Accession Number : ADA257385


Title :   Evaluation of a Diffusion/Trapping Model for Hydrogen Ingress in High-Strength Alloys


Descriptive Note : Annual rept. 15 Sep 1991-15 Sep 1992


Corporate Author : SRI INTERNATIONAL MENLO PARK CA


Personal Author(s) : Pound, Bruce G


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a257385.pdf


Report Date : Oct 1992


Pagination or Media Count : 36


Abstract : Alloys developed to improve properties such as strength, weight, and corrosion resistance often show decreased resistance to hydrogen embrittlement. The objective of this research was to determine the hydrogen ingress behavior of high performance alloys, particularly in terms of irreversible trapping, with a view to characterizing their interaction with hydrogen and resulting susceptibility to hydrogen embrittlement. A technique referred to as hydrogen ingress analysis by potentiostatic pulsing (HLAPP) was applied to three beta- titanium alloys (Beta-C, Ti10V-2Fe-3Al, and Ti-l3V- 11Cr-3A1), an alp titanium alloy (Ti-6AI-4V), and two copper-nickel alloys (Marinel and Monel K-500). Anodic current transients were obtained for these alloys in an acetate buffer (1 mol/L HAc-1 mol/L NaAc where Ac = acetate) and analyzed using a diffusion/trapping model under interface control conditions to evaluate the trapping constant and hydrogen entry flux. A marked increase observed in the trapping constants for the beta-titanium alloys with aging is attributed to precipitation of the secondary alpha phase. Aging also affects the passive film and therefore the hydrogen entry flux. The trapping constants for aged Marinel and Monel K-500 are not considered to differ significantly, but a smaller entry flux for the Marinel appears to account, at least partly, for the lower susceptibility to hydrogen embrittlement reported for Marinel.


Descriptors :   *HYDROGEN EMBRITTLEMENT , *TITANIUM ALLOYS , *COPPER NICKEL ALLOYS , BUFFERS , TRANSIENTS , AGING(MATERIALS) , CORROSION , MODELS , INTERACTIONS , INTERFACES , SECONDARY , RESISTANCE , FILMS , EMBRITTLEMENT , ALLOYS , STRENGTH(MECHANICS) , PHASE , HYDROGEN , CHEMICAL COMPOSITION , PRECIPITATION , ACETATES , POTENTIOSTATIC TECHNIQUES , PULSES , CORROSION RESISTANCE , COPPER , CONSTANTS , WEIGHT , NICKEL , TITANIUM , NICKEL ALLOYS , DIFFUSION


Subject Categories : Physical Chemistry
      Properties of Metals and Alloys


Distribution Statement : APPROVED FOR PUBLIC RELEASE