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U.S. Department of Energy
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Hydrogen effects on Ti Code 12 properties and microstructure

Technical Report ·
OSTI ID:5962300
This study characterized the effects of hydrogen and annealing temperature on Ti Code 12 tensile properties, microstructure and fracture. Annealing temperature had little effect on properties except when in the sensitization regime of 625 to 675/sup 0/C where the only effect was a slight drop in ductility and fracture stress. For samples annealed at 750/sup 0/C, hydrogen also had little effect on strength, but decreased both ductility and fracture stress slightly at concentrations in excess of 160 wppM H. This decrease in properties was accompanied by a change in fracture mode from ductile rupture to a mixed mode that consisted of ductile rupture, intergranular failure and stepped and transgranular cleavage. The two most prevalent hydrogen-induced fracture modes, intergranular failure and stepped cleavage, occurred along or within interface phase hydrides. Increased hydrogen concentration increased the amount of the interface phase and consequently the amount of hydrogen-induced fracture. Hydrogen gas-phase charging also decreased the amount of ..beta.. phase and increased the amount of Ti/sub 2/Ni. However, these changes were small at hydrogen concentrations less than 400 wppM. These results permit correlation of the gas-phase charged properties to anticipated nuclear waste repository service behavior. When tensile loads are applied for short times, little degradation is expected.
Research Organization:
Sandia National Labs., Livermore, CA (USA)
DOE Contract Number:
AC04-76DR00789
OSTI ID:
5962300
Report Number(s):
SAND-85-8203; ON: DE85009284
Country of Publication:
United States
Language:
English