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arXiv · 2202.09197

Synergism between B and Nb improves fire resistance in microalloyed steels

Pedro P. Ferreira·Felipe M. Carvalho·Edwan A. Ariza-Echeverri·Pedro M. Delfino·Luiz F. Bauri·Andrei M. Ferreira·Ana P. V. Braga·Luiz T. F. Eleno·Hélio Goldenstein·André P. Tschiptschin
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Abstract

The development of new fire-resistant steels represents a challenge in materials science and engineering of utmost importance. Alloying elements such as Nb and Mo are generally used to improve the strength at both room- and high-temperatures due to, for example, the formation of precipitates and harder microconstituents. In this study we show alternatively that the addition of small amounts of boron in Nb-microalloyed steels may play a crucial role in maintaining the mechanical properties at high temperatures. The 66\,\% yield-strength criteria for fire resistance is achieved at $\approx 574$\,{\deg}C for a boron steel, whereas without boron this value reaches $\approx 460$\,{\deg}C, a remarkable boron-induced mechanical strengthening enhancement. DFT calculations show that boron additions can lower the vacancy formation energy when compared to pure ferrite and, for Nb-B steels, there is a further 24\,\% reduction, suggesting that the boron-niobium combination acts as an effective pinning-based strengthening agent.

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Pedro P. Ferreira, Felipe M. Carvalho, Edwan A. Ariza-Echeverri, Pedro M. Delfino, Luiz F. Bauri, Andrei M. Ferreira, Ana P. V. Braga, Luiz T. F. Eleno, Hélio Goldenstein, André P. Tschiptschin. 2022-02-18. Synergism between B and Nb improves fire resistance in microalloyed steels. https://arxiv.org/abs/2202.09197

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