified, the average thickness of.each testplate shall be determined at the test site by taking the average of fourthickness measurements. Measurements shall be made at least 1 inch from each
edge but preferably at random in.the intended imPact area. Thickness
measurements for plates .UP to and includin9 2.?50 inch shall be read tO thenearest 0.001 inch. Plates over 2.750 inch shall be read to the nea~est 0.01
inch. If a producer submits plates outside the specified plate tolerances
(see tables III, IV and V) the procuring activity shall be notified. A checklist, Format I of MIL-STD-367 (see 6.7), shall be completed and submitted with
each ballistic test plate.
4.5 Examination.
4.5.1 Visual. All steel plate shall be subject t~.visual inspection forcompliance -he requirements for surface conditions’ (see 3.2.10. 1), edgequality (see 3.2.10.3 and 3.2.10.4) and identification marking (see 3.2.8).
4.5.2 Dimensions. All steel plates shall be subject to inspection for
compliance with dimensional and tolerance requirements (3.2.7 ). Each class 1
and class 2 plate shall be inspected using a calibrated micrometer at threeevenly distributed points 3/8 to 3/4 inches’ in from the longitudinal edge andat two evenly distributed points along each transverse edge. Each class 3
armor plate shall be divided into one foot squares painted on one surface andthe results of each. thickness measurement shall be painted in the square in
which it was taken.
4.5.3 Preparation for shipment. Examination shall be made to determine
compliance with the requirements for preparation for shipment (see section 5 ).
4.6.1 Chemical analysis. Chemical analysis shall be conducted inaccordance with the applicable method specified in ASTM A751 (see 6.6). The
analysis shall comply with the declared composition established in accordance
with the requirement of table I (see 3.2.2).
4.6.2 Hardness tests. Brinell hardness tests shall be conducted in
accordance with either ASTM E1O or ASTM E11O using a 10 mm carbide ball and a3000 kilogram load. surface scale and decarburization shall be removed from
the areas where the tests are to be made. Hardness tests may be made on the
surfaces of pieces cut from the plate after heat treatment.
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MIL-A-12560H(MR)
TABLE IX. Ballistic test plate sizes and corresponding test projectilesfor first article and acceptance testing.
Nominal thickness Minimum SiZe (a) Of Test projectile
range (iIICheB) test plates (inches) and obliquity
0.25 to 0.565 incl. 12 X 36 Cal .30AP, )42at 0°
0,565 to 1,125 incl. 12 X 36 Cal .50AP, M2 at 0°
1.126 to 2.750 incl. 12 X 36 20-mm APIT, M602 at 0°
2.751 to 3.500 incl, 60 X 60 90-mm APC, M82 at 450
.3.501 to 3.999 incl. 60 X 60 90-mm APC, M82 at 30°
4.000 to 6.250 incl 60 X 60 90-mm AP, M318 at 0°
Over 6.251 (b)
NOTE: (a) Other sizes may be submitted for the convenience of the manufacturerif approved by the ArmOK Vulnerability Divi8ion, USAcs!rA,Aberdeen ProvingGround.
(b) No ballistic test required.
4.6.2.1 Hardness teets on impact test specimens. Except as provided in4,6,2,2, each sample from which impact test specimens are taken shall have ahardness check made upon it as follows: For samples 1/4 to 1/2.inch inclusivethe hardness check shall be made on the surface. For samples of 1/2 inch upto
4 inches in thickness, at least two hardnees tests shall be taken fromanadjacent location, midway between the surfaces of the plate. Fox samples of
4 inches in thickness or greater, at least six hardness tests shall be made atequal intervals across the plate thickness.
4.6.2.2 Rockwell bardnese tests on impact specimens. At the option oftbe contractor at least two Rockwell C hardness tests may be made on eachimpact test specimen sampled from each lot. The test specimens shall beprepared and tested in accordance with ASTM E18. The average shall not exceedthe maximum requirement for thickness specified in table II.
4,6,3 Charpy V-notch impact tests. At leaSt two Charpy V-notch impacttest specimens shall be taken in each direction from each sample as obtained
in accordance with 4.6.3.1 or 4.6.3.2, and shall be prepared and tested in
accordance with ASTM E23.
