Crystallography and growth mechanism of TiN in Fe-17Cr stainless steel during solidification

Orientation relationships between the TiN precipitates and ferrite grains in the solidified microstructure of Fe-17Cr stainless steel were systematically investigated. Remelting experiments were carried out to obtain more TiN precipitates within an electron backscattered diffraction (EBSD) observed zone. Accumulation of TiN precipitates in the microstructure in the central section of the remelted samples is resulted from the redistribution of Ti and N during solidification. Pole figures by EBSD show that seven orientation relationships between the TiN precipitates and ferrite grains, including Kurdjumov-Sachs and other six ones, exist in the solidified samples after remelting. Based on the misfits and orientation relationships between the TiN precipitates and ferrite grains obtained EBSD, the preferential growth direction of ferrite grains is [111] along [001] and [110] in (001) of the TiN precipitates. The refinement mechanism of ferrite grains by the TiN precipitates in the steel was then discussed according to the experimental results and the orientation relationships between the TiN precipitates and ferrite grains.