Papers by Keyword: TiN Precipitates

Abstract: By using vacuum melting, nitrogen protection and a high molten flow rate during pouring, many nano-TiN particles with the size of 20~100nm are formed during solidification of the alloy steel composed of C0.12- Si0.24 - Mo0.45 - Cr0.35 - V0.2 - Ti0.29 (wt.%). In addition, there are 0.9-1.4μm micron-sized particles separated by a space of 15~40μm. Precipitable TiN particles greatly refine the microstructure of the alloy steel. In this paper, the thermodynamic, kinetic mechanisms and related factors of TiN formation are analyzed.

Abstract: In this work the pinning forces exerted by TiN particles in the austenitic phase in two Ti microalloyed steels have been determined and compared with the driving forces for austenite grain growth and for static recrystallisation between hot rolling passes, respectively. TiN precipitate sizes were measured by transmission electron microscopy (TEM) and the precipitated volumes were calculated. These results were then used to calculate pinning forces. The driving forces for recrystallisation were found to be approximately two orders of magnitude higher than the pinning forces, which explains why the austenite in these steels barely experiences hardening during rolling and why the accumulated stress prior to the austenite→ferrite transformation is insufficient (low dislocation density) to refine the ferritic grain.