Electromagnetic effects at metallic fracture

Abstract

JUST at the instant of tensile fracture of low-carbon iron specimens a transient magnetic field of the order of 1,000 gauss is produced¹. This phenomenon is observed even in the absence of any external magnetic field. Only the surface region of the fractured pieces are magnetised, with the fractured ends exhibiting distinct and opposite polarities. The magnetisation of each piece varies along the length, with maximum at the fractured end. Moreover, the induced magnetisation is retained for about 15 d in larger specimens and then decays almost exponentially. Iron specimens fractured under impact forces did not show any magnetisation. I now report observations of the complementary phenomenon of generation of an electric field at the instant of tensile fracture of metallic specimens, ferromagnetic as well as non-ferromagnetic.