4.6.3.1 For samples’ less than 4 inches in thickness. Charpy v-notchimpact test specimens from samples less than 4 inches in thickness shall betaken in both tbe TL orientation and in the LT (see 3.2.5.2) orientation from
a location midway between the top and bottom surfacea of the plate and atleast 4 inches or 2T, whichever is less, from any quenched edge as well asoutside the heat affected zone of any thermal-cut edge. When tbe amount of
material available ia insufficient to obtain standard specimens, tbe largest
16
MIL-A-12560H(MR)
attainable subsize
E23 shall be used,
Itable VI.
Charpy V-notch impact specimens shown in figure 4 of ASTM
and the results compared to tbe applicable requirements of
4.6.3.2 For samples 4 inches or greater in thickness. Charpy V-notch
impact test specimens from samples 4 inches or greater in thickness shall betaken from a location such that the centerlines of the specimens are
approximately 1 inch below the surface of the plate and at least 4 inches fromany quenched edge as well as outside the heat-affected zone of any thermally-cut edge.
4.6.4 Ballistic Tests. Ballistic testing of armor plate shall be
conducted at a Government test facility specified in the contract or order “or
at a test facility aPProved by tbe Government. Testing shall be conducted in
accordance with the requirements of the Appendix.
4 .6.5 Ultrasonic examination.
4.6,5.1 Inspection equipment. The ultrasonic soundness inspection
equipment Bhall conform to ASTti A578.
4.6.5.2 Procedure. Unless otherwise specified (see 6.2) the ultrasonic
examination shall be carried out in accordance with ASTM A578 with thefollowing exceptions:
(a) Scanning shall be continuous over 100% of the plate surface.(b) Scanning rate shall be at a speed where recordable discontinuities
can be detected.
(c) The testing frequency shall be a minimum of 2 megahertz (MHz).
(d) AnY area within a plate where a discontinuity produces a ccmti”uoustotal lass of back reflection accompanied by continuous indicationson the same plane that cannot be encompassed within a circle whose
diameter is l-in. shall be cause for rejection of that plate. Alldiscontinuities will be evaluated using a frequency of 2 megahertz
(MHz).
4.6.5.3 Certification of inspection’ personnel. Unless otherwisespecified (see 6.2), personnel performing ultrasonic inspection shall comply
with the qualification requirements of MIL-sTD-41O, level 1, or equivalent, asdetermined by QSTAG 335. Personnel making accept/reject decisions in
accordance with the process described by this specification shall be qualifiedto at least a level II per MIL-sTD-41O or equivalent, as determined by QSTAG335,
4.6.6 Reduced testing. At the discretion of the procuring activity, theamount of testing may be reduced provided the results on consecutive@ lotsindicate that a “satisfactory uniform product meeting the testing requirementsis being produced (see 6,2) . Reduced teeting shall be in accordance with asystem previously approved or established by the procuring activity involved.
1?
MIL-A-12560H(MR)
4.6.7 Rejection and retest.
4.6 ,7.1 Rejection, Unless otherwi8e specified in the contract or order
(see 6.2), failure of the first article samples to meet the requirements ofthis specification shall he cause for rejection of the process, and failure of
the acceptance samples to meet the requirements of this specification shall because for rejection of the lot (see 4.6.7.2).
4.6.7.2 -. Unless a specific retest.procedure is specified in thecontrack or order (see 6.2), two retest samples shall be submitted for eachfailed sample. Failure of either of the retest samples (plates) shall because foc rejection of the material. First article retests shall not bepermitted until the supplier has made the necessary corrections in the
processing of the material to tbe satisfaction of the procuring activity.
4.6.8 Hardness traverse test. Prior to production to assure compliance
to paragraph 3.2.10.2, the size of the heat affected zone for thermally cut
edges shall be determined by takin9 Rockwell c hardness tests at 1/16 inchincrements from the edge. Surface scale and decarburization shall be removedfrom the test surface. The distance at which there is no change in surfacehardness shall be considered the depth of the heat affected zone. Thecontractor ehall document the test results for each thickness and thermalcutting method used in production. The contractor is also responsible fOrdocumenting all heat input controls to assure the cutting process is undercontrol. Re-verification of heat affected zone size for subsequent productionlots is not required provided there is no change in the cutting method or heatinput from that previously tested. Tbe records shall he available for KeVieWby the cognizant government representative.
