A01_-_MIL-A-12560H_RHA_Amend_4.pdf

MIL-A-12560H (MR)

w/INT. AMENDMENT 4 20 July 2007

USED IN LIEU OF

MIL-A-12560H (MR)

w/AMENDMENT 3 27 September 2000

MILITARY SPECIFICATION

ARMOR PLATE, STEEL, WROUGHT, HOMOGENEOUS

(FOR USE IN COMBAT-VEHICLES AND FOR AMMUNITION TESTING)

This specification is approved for use by all Departments and Agencies of the Department of Defense.

1. SCOPE

1.1 Scope. This specification covers wrought-steel homogeneous armor plate in thicknesses for 1/4 to 6 inches inclusive for use in combat-vehicles and 1/2 to 12 inches inclusive for use in proof and acceptance testing of armor defeating ammunition (see 6.1 and 6.4.3).

1.2 Classification. Wrought armor should 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 treated to develop specific hardness and impact values for evaluation of armor defeating ammunition only. This class armor is not intended for use in combat-vehicles. To meet the thickness tolerances of this class armor special surface finishing may be required.

AMSC N/A FSC 9515

INCH-POUND

Comments, suggestions, or questions on this document should be addressed to: Director, U.S.

Army Research Laboratory, Weapons and Materials Research Directorate, Materials Applications Branch, Attn: AMSRD-ARL-WM-MC, Aberdeen Proving Ground, MD 21005- 5069 or emailed to rsquilla@arl.army.mil. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database at 8Hhttp://assist.daps.dla.mil/.

Downloaded from http://www.everyspec.com

1.2.4 Class 4. Wrought armor plate which is heat treated to higher hardness levels than class 1 armor plate to develop maximum resistance to penetration.

1.2.5 Class 4a. Wrought armor plate tempered to attain a minimum through hardness of HRc 47

(BHN 442).

1.2.6 Class 4b. Wrought armor plate tempered to attain a maximum through hardness of HRc 41

(BHN 381).

2. APPLICABLE DOCUMENTS

2.1 General. The documents listed in this section are specified in sections 3, 4, or 5 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3, 4, or 5 of this specification, whether or not they are listed.

2.2 Government documents.

2.2.1 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 cited in the solicitation or contract.

DEPARTMENT OF DEFENSE STANDARDS

MIL-STD-367 - DELETED

MIL-STD-410 - DELETED

(Copies of these documents are available online at http://assist.daps.dla.mil/quicksearch/ or http://assist.daps.dla.mil/ or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.)

2.2.2 Other Government documents, drawings, and publications. The following other Government documents, drawings, and publications form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

QSTAG 335 - DELETED

USATECOM TOP 2-2-710 - Ballistic Tests of Armor Materials

(Application for copies is available from the Defense Technical Information Center, 8725 John J.

Kingman Road, Suite 0944, Fort Belvoir, VA 22060-6218.)

http://assist.daps.dla.mil/ http://assist.daps.dla.mil/quicksearch/

2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. (AIA)

NAS410 - NAS Certification & Qualification of Nondestructive Test Personnel

(Copies of these documents are available from Aerospace Industries Association, 1000 Wilson Boulevard, Suite 1700, Arlington, VA 22209-3901 or online at http://www.aia-aerospace.org.)

ASTM INTERNATIONAL

ASTM A578/ - Standard Specification for Straight-Beam Ultrasonic A578M Examination of Plain and Clad Steel Plates for Special Applications

ASTM A751 - Standard Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products

ASTM E10 - Standard Test Method for Brinell Hardness of Metallic Materials ASTM E18 - Standard Test Methods for Rockwell Hardness of Metallic Materials ASTM E23 - Standard Test Methods for Notched Bar Impact Testing of Metallic

Materials ASTM E110 - Standard Test Method for Indentation Hardness of Metallic Materials by

Portable Hardness Testers (DoD adopted) ASTM E140 - Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, and Scleroscope Hardness

(Copies of these documents are available from http://www.astm.org or ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959.)

SOCIETY OF AUTOMOTIVE ENGINEERS (SAE)

SAE J406 - Methods of Determining Hardenability of Steels

(Copies of these documents are available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001 or online at http://www.sae.org/.)

2.4 Order of precedence. In the event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been retained.

http://www.sae.org/ http://www.aia-aerospace.org/ http://www.astm.org/

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 1700°F (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.

TABLE I. Chemical composition (product analysis). 1/

Element Maximum range, weight percent

Maximum limit, weight 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.

Over 1.00%

0.30 0.40

Phosphorus --- 0.025 Sulfur --- 0.015 Silicon:

Up to 0.60% incl.

Over 0.60% to 1.00% incl.

Over 1.00%

0.20

Nickel 0.50 --- Chromium:

Up to 1.25% incl.

Over 1.25%

Molybdenum:

Up to 0.20% incl.

Over 0.20%

0.07 0.15

Vanadium 0.10 --- Boron --- --- 2/ Copper --- 0.25 3/ Titanium --- 0.10 3/ Zirconium --- 0.10 3/ Aluminum --- 0.10 3/ Lead --- 0.01 Tin --- 0.02 3/ Antimony --- 0.02 3/ Arsenic --- 0.02 3/

1/ This table lists the maximum range for elements of the manufacturer’s established chemical composition.

