1.1 This specification covers ductile iron castings that are subsequently heat treated by an austempering process as defined in 8.1.

1.2 The application of the austempering heat treatment extends the range of properties achievable in ductile iron castings.

1.3 No precise quantitative relationship can be stated between the properties of the iron in various locations of the same casting or between the properties of castings and those of a test specimen cast from the same iron (see Appendix X1). However, austempering heat treatment will tend to diminish any differences in mechanical properties.

1.4 The production of castings, machining (if required), and the austempering heat treatments may be performed by different manufacturers, as covered in Section 13. The purchaser should establish by contract agreement, at the time of ordering, the responsibility of the various parties for meeting the specification requirements.

1.5 The values in this specification are stated in SI units.

Note 1-A companion specification, A897, has been developed in which the values are stated in inch-pound units. Each specification is independent and the mathematical conversions are not exact equivalents.