Assessment of fatigue striation counting accuracy using high resolution scanning electron microscope

A well-known method for determining the number of fatigue load cycles prior to failure is to perform a striation counting on the fractured surface. The primary objective of this study is to evaluate the accuracy of a striation counting performed using a high-resolution scanning electron microscope. Fatigue experiments were conducted on two aluminum alloy AA-2024-T3 specimens and two low alloy steel AISI-4130-O specimens. We then performed a fractographical analysis of the fractured specimens and compared the results to the experimental data. The second objective of this study is to determine several guidelines regarding the method of striation counting process which will raise its accuracy. This study shows that high accuracy can be achieved by counting fatigue striation using a scanning electron microscope, but one must be aware of several problems and difficulties which can occur during the counting process. Several guidelines that will raise the accuracy were determined.