Volume 31, Issue 2

A review of available hypotheses for hydrogen embrittlement (HE) in its relation to austenitic steels is presented. It is shown that the hydrogen-enhanced localized plasticity theory adequately describes the features of HE. Nevertheless, being developed within the frame of continuum mechanics, it overestimates the hydrogen-induced shielding of the elastic interaction between dislocations and does not take into account the hydrogen-induced change in the electron structure of austenitic steels. Ab initio calculations and experimental studies of the electron structure show that the hydrogen in austenitic steels increases the concentration of free electrons, n f , and the interpretation of available experimental data shows that when designing steel, alloying the steel with elements that decrease n f improves hydrogen resistance. Experimental tests are carried out, and their results are discussed. Based on the hydrogen-increased concentration of thermodynamic equilibrium vacancies in the interstitial solid solutions, a new model for hydrogen-induced shear localization is proposed.

The science of metallic iron for environmental remediation is yet to be established. The prevailing theory of the Fe 0 /H 2 O system is characterized by its inability to fully rationalize the concept that holds up the technology. The present article demonstrates that Fe 0 technology was introduced by altering the course of mainstream science and by distorting the work of corrosion scientists. The Fe 0 research community is now facing the consequences of this initial “forcing”. The technology is still innovative despite two decades of commercialization.

A quaternary ammonium cationic surfactants mixture was synthesized from light naphtha, petroleum fraction. The mixture was analyzed by Fourier transform infrared spectroscopy and UV/Visible spectroscopy and was evaluated as a corrosion inhibitor for carbon steel in 1 m HCl, by gravimetry, potentiodynamic polarization and electrochemical impedance spectroscopy. The results showed that inhibiting efficiency increased with inhibitor concentration and temperature, and was independent of pH (in the range of 0–4) and immersion time; its optimal value was up to 84% for 560 mg/l at 25°C. Experimental data showed that the cationic surfactants mixture acts as a mixed (anodic and cathodic) inhibitor and conformed to the Langmuir adsorption isotherm. Scanning electron microscopy images revealed the inhibiting capacity of the mixture against carbon steel acid corrosion.