Skip to main content Accessibility help
×
Home

Effect of boron on the continuous cooling transformation kinetics in a low carbon advanced ultra-high strength steel (A-UHSS)

  • G. Altamirano (a1), I. Mejía (a1), A. Hernández-Expósito (a2) (a3) and J. M. Cabrera (a2) (a3)

Abstract

The aim of the present research work is to investigate the influence of B addition on the phase transformation kinetics under continuous cooling conditions. In order to perform this study, the behavior of two low carbon advanced ultra-high strength steels (A-UHSS) is analyzed during dilatometry tests over the cooling rate range of 0.1-200°C/s. The start and finish points of the austenite transformation are identified from the dilatation curves and then the continuous cooling transformation (CCT) diagrams are constructed. These diagrams are verified by microstructural characterization and Vickers micro-hardness. In general, results revealed that for slower cooling rates (0.1-0.5 °C/s) the present phases are mainly ferritic-pearlitic (F+P) structures. By contrast, a mixture of bainitic-martensitic structures predominates at higher cooling rates (50-200°C/s). On the other hand, CCT diagrams show that B addition delays the decomposition kinetics of austenite to ferrite, thereby promoting the formation of bainitic-martensitic structures. In the case of B microalloyed steel, the CCT curve is displaced to the right, increasing the hardenability. These results are associated with the ability of B atoms to segregate towards austenitic grain boundaries, which reduce the preferential sites for nucleation and development of F+P structures.

Copyright

References

Hide All
1. Committee on Automotive Applications, International Iron & Steel Institute, Advanced High Strength Steel Application Guidelines, pp. 113 (2009).
2. Zhao, J. C. and Notis, M. R., Mater. Sci. Eng. Rep. 15, 135207 (1995).
3. Cota, A. B., Modenesi, P. J., Barbosa, R. and Santos, D. B., Scripta Mater. 40, 165169 (1999).
4. You, W., Xu, W. H., Liu, Y. X., Bai, B. Z. and Fang, H. S., J. Iron Steel Res. Int. 14, 3942 (2007).
5. Bhadeshia, H. K. D. H. and Honeycombe, R. W. K., Steels, Microstructures and Properties, third edition (Elsevier, Butterworth-Heinemann, 2006), pp. 7192.
6. Zhang, C., Cai, D., Wang, Y., Liu, M., Liao, B. and Fan, Y., Mater. Charact. 59, 16381642 (2008).
7. Wang, X. M. and He, X. L., ISIJ Int. 42, 3846 (2002).
8. Mejía, I., García de la Rosa, A., Bedolla-Jacuinde, A. and Cabrera, J. M., Mater. Res. Soc. Symp. Proc. 1373, 8994 (2012).
9. Zhu, K., Oberbilling, C., Misik, C., Loison, D. and Iung, T., Mater. Sci. Eng. A528, 42224231 (2011).
10. Lanier, L., Metauer, G. and Moukassi, M., Mikrochim. Acta 114115, 353361 (1994).

Keywords

Effect of boron on the continuous cooling transformation kinetics in a low carbon advanced ultra-high strength steel (A-UHSS)

  • G. Altamirano (a1), I. Mejía (a1), A. Hernández-Expósito (a2) (a3) and J. M. Cabrera (a2) (a3)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed