Effect of Deformation Temperature on Deformation Mechanism of Fe-6. 5Si Alloys with Different Initial Microstructures

Deformation behaviors and mechanisms under different temperatures for columnar-grained Fe-6. 5Si (mass%) alloys fabricated by directional solidification and equiaxed-grained Fe-6. 5Si alloy fabricated by forging were comparatively investigated. The results showed that, with increasing the deformation temperature from 300 °C to 500 °C, the elongation increased from 2. 9% to 30. 1% for the equiaxed-grained Fe-6. 5Si alloy, while from 6. 6% to about 51 % for the columnar-grained Fe-6. 5Si alloy. The deformation mode of equiaxed-grained Fe-6. 5Si alloy transferred from nearly negligible plastic deformation to large plastic deformation dominated by dislocation slipping. Comparatively, the deformation mode of the columnar-grained alloy transferred from nearly negligible plastic deformation to plastic deformation dominated by the twining, and finally to plastic deformation dominated by dislocation slipping. Meanwhile, compared with the alloy with equiaxed grains, it was found that ultimate tensile strength and elongation could be increased simultaneously, which was ascribed for the twinning deformation in columnar-grained Fe-6. 5Si alloy. This work would assist us to further understand the plastic deformation mechanism of Fe-6. 5Si alloy and provide more clues for high-efficiency production of the alloy.