Volume 41, Issue 1

Titanium and its alloys show outstanding application prospects in many industrial fields due to their high specific strength, good corrosion resistance, high temperature resistance, etc. However, at present the corrosion failure of Ti alloys is attracted great attention with gradual increasing applications. The different localized corrosion forms are introduced in this review, including galvanic corrosion, crevice corrosion, pitting corrosion, hydrogen-induced cracking, stress corrosion crack, microbiological corrosion, corrosion fatigue, and corrosion wear. Among them, the corrosion failure caused by stress corrosion crack and hydrogen-induced cracking is the most serious, accounting for about 40–60% of the actual failure accidents. The effects of temperature, pressure, corrosive media and microstructure on the failure of titanium alloys are discussed. Particularly noteworthy, F − is extremely aggressive to the passive film of titanium alloys. The corrosion behavior of titanium alloys applied in aerospace, marine, petrochemical industries and biomedical environments are introduced. In the above environments, the passive film is most easily damaged and difficult to passive in high temperature and oxygen-deficient environments. The current controversies in the corrosion mechanism have also been proposed, especially the stress corrosion that has the most serious impact on titanium alloys, and its mechanism will be the focus of future research.

Superhydrophobic surface (SHS) fabrication has gained popularity as a corrosion prevention method for metals in recent years. Because of the vast range of sectors that are interested in and using nature-inspired biomimetic SHS, this field of advanced materials science is experiencing rapid growth. Corrosion prevention can be achieved with SHS because it effectively blocks moisture from entering. By generating an air layer between the metal and the coating, SHS provides corrosion prevention. Corrosion-inducing ions are less likely to adhere to metal surfaces with low surface energy and high surface roughness. Combining the right materials and fabrication methods allows you to fine-tune SHS’s many unique features. This review article provides a survey of the superhydrophobic coatings’ performances as metallic protection. Then, various models were utilized to assess the wettability of the rough surface, and the relations governing the contact angle (CA) were reported. Lastly, various methods utilized to prepare the superhydrophobic coatings and their effects on the corrosion processes for metals were also discussed.

In the current study, we report an excellent high temperature oxidation resistance of AlCoCrFeNi high entropy alloy (HEA) following surface modification. The surface properties of HEA were tailored through a severe surface deformation technique. The as cast HEA exhibited coarse grain B2/BCC microstructure. In contrast, processed specimen showed significant grain refinement along with B2/BCC to FCC phase-transition. The processed specimen demonstrated 11–67% reduction in the oxidation kinetics. Cr 2 O 3 and Al 2 O 3 were the predominant oxides formed in all the oxidized specimens. In addition, Cr, Fe and Co rich spinels were also found in the as cast oxidized specimens. The superior oxidation resistance of the processed specimen is attributed to the microstructural refinement resulting in the formation of protective dense chromia layer.

Notch sensitivity under sulfide stress corrosion cracking (SSC) conditions is quantified in this work, considering its tolerance to short cracks that start at notch tips and become non-propagating after growing for a short while. The considered material is an UNS S41426 super 13Cr5Ni2Mo martensitic stainless steel, frequently used in pipelines to transport aggressive fluids in offshore applications. Tolerance to short SCC cracks depends on the notch size and shape, on the stress gradient ahead of its tip, and on basic material resistances to crack initiation S SSC and growth K ISSC inside the aggressive environment. The proposed notch-sensitivity model can be a powerful and economical alternative design tool to substitute traditional pass/non-pass criteria normally used to choose materials for SSC and similar environmentally assisted cracking (EAC) service conditions. This model is validated by testing the steel into an aqueous solution of 100 g/L of Cl − , pH 4.0, 25 kPa of H 2 S, and 75 kPa of CO 2 , at 23 ± 2 °C. After measuring S SSC (461 ± 23 MPa) and K ISSC (36.9 ± 0.6 MPa√m), short crack tolerance predictions are verified on notched specimens loaded under a peak stress at their tips σ max  = 0.95⋅ S Y  >>  S SSC , where S Y  = 826 MPa is the yield strength of the tested steel.

Influence of Fe 3+ on the corrosion of titanium in H 2 SO 4 solution without F − and with F − was investigated by electrochemical tests. The electrochemical test results showed that Fe 3+ could significantly inhibit titanium corrosion in H 2 SO 4 solution without F − and with F − by promoting the protective film formation on titanium. Titanium corrosion resistance (R c ) was positively related to the concentration of Fe 3+ in H 2 SO 4 without and with F − . A mechanism was proposed for Fe 3+ inhibiting the corrosion of titanium in H 2 SO 4 solution without and with F − .

Steel, an indispensable enduring metal used in all facets of life, contributes significantly to the global economy. Atmospheric corrosion is the inexorable natural degradation of alloys to ores in the presence of the atmosphere. The rate of deterioration is a decisive life factor of environmentally exposed steel, and it is necessary to trace its dynamics in different atmospheres at different exposure times. Spatial hazard corrosion maps for rural and urban conditions have been developed for over five decades to apprehend metal loss or corrosion rate dynamics in diverse conditions (PS 11 , PS 21 and PS 31 ) across the Indian subcontinent. The impact of cumulative hazards on Indian standard structural steels is interpreted to perceive sectional losses of beams in various environments for different zones. Sectional losses are greater in zone 5 of the PS 31 environment and are significant in junior and lightweight beams, while heavy beams are relatively unaffected.

This work presents a summary of environmental data from 3600 h of data collected during operations of a U.S. Coast Guard HC-130H aircraft performing its routine missions over a five-year period. The aircraft operated from multiple U.S. and deployed locations during the data collection period in the tropical and mid-latitudes at altitudes up to 8.5 km (28 kft). The aircraft collected pressure, temperature and humidity data during the period. No aerosol components were sampled (chlorides, sulfur dioxide, etc.). While there was no Time of Wetness sensor, the ISO 9223 definition is used for the present work as an estimator. These data are presented in the context of research into corrosion and environmental severity, or the potential conditions for it. About 40% of the data were collected while the aircraft was parked on the ground at various based and deployed locations. The purpose of this work is to present and summarize the flight data as an aid in providing some context for future research into environmental effects as they relate to both corrosion and environmentally assisted cracking (EAC) of aircraft structure, and perhaps for comparisons with existing or future datasets from aircraft having other missions. Prediction models need realistic, real-world inputs, such as those presented here. An example for the use of these data in corrosion prediction based on the ISO 9223 international standard is presented. Perhaps not surprisingly, these data show that, for this aircraft, conditions most favorable to corrosion occurred while the aircraft was on the ground.