2/ When the amount of boron is specified in the alloy, its content so determined by heat analysis shall not exceed 0.003 percent.

3/ When the amount of an element is less than 0.02 percent the analysis shall be reported as 0.02 percent.

3.2.4 Processing controls.

3.2.4.1 Heating. Stress relieving the plates, local or general, shall be allowed after final quenching and tempering at a maximum temperature of 50°F below the tempering temperature.

Plates shall not be stress relieved in a temperature range of 600-800 °F. After stress relieving, the plates shall be tested for hardness and shall meet the requirements of table II.

TABLE II. Hardness requirements.

Specified nominal thickness of plate, inches From To and incl.

Armor class

Brinell hardness range, BHN, 3000 kg load

Brinell indentation diameters, mm

Rockwell C hardness range, HRC

0.250 0.499 1&3 341-388 3.30-3.10 36.6-41.8

0.500 0.749 1&3 331-375 3.35-3.15 35.4-40.5

0.750 1.249 1&3 321-375 3.40-3.15 34.3-40.5

1.250 1.990 1&3 293-331 3.55-3.35 30.9-35.4

2.000 3.990 1&3 269-311 3.70-3.45 27.7-33.0

4.000 6.000 1&3 241-277 3.90-3.65 22.7-28.7

6.001 6999 3 241-277 3.90-3.65 22.7-28.7

7.000 8.999 3 223-262 4.05-3.75 19.2-26.7

9.000 12.000 3 212-248 4.15-3.85 16.4-24.2

0.250 1.250 2 277-321 3.65-3.40 28.7-34.3

3.2.4.2 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 tempering operations shall not be done except when authorized by the procuring activity.

3.2.4.4 Grinding. Grinding is not required but shall be performed to remove minor defects not affecting the serviceability of the material provided that, unless otherwise authorized by the procuring activity, the grinding does not result in the reduction of the plate thickness in the ground area 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 the Brinell hardness range shown in table II for the applicable class and thickness. The diameters of Brinell hardness impressions on any individual plate shall not vary by more than 0.15 mm.

3.2.5.1.1 Class 4 armor plate. Surface hardness is required on every plate to insure quality and uniformity of product. In addition, first article samples shall be tested for through hardness to verify that they are within the HB range specified in 1.2.5 and 1.2.6. Respective diameters of the Brinell hardness impression taken on an individual plate shall not vary by more than 0.15 mm.

Each lot shall be tested for through hardness. Acceptance for Class 4a material requires a minimum through hardness of HRc 47 (BHN 442). Acceptance for class 4b material requires a maximum through hardness HRc 41 (BHN 381).

3.2.5.2 Impact. The Charpy V-notch impact test results of armor plate submitted shall meet the requirements shown in table VI for the applicable hardness and thickness. The Charpy V-notch impact specimens shall be obtained in the both the TL orientation (transverse to the major direction of rolling with the notch perpendicular to the plate surface so that the crack propagates in the longitudinal direction) and the LT orientation (parallel to the major direction of rolling).

The Charpy value for class 4 armor plate shall be greater than 20 ft-lb (27 J) for all thickness.

3.2.5.3 Bend test. When specified in the contract or order a bend test shall be performed. Bend test criteria shall be agreed upon by the supplier and fabricator.

3.2.6 Ballistic requirements. Ballistic requirements for class 1, 3 and 4 wrought homogeneous armor plate shall be in accordance with the appendix of this specification. Class 2 armor plate shall not be subject to ballistic test requirements. When a complete penetration can not be obtained for either class 1 or class 4 armor material, the following rule shall be in effect until a new ballistic acceptance round can be utilized. When four (4) partial penetrations are above the minimum requirement for the specific thickness, the material shall be certified as acceptable with a V50 (which obviously can not be specified) above the minimum requirement.

3.2.7 Dimensions and tolerances.

3.2.7.1 Dimensions. Classes 1 and 2 armor plate shall comply with the dimensions and tolerances specified on applicable drawings or in the contract (see 6.2). Class 3 armor tolerances on length and width dimensions shall be plus 1 1/2 inches and minus zero.

3.2.7.2 Thickness.

3.2.7.2.1 DELETED.

3.2.7.2.1 Thickness measurements (class 3 armor). The thickness of all class 3 plates shall be determined by measurements made one foot on centers over the entire surface of each plate. The measurements shall be to the nearest thousandth of an inch. The acceptance of each plate shall be based on these measurements meeting the thickness requirements of table V for class 3 armor.

3.2.7.2.2 Thickness tolerances. The thickness tolerances of each plate, after final treatment, shall be in accordance with tables III and IV for classes 1 and 2 armor or with table V for class 3 armor.

3.2.7.3 Flatness. Unless otherwise specified in the contract or order (see 6.2), the flatness tolerance of each plate shall be within the requirements specified in table VII. Tighter tolerance requirements shall be specified in the contract or order and shall be as agreed upon between the contractor 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 the requirements of table VIII for the applicable thickness.

