Tension and strain annealing for abnormal grain growth in magnetostrictive Galfenol rolled sheet

Abstract

This paper investigates the effect of tension annealing and of strain annealing on abnormal grain growth (AGG) in polycrystalline rolled sheet of NbC-added Fe81Ga19. Electron backscattering diffraction patterns captured by orientation imaging microscopy were used for analyzing texture and grain configuration of tension annealed samples. Tension annealing, with simultaneous application of tension and high temperature annealing, with strain rate control, was conducted to study “dynamic recrystallization” for AGG. Strain annealing, application of tension to produce uniform strain and subsequent high temperature annealing, was carried out to study the effect of “strain induced boundary migration” on AGG. A small amount of texture variation resulted, but no significant AGG was observed during tension annealing. During strain annealing, no texture or grain size variation was observed in the gauge region of uniform strain in the sample; however, abnormally grown Goss-texture was observed in regions of high stress concentration outside of the gauge region of the sample.