QQ-N-286 Nickel-Copper-Aluminum Alloy, Wrought Uns N05500This specification covers all nickel-copper-aluminum alloy wrought forms formerly classified as class A. This alloy is designated under the Unified Numbering System for Metals and Alloys as UNS N05500. Except for cases where nonmagnetic properties are paramount, this alloy is intended to be age hardened prior to placing the material in service.

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QQ-N-286G plus or minus 1/8 inch), shape, and material (or acoustically similar material). The hole shall be drilled to a depth of one- half the thickness or 1 inch whichever is less. Plate shall be scanned continuously on either a 24 inch grid and one diagonal

on each grid, or a 12 inch grid.

4.3.3.3.1 Reference notch removal. If reference notches or flat bottomed holes are made in the material to be tested, they shall be so located that their subsequent removal will not impair the suitability of the material for its intended use.

4.3.3.4 Acceptance criteria.

4.3.3.4.1 For ultrasonic inspection for large size bars, rods and forgings.

4.3.3.4.1.1 Longitudinal end scan. A 90 percent or greater loss of back reflection signal (except when the transducer is within one transducer diameter of the side of the bar) or any discontinuity signal greater than 25 percent of the established reference level shall be cause for rejection.

4.3.3.4.1.2 Shear wave pitch-catch scan. Abrupt reductions in signal amplitude (6 db or more in one inch or less of length) shall be cause for rejection.

4.3.3.4.2 Other ultrasonic inspections.

A) Shear wave. Any material which produces indications equal to or larger than the response from the reference notch or higher than the straight line joining the two peak amplitudes shall be rejected.

B) Longitudinal wave. Any material which produces indications equal to or larger than the response from the reference hole, or contains areas which result in a 90 percent or greater loss of back reflection (except when the transducer is within one transducer diameter of the side of the bar) shall be rejected.

Material shall be tested using a square, rectangular, or circular transducer having an effective area of 1 square inch

or less, but no dimensions shall be smaller than the diameter of the reference hole. In the event of disagreement on the degree of back reflection loss, it shall be determined by the contact

method using a 1 to 11/8

inch diameter transducer or one whose

area falls within this range.

4.3.4 Liquid penetrant inspection.

4.3.4.1 Procedure. Liquid penetrant inspection shall be in accordance with NAVSEA T9074-AS-GIB-010/271 or MIL-STD-2132.

4.3.4.2 Surface requirements. The surface produced by hot working is not suitable for liquid penetrant testing. Therefore, liquid penetrant testing will not be applicable to products ordered with a hot finished surface.

4.3.4.3 Acceptance criteria. Linear defects revealed by liquid penetrant inspection shall be explored by grinding or other suitable means. Depth of defects shall not exceed the dimensional tolerance of the material.

4.3.5 Duplex structure determination. The sample selected for duplex structure determination shall be macroetched to reveal the grain structure. The sample shall be prepared so that the surface to be etched has a suitable