Impact strength and transmission electron microscopy investigations of aged and carburized alloy 800H

Journal Article · Sun Jul 01 04:00:00 EDT 1984 · Nucl. Technol.; (United States)

OSTI ID:6056640

Czyrska-Filemonowiez, A; Ennis, P J

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 about 50 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: 6056640
• Journal Information: Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 66:1; ISSN NUTYB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALKANES
ALLOYS
ATMOSPHERES
CARBON COMPOUNDS
CHROMIUM ALLOYS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
ELEMENTS
FLUIDS
GASES
HARDENING
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HYDROCARBONS
INCOLOY ALLOYS
IRON ALLOYS