5, PACKAGING.
5.1 Preservation and packagi”n~. Unless otherwise specified in thecontract or order, preservation and packaging shall be level”C (see 6.2).
5.1.1 Level C. Cleaning, drying, preservation, and packaging shall be in
accordance with manufacturer’s commercial practice.
5,2 Packing. Unless otherwise specified in the contract or order,
packing shall he level C (see 6.2).
5.2.1 Level c. All plates shall be packed for shipment in such a manner‘as to ensure acceptance and safe delivery by tbe carrier for the mode oftransportation employed.
5.3 Markinq. In addition to any special marking specified in thecontract or order, shipments shall be marked in accordance with the
requirements of the cognizant activity.
6. NOTES
(This section contains information of a general or explanatory nature thatmay be helpful, but is not mandatory. )
18
I MIL-A-12560H(MR)
6.1 Intended use. The armor specified herein is intended for use on
combat vehicles and proof and acceptance testing of armor defeating
ammunition. but mav also be applicable to armor for emplacements, shields,
~
pill boxes: testin~,,and the i~ke.
6.1.1 Class 1, Class-1 wrought armorwhere maximum resistance to penetration byis required.
is intended for use in those areasarmor piercing types of ammunition
6.1.2 Class 2. Class-2 wrought armor. is intended for use in those areas
where maxim-stance .to failure under conditions of high rates of shockloading is required and where resistance to penetration by armor piercingammunition is of secondary importance. It is intended for use as protection
against anti-tank land mines,. hand grenades, bursting shells, and otbec blast-producing weapons,
6.1.3 Class 3. Class 3 wrought armor is intended for use in the proof
and acceptance testing of armor defeating ammunition. This class is notintended for.use in combat vehicles. Lift hole requirements for class 3 armor
will be specified by the procuring activity.
6.2 Ordering data. Procurement documents should specify:
6.2.1
a.b.c.d,e.f.
9.
b.
i.
j.
k.1.
m.n.0.
P.
Procurement requirements.
Title, number, and date of this specification.Class of steel.If first article eample is required (see 3.1) ,If local or general heating is permitted (see 3.2.4.1).If weld repairing is permitted (see 3.2.4.1.2).Dimensional IegUirementS (see 3.2.7 ).Name of inspecting agency when inspection shall be performedby other than the contractor (see 4.1) .When a special first article ballistic test is required
(see 3.1, 4.2.1,1.2 and 6.11).If ballistic test plates may be separately heat-treated from theproduction plates it represents, (see 4.,3.1).If ballistic acceptance samples should be other than in4.4.2.5.If ultrasonic examination is to be different than 4.6.5.2.If certification of inspection pereon.nel is different from 4,6.5.3.If rejection and retesting differs from 4.6.7.
Tbe reduced testing plan when applicable (see 4.6.8).Preparation for delivery if different than specified in.section 5.If lifting holes are required (see 6.1.3).
6.2.2 Consideration of data requirements. The following datarequirements should be considered when this specificat.io” is applied on a
contract. The applicable Data Item Descriptions (DID’s) should be reviewed inconjunction with the specific acquisition to ensure that only essential dataare requested/provided and that the DID’s are tailored to reflect the
requirements of the specific acquisition. To ensure correct contractual
aPPlication of the’data SequiZemen!s, a Contract Data Requirements List (DD
~ MIL-A-12560H(MR)
Form” 1423) must be prepared to obtain the data, except where DOD FAR
Supplement 27.475-1 exempts the requirement Ear a DO Form 1423.I
I Suggested
Reference Para. DID Number DID Title Tailorinq
3.1 UDI-T-23790 Report, FiKat Article ---
3.2.9 UDI-T-23264 Certification Data Report ---
3,2.2 DI-MISC-80073 Armoc Material Test Reports Format
(copies of data item descriptions related to this specification, and
identified in section 6 will be approved and listed as such in DOD 501O.12L,Vol. 11, AMSDL. Copies of data item descriptions required by the contractorsin connection with specific acquisition functions should be obtained from theStandardization Documents OrdeK Desk, Sldg. 4D, 700 Robbins Avenue,Philadelphia, PA 19111-5094
6.3 Thickness. The symbol ‘T” is used throughout this specification to
indicate the nominal thickness of the plate under consideration.
