The effect of molybdenum on the grain boundary segregation of phosphorus in steel
The beneficial effect of molybdenum on the temper embrittlement of steels is well known but has not yet been satisfactorily explained. Yu and McMahon suggested a strong interaction between molybdenum and phosphorus to form Mo-P clusters which decrease the concentration of phosphorus in the matrix and consequently the amount segregated to grain boundaries. Such clusters have as yet not been observed but this may have been owing to the insufficient resolution of conventional analytical methods. However, since no scavenging of phosphorus was observed in carbon-free Fe-Mo-P alloys, i.e. Mo alone did not affect the grain boundary concentration of phosphorus, it is improbable that the Mo-P cluster formation mechanisms can be operative. Instead, it is more likely that a requisite for the scavenging of phosphorus is the formation of Mo carbides in the steel. This work was undertaken to determine the distribution of phosphorus in two similar Fe-Mo-P alloys, one of which contained carbon while the other was carbon-free. The emphasis of the study was to determine the interaction of phosphorus with molybdenum and molybdenum carbides in the steel. Field-ion microscopy combined with atom probe microanalysis was used for this purpose. The atom-by-atom sampling method and the near-atomic spatial resolution of the FIM/atom probe make this instrument ideally suited for this type of investigations.
- Research Organization:
- Max Planck Institut fur Eisenforschung, Dusseldorf
- OSTI ID:
- 5821275
- Journal Information:
- Scr. Metall.; (United States), Journal Name: Scr. Metall.; (United States) Vol. 20:4; ISSN SCRMB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
CARBIDES
CARBON
CARBON COMPOUNDS
CRYSTAL STRUCTURE
ELEMENTS
EMBRITTLEMENT
GRAIN BOUNDARIES
HEAT TREATMENTS
ION MICROSCOPY
IRON ALLOYS
IRON BASE ALLOYS
METALS
MICROANALYSIS
MICROSCOPY
MICROSTRUCTURE
MOLYBDENUM
MOLYBDENUM CARBIDES
MOLYBDENUM COMPOUNDS
NONMETALS
PHOSPHORUS
QUANTITY RATIO
REFRACTORY METAL COMPOUNDS
RESOLUTION
SAMPLING
SEGREGATION
SPATIAL RESOLUTION
STEELS
TEMPERING
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS