COMPARATIVE STUDY OF HYDROGEN TRANSPORT BEHAVIORS IN ARMCO-FE AND AF1410 STEELS

摘要

Hydrogen is known to dissolve in steel materials with accompanying degradation of properties, and eventual materials failure. The extent of hydrogen transport effects, and eventual materials failure depends on both the nature of steel material, and its ingressing method. The study focuses on the comparative study of hydrogen transport in Armco-Fe and ultra high strength AF1410 steels. The Devanathan and Stachursky double cell (DSDC) configuration otherwise known as the permeation set-up is adopted for hydrogen charging as a function of materials thickness via cathodic polarizations in varying aqueous media. The input side cell consisted of a mixture of sulfuric acid (0.1M H_2SO_4) impregnated with 1g/l of (Na_2HAsO_4 centre dot 7H_2O) sodium arsenate (as a hydrogen promoter, otherwise known as poison) after comparative tests proved it best amongst others investigated for hydrogen permeation at ambient temperatures. The input cell was powered with a potentiostat for the purpose of ensuring reproducibility between experimental runs. Based on the analyses of the permeation profiles, the coefficient of diffusion is determined to be 1.50 -5.05 X 10~(-8) cm~2/s for the AF1410 steel and 1.39 - 2.40 X 10~(-5) cm~2/s for the Armco-Fe. Though blister formation was found to depend on charging medium, polarization current, and the thermodynamic state of the material, it was generally, substantially higher in Armco-Fe than with AF1410. Their blistering behaviors can be reconciled on the basis of their differing inherent contents and microstructural differences.