Volume 38, Issue 1

Fluorides, bromides, and iodides, despite being less common than chlorides, are present in various environments of industrial relevance. Stainless steels suffer pitting corrosion in solutions of all halides except fluorides, which can be understood considering that fluoride is the anion of a weak acid. The aggressiveness of the rest of the halides for pitting corrosion is on the order Cl −  > Br −  > I − for stainless steels with Mo content below 3 wt.%. Mo is not as effective in inhibiting Br − pitting corrosion as it is for inhibiting Cl − pitting corrosion. Most of those observations were rationalized based on the effect of anions on pit growth kinetics. Sensitized austenitic stainless steel suffers stress corrosion cracking (SCC) in solutions of all halides, albeit chlorides seem to be the most aggressive. Fluoride SCC is relevant for SCC under insulation of stainless steels, and standards and regulations developed to mitigate this problem consider this ion as aggressive as chloride. For the solubilized stainless steels, aggressiveness toward SCC is in the order Cl −  > Br − . The SCC of solubilized stainless steels was not observed in solutions of F − and I − , and the possible reasons for this fact are discussed.

This paper presents an overview of the corrosion behavior of titanium (Ti) alloys in both acidic and saline solutions. The solutions covered in this review are essentially the typical electrolytes encountered by Ti alloys when applied under service conditions. Although Ti alloys are generally known to be corrosion resistant, this review identifies strong reducing acids and fluoride-containing solutions as electrolytes that corrode Ti and its alloys. The pathways that the knowledge of the corrosion behavior of Ti alloys have followed from the 1950s to date are captured in this review. Based on this, the different factors influencing the corrosion behavior of Ti alloys are highlighted and the different research concepts for improving the corrosion resistance of Ti alloys in both solutions are discussed. The limitations of these research concepts are mentioned and the directions for future research are proposed.

A framework is presented in this paper to assess the structural integrity of steel bridges for environment-assisted corrosion damage. Forms of corrosion of steel bridges and their effects, possible locations of occurrence, and most appropriate inspection techniques are first studied and the lessons learned from past steel bridge failures are discussed. A review of the corrosion damage of steel bridges, including causes, effects, and control measures, is presented along with guidelines for the recognition and investigation of environment-assisted cracking (EAC) of steel bridges. Experimental approaches are proposed to investigate the EAC of structural steel. The proposed approach is used to investigate the EAC susceptibility of cathodically protected ST52 steel. In addition, the feasibility of the proposed approach is tested. Hence, the conceptual framework is proposed. The framework aims to support the inspection and maintenance practices of steel bridges.

Various methodologies are practically used to control corrosion. Coatings are the most widely used to protect metals against corrosion. However, due to the weak resistance of polymer coating against the penetration of corrosive solution to the metal/coating interface, the long-term corrosion resistance of the polymer coating is reduced gradually. Recently, nanoparticles have been added to coatings to improve their chemical, mechanical and optical properties. Nanocoatings either have constituents in the nanoscale or are made out of layers that are under 100 nm. Nanocoatings are used effectively to lessen the impact of a corrosive environment due to its various preferences, such as surface hardness, adhesive quality, long haul and, additionally, high-temperature corrosion opposition, and to improve its tribological properties, and so forth. Moreover, nanocoatings can be utilized in more slender and smoother thickness, which permits adaptability in equipment design and lower upkeep and working expenses. This review covers applications related to the management of metal corrosion, including the use of nanomaterials to produce high-performance corrosion inhibitors and corrosion-resistant coatings.

In the present study, the effects of aging and formation potential on the semiconducting behavior of AISI 321 stainless steel as well as the kinetics of the early stages of pitting are discussed. The donor and acceptor densities decrease with increasing formation potential. The steady-state passive film thickness and the coefficient of oxygen vacancies are estimated. The electrode polarization at higher anodic potentials causes the increase in the rate of pit initiation and slows down the growth rate of passive film. Also, the openness of the pits and their coalescence are highly promoted with the increase in the applied potential.