Intergranular fracture, corrosion susceptibility, and impurity segregation in sensitized type 304 stainless steel
Austenitic stainless steels such as Types 304 and 316 are susceptible to intergranular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC) when heat treated at temperatures in the range of 450/sup 0/ to 850/sup 0/C. This thermal treatment results in precipitation of Cr-rich carbides at the grain boundaries and chromium depletion in the regions adjacent to the carbides, conditions which promote susceptibility to corrosive attack and intergranular fracture. These phenomena, referred to as sensitization, have caused concern because of failures of stainless steel components in light water reactors and coal conversion plants. It has been shown, however, that chromium depletion may not be the sole contributing cause of sensitization. Certain heats of Type 304 stainless steel which have the same nominal bulk compositions of Cr and C are more susceptible to IGC and this has been attributed to residual impurities which segregate to the grain boundaries and alter the mechanical and chemical properties of the steel. When present as residual impurities, sulfur and phosphorus have been detected at the grain boundaries of Type 304 by Auger electron spectroscopy. In one case, the grain boundary concentration of sulfur was in excess of 100 times the bulk concentration and in two other studies phosphorus was the major segregating species whose concentration depended on the heat treatment temperature. However, the grain boundary segregation of phosphorus or sulfur has not been correlated with systematic variations of these elements in one standard heat, and their effect on intergranular fracture and corrosion resistance has not been studied. It is the purpose of this paper to do so in a study of 10 vacuum remelted heats which have been doped with systematic additions of sulfur and phosphorus.
- Research Organization:
- Univ. of Illinois at Chicago, Chicago, IL
- OSTI ID:
- 6344089
- Journal Information:
- J. Mater. Energy Syst.; (United States), Vol. 7:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
STAINLESS STEEL-304
CORROSION RESISTANCE
CRYSTAL DOPING
FRACTURE PROPERTIES
HEAT TREATMENTS
IMPURITIES
INTERGRANULAR CORROSION
STRESS CORROSION
THERMAL STRESSES
AUGER ELECTRON SPECTROSCOPY
AUSTENITIC STEELS
CHROMIUM
CRACKS
GRAIN BOUNDARIES
PHOSPHORUS
PRECIPITATION
SEGREGATION
STRESS ANALYSIS
SULFUR
TEMPERATURE EFFECTS
ALLOYS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION
CORROSION RESISTANT ALLOYS
CRYSTAL STRUCTURE
ELECTRON SPECTROSCOPY
ELEMENTS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
NICKEL ALLOYS
NONMETALS
SEPARATION PROCESSES
SPECTROSCOPY
STAINLESS STEELS
STEELS
STRESSES
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion
360103 - Metals & Alloys- Mechanical Properties