TABLE III. Thickness tolerances for class 1 and class 2 armor plates up to 2 inches thick inclusive.

Thickness tolerances in inches over and under ordered thickness 1/ for a single plate 2 inches and under in thickness 2/

Tolerances Over and Under Ordered Thickness for Widths Given, inches Specified

Thickness, Inches

To 60

60 to excl.

72 to excl.

84 to excl.

96 to excl.

108 to excl.

120 to excl.

132 to excl.

144 to excl.

168 to excl.

and over

1/4 2/ 0.016 0.016 0.019 0.019 0.023 ---- ---- ---- ---- ---- 5/16 2/ 0.016 0.019 0.019 0.019 0.023 0.026 ---- ---- ---- ---- 3/8 2/ 0.016 0.019 0.019 0.023 0.023 0.026 ---- ---- ---- ---- 7/16 2/ 0.016 0.019 0.019 0.023 0.026 0.026 0.031 ---- ---- ---- 1/2 2/ 0.016 0.019 0.019 0.023 0.026 0.026 0.031 0.036 ---- ---- 9/16 2/ 0.019 0.019 0.019 0.023 0.026 0.031 0.031 0.036 ---- ---- 5/8 2/ 0.019 0.019 0.019 0.023 0.026 0.031 0.031 0.036 ---- ----

11/16 2/ 0.019 0.019 0.019 0.023 0.026 0.031 0.031 0.036 ---- ---- 3/4 2/ 0.019 0.019 0.023 0.023 0.026 0.031 0.039 0.043 ---- ----

13/16 2/ 0.023 0.023 0.023 0.026 0.031 0.031 0.039 0.043 ---- ---- 7/8 2/ 0.023 0.023 0.026 0.026 0.031 0.036 0.039 0.043 ---- ----

15/16 2/ 0.023 0.023 0.026 0.026 0.031 0.036 0.043 0.048 ---- ---- 1 2/ 0.026 0.026 0.026 0.026 0.031 0.036 0.043 0.048 ---- ----

1-1/16 2/ 0.026 0.026 0.026 0.031 0.031 0.036 0.043 0.048 ---- ---- 1-1/8 2/ 0.026 0.026 0.026 0.031 0.031 0.039 0.043 0.048 ---- ---- 1-3/16 2/ 0.031 0.031 0.031 0.031 0.036 0.043 0.048 0.053 ---- ---- 1-1/4 2/ 0.031 0.031 0.031 0.036 0.036 0.043 0.048 0.053 ---- ---- 1-516 2/ 0.031 0.031 0.031 0.036 0.036 0.043 0.053 0.058 ---- ---- 1-3/8 2/ 0.031 0.031 0.031 0.036 0.039 0.048 0.053 0.058 ---- ---- 1-7/16 2/ 0.036 0.036 0.036 0.036 0.043 0.048 0.058 0.063 ---- ---- 1-1/2 2/ 0.036 0.036 0.036 0.039 0.043 0.048 0.058 0.063 ---- ---- 1-9/16 2/ 0.036 0.036 0.036 0.039 0.043 0.053 0.058 0.070 ---- ---- 1-5/8 2/ 0.036 0.036 0.036 0.043 0.048 0.053 0.063 0.070 ---- ----

TABLE III. Thickness tolerances for class 1 and class 2 armor plates up to 2 inches thick inclusive – Continued.

1-11/16 2/ 0.039 0.039 0.039 0.043 0.048 0.058 0.063 0.070 ---- ----

1-3/4 2/ 0.039 0.039 0.039 0.043 0.048 0.058 0.068 0.078 ---- ---- 1-13/16 2/ 0.043 0.043 0.043 0.048 0.053 0.058 0.068 0.078 ---- ---- 1-7/8 2/ 0.043 0.043 0.043 0.048 0.053 0.063 0.068 0.078 ---- ----

1-15/16 2/ 0.043 0.043 0.043 0.048 0.053 0.063 0.076 0.084 ---- ---- 2 2/ 0.043 0.043 0.043 0.048 0.053 0.063 0.076 0.084 ---- ----

1/ For intermediate thickness, the tolerance of the closer-specified gage shall apply. In case of mid-point, the tolerance for lower gage or interpolated value shall apply.

2/ When plates under 60 inches are rolled double width, the equivalent wider plate tolerances shall apply.

TABLE IV. Thickness tolerances for class 1 and class 4 armor plates over 2 inches thick.

Thickness tolerances in inches over and under ordered thickness for single plate over 2 inches in thickness when ordered to thickness in inches.

Specified thickness, Tolerances over and under specified thickness for widths given, inches inches

From To Under 60 excl.

60 to 84 excl.

84 to 120 excl.

120 to 132 excl.

132 and over 2 4, excl. 1/ 0.060 0.068 0.068 0.076 4 6, incl. 1/ 0.076 0.076 0.083 0.091 6 8, incl. 1/ 0.091 0.091 0.098 0.107 8 10, incl. 1/ 0.107 0.107 0.122 0.138 10 12, incl. 1/ 0.138 0.138 0.144 0.160

1/ When plates under 60 inches are rolled double width, the equivalent wider plate tolerances shall apply.

