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.