Influence of Lightning Discharge on Microstructure, Mechanical Properties and Failure of Armature Steel

Abstract

Influence of lightning discharge on microstructure, mechanical properties and failure of armature steel was investigated. The studied specimens were picked out from the reinforcement construction destroyed during storm. Metallographic analysis by optical microscope LMA combined with video camera YCH15 was carried out. Pictures of the affected structure were picked out by electron scanning microscope SEM EVO 50 as well using secondary electron detector SE. Chemical composition was determined with the dispersive energy spectrometer INCAx-sight EDS. Micro hardness of the specimens was measured by ПМТ 3 device with load 0.49 N (in some cases 0.196 N and 0.098 N). Grey, black or white zones in the cross-section of steel samples were determined. It was found that these zones might be hard or brittle, may vary in shape, size and phase composition. It may have or not metallic properties. The article presents analysis of the chemical composition changes at the affected zones, but it also requires for further investigations of lightning discharge effect on armature steel.