A potential metallographic technique for the investigation of pipe bombings

This study was conducted in an attempt to develop a metallographic method for the investigation of pipe bombings. Three common pipe materials, ASTM A53 steel, AISI 304L stainless steel, and 6061-T6 aluminum, were shock-loaded using five high explosives and three propellants. The explosives used were ANFO, Composition C4, C6 detasheet, nitroglycerine-based dynamite, and flake TNT. The propellants used were FFFFg black powder. Red Dot smokeless powder, and Turbo Fuel A. The post-blast microstructure, hardness, and, in the case of 304L, transformed martensite content were examined for each test. The damage done to the microstructure was found to increase with increasing detonation velocity of the explosives and increase in pressure generated by the shock-metal interaction. Material hardness and, in the case of 304L, martensite content showed a sharp increase followed by a plateau as the shock pressure and detonation velocity increased.