I
6,4 Definitions.
6.4.1 Contractor. The contractor is the company which has a directcontract from the Government to furnish an end item - usually a vehicle. Alsoknows as the prime contractor.
6.4.2 Contracting officer. The term “contracting officer” means theperson executing a contract on bebalf of the Government and any other officeror civilian employee who is properly designated contracting officer; and theterm includes, except ae otherwise provided, the authorized representative ofa contracting officer acting within the limits of his authority.
6.4.3 Homogeneous rolled armor. Homogeneous rolled a~m?r is armor having
uniform composition and heat treatment throughout.
6.4.4 Manufacturer. The manufacturer is defined as the company producingthe steel alloy plate.
6.4.5 Procuring activity. The term ‘procuring activity” iS that aCtiVitYof the Government which actually initiates the request for procurement and
maintains tbe records of the procurement.
6.4.6 Slivere. An imperfection coneiating of a very thin elongated Pieceof metal attached by only one end to the parent metal into whose surface it
has been worked.
6.4.7 ~. A surface imperfection with the appearance Of a seam,.caused
by hot metal, fins or sharp corners being folded Over and thus being fOrged Orrnlled into the surface but without being welded.
6.4.8 _. Numerous very fine cracks at tbe aurfac~ Of a metal Part.Checks may appear during processing or during service and are most often
associated with thermal cycling or thermal treatment. Also called check
markg, checking, heat check8.
20
I MIL-A-12560H(MR)
6.4.9 g. An unwelded fold, or lap that appears as a.crack, usuallY
resulting from a discontinuity on a metal surface.I
~6.4.10 Blisters. A raised area, often dome shaped, resulting from
delamination under pressure of expanding gas trapped in a metal in a near
sub-surface zone. Very small blisters may.be called pinhead blishers OKpepper blisters.
~
6.4.11resembling
=. Any crooked surface imperfection in a metal plate,a Snake,
Cold shuts. Freezing of tbe top surface of an ingot before mold6.4.12is full.
6.4,13 Burning. Permanently damaged metal due to overheating enough tocause incipient melting or intergranular oxidations. Note: This condition is
usually obscured by normal cleaning methods and would require deep pickling
6.4.14 Lamination. A type of discontinuity with separation or weaknessgenerally aligned parallel to direction of the worked surface of the Metal and
way be tbe result .ofpipe, blisters, seams, inclusions, Or ae9re9ati0njelongated and made directional by working.
6.4.15 ~. A cavity or depressed area on tbe surface of “a plate.
6.4.16 Linear indication. For nondestructive eXaIhinakiOn purposes, alinear indication is evidence of a discontinuity that requires interpretationto determine its significance.
6.5 Changes in composition. Changes in composition shall not necessarily
be cause for retesting but shrill be subject to review by the procuringactivity to determine whether additional ‘first article testing is required.
6.6 Chemical Analysis. Suggested ASTM instrumental Methods that can beused are chemical analysis E415, E282, E484 and E322. ASTM A751 should beconsulted for a complete list of methods.
6.7 MIL-STD-367 . Format I of MIL-STD-367 replaces POKm MIL12560 and TACForm 3983,
6.8 Potential suppliers. Potential suppliers who have not previously
supplied armor plate to ‘MIL-A-12560 and wish to have their’material
ballistically tested, may do so at their own expense. It is recommended thatinquiries for such testing be directed to Commander, US Army CSTA, AT2Ti:STECS-LI-A,. Aberdeen Proving Ground, MD 21005-5059.
