Full Description

1.1This test method is intended as a procedure for the performance of rotating bending fatigue tests of solid round fine wire to obtain the fatigue strength of metallic materials at a specified life in the fatigue regime where the strains (stresses) are predominately and nominally linear elastic. This test method is limited to the fatigue testing of small diameter solid round wire subjected to a constant amplitude periodic strain (stress). The methodology can be useful in assessing the effects of internal material structure, such as inclusions, in melt technique and cold work processing studies. However, there is a caveat. The strain, due to the radial strain gradient imposed by the test methodology, is a maximum at the surface and zero at the centerline. Thus the test method may not seek out the weakest link, largest inclusions, that govern uniaxial high cycle fatigue life where the strain is uniform across the cross section and where fatigue damage initiates at a subsurface location (1-5).2 Also, pre-strain, which can influence fatigue life, is not included in this test method.

Note 1:The following documents, although not specifically mentioned, are considered sufficiently important to be listed in this test method:
ASTM STP 566 Handbook of Fatigue Testing
ASTM STP 588 Manual on Statistical Planning and Analysis for Fatigue Experiments
ASTM STP 731 Tables for Estimating Median Fatigue Limits (6-8)

1.2The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.