3.2.8 Identification marking. Identification marking and records shall be such as to ensure positive identification of all plates, including test samples and specimens, with the lot and corresponding heat from which they were produced. First article and acceptance ballistic test plates shall also be marked with the manufacture’s name or trademark, the number of this specification, and the ordered plate thickness in inches. First article plates shall be marked “PRE,” acceptance plates “ACC,” and retest plates shall be marked “R1” and “R2.” If a second set of retest plates are submitted they shall be marked “RR1” and “RR2.” The 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 the surface unless the plate hardness makes painting necessary. All plate markings shall be highlighted with a highly visible yellow or orange border such as fluorescent paint 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 shall be based on these measurements meeting the thickness requirements set forth in table V.

b. Stamp each plate “HOMO, class 3, MIL-A-12560, plate No. ____, heat No.____.”

Stamping shall be approximately 1/2 inch high letters to a depth approximately 1/16 inch. Location of stamping for all plates shall be in the upper right hand corner.

3.2.9 Information required. 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.

All elements of the chemical composition shall be shown in the statement, including special additives or hardening agents, whether shown in table I or not.

TABLE V. Thickness tolerances for class 3 armor plate. 1/

Specified plate thickness, Over To and including

Permissible variation plus or minus, inches

0.250 0.500 0.015

0.500 1.125 0.020

1.125 1.499 0.025

1.499 1.749 0.030

1.749 1.999 0.035

1.999 2.999 .0.040

2.999 4.000 0.045

4.000 6.000 0.075

6.000 8.000 0.083

8.000 10.000 0.098

10.000 12.000 0.122

1/ This armor is not intended for use in combat vehicles. To obtain these thickness tolerances special surfacing finishing shall be required.

TABLE VI. Minimum Charpy V-notch impact requirements (at -40°F ± 2°F). 1/

Average Brinell hardness, Plate thickness, Minimum impact values (average of two or more test specimens), ft-lb

BHN inches Specimen Size Standard 3/4 width 1/2 width

207 4-12 incl. 65 212 4-12 incl. 63 217 4-12 incl. 61 223 4-12 incl. 59 229 4-12 incl. 57 235 4-12 incl. 55 241 4-12 incl. 53 248 4-12 incl. 50 255 4-12 incl. 47 262 4-12 incl. 44 269 4-12 incl. 40 277 4-12 incl. 37 285 4-12 incl. 33 262 1/4 to less than 4 55 269 1/4 to less than 4 51 277 1/4 to less than 4 47 36 24 285 1/4 to less than 4 43 33 22 293 1/4 to less than 4 39 30 20 302 1/4 to less than 4 35 27 18 311 1/4 to less than 4 31 24 16 321 1/4 to less than 4 28 21 14 331 1/4 to less than 4 25 19 13 341 1/4 to less than 4 22 17 11 352 1/4 to less than 4 19 15 10 363 1/4 to less than 4 17 13 9 375 1/4 to less than 4 16 12 8 388 1/4 to less than 4 16 12 8

1/ ASTM E140 shall be used to convert HRC readings to BHN equivalents.

3.2.10 Workmanship.

3.2.10.1 Surface imperfections. The 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 (see 6.4). 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 nature as to affect the fabrication of the material, are rejectable.

3.2.10.1.1 Depth of imperfections. The depth of rolled-in scale, scale pitting, mechanical gouges, or snakes shall not exceed 0.015 inch and shall not reduce the steel thickness below the allowable minimum. Isolated individual pits over 0.015 inch deep but not over 0.03 inch deep and not within 6 inches of each other and which do not violate the minimum allowable thickness, as specified in the applicable drawings and fabrication documents, are acceptable.

3.2.10.2 Edge preparation. Thermal cutting shall be permitted after final heat treatment provided the procedure, which may include grinding after thermal cutting, is such that no cracks develop on any thermally cut edge whether detected by nondestructive inspection, or as agreed upon in the contract. The heat affected zone of thermally cut plates (up to and including 1/2 inch in thickness) shall not exceed 1.2 times the plates thickness from the cut edge. For plates over 1/2 inch thick, the heat affected zone shall not exceed 5/8 inch from the cut edge. In order to have the heat affected zone exceed these limits approval shall be obtained from the procuring activity.

TABLE VII. Permissible variations for flatness, inches.

Specified Variations from a flat surface for specified widths, inches thickness, inches Under

48 to

60 excl.

60 to 72 excl.

72 to 84 excl.

84 to 96 excl.

96 to 108 excl.

1/4 to 3/8 excl. 3/4 15/16 1-1/8 1-3/4 1-7/8 - 3/8 to 1/2 excl. 1/2 9/16 5/8 3/4 7/8 - 1/2 to 3/4 excl. 1/2 9/16 5/8 3/4 7/8 -

3/4 to 1-1/4 excl. 1/2 9/16 5/8 3/4 7/8 - 1-1/4 to 1-5/8 excl. 3/8 1/2 1/2 5/8 3/4 -

1-5/8 to 3 excl. 3/8 3/8 7/16 1/2 5/8 3/4 3 to 4 excl. 3/8 1/2 1/2 5/8 3/4 3/4 4 to 6 excl. 1/2 5/8 5/8 3/4 7/8 7/8 6 to 8 excl. 9/16 11/16 11/16 13/16 15/16 15/16 8 to 10 excl. 5/8 3/4 3/4 7/8 1 1 10 to12 excl. 11/16 13/16 13/16 15/16 1-1/8 1-1/8

Note: The above variations apply to plates up to 12 feet in length, or to any 12 feet or longer plates.