6.9 New contracts sponsored by government agencies. At tbe time that a
new contract is initiated for the production. of combat vehicles, thecontractor’s supplier is to ‘estimate the number, size and delivery schedule ofthe ballistic test plates which are to be submitted for first article or
acceptance testing. A lead time of 60 days after tbe contract has been signed
is to be allowed prior to shipment of the first ballistic test plate(s) to AFG
21
MIL-A-12560H(MR)
to insure that all administrative functions for the establishment of a new
TECOM pto]eCk have been completed in preparation for the teat, The
contracting government a9ency is to initiate the new project through a letterto Commander, US Army TECOM, ATTN: AMSTE-TA-0, APG, MD 21005-5055 requesting
a cost estimate for the ballistic testing of the applicable number of sizes ofplates. In the case of increases in scope of existing projects, similar
correspondence is needed.
6.10 Metric units. When metric dimensions are required, units for inch,
foot, foot-pounds and feet Psr second may be converted to the metricequivalent by multiplying them hy the following conversion factors:
To go from TO getEnglish Multiplv by Metric S1 unitinch 0.0254foot
metre (m)0.3048 metre (m)
foot-lb 1.3558 joule (J)
feet/see 0.3048 metre per second (m/s)
NOTE: COnVer SiOn faCtOKS Can be associated with ASTM E380 entitled ‘MetricPractice Guide. m
6.11 Special first article ballistic test. Special first article
ballistic tests are required when tbe manufacturer changes either the meltingprocedure or heat treatment or the declared chemistry of tbe armor.
6.12 Fabrication. The armor plate covered by this specification iseubject to fabrication involving cutting, drilling, forming and welding. Itis intended that selection and control of chemical composition, cleanliness,and plate processing will be ouch that the armor will be suitable forfabrication under procedures and controls such as specified fn MIL-STD-1941,Metal–Arc Welding of Homogeneous ArIiIOr.
6.13 Production plates. Material made to this specification has a
tendency to develop stress cracks if not tempered as Boon as possible after
austenizing treatment. TO avoid this situation all plates should be left inthe hot-rolled or tempered condition while waiting for the ballistic testresults.
6.14 Subject term (key word) Iistinq
AKMOK plate 0.30 caliber AP, M2 projectile
Steel 20 mm AP-T, M602 projectile
Homogeneous 5 mm AP, M70 projectile
Ballistia limit 90 mm AP, M318 projectile0.50 caliber API M2 projectile 90 mm AP, M82 projectile
6.15 Changes from previous issue. Marginal notations are not used in this
revision to identify changes with respect to the previous issue due to theextensiveness of the changes.
.,,,2.2
Custodian:Army - NR
Review activi ties:
Army - AR, Al’,AV,DLA - 1S
MIL-A-12560H(MR)
TE
I(WP# ID-0186A/DISK-0207A. FOR MTL USE ONLY)
Preparing activity:Army - MR
Project 9515-A057
23
MIL-A-12560H(MR)
APPENDIX
BALLISTIC TESTING OF AiMOR, STEEL PLATE, WROUGHT, HOMOGENEOUS
10. SCOPE
10.1 This appendix covers the requirements for ballistic testing ofwrought homogeneous steel armor plate.
20. DEFINITIONS
20.1 Fair impact.
20.1.1 Caliber .30 AP through 20 mm tests. A fair impact 16 an impactresulting from tbe striking of the test plate by a projectile in normal flight
(KKOeXCeSSiVe YaWin9 or tumbling) and separated from another impact or theedge of the plate, hole, crack or spalled area by an undisturbed area of at
least two test projectile diameters.
20 ,1.2 57mm AP and larger calibers. A fair impact is an impact resulting
from the striking of the test plate by a projectile in normal flight (no
yawing or tumbling) and separated frDm anothez impact or from the edge ofplate, hole, crack or spalled area by at least one test projectile diameter ofundisturbed area.
20.2 witness plate. A witness plate is nDrmally a 0.014 inch thick sheetof 5052 aluminum alloy (or a 0.020 inch thick sheet of 2024-T3 aluminum alloyplaced 6 inches (~ 1/2 inch) behind and parallel to tbe test plates or otherballistic sample,
20,3 Complete penetration, protection, CP (P).
