Accession Number : ADA229288


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


Descriptive Note : Final technical rept. Nov 1988-Nov 1990,


Corporate Author : SRI INTERNATIONAL MENLO PARK CA


Personal Author(s) : Pound, Bruce G.


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA229288


Report Date : 14 NOV 1990


Pagination or Media Count : 94


Abstract : The objective of this research was to obtain the hydrogen ingress and trapping characteristics for a range of microstructures and so identify the dominant type of irreversible trap in different alloys. A diffusion/trapping model was used in conjunction with a potentiostatic pulse technique to study the ingress of hydrogen in three precipitation-hardened alloys (Inconel 718, Incoloy 925, and 18Ni maraging steel), two work-hardened alloys (Inconel 625 and Hastelloy C-276), titanium (pure and grade 2), and copper-enriched AISI 4340 steel in 1 mol/L acetic acid-1 mol/L sodium acetate containing 15 ppm arsenic oxide. In all cases except pure titanium, the data were shown to fit the interface-control form of the model and values were determined for the irreversible trapping constants (k) and the flux of hydrogen into the alloys. The density of irreversible trap defects were calculated from k and generally found to be in close agreement with the concentration of a specific heterogeneity in each alloy. Moreover, the trapping constants for the alloys were found to be consistent with their relative susceptibilities to hydrogen embrittlement. (TTL)


Descriptors :   *MICROSTRUCTURE , *HIGH STRENGTH ALLOYS , *TRAPPING(CHARGED PARTICLES) , *HYDROGEN , *DIFFUSION , PULSES , OXIDES , HETEROGENEITY , TITANIUM , HYDROGEN EMBRITTLEMENT , POTENTIOSTATIC TECHNIQUES , ARSENIC , HARDENING , DEFECTS(MATERIALS) , PRECIPITATION , PURITY , ALLOYS , IRREVERSIBLE PROCESSES , FLUX(RATE)


Subject Categories : PROPERTIES OF METALS AND ALLOYS


Distribution Statement : APPROVED FOR PUBLIC RELEASE