3.2.10.3 Edge condition. Plate edge on plates delivered after heat treatment shall be free of cracks. The supplier shall practice such necessary process controls to prevent this condition.

3.2.10.4 Internal soundness. All plates 1/2 inch and greater in thickness shall be ultrasonically examined for internal soundness in accordance with 4.6.5. The steel supplier shall institute process controls such that any edge of 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.

TABLE VIII. Waviness tolerances for plates.

Flatness When number of waves in 12 ft is:

tolerance from table VII

5/16 5/16 1/4 3/16 1/8 1/8 1/16 1/16 3/8 3/8 5/16 3/16 3/16 1/8 1/16 1/16 7/16 7/16 5/16 1/4 3/16 1/8 1/8 1/16 1/2 1/2 3/8 5/16 3/16 3/16 1/8 1/16 9/16 9/16 7/16 5/16 1/4 3/16 1/8 1/8 5/8 5/8 1/2 3/8 1/4 3/16 1/8 1/8

11/16 11/16 1/2 3/8 5/16 3/16 3/16 1/8 3/4 3/4 9/16 7/16 5/16 1/4 3/16 1/8

13/16 13/16 5/8 7/16 5/16 1/4 3/16 1/8 7/8 7/8 11/16 1/2 3/8 1/4 3/16 1/8

15/16 15/16 11/16 1/2 3/8 5/16 1/4 3/16 1 1 3/4 9/16 7/16 5/16 1/4 3/16

1-1/8 1-1/8 7/8 5/8 1/2 3/8 1/4 3/16 1-1/4 1-1/4 15/16 11/16 1/2 3/8 5/16 1/4 1-3/8 1-3/8 1-1/16 3/4 9/16 7/16 5/16 1/4 1-1/2 1-1/2 1-1/8 7/8 5/8 1/2 3/8 1/4 1-5/8 1-5/8 1-1/4 15/16 11/16 1/2 3/8 5/16 1-3/4 1-3/4 1-5/16 1 3/4 9/16 7/16 5/16 1-7/8 1-7/8 1-7/16 1-1/16 13/16 9/16 7/16 5/16

2 2 1-1/2 1-1/8 7/8 5/8 1/2 3/8 2-1/8 2-1/8 1-5/8 1-3/16 7/8 11/16 1/2 3/8 2-1/4 2-1/4 1-11/16 1-1/4 15/16 11/16 9/16 3/8 2-3/8 2-3/8 1-13/16 1-5/16 1 3/4 9/16 7/16 2-1/2 2-1/2 1-7/8 1-7/16 1-1/16 13/16 9/16 7/16 2-5/8 2-5/8 2 1-1/2 1-1/8 13/16 5/8 7/16 2-3/4 2-3/4 2-1/16 1-9/16 1-1/8 7/8 5/8 1/2

Note 1. Waviness denotes the deviation of the top or bottom surface from a horizontal line, when the plate is resting on a flat surface, as measured in an increment of less than 12 ft of length. The waviness tolerance is a function of the flatness tolerance as obtained from Table VII.

Note 2. When the flatness tolerance is 1/2 inch or less for plates 1/2-inch or less in thickness, the waviness tolerance shall not apply.

3.2.10.4.1.2 Multiple linear indications. Multiple linear indications shall 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 Cracks. All cracks shall be rejectable.

3.2.10.4.1.4 Removal of large indications. Large indications shall be removed by the manufacturer or processor by grinding, provided the resulting cavity does not exceed 1/4 inch.

4. VERIFICATION

4.1 Responsibility for inspection. DELETED.

4.1.1 Responsibility for compliance. DELETED.

4.1 Classification of inspection. The inspection requirements specified herein are classified as follows:

a. First article inspection (see 4.1.1).

b. Conformance inspection (see 4.2).

4.1.1 First article inspection. When required (see 6.2), the first article samples submitted in accordance with 3.1, shall be examined for all the provisions of this specification applicable to end item examination.

4.1.2 First article tests. First article tests (see 6.2) shall consist of all the tests specified in 4.6.

4.1.3 First article ballistic test. Unless otherwise specified (see 3.1, 6.2, and 6.11), the first article ballistic test shall not be required provided (a) the manufacturer, within 37 months, has produced acceptable plates within the same nominal thickness ranges of table IX, and (b) the production conditions are the same as for previously accepted plates. A supplier who has previously met the first article requirements shall furnish the procuring activity the firing record of the ballistic test plate and other pertinent data relative to compliance with first article. Neither first article nor acceptance ballistic tests shall be required for plates ordered to thicknesses of more than 6.25 inches. Acceptance of these thicker plates shall be based on meeting the other requirements of the specification.

