Characterization of hypervelocity gouge craters in rail conductors

Gouging is a frequently encountered rail damage phenomenon and has been observed in several large-bore guns. In this study the size and number of gouges have been determined as a function of position and velocity. Detailed analysis was performed on rails recovered from single shot experiments. Rail hardness and surface and microstructural characteristics of gouges have been determined and analyzed to relate materials properties to gouge formation. We observed hardening and plastic flow of copper beneath a gouge crater. Transmission electron microscope studies showed twinning in copper. We find that gouge sizes are closely related to armature contact size. The gouge is generally shorter than the contact length and no wider than the contact. Our study shows that rail hardness is affected in the vicinity of a gouge. After gouges are formed on a rail, the hardness is no longer uniform and performance of the rail conductor is affected.