MIL-S-851D
4.2 Quality Conformance Inspection. Quality conformance inspection shall consist of the following tests:
a. Chemical composition (See 3.1).
b. Shape and surface condition (See 3.3). c. Hardness (See 3.4).
d. Microstructure (See 3.5). e. Sizing (See 3.6).
4.3 Test Methods.
4.3.1 Chemical composition. The chemical composition of grit and shot as specified in 3.1 shall be determined in accordance with procedures outlined in Federal Test Method Standard No. 151.
4.3.2 Shape and surface condition. The shape and surface condition of grit and shot as specified in 3.3 shall be determined by visual examination. Particles selected at random from the samples in
4.1.3 shall be spread in a single layer on a suitable flat surface and examined visually with the aid of suitable lighting and magnification for single view identification and count of nonconforming particles. Areas selected for counting shall have a 70% site occupancy (70% of area obscured by particles).
4.3.3 Hardness. The hardness of the grit and shot as specified in 3.4 shall be determined in accordance with procedures outlined in Federal Test Method Standard No. 151. At least 20 particles shall be selected from the samples in 4.1.3. For small size grit and shot, when necessary, hardness may be determined with a micro hardness test machine using a knoop indenter and a 1 kilogram load, and then converting to Rockwell C. The average hardness of the 20 particles shall conform to the specified requirement.
4.3.4 Microstructure. The microstructure of cast steel as specified in 3.5 shall be determined by metallographic examination procedure after preparation as outlined in Federal Test Method Standard No. 141. Particles selected at random from the samples in 4.1.3 shall be used for this test.
4.3.5 Sizing.
4.3.5.1 Screening tests. The size of grit and shot, Type I and II, as specified in 3.6.1 and 3.6.2, shall be determined by using 100-gram portions of samples in 4.1.3, and screening as follows: using standard testing sieves in accordance with RR-S-366, nest the required sieves in ascending order with a pan on the bottom. Place the 100 gram sample in the top sieve and place the nested sieves in a rotating and tapping type of shaking machine. The rotating speed shall be 275 to 295 rotations per minute, and 145 to 160 taps per minute. Shaking and tapping shall be continued for
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