Volume 11, Issue 5 (September 1983)
Positron Evaluation of Hydrogen in a 17 Nickel Maraging Steel
Doppler broadening measurements of the γ-ray emmision from positron annihilations have been made on a 17 nickel maraging steel, heat treated to Rockwell hardness, C Scale 49, and subsequently cathodically charged with hydrogen. Changes in the positron annihilation γ-ray spectra were measured using a line shape parameter (S) based on the ratio of central to total spectra area. The recovery of the S parameter as a function of time after hydrogen charging is correlated with hydrogen egress from the metal. The observed sensitivity of this Doppler broadening positron annihilation technique to hydrogen content is attributed to hydrogen compensation of lattice defects (dislocations) in the maraging steel.