20.3.1 For caliber .30AP M2 through 20mm API-T M602. A protection
complete penetration occurs when the projectile oc one or more fragments of a
projectile or plate pass beyond the back of the test plate and perforates thewitness plate.
20.3.2 For Projectiles larger than 20mm. A protection complete
penetration occurs when one ‘ormore fragments of a projectile or plate has
been ejected from the rear of the plate as determined by visual inspection.
20.4 Partial penetration, protection, PP (P). ‘A partial penetration is
any impact that is not a complete penetration.
20.5 ~. The difference in velocity between the high partialpenetration velocity and the low complete penetration velocity used incomputing the ballistic limit where the high partial penetration velocity is
lower than the low complete penetration velocity.
~MIL-A-12560H(MR)
APPENDIX
20.6 Protection ballistic limit, BL(P).
20.6.1 Caliber .30 AP, M2 caliber .50 AP M2, 20NN API-T M602 penetration=. The BL(P) shall consist of an equal number of fair impact complete and
partial penetration velocities attained by the up-and-down firin9 method. All
EL(P) ‘s shall be computed using the highest partial penetration velocities andthe lowest complete penetration velocities. Firing shall continue untileither a 4 round BL(P) having a maximum velocity spread of 60 fps or a 6 round
BL(P) having a maximum .velocity spread of 90 fps has’been attained, whichevercomes first in the normal .vequence of firing. If both occur simultaneously,
the 6 round BL(P) will be reported. f.
20.6 .1.1 In the event that the zone of mixed results (difference betweenthe high partial penetration velocity and the low complete penetration
velocity, the PP(P) velocity being bigber. than the low CP(P ) VelOCitY) exceeds
~90 fps, the firing data will be compared. with the specification minimumballistic requirements. If the lowest complete penetration VelOCitY iS eqUalto or above the minimum specified ballistic limit velocity for the plate
thickness, the ballistic limit will be computed on the basis of 4 or 6 roundsusing the smallest possible velocity spread. If the lowest. complete
penetration velocity is below tbe m“inimum allowable ballistic limit velocitythen testing will continue until a ten round ballistic limit has been attainedusing the smallest possible velocity spread.
20.6.2 57mm AP, M70 and larger caliber projectiles. For the purpose ofthis specification, the protection ballistic limit is the average of four fair
protection criteria impact velocities comprising tbe first two lowestvelocities in the firing order resulting in complete penetrations and thefirst two highest velocities in the firing order resulting in partial
penetrations which meet the condition that the velocitY spread fOr the 4rounds shall not exceed 100 fps.
20.6.3 Reduction of large velocity gap in borderline cases. If theballistic limit which has been determined is within ~ 10 fps from the minimumallowable ballistic .limit and a gap exists which is greater that 25 fps, thenanother round, or rounds, will be fired to reduce the gap to 25 fps or less.The ballistic limit will then be recomputed using the criteria of paragraphs20,6.1 or 20.6.2 as applicable. The recomputed BL(P) will be reparted as ‘tie
BL(P) of tbe plate (in borderline cases a reduction of the gap between thehigh partial penetration velocity and the low complete velocity should resultin a better evaluation of the BL(P) .
30. REQUIREMENTS
30,1 Resistance to peiletration. The minimum acceptable ballistic Iimits
shall be in accordance with the values shown in tables X through SVII.
30,1.1 For class 3 armor plate, upper ballistic limit (maximum) values
shall be as specified in the applicable footnotes
-25
of tables X through XVII.
MIL-A-12560H(MR)
. .
APPENDIX
30.2 Back spallinq,
30,2.1 Plates 1/2 to 11/16 inch in thickness. Plates of these orderedthickness shall bs .vubjectsd to a backspall test consisting of firing two
rounds of 20 mm AP M95 ammunition at a 0° obliquity at the test 91ete. The
striking velocity shall be in the velocity range of 2500-2550 fps. The
maximum allowable backspall dimension shall be 1 5/8 inches.