4.2 Conformance inspection. The acceptance examination under 4.5 and the tests under 4.6 shall serve as a basis for the acceptance 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 same treatment, and heat treated with the same thermal cycle in the same production furnace(s) in the same facility. When specified by the procuring activity (see 4.3.1), production and ballistic test plates shall be allowed to be heat treated separately. The test plate shall be heat treated in a production furnace.

4.3.1 Separately heat treated ballistic test plate. When the procuring activity allows a ballistic test plate to be heat treated separately from the production plates it represents (see 6.2), it shall be so stated in the data (see 6.7).

4.4 Sampling.

4.4.1 First article sampling.

4.4.1.1 Chemical composition. Samples for chemical analysis shall be taken from each plate selected for the ballistic tests.

4.4.1.2 Impact samples. At least one impact test sample shall be taken from each submitted test plate in accordance with 4.6.3.1 or 4.6.3.2 and each shall 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 with 4.6.5.

4.4.1.4 Ballistic test plates. Three ballistic test plates for each nominal thickness range (see table IX) shall be randomly selected and submitted for ballistic test. Any thickness within the range can be chosen to represent any other thickness in the range but the three plates submitted shall be of the same ordered thickness. Unless otherwise specified, the average thickness of each test plate shall be determined at the test site by the test agency as indicated in 4.4.2.5.

4.4.2 Sampling for quality conformance inspection.

4.4.2.1 For chemical analysis. At least one sample for chemical analysis shall be taken from each heat in accordance with the applicable method specified in ASTM A751 (see 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 inches thick shall be measured in two places, one at each end of a diagonal on both plate surfaces. The Brinell hardness of each plate as heat treated in each lot over 1 1/2 inches thick shall be measured in four places, one at each end of a diagonal on both plate surfaces.

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 large enough 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 1/2 inch and greater in thickness shall be examined ultrasonically. The 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. The minimum plate size shall be as shown in table IX for the applicable thickness. Unless otherwise specified, the average thickness of each test plate shall be determined at the test site by taking the average of four thickness 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 including 2.750 inch shall be read to the nearest 0.001 inch. Plates over 2.750 inch shall be read to the nearest 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 check list shall be completed and submitted with each ballistic test plate.

4.5 Examination.

4.5.1 Visual. All steel plate shall be subject to visual inspection for compliance with the requirements for surface conditions (see 3.2.10 .1), edge quality (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 3 armor plate shall be divided into one foot squares painted on one surface and the 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 Tests.

4.6.1 Chemical analysis. Chemical analysis shall be conducted in accordance 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 E10 or ASTM E110 using a 10 mm carbide ball and a 3000 kilogram load. Surface scale and decarburization shall be removed from the areas where the tests are to be made. Hardness tests shall be made on the surfaces of pieces cut from the plate after heat treatment.

TABLE IX. Ballistic test plate sizes and corresponding test projectiles for first article and acceptance testing.

Nominal thickness range, Minimum size 1/ of test plates, inches Test projectile and obliquity

0.25 to 0.565 incl. 12 x 36 Cal .30 M2 AP at 0°

0.566 to 1.125 incl. 12 x 36 Cal .50 M2 AP at 0°

1.126 to 2.750 incl. 12 x 36 20 mm M602 APIT at 0°

2.751 to 3.500 incl. 60 x 60 90 mm M82 APC at 45°

3.501 to 3.999 incl. 60 x 60 90 mm M82 APC at 30°

4.00 to 6.250 incl. 60 x 60 90 mm M318A1 AP at 0°

Over 6.251 2/ --- ---

1/ Other sizes may be submitted for the convenience of the manufacturer if approved by the Armor Vulnerability Division, USACSTA, Aberdeen Proving Ground.

2/ No ballistic test required.

4.6.2.1 Hardness tests on impact test specimens. Samples for all classifications shall be examined on a lot by lot basis. Except as provided in 4.6.2.2, each sample from which impact test specimens are taken shall have a hardness check made upon it as follows: For samples 1/4 to 1/2 inch inclusive the hardness check shall be made on the surface. For samples of 1/2 inch up to 4 inches in thickness, at least two hardness tests shall be taken from an adjacent location, midway between the surfaces of the plate. For samples of 4 inches in thickness or greater, at least six hardness tests shall be made at equal intervals across the plate thickness.

4.6.2.2 Rockwell hardness tests on impact specimens. At the option of the contractor at least two Rockwell C hardness tests shall be made on each impact test specimen sampled from each lot.

The test specimens shall be prepared and tested in accordance with ASTM E18. The average shall not exceed the maximum requirement for thickness specified in table II.

4.6.3 Charpy V-notch impact tests. At least two Charpy V-notch impact test 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-notch impact test specimens from samples less than 4 inches in thickness shall be taken in both the TL orientation and in the LT (see 3.2.5.2) orientation from a location midway between the top and bottom surfaces of the plate and at least 4 inches or 2T, whichever is less, from any quenched edge as well as outside the heat affected zone of any thermal-cut edge. When the amount of materials available is insufficient to obtain standard specimens, the largest attainable subsize Charpy V-notch impact specimens shown in figure 3 of ASTM E23 shall be used and the results compared to the applicable requirements of table VI.

