Comparison of thermally- and irradiation-induced grain boundary segregation in austenitic stainless steels

Conference · Mon Dec 31 23:00:00 EST 1990

OSTI ID:5902183

Kenik, E A

Segregation at grain boundaries in austenitic stainless steels sensitized by either thermal annealing or irradiation was studied by analytical electron microscopy. Characterization of grain boundary compositions in both types of materials was performed by high spatial resolution ({ge} 2 nm) X-ray microanalysis. Whereas similar chromium depletion is observed in both processes, there are differences in the behavior of the other alloying elements and in the mechanisms responsible for the segregation. In thermal sensitization, the nickel/iron ratio and the silicon level observed at grain boundaries are similar to those for the matrix. In cases where little or no precipitation occurs, cosegregation of phosphorus, chromium, and molybdenum occurs at boundaries and interfaces. For radiation sensitization, radiation-induced segregation (RIS) results in enrichment of nickel, silicon, and, in certain cases, phosphorus and in depletion of iron at grain boundaries. There appears to be some synergism between segregation of nickel and silicon, which increases the magnitude of RIS effects. Grain boundary precipitation is often observed in both thermally- and irradiation-sensitized materials. However, the nature and origins of the two types of precipitation are different. The formation of chromium-enriched grain boundary carbides is the cause of the chromium depletion in thermal sensitization. In contrast, the precipitates produced by irradiation are enriched in nickel and silicon and depleted in chromium relative to the matrix and therefore are the result of RIS. Results for thermal- and radiation-induced segregation in manganese-stabilized austenites are compared to that for nickel-stabilized austenites.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5902183
• Report Number(s): CONF-911202-15; ON: DE92005172
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
360105* -- Metals & Alloys-- Corrosion & Erosion
360106 -- Metals & Alloys-- Radiation Effects
ALLOYS
ANNEALING
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
CHROMIUM
CORROSION
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
ELEMENTS
GRAIN BOUNDARIES
HEAT TREATMENTS
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
METALS
MICROSCOPY
MICROSTRUCTURE
NICKEL
RADIATION EFFECTS
SEGREGATION
SEMIMETALS
SENSITIVITY
SILICON
STAINLESS STEELS
STEELS
STRESS CORROSION
TRANSITION ELEMENTS