Abnormal grain growth in electrical steels,  Soran Birosca
Channel: bhadeshia123
Date: 14/09/2021

The first Si-Fe electrical steel was produced in 1905; grain-oriented steel was discovered in 1930 when Goss demonstrated how optimal combinations of heat treatment and cold rolling could produce a texture giving Si-Fe strip good magnetic properties when magnetised along its rolling direction. 

This technology has reduced  power loss in transformers and remains the basis of the manufacturing process today. Since then many postulations reported on the mechanism on abnormal grain growth  which is the key for Si-Fe superior magnetic properties, however, none have provided a concrete understanding of this phenomenon. Here, we established and demonstrated a new theory that underlines the fundamental mechanistic approach of abnormal grain growth in 3 wt% Si-Fe steel. It is demonstrated, that the external heat flux direction applied during annealing and Si atom positions in the solid solution disordered α-Fe cube unit cell that cause lattice distortions and BCC symmetry reduction are the most influential factors in the early stages of abnormal growth than was previously thought to be dislocation related stored energy, grain boundary characteristics and grain size/orientation advantages.

Professor Soran Birosca of the University of Plymouth gives a lecture in the Warwick University Manufacturing Group Seminars organised by Kotadia Hiren.