4.6.3.2 For sample 4 inches or greater in thickness. Charpy V-notch impact test specimens from samples 4 inches or greater in thickness shall be approximately 1 inch below the surface of the plate and at least 4 inches from any 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 the 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 shall conform to

ASTM A578/A578M.

4.6.5.2 Procedure. Unless otherwise specified (see 6.2), the ultrasonic examination shall be carried out in accordance with ASTM A578/A578M with the following 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 continuous total loss of back reflection accompanied by continuous indications on the same plane that cannot be encompassed within a circle whose diameter is 1 inch shall be cause for rejection of that plate. All discontinuities shall be evaluated using a frequency of

2.25 megahertz (MHz).

4.6.5.3 Certification of inspection personnel. Unless otherwise specified (see 6.2), personnel performing ultrasonic inspection shall comply with the qualification requirements of NAS410.

Personnel making accept/reject decisions in accordance with the process described by this specification shall be qualified to at least a level II.

4.6.6 Reduced testing. At the discretion of the procuring activity, the amount of testing shall be reduced provided the results on consecutive lots indicate that a satisfactory uniform product meeting the testing requirements is being produced (see 6.2). Reduced testing shall be in accordance with a system previously approved or established by the procuring activity involved.

4.6.7 Rejection and retest.

4.6.7.1 Rejection. Unless otherwise specified in the contract or order (see 6.2), failure of the first article samples to meet the requirements of this specification shall be cause for rejection of the process, and failure of the acceptance samples to meet the requirements of this specification shall be cause for rejection of the lot (see 4.6.7.2).

4.6.7.2 Retest. Unless specific retest procedure is specified in the contract or order (see 6.2), two retest samples shall be submitted for each failed sample. Failure of either of the retest samples (plates) shall be cause for rejection of the material. First article retests shall not be permitted until the supplier has made the necessary correction in the processing of the material to the 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 taking Rockwell C hardness tests at 1/16 inch increments from the edge. Surface scale and decarburization shall be removed from the test surface. The distance at which there is no change in surface hardness shall be considered the depth of the heat affected zone. The contractor shall document the test results for each thickness and thermal cutting method used in production. The contractor is also responsible for documenting all heat input controls to assure the cutting process is under control.

Re-verification of heat affected zone size for subsequent production lots is not required provided there is no change in the cutting method or heat input from that previously tested. The records shall be available for review by the cognizant government representative.

5. PACKAGING

5.1 Preservation and packaging. DELETED.

5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the contract or order (see 6.2). When packaging of materiel is to be performed by DoD or in-house contractor personnel, these personnel need to contact the responsible packaging activity to ascertain packaging requirements. Packaging requirements are maintained by the Inventory Control Point’s packaging activities within the Military Service or Defense Agency, or within the military service’s system command. Packaging data retrieval is available from the managing Military Department’s or Defense Agency’s automated packaging files, CD-ROM products, or by contacting the responsible packaging activity.

5.1.1 Level C. DELETED.

5.2 Packing. DELETED.

5.2.1 Level C. DELETED.

5.3 Marking. DELETED.

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 armor specified herein is intended for use on combat vehicles and/or proof and acceptance testing of armor defeating ammunition, but should also be applicable to armor for emplacements, shields, pill boxes, testing, and the like.

6.1.1 Class 1. Class 1 wrought armor is intended for use in those areas where maximum resistance to penetration by armor piercing types of ammunition is required.

6.1.2 Class 2. Class 2 wrought armor is intended for use in those areas where maximum resistance to failure under conditions of high rates of shock loading is required and where resistance to penetration by armor piercing ammunition is of secondary importance. It is intended for use as protection against anti-tank land mines, hand grenades, bursting shells, and other 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 not intended for use in combat vehicles. Lift hole requirements for class 3 armor should be specified by the procuring activity.

6.1.4 Class 4. Provision for this new class 4 type of armor plate is the result of an Army Research Laboratory (ARL) Research & Development (R&D) Program. The information related to this study was published in a Technical Report, ARL-TR-1347 dated April 1997, entitled Improved Rolled Homogeneous Armor (IRHA) Steel Through Higher Hardness. Copies of this report are published as ADA 329222 and are available from the Defense Technical Information Center (DTIC), Suite 0944, 8725 John J. Kingman Road, Fort Belvoir, VA 22060-6218. The R&D study illustrated enhanced ballistic performance with the use of increased hardness levels for maintaining tougher and more ductile characteristics. This new classification was developed to use in combat vehicles (3/4 inches to 6 inches) and tank construction. Class 4 material provides higher ballistic protection than class 1 material against conventional hard steel core AP projectiles, such as, the 0.50 cal, M2 AP. Class 4 material also provides greater ballistic protection than class 1 material against very hard and brittle tungsten carbide penetrators, such as, the 20 mm M602 APIT. In semi-infinite or appliqué-type armor configurations, class 4 material erodes heavy metal (DU or tungsten alloys) long-rod penetrators more efficiently than class 1 material. Approximately 22% and 14% less penetration was observed on this class 4 armor at HRc 48 (BHN 451) and HRc 40 (BHN 371), respectively in the ARL R&D study.

