QQ-N-286G dimension at the site of the imperfection. Sufficient material shall be removed to reach the bottom of the imperfection. The cross-section dimension is measured at this point. If the depth of the imperfection does not exceed the machining allowance in table XXIII for the applicable size and form, the product will be acceptable.
4.3 Test procedures.
4.3.1 Chemical analysis. The sample selected in accordance with 4.2.2.1 shall be analyzed by the wet chemical or spectrochemical methods to determine conformance with table I. In case of disagreement, the chemical composition shall be determined in accordance with ASTM E 76.
4.3.2 Mechanical tests.
4.3.2.1 Aged material. Mechanical tests required for material shipped in the aged condition shall be done on a sample taken from the material after the final heat treatment. Mechanical tests used to demonstrate the capability of
a lot to meet the mechanical test requirements (see 4.3.2.2) may not be used certify a lot of material shipped in the aged condition.
4.3.2.2 Unaged material. When mechanical tests are required for material ordered in the unaged condition to demonstrate the capability of the lot to meet the mechanical testing requirements (see 6.2), the test specimens, taken from each lot per 4.2.2.2, 4.2.2.3, 4.2.2.4 and 4.2.2.5, shall be obtained from the material as it is to be to be shipped or from a forged test coupon, when applicable and heat treted as specified (see 6.2). When no heat treatment is specified, the specimen shall be annealed, if the material to be shipped has not been annealed, and aged in accordance with 4.3.2.2.1. Mechanical tests on a lot from the same heat that has previously been tested in the same condition (see 1.2.1), heat treated as specified above, and found to meet the requirements of this specification may be used to demonstate the capability of the lot of unaged material to meet the mechanical test requirements.
4.3.2.2.1 Heat treatment of unaged mechanical test specimens. Unless otherwise specified (see 6.2), age hardening of the test specimens in 4.3.2.2
shall be performed by heating to 1100-1125 F, holding at temperature for 8 to
16 hours depending on hardness of material and desired hardness after aging,
furnace cooling to an aim temperature of 900 F then air cooling to room temperature.
4.3.2.3 Bar, rod, rectangles, and forged parts. All bar, rod,
rectangles, and forged parts shall be tested full-size when practicable. When
a machined specimen becomes necessary, enough metal may be removed from the
gauge section to meet the limitations of the testing machine or the specimen
may be machined to the form and dimensions of the largest standard round
specimen in ASTM E 8 obtainable from the product being tested. When the
product being tested is of such size that an ASTM E 8 round specimen less than
0.250 inch diameter is needed, minimum elongation requirements of table III
shall not apply.
4.3.2.3.1 Axis of the test specimens. For bar, rod, rectangles, and forged parts up to and including 1� inches in diameter or thickness, the axis of the test specimen shall coincide with the central axis of the piece; over
1� inches, the axis shall be located midway between the center and surface of the piece.
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