Development of grain boundary chromium depletion in type 304 and 316 stainless steels
Sensitization of austenitic stainless steels is dependent on the thermodynamics of carbide precipitation and the kinetics of chromium diffusion. Heat treatment in, or slow cooling through, the temperature range from 500 to 800/sup 0/C promote intergranular, chromium-rich precipitation and concomitant depletion of chromium in adjacent regions. These local chromium depleted regions are more electrochemically active than the bulk material and may become susceptible to intergranular corrosion and/or stress corrosion in many environments. The ability to adequately predict sensitization behavior in stainless steels requires a better understanding of the development of chromium-depleted regions. The present study examined the development of chromium depletion during isothermal sensitization in high carbon Type 304 and 316 stainless steels. Chromium minimums and concentration profiles were determined at grain boundaries using the STEM-EDS technique. Chromium depletion measurements are discussed in reference to equilibrium and kinetic aspects of existing models for sensitization development in austenitic stainless steels.
- Research Organization:
- Pacific Northwest Lab., Richland, WA 99352
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5350900
- Journal Information:
- Scr. Metall.; (United States), Vol. 20:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHROMIUM
DIFFUSION
STAINLESS STEEL-304
GRAIN BOUNDARIES
SEGREGATION
STAINLESS STEEL-316
ANNEALING
HEAT TREATMENTS
HIGH TEMPERATURE
ISOTHERMAL PROCESSES
QUANTITY RATIO
TEMPERATURE EFFECTS
THERMODYNAMICS
TIME DEPENDENCE
VERY HIGH TEMPERATURE
WIDTH
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CRYSTAL STRUCTURE
DIMENSIONS
ELEMENTS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
METALS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
STAINLESS STEELS
STEELS
TRANSITION ELEMENTS
360102* - Metals & Alloys- Structure & Phase Studies