6.2 Ordering data.

6.2.1 Procurement requirements. Procurement documents should specify the following:

a. Title, number, and date of this specification.

b. Class of steel.

c. If first article sample is required (see 3.1).

d. If local or general heating is permitted (see 3.2.4.1).

e. If weld repairing is permitted (see 3.2.4.2).

f. Dimensional requirements (see 3.2.7).

g. First article tests (see 4.1.2).

h. When a special first article ballistic test is required (see 3.1, 4.1.3 and 6.11).

i. If ballistic test plates may be separately heat treated from the production plates it represents, (see 4.3.1).

j. If ballistic acceptance samples should be other than in 4.4.2.5.

k. If ultrasonic examination is to be different than 4.6.5.2.

l. If certification of inspection personnel is different from 4.6.5.3.

m. If rejection and retesting differs from 4.6.7.

n. The reduced testing plan when applicable (see 4.6.8).

o. Preparation for delivery if different than specified in section 5.

p. If lifting holes are required (see 6.1.3).

6.2.2 Associated Data Item Descriptions (DIDs). This specification has been assigned an Acquisition Management Systems Control number authorizing it as the source document for the following DIDs. When it is necessary to obtain data, the applicable DIDs must be listed on the Contract Data Requirements List (DD Form 1423).

DID Number DID Title

UDI-T-23790 Report, First Article Test UDI-T-23264 Certification Data Report

DI-MISC-80073 Armor Material Test Reports

The above DIDs were current as of the date of this standard. The ASSIST database should be researched at http://assist.daps.dla.mil/quicksearch/ or http://assist.daps.dla.mil/ to ensure that only current and approved DIDs are cited on the DD Form 1423.

http://assist.daps.dla.mil/quicksearch/

6.3 Thickness. The symbol “T” is used throughout this specification to indicate the nominal thickness of the plate under consideration.

6.4 Definitions.

6.4.1 Contractor. The contractor or prime contractor is the company which has a direct contract from the Government to furnish an end item, usually a vehicle.

6.4.2 Contracting officer. The term “contracting officer’ means the person executing a contract on behalf of the Government and any other officer or civilian employee who is properly designated contracting officer; and the term includes, except as otherwise provided, the authorized representative of a contracting officer acting within the limits of his authority.

6.4.3 Homogeneous rolled armor. Homogeneous rolled armor is armor having uniform composition heat treatment.

6.4.4 Manufacturer. The manufacturer is defined as the company producing the steel alloy plate.

6.4.5 Procuring activity. The term “procuring activity” is that activity of the Government which actually initiates the request for procurement and maintains the records of the procurement.

6.4.6 Slivers. An imperfection consisting of a very thin elongated piece of metal attached by only one end to the parent metal into whose surface it has been worked.

6.4.7 Laps. A surface imperfection with appearance of a seam caused by hot metal, fins or sharp corners being folded over and thus being forged or rolled into the surface but without being welded.

6.4.8 Checks. Numerous very fine cracks at the surface 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 marks, checking, and heat checks.

6.4.9 Seams. An unwelded fold or lap that appears as a crack, usually resulting from a discontinuity on a metal surface.

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 blisters or pepper blisters.

6.4.11 Snakes. Any crooked surface imperfection in a metal plate, resembling a snake.

6.4.12 Cold shuts. Freezing of the top surface of an ingot before mold is full.

6.4.13 Burning. Permanently damaged metal due to overheating enough to cause incipient melting or intergranular oxidations. Note: this condition is usually obscured by normal cleaning methods and would require deep pickling and/or metallography to note the continuous oxidation (chicken wire effect) of the enlarged grain boundaries.

6.4.14 Lamination. A type of discontinuity with separation or weakness generally aligned parallel to direction of the worked surface of the metal and may be the result of pipe, blisters, seams, inclusions, or segregation; elongated and made directional by working.

6.4.15 Pit. A cavity or depressed area on the surface of a plate.

6.4.16 Linear indication. For nondestructive examination purposes, a linear indication is evidence of a discontinuity that requires interpretation to determine its significance.

6.5 Changes in composition. Changes in composition may not necessarily be cause for retesting but should be subject to review by the procuring activity to determine whether additional first article testing is required.

6.6 Chemical analysis. Suggested ASTM instrumental methods that can be used for chemical analysis are E322 and E415. ASTM A751 should be consulted for a complete list of methods.

6.7 MIL-STD-367. DELETED.

6.7 Production plates. Material made to this specification has tendency to develop stress cracks if not tempered as soon as possible after austenitizing treatment. To avoid this situation, all plates should be left in the hot rolled or tempered condition while waiting for the ballistic test results.

6.8 Potential suppliers. Potential suppliers who have not previously supplied armor plate to MIL- A-12560 and wish to have their material ballistic tested may do so at their own expense. It is recommended that inquiries for such testing be directed to Commander, US Army CSTA, ATTN: STECS-LI-A, Aberdeen Proving Ground, MD 21005-5059.

6.9 New contracts sponsored by Government agencies.