Effects of deformation temperature on the microstructure, ordering and mechanical properties of Fe–6.5wt% Si alloy with columnar grains

The effects of deformation temperature on the microstructure, ordering and mechanical properties of Fe−6.5 wt%Si alloy with columnar grains compressed at 300–900 °C were studied. The results show that under the conditions of temperature ≤700 °C and compression reduction of 50%, the columnar grains remain intact without occurrence of recrystallization in the samples. After deformation at 800 °C, the columnar grain boundaries become serrated and subgrains form in the sample during dynamic recovery. With further increasing the temperature to 900 °C, dynamic recrystallization takes place obviously. High-density of deformation twins form in the samples deformed at 500 °C or below, while deformation twins are not observed in the samples deformed at 550 °C or above. The Fe−6.5 wt%Si alloy has the characteristic of deformation disordering and reordering at intermediate temperatures. The degree of deformation disordering is larger than that of reordering at the deformation temperature of 400–600 °C, while this relationship is opposite at 700–800 °C. At the deformation temperature lower than 700 °C, deformation resistance of the Fe−6.5 wt%Si alloy decreases drastically with the increase of the temperature, while it decreases slowly as the temperature increased to 800–900 °C. The appropriate deformation temperature of the Fe−6.5 wt%Si alloy with columnar grains is suggested at 400–700 °C.