Impact strength and transmission electron microscopy investigations of aged and carburized alloy 800H
The effect of carburization on the impact strength and microstructure of the commercial Fe-32 Ni-20 Cr alloy 800H has been investigated in the 20 to 800/sup 0/C temperature range. The properties and microstructure of test pieces carburized at 850/sup 0/C for up to 500 h in an argon-10 vol% methane atmosphere and of specimens heat treated at 850/sup 0/C in an inert atmosphere for the same times were compared. The results showed that aging at 850/sup 0/C reduced the impact strength at 20 to 800/sup 0/C. With an increasing degree of carburization, the impact strength was progressively reduced to about50 J at a bulk carbon content of 0.6 wt%. Heat treatment after carburization caused a further decrease in impact strength as the depth of carbon penetration increased. Microstructural examination by optical and transmission electron microscopy (TEM) of broken test specimens showed precipitation of M/sub 23/C/sub 6/ carbides on grain and twin boundaries and intragranular fine precipitation of TiC and M/sub 23/C/sub 6/ as well as the presence of primary titanium carbonitrides. The TEM investigations using extraction replica and thin foil techniques established that the M/sub 23/C/sub 6/ carbides at grain boundaries retained a crystallographic orientation to one grain and grew into the adjacent grain. Lamellae of M/sub 23/C/sub 6/ carbides precipitated on noncoherent twin boundaries grew into the grain parallel to the twin plane, whereas M/sub 23/C/sub 6/ on coherent twin planes grew as plates along the twinning plane.
- Research Organization:
- Institute for Reactor Materials Kernforschungsanlage Julich GmbH, Postfach 19 13 D-5170 Julich
- OSTI ID:
- 6325871
- Journal Information:
- Nucl. Technol.; (United States), Vol. 66:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
INCOLOY 800H
AGING
CARBURIZATION
IMPACT STRENGTH
MICROSTRUCTURE
CARBIDES
CARBONITRIDES
CRYSTAL-PHASE TRANSFORMATIONS
GRAIN BOUNDARIES
GRAIN GROWTH
GRAIN ORIENTATION
HEAT TREATMENTS
LAMELLAE
MATERIALS TESTING
OPTICAL MICROSCOPY
PRECIPITATION
REACTOR MATERIALS
REPLICA TECHNIQUES
TITANIUM CARBIDES
TITANIUM COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
TWINNING
ALLOYS
ALUMINIUM ADDITIONS
ALUMINIUM ALLOYS
CARBON COMPOUNDS
CHROMIUM ALLOYS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
HARDENING
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCOLOY ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MANGANESE ADDITIONS
MANGANESE ALLOYS
MATERIALS
MECHANICAL PROPERTIES
MICROSCOPY
NICKEL ALLOYS
NITROGEN COMPOUNDS
ORIENTATION
PHASE TRANSFORMATIONS
SEPARATION PROCESSES
SILICON ADDITIONS
SILICON ALLOYS
SURFACE HARDENING
SURFACE TREATMENTS
TESTING
TITANIUM ADDITIONS
TITANIUM ALLOYS
TRANSITION ELEMENT COMPOUNDS
360100* - Metals & Alloys