Hydrogen Diffusion and Embrittlement in 4340 Steel.
Abstract
The sensitive electrochemical permeation technique was used in conjunction with scanning electron microscopy and tensile loading to determine hydrogen diffusivity and solubility, effect of plastic deformation on the above parameters, and structural features and kinetics of hydrogen embrittlement, in 4340 steel. The salient results are: (1) time to failure is directly proportional to the square of the distance through which hydrogen must travel in order to reach a stressed region at the root of a notch, clearly indicating the role played by diffusion; (2) the critical hydrogen concentration for embrittlement of quenched and tempered 4340 steel is on the order of 0.5 ppm. Also of interest: (3) small amounts of plastic deformation of annealed 4340 result in drastic increases in hydrogen solubility and proportional reductions in diffusivity; (4) hydrogen diffusivity of quenched and tempered 4340 is about 25 times smaller than that of annealed material; (5) in quenched and tempered 4340, plastic yielding precedes hydrogen embrittlement; and (6) the ductility of annealed 4340 is reduced by 50% when fully charged with hydrogen. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1976
- Accession Number
- ADA032449
Entities
People
- Leonard Nanis
- T. K. Govindan Namboodhiri
Organizations
- University of Pennsylvania