Abstract

In this project, torsion tests on hot-rolled and annealed Fe 3 Al (Fe-15.5Al-5.8Cr-1.0Nb-0.05C) were carried out over the ranges 750-950°C and 0.01{598}1s -1 . The experimental results showed that when peak stress v P >90MPa (LogZ>16 -1 , Z: temperature-compensated strain rate, Z = [Special characters omitted.] exp( Q HW / RT ) , R : universal gas constant; Q HW , :activation energy; T : absolute temperature), specimens cracked at randomly low strains. Optical microscopy exhibited original elongated grains and many grain boundary cracks associated with segregation. With v P {600}40MPa (LogZ{600}16s -1 ), specimens deformed with low random v P but considerably high fracture strains; slowly propagating cracks may explain the reduced flow stress. Optical microscopy showed both elongated grains and equiaxed subgrains with some indications of geometric dynamic recrystallization (gDRX) and of static recrystallization (SRX). Compression tests gave higher stress with little effect of the preexisting cracks. Q HW of current material in satisfactory torsion and compression tests is about 10% higher than previously published results. Fe 3 Al has body-centered cubic structure in the experimental range, so it was compared with ferritic steel 434C (Fe- 16.55Cr-0.96Mo-0.21Ni, wt%). Ferritic steels with approximately 3.0wt%Si are of great interest in transformer applications. Isothermal continuous deformation of Fe-2.7Si-0.06C was analyzed and compared with 434C and 409C (11.0Cr-0.0lMo-0.16Ni-0.19Ti, wt%). Multi-stage deformation of the material was investigated to determine the relative softening and relative stress reduction during the intervals between successive stages. Constitutive constants and restoration mechanism were compared between the materials