Role of Niobium in Influencing Transformation of
Microalloyed Austenite

C. Fossaert, G. Rees, T. Maurickx and H. K. D. H. Bhadeshia

Abstract

The powerful effect that varying the extent of niobium-carbide dissolution has on the ''hardenability'' of microalloyed austenite is demonstrated using dilatometric measurement of the critical cooling rate required to from microstructures containing >95 % martensite. The results can be rationalized on the hypothesis that the hardenability of austenite is enhanced by niobium in solid solution, possibly by its segregation to austenite grain boundaries, but is decreased by precipitation of niobium-carbide particles. This effect appears analogous to that of boron in steels and is found to be independent of variations in the austenite grain size.

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 1995, Vol.26, No.1, pp.21-30

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This paper was won the 1996 Charles Hatchett Award from the CBMM (Brazil) and the Institute of Materials, London.



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