Hydrogen embrittlement of solution heat-treated and aged [beta]-titanium alloys Ti-15%V-3%Cr-3%Al-3%Sn and Ti-15%Mo-3%Nb-3%Al
- Univ. of Virginia, Charlottesville, VA (United States)
Effects of electrochemically introduced hydrogen on the room-temperature mechanical properties of two [beta]-titanium alloys were compared. Solution heat-treated (SHT), single-step peak-aged (PA), and duplex-aged (DA) conditions were investigated using notched tensile bars and Bridgman's analysis of longitudinal stress and average effective diametral plastic strain. Ti-15%Mo-3%Nb-3%Al (referred to as 21S) was more susceptible to hydrogen embrittlement than Ti-15%V-3%Cr-3%Al-3%Sn referred to as 15-3 based on reductions in longitudinal stress, plastic strain, and fractography at H concentrations > 1,000 ppm by weight. Hydriding of the [alpha] or [beta] phase was not observed over the range of H concentrations investigated. Instead, changes in fracture behavior with H were correlated with deformation behavior and [alpha] precipitation. Susceptibility of 21S was attributed to a high-temperature, long solution treatment that affected deformation behavior in the SHT condition and promoted grain boundary [alpha] precipitation in the PA condition. The high-temperature reduced [alpha] nucleation sites in grain interiors and promoted planar slip. Subsequent [alpha] precipitation occurred preferentially on [beta] grain boundaries and, lastly, in grain interiors, resulting in fine intragranular precipitates. In contrast, a lower temperature of shorter duration for 15-3 resulted in wavy slip after SHT and more homogeneous, slightly coarser [alpha] precipitates upon aging, which may have been less prone to slip localization by dislocation shearing. Localized planar slip and grain boundary [alpha] colonies were believed to promote internal H embrittlement and aqueous environmentally assisted cracking. These factors were linked more closely to thermomechanical processing than to alloy composition in the present study.
- OSTI ID:
- 6672846
- Journal Information:
- Corrosion (Houston); (United States), Journal Name: Corrosion (Houston); (United States) Vol. 50:12; ISSN 0010-9312; ISSN CORRAK
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103 -- Metals & Alloys-- Mechanical Properties
360105* -- Metals & Alloys-- Corrosion & Erosion
AGE DEPENDENCE
ALLOYS
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
EMBRITTLEMENT
FRACTURE PROPERTIES
HEAT TREATMENTS
HYDROGEN EMBRITTLEMENT
MATERIALS TESTING
MECHANICAL PROPERTIES
MECHANICAL TESTS
MOLYBDENUM ALLOYS
NIOBIUM ALLOYS
TESTING
TIN ALLOYS
TITANIUM ALLOYS
TITANIUM BASE ALLOYS
VANADIUM ALLOYS