Failure Analysis of 120-Mortar Bushings and Firing Pins

摘要

A failure analysis was performed on several 120-mm mortar bushings and firingpins. The analysis entailed examining (1) the failed firing pins and bushings for conformance to drawing requirements, and (2) the material differences between the U.S.-made and the Israeli-made components. The evaluation included visual examination, metallographic examination, microhardness determination, chemical composition determination, and scanning electron microscopy. The firing pins essentially met the required material specifications. However, it could not be determined whether the bushings met the requirements due to the vagueness of the drawing specifications. There were no observable material differences between the U.S. made and the Israeli-made firing pins. The U.S.-made bushings did have a larger grain size, and the inner diameter of the bushing showed a slight surface degradation and rougher topography than the Israeli-made bushing. This difference in the inner diameter was due to the machining process, wire electrical discharge machining, that was used to produce the U.S. made bushings. Failure analysis, 120-mm Mortar, Wire electrical discharge machining, Remelt.