Dominick Pagano
DPR Ultrasonic Technologies, LLC

One of the more problematic defects to locate with existing technology has been detail fractures caused by metal fatigue which are masked by rail surface and subsurface shelling conditions caused by RCF defects.

This presentation presents the results of an in-depth investigation into subsurface deep shells that originated out of RCF surface defects found using the deployment of new ultrasound technology that is capable of reliably detecting these deep shells as well as sub-surface conditions. The presentation will give a quick introduction into ultrasound testing in general before detailing the physical characteristics and the potential impact on current regulations surrounding the horizontal split head and deep shell defects associated with the fractures. Furthermore, factors such as rail grinding, profile crown radius, and metal fatigue behavior that will impact the formation and growth of these defects will be analyzed and discussed.

With the deployment of this new technology, it is possible to detect and better define the location and general sizing of these conditions, allowing railways to monitor and remove the precursors and masking effects of detail fractures. Additional research might be required to better understand and control the variables directly impacting the formation of these defects.