30.2.2 Plates 3/4 inch and greater in thicknsss. Spalling shall notexceed 2.0 tsst projectile diameters after proof firing at normal obliquityaccordance with the appropriate table of the Appendix, and shall not exceed
2.5 test projectile diameters in the case of oblique psnstration tests.
30.3 Crackinq.
30,S.I 00 ~b~iquity attack. Immediately after ballistic testin91
plates subje=ted to 0° obliquity attack shall not develop any crack which,
when measured from the center of impact, extends outside a circle having aradius equivalent to twice the test projectile diameter.
30.3.2 Oblique attack. Immediately after ballistic testing, platessubject to oblique attack shall not develop any crack which, when meaeured
in
from the center’of impact, extends outside a circle having a radius equivalentto three test projsctile diameters.
30.4 Rejection. Failure to meet any of the ahove requirements shall becauee fOK plate rejection.
40. TESTS
40,1 Ballistic teStB. v50 ballistic tests shall be peffOrm@d inaccordance with USATECOM TOP 2-2-710, Ballistic Tests of Armor Materials to
determine compliance with the requirements of tables X through XVII.
40.1.1 Plate thickness as measured by the ballistic test agency shall be
used to detecmine the required ballistic limit for the plate. The required
ballistic limit will be determined by interpolation of the tabled”’in theAppendiX, if necessary.
40,1.2 Lift hole requirement for test plates.
40,1.2.1 Ballistic acceptance testing plates.
a. Ballistic acceptance test plates far either class 1 or armo~ which areless than 2.751 inches ordered thickness are to be supPlied without a liftinghole.
b. Ballistic acceptance test Plates for either Class 1 or 3 armor whichare 2.7.5.1 inches through 6.25 inches thick shall be provided with 3-inchdiameter lifting holes, one in each of two adjacent sides an showh in figure 1.
26
II MIL-A-12560H(MR)
~
APPENDIX
40.1.3 Rejection and retest of ballistic plates.
‘40.1.3.1 First article tests (rejection). Unless noted otherwise in the
contract or order, failure of any one or more of the three first article”.test ..?<plates to meet the minimum’ ballistic requirements as specified “in the APPendixto this specification indicates failure of the product and process.
40.1.3.2 First artiCle (Ket&tS). Resubmission of ballistic retest plates
shall not be made until the manufacturer has made the necessary corrections inthe processing of the material to the satisfaction of the procuring activity.Three retest plates must “be submitted for first article testing and all three
I must pass.
40.1.3.3 Acceptance tests (rejection) . Unless otherwise noted in the
contract OK order, failure of a test plate tO.meet the ballistic requirement
indicates failure of the lot, however, the final decision will depend on theoutcome of retests,. if submitted.
40.1,3.4 Acceptance tests (retests). If a test plate representing a lotfails to meet the ballistic requirement, the manufacturer has the following
options: Immediately upon notification of the failure, he may:
(1) At his Own expense submit two additional test plates from the samelot for ballistic retest, or
(2 ) He may first re-beat treat (quenching. and tempering] the lot andthen submit a test plate from the re-treated lot, or
(3) He may scrap the lot and submit a plate representing a new lot foracceptance.
If he chooses any one of these options and the ballistic. retest plate (orplates) meet the requirements then the lot represented is acceptable. If he
, chooses option (1) and one or both of tbe retest plates fail, the manufacturermay ce-heattreat the lot and submit a test plate from tbe retreated lot. If
this plate fails tbe lot is rejected. If he chooses option (3) and the testplate fails, he may again resort to any one of the ‘three options.
40.1,4 Disposition of ballistic test plateS.
40.1.4.1 First article test plates. upon request of the applicant within
15 days after ballistic testing, first’ article plates will be returned “as isnto the applicant, at bis expense, unless the plates were destroyed in testing.
40,1.4,2 Acceptance test plates. Acceptance test plates that comply withthe requirements of this specification are considered as part of the lot ofsteel they represent and ownership of them passes to tbe Government with tbe
acceptance of that lot. Acceptance test plates that fail to comply with the
requirements of this specification are considered as part of the lot theyrepresent and remain tbe property of the producer just as the rejectable lotdoes. The failed plates will be returned, upon request, as in 40.1.4.1.