Abstract
The effect of the specimen size on tensile and fatigue properties was studied by using thin wires with the grain size of 22μm and the diameter, Dmin, of 800μm, 700μm and 500μm (these are named Specimen-800, 700 and 500, respectivly). For tension test results, the yield strength (proof stress) strongly depended on the specimen diameter. All Specimen-800 and Specimen-700 and a part of Specimen-500 show the clear yield phenomena. However, most of Specimen-500 did not show yielding. For all specimens fractured under cyclic loading, the necking was occurred at the final stage of the fatigue process, and the initiation and the propagation of fatigue cracks were not observed. Two kinds of failure processes were observed. One was ratcheting failure and the other was delayed yielding failure. After the delayed yielding, specimens showed the process similar to ratcheting failure. It was concluded that these size effect are caused by the difference in the number of grains at the minimum cross section. Regardless of diameters of specimens, the scatter in fatigue life was very large compared with that of bulk specimen. It was concluded that the main cause of the large scatter in fatigue life was attributed to the scatter in the number of cycles to start ratcheting deformation (delayed yielding).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
