This test method deals with the acceptance criteria for the magnetic particle examination of forged steel crankshafts and forgings having large main bearing journal or crankpin diameters. Covered here are three classes of forgings, which shall be evaluated under two areas of inspection, namely: major critical areas, and minor critical areas. During inspection, magnetic particle indications shall be classified as: surface indications, which include nonmetallic inclusions or stringers, open or twist cracks, flakes, or pipes; open or pinpoint indications; and non-open indications. Procedures for dimpling, depressing, inspection, and product marking are also mentioned.

1.1 This is an acceptance specification for the magnetic particle inspection of forged steel crankshafts having main bearing journals or crankpins 4 in. [200 mm] or larger in diameter.

1.2 There are three classes, with acceptance standards of increasing severity:

1.2.1 Class 1.

1.2.2 Class 2 (originally the sole acceptance standard of this specification).

1.2.3 Class 3 (formerly covered in Supplementary Requirement S1 of Specification A 456 – 64 (1970)).

1.3 This specification is not intended to cover continuous grain flow crankshafts (see Specification A 983/A 983M); however, Specification A 986/A 986M may be used for this purpose.

Note 1—Specification A 668/A 668M is a product specification which may be used for slab-forged crankshaft forgings that are usually twisted in order to set the crankpin angles, or for barrel forged crankshafts where the crankpins are machined in the appropriate configuration from a cylindrical forging.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch units.