Precipitation Behaviour in a Medium Carbon, Ti-V-N Microalloyed Steel
The precipitation behavior of a medium carbon steel microalloyed with Ti, V, and N has been studied by analytical transmission electron microscopy in the as-cast and isothermally heat-treated states, as well as at different stages in the thermomechanical processing of the steel. Mixed (Ti,V) nitrides were found in all the structures, but there was no evidence for mixed carbonitride formation. The Hillert-Staffansson model was used to predict the composition of the nitrides as a function of temperature. Upon prolonged aging many of the precipitates became “fragmented” and were no longer single crystals. At the same time, the volume fraction of precipitates dropped, while their average Ti content increased. Possible explanations for this unexpected behavior are discussed in this article.
vanadium microalloyed medium carbon steel, nitrides TiN, VN, (Ti, V)N, carbides VC, precipitation.
M. Prikryl (1), A. Kroupa (2), G. C. Weatherly (1) and S. V. Subramanian (1)
- Department of Materials Science and Engineering, McMaster University, Hamilton, ON, L8S 4M1, CANADA
- The Institute of Physics of Materials, Academy of Sciences of the Czech Republic, 616062 Bino, Czech Republic.
Metallurgical and Materials Transactions A., Vol. 27A, May, 1996, pp.1149-1166