MIL-A-21180D
g. When an old pattern is transferred to a new vendor, or a new facility.
h. When another alloy is used.
i. When melting or processing techniques are changed.
j. When an existing pattern is re-rigged or remounted.
k. When mold systems are changed.
3.3 Composition.
3.3.1 Chemical composition of castings. The chemical composition of castings shall be as
specified in Table I.
3.3.2 Chemical analysis. Analysis shall routinely be made only for the elements specifically
mentioned in Table I. If however, the presence of other elements is suspected or indicated in the
course of routine analysis, further analysis shall be made to determine conformance to the limits
specified for other elements.
3.4 Radiographic and surface requirements.
3.4.1 Process control castings (first article foundry control).
3.4.1.1 Radiographic soundness, mechanical property and surface roughness control. Prior
to production of a given casting, radiographic, mechanical property and, when specified
(see 6.2.1), surface roughness controls shall be established. Sample castings (see 4.3.1) shall be
examined by radiographic methods aided by sectioning and etching to determine the presence of
internal defects. In addition, the full-size casting or tension test specimens machined from
castings or cast-on coupons (where permitted) shall be tested for conformance to the required
mechanical properties. The full-size casting, either as-cast or surface-finished, shall be tested for
roughness, when roughness requirements are specified on the casting drawing or other acquisition
documents. In order for foundry control to be acceptable, each location of a casting must exhibit
soundness, surface roughness, and tensile properties conforming to those specified for that
location on the drawing or other acquisition document. When acceptable foundry practices have
been established, the production method shall not be changed (see 3.2.2) without demonstrating
to the satisfaction of the purchaser that the change does not adversely affect the quality of the
casting.
3.4.1.1.1 Radiographic inspection. The casting shall be radiographically inspected for
acceptability of the casting process in relation to the soundness requirements of 3.4.1.1.2.
Inspection procedures shall conform to 4.5.2.
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