The Inhibition Effect And Mechanism Of Hydrogen Anti-permeation Agent On Hydrogen Permeation And Hydrogen Induced Damage Of High Strength Steel In 3.5% NaCl Acidic Solution

Degradation of mechanical properties or premature failure caused by hydrogen, generally in terms of hydrogen embrittlement (HE) and hydrogen-induced cracking (HIC), etc.Hydrogen-induced damage (HID) has been a cricial issue in petrochemical engineering,nature gas, nuclear power, hydrogen energy, aircraft or spacecraft industries, etc. Most seriously, HID susceptibility increases dramatically with the upgrade of strength level of materials particularly under chloride environment and loading. Therefor it is imperative for us to explore an effective, practical and environmental alterlative for HID prevention to address the limitation by the high risk of HID in high-strength-steels and weldments in marine application.Based on the preliminary discovery that X salt agent can effectively inhibit the "poison e ffect" of tensile stress and acidic environment on hydrogen permeation behavior and mechani cal degradation of 10CrSiNiCu steel,then the concept of "hydrogen anti-permeation agent" is creatively raised in this paper. The primary objective of this paper is to investigate the inhibiti on effect of X salt agent on the hydrogen permeation, mechanical degradation, hydrogen blist ering and HIC of steel in acidic 3.5%NaCl solutions by hydrogen permeation texts, SSRT test s,cathodic electrochemical-hydrogen-charging tests and hydrogen collection tests. Furthermo re, by combination of chemical, electrochemical, XPS and morphological measurements, we i dentified the hydrogen anti-permeation machanisms and the dehydrogenation catalytical effec t of RE salt agent on the h.e.r. The results indicate that:Appropriate concentration of hydrogen anti-permeation agent effectively inhibited the hy drogen permeation behavior and mechanical degradation,decreased the sub-surface and inner diffusible hydrogen concentrations, alleaviated the hydrogen blistering and HIC behavior of 1 OCrSiNiCu steel in acidic 3.5 % NaCl solutions. This mysterous result can be attributed to the superior nature of X species. X-precipitation on steel surface by an appropriate of RE salt age nt (1000?1250 ppm) preferencially sheilded the cathodic active sites and reduced the propensi ty for accumulation and permeation of H. Meanwhile, its presence was greatly beneficial for t he pronounced dehydrogenation catalytical activity on the h.e.r, due to the abundance of nonb onding pair of d/f electrons and empty or semi-empty d/f-orbitals in electronic configuration o f X species. The enhanced electro-catalytical activity offers an optimized metal surface for ch arge transfer and H+ discharge, Whilst, the M-H bonding energy is medium, which was subse quently favorable for Hads deadsorb and recombination, as well as rapidly desorption of evolv ed H2 off the surface as soon and much as possible, thereby continually reduced the surface di ffusible hydrogen concentrations and permeated hydrogen . Whereas, at relative high concentr ations of hydrogen anti-permeation agent (?1500ppm), the pronounced dehydrogenation catal ytical activity may help depolarize for the h.e.r. process and impose the h.e.r forwards,which somewhat may be responsible for the slight increament in cathodic hydrogen currents and inst eadly an aggravation of local corrosion in these cases.