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):

Report Date:

1990-11-14

Pagination or Media Count:

94.0

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 diffusiontrapping 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 molL acetic acid-1 molL 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

Subject Categories:

  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE