Accession Number : ADA320666

Title :   Characterization of Hydrogen Ingress in High-Strength Alloys.

Descriptive Note : Annual rept. 20 Sep 95-19 Sep 96,

Corporate Author : SRI INTERNATIONAL MENLO PARK CA

Personal Author(s) : Pound, B. G.

PDF Url : ADA320666

Report Date : JAN 1997

Pagination or Media Count : 18

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.

Descriptors :   *HIGH STRENGTH ALLOYS, *HYDROGEN EMBRITTLEMENT, ANNEALING, AGING(MATERIALS), HYDROGEN, HEAT TREATMENT, PULSES, POTENTIOSTATIC TECHNIQUES, IRREVERSIBLE PROCESSES.

Subject Categories : Properties of Metals and Alloys
      Inorganic Chemistry
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE