Effects of precipitated phase and order degree on bending properties of an Fe-6.5 wt%Si alloy with columnar grains

Effects of the precipitated phase and the ordered phase domain of an Fe-6.5 wt%Si alloy before and after heat treatment on the bending properties were investigated in this study. The results showed that original needle-like phases were spheroidized after the heat treatment at 900 °C for 1 h followed by slow or rapid cooling. Compared with the directional solidified sample, the slow cooling sample had a higher order degree, whereas the rapid cooling samples had a lower order degree. After rapid cooling heat treatment, the fracture deflection of the sample was increased by 73.8%. Fracture analysis showed that transition from quasi-cleavage fracture to tear pit-like fracture took place in the rapid cooling sample. The bending properties of the Fe-6.5 wt%Si alloy were improved mainly due to the changes in morphology and amount of the precipitated phase as well as the reduction of order degree.