MIL-A-21180 Aluminum-Alloy Castings, High Strength \(S/S By Sae-Ams-A-21180\)

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MIL-A-21180D

3.4.2.2 Radiographic acceptability. Unless otherwise specified (see 6.2.1), radiographic

acceptability shall comply with Table II. Radiographic acceptability is indicated by the applicable

reference ASTM E 155 radiograph which is acceptable for the specified grade, or such

acceptability is indicated by the applicable radiograph in an alternate standard set (see 6.6). To be

acceptable as to the specified grade, a casting must be acceptable for all discontinuitiues listed in

Table II relative to that grade. Nonconformance with the applicable standard for any single defect

shall make a casting unacceptable. Unacceptable shrinkage, porosity or sponge in alloy A201.0

may assume a radiographic appearance similar to mottling, and when this condition is suspected,

metallographic examination is required.

3.4.3 Mechanical properties. The mechanical properties of test specimens, taken as specified

in 4.4.2.4, shall conform to the applicable requirements of Tables III and IV or as specified on the

drawing. The strength requirement of the casting tested in full-size shall be as specified in the

drawing for the part concerned or in other purchase information.

3.4.4 Electrical conductivity. The electrical conductivity of Alloy A201.0 in the -T7 temper

shall be 31.0 percent or greater, International Annealed Copper Standard (IACS).

3.4.5 Surface roughness. When specified, maximum surface roughness in any area of a

casting shall be that specified in drawings of the casting or in other acquisition documents, and

shall be expressed in terms of comparator numbers on as-cast surfaces and in terms of height

ratings on machined or ground surfaces including gate and riser areas. Surfaces other than as-cast

shall not have a roughness exceeding that of an as cast surface. Comparison standards used for

measuring surface roughness shall be as specified in the acquisition documents (see 6.2.1).

3.5 Heat treatment. Unless otherwise specified on a casting drawing or elsewhere in the

acquisition documents, castings shall be heat-treated in accordance with MIL-H-6088 except as

modified herein. Castings of alloys A201.0, 354.0, A357.0 and 359.0 shall be solution

heat-treated within the range of temperatures specified in Table V of this specification. An

aqueous solution of polyalkylene glycol meeting the requirements of AMS 3025 may be used as a

quenchant to minimize distortion, provided that the castings meet the mechanical property

requirements of this specification or applicable drawing. Heat treatment shall be performed on a

whole casting and never on a portion only. Castings shall be artificially aged by heating uniformly

over the time and at the temperature necessary to obtain the required mechanical properties. The

recommended time and temperature cycle for precipitation heat treatment of alloy A201.0, 354.0,

A357.0, and 359.0 are shown in Table VI.

3.6 Marking. Unless otherwise specified on the casting drawing, castings shall be identified

with a part number and a serial number or lot number, and radiographic control number (see

6.2.1). Markings shall be so located as to be preserved throughout the finishing process.