scope:

This method applies to ferrous materials that have an endurance limit. The endurance limit is that stress below which the material will not fail in 10⁷ cycles.

This method may be used to measure the fatigue strength of nonferrous materials that do not have an endurance limit.

This standard uses the staircase method to analyze the data and determine statistically the mean endurance limit as well as estimating the standard deviation and the stresses for which 10% and 90% of test bars would survive for 10⁷ cycles at the 50% confidence level. Refer to the Appendix for details outlining the statistical methods of analysis.

The specimens may be as-sintered or heat treated.

This test method uses an unnotched test specimen and prescribes its design. A notched test specimen could be used, but the shape and location of the notch must be reported with the data.

In a rotating beam machine, the specimen is gripped between two collets and subjected to a bending stress as it rotates. During each revolution, the stress in the outer surface of the reduced diameter gauge region alternates from tension to compression and back to tension, R = -1 (where R = σ_min/σ_max).

NOTE 1- There is no precise relationship between rotating beam endurance data and axial fatigue data. A correlation analysis between axial fatigue limit and rotating beam fatigue limit found the axial fatigue limit to be 80-90% of the rotating beam fatigue limit.

With the exception of density, for which g/cm³ is the industry standard, this standard uses inch-pound units. Values in SI units are shown in parentheses and result from conversion in accordance with IEEE/ASTM Standard SI 10. They may be approximate and are only for information.

This standard may involve hazardous materials, operations and equipment. This standard does not purport to address all of the potential safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.