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Effects of the alloying elements Ti, Nb, Mo and V on the grain boundary segregation of P in iron and steels
Author(s) -
Grabke H. J.,
Möller R.,
Erhart H.,
Brenner S. S.
Publication year - 1987
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740100405
Subject(s) - grain boundary , materials science , metallurgy , carbide , embrittlement , intergranular corrosion , alloy , molybdenum , grain boundary strengthening , microstructure
Investigations have been performed on the effects of the alloying elements Ti, Nb, Mo and V on the grain boundary segregation of phosphorous in iron and steels. The methods are AES analysis of grain boundaries on intergranular fracture faces and field‐ion microscopy and mass spectrometry (atomprobe). The elements Ti and Nb show strong interaction with P, keeping P in the grain and decreasing its grain boundary segregation. In the alloys and steels containing carbon, Ti and Nb react under formation of carbides, therefore with increasing C content the grain boundary segregation of P increases. For stoichiometric ratio Ti/C and Nb/C the segregation reaches a maximum; at higher carbon contents C displaces P from the grain boundaries. Some interfacial segregation of P is observed at or near the ferrite/carbide interface in the case of TiC, leading to a decrease of grain boundary segregation. The same effect applies for Mo 2 C but not for NbC. In contrast to Ti and Nb there is no direct interaction of Mo and P, which is also in contradiction to previous assumptions on the role of molybdenum in the temper embrittlement of low alloy steels.