Effects of the Valence Electron Structures of Nitride on Cold Shortness in Steel

Abstract:

Up to now, most of work focused on the grain boundary segregation and the cold shortness caused by non-metallic element of nitrogen had been done. However, it is not clear that the reasons why the nitrogen element can generate the grain boundary segregation and the cold shortness at electron structural level. Therefore, based on the empirical electron theory of solids and molecules(EET), valence electron structures of α-Fe-N, Fe₄N and AlN were calculated, and the cold shortness generated by the nitrogen element as well as the removal mechanism of cold shortness with the help of Al element were analyzed with the phase structure factor n_A. It was found that the phase structure unit of α-Fe-N with bigger n_A firstly segregates on grain boundary，then the Fe₄N with smaller n_A on grain boundary was precipitated from supersaturated solid solution α-Fe-N, resulting in the formation of Fe₄N+α-Fe hybrid followed by the cold short in steel. However, because the value of AlN is larger than that of TiN and VN, the addition of Al element can make the cold shortness starting point decrease distinctly and thus result in the removal of segregation of nitrogen and cold shortness generated by Fe₄N. The results analyzed with the EET were in agreement with experimental fact.

• Periodical: Advanced Materials Research (Volumes 299-300)
• Pages: 155-158
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.299-300.155
• Online since: July 2011
• Authors: Li Dai Zhou, Guo Wei Chen, Gui Li Yin
• Keywords: Cold Shortness, Nitride, Segregation, Valence Electron Structure

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