Role of twinning and transformation in hydrogen embrittlement of austenitic stainless steels
Internal hydrogen embrittlement may be viewed as an extreme form of environmental embrittlement that arises following prolonged exposure to a source of hydrogen. Smooth bar tensile specimens of three stainless steels saturated with deuterium (approximately 200 mol D/sub 2//m/sup 3/) were pulled to failure in air at 200 to 400/sup 0/K or in liquid nitrogen at 78/sup 0/K. In Type 304L stainless steel and Tenelon ductility losses are a maximum around 200 to 273/sup 0/K; Type 310 stainless steel is not embrittled at this hydrogen concentration. A distinct change in fracture mode accompanies hydrogen embrittlement, with fracture proceeding along coherent boundaries of pre-existing annealing twins. This fracture path is observed in Tenelon at 78/sup 0/K even when hydrogen is absent. There is also a change in fracture appearance in specimens with no prior exposure to hydrogen if they are pulled to failure in high-pressure hydrogen. The fracture path is not identifiable, however. Magnetic response measurements and changes in the stress-strain curves show that hydrogen suppresses formation of strain-induced ..cap alpha..'-martensite at 198/sup 0/K in both Type 304L stainless steel and Tenelon, but there is little effect in Type 304L stainless at 273/sup 0/K.
- Research Organization:
- Du Pont de Nemours (E.I.) and Co., Aiken, S.C. (USA). Savannah River Lab.
- DOE Contract Number:
- EY-76-C-09-0001
- OSTI ID:
- 7087751
- Report Number(s):
- DP-MS-77-46; CONF-771010-1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
080800 -- Hydrogen-- Properties & Composition
36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CRYOGENIC FLUIDS
ELEMENTS
EMBRITTLEMENT
FLUIDS
HEAT RESISTING ALLOYS
HYDROGEN
IRON ALLOYS
IRON BASE ALLOYS
LOW TEMPERATURE
MEDIUM TEMPERATURE
METALLURGICAL EFFECTS
NICKEL ALLOYS
NONMETALS
PHASE TRANSFORMATIONS
STAINLESS STEEL-304L
STAINLESS STEEL-310
STAINLESS STEELS
STEELS
TWINNING
VERY LOW TEMPERATURE