DIFFUSIVITY, SOLUBILITY AND TRAPPING BEHAVIOR OF HYDROGEN IN ALLOY-600, ALLOY-690TT AND ALLOY-800

The permeation technique and a potentiostatic pulse technique were use d to investigate the diffusivity, solubility, and trapping behavior of hydrogen (H) in three austenitic alloys: 600, 690tt and 800. The appa rent diffusivity increases with nickel content, whereas the solubility decreases. The diffusivity decreases with cold work. In the alloys wi th 50% cold work, H is reversibly trapped in the stress field of dislo cations. The rate constants for irreversible trapping paralleled the o bserved resistance to environmentally assisted cracking of the non-col d-worked alloys. The principal irreversible traps appeared to be carbi de/carbonitride precipitates. Microvoids provided additional irreversi ble traps in precharged, cold-worked alloy 600. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.