Characterization of Hydrogen Ingress in High-Strength Alloys.
Abstract
The effect of heat treatment on irreversible hydrogen (H) trapping was investigated for Alloy K-500 UNS N05500, with the goal of providing a more detailed insight into the factors governing the intrinsic susceptibility to hydrogen embrittlement (HE). A potentiostatic pulse technique was used to determine irreversible trapping constants (k) and H entry fluxes for annealed and annealed-aged (AA) specimens of old drawn Alloy K-500 that had been used earlier to provide as-received (unannealed, cold drawn) and direct aged (DA) specimens. The alloy was tested in four conditions: annealed for 0.5 h, annealed for 0.5 h and aged for 8 h, annealed for 0.5 h and aged for 16 h, and annealed for 0.25 h and aged for 8 h. The type of heat treatment can produce marked differences in irreversible trapping. The key factor was the annealing step rather than the aging time. The intrinsic susceptibility to HE, as defined by k, is increased considerably by annealing, whereas aging has a negligible effect for the annealed alloy and only a modest effect for the unannealed alloy. The intrinsic susceptibilities for the AA and DA alloys can be correlated with the observed resistances to HE, implying that the decrease in the resistance to HE produced by annealing is caused to a large extent, if not entirely, by a change in the number or the type of irreversible traps.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1997
- Accession Number
- ADA320666
Entities
People
- B. G. Pound
Organizations
- SRI International