Alternate Corrosion Research Articles

Chlorine-induced high-temperature corrosion of the Pt-modified aluminide coating in simulated marine environment

The corrosion behavior of a single phase Pt-modified aluminide coating in the marine environment was investigated through a novel cyclically alternate corrosion test. The results showed that the multilayer oxide scale with loose structure was formed on the coating. NaCl and water vapor were verified to play important roles in enhancing the aggressivity during the corrosion test, in which the presence of NaCl increased cracking and spallation tendency of the oxide scale, and the addition of water vapor accelerated the oxidation rate and promoted internal oxidation to the coating.

Protection of 304 stainless steel by nano-modified silicone coating in cyclically alternate corrosion environment

A nano-modified silicone-based composite coating was developed to protect 304 stainless steel under a cyclically alternate corrosion condition. Each cycle contained alternate exposure in a neutral salt spray test chamber at 35 °C and in a muffle furnace at 400 °C. The results showed that the corrosion of 304SS was serious. The nano-modified silicone coating, which is composed of a continuous amorphous SiO2 matrix, dispersive Al, Al2O3, TiO2 and ZrO2 particles and discrete voids after the cyclically alternate corrosion, are inert at 400 OC in the environment containing NaCl deposit and oxygen and significantly improved the corrosion resistance of the 304SS.

Effect of Alternate Corrosion and Fatigue on Fatigue Crack Growth Characterization of 2024-T4 Aluminum Alloy

To investigate the effect of alternate corrosion and fatigue on fatigue crack growth characterization of 2024-T4 aluminum alloy, the pure fatigue test, “corrosion + fatigue” test (commonly known as pre-corrosion fatigue), and the “fatigue + corrosion + fatigue” alternating test of single-sided notched specimen of 2024-T4 aluminum alloy were carried out. The fatigue crack life of alternate corrosion and fatigue is longer than that of the pre-corrosion fatigue when the corrosion time is the same. And the more the times of alternating, the longer the crack growth life will be. This is mainly because the fatigue crack growth rate will change suddenly, which will have a certain hysteresis effect on the fatigue crack growth. The corrosion and fracture morphology characteristics of the alternate test were examined by scanning electron microscopy (SEM), and the composition of corrosion products was examined by the energy dispersion spectrum (EDS). The prediction model of fatigue crack growth rate considering the alternating hysteresis effect of corrosion and fatigue based on the Paris formula was established, and the parameters and precision of the model were calculated and verified. The results show that the model has certain engineering application value.

Seed Extract of Dypsis lutescens as Ecofriendly Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Medium

The seed extract of Dypsis lutescens, had been analyzed for mild steel corrosion inhibition in acid medium with weight loss, thermodynamic, adsorption and electrochemical parameters. The results reflected that the extract is a potential corrosion inhibitor. IR spectra and SEM photographs recorded for functional group and surface modification analysis of mild steel, were agreeing with other parameters. Entire study revealed that the inhibitor works through adsorption of its molecules over the mild steel. From this study it is inferred that the seed extract of D. lutescens is an efficient, eco-friendly and alternate corrosion inhibitor for mild steel in acid medium.

Application of 1,2,3-Benzotriazole as Corrosion Inhibitor for Mild Steel in Sulphuric Acid Medium at Different Temperature

Corrosion inhibition property of 1,2,3-benzotriazole for mild steel in 0.1 N sulphuric acid was evaluated at different concentrations and temperatures using weight loss, electrochemical polarization, differential pulse, stripping voltammetry and impedance spectroscopy. The surface study was carried out using metallurgical research and SEM microscopy. Increase in Warburg impedance and capacitive current and decrease in Faradaic current and capacitive loop was observed with increase in concentration of inhibitor. 1,2,3-Benzotriazole was found as a best corrosion inhibitor (94 %) for mild steel as compared to other inhibitors suggesting 1,2,3-benzotriazole as a potential alternate corrosion inhibitor for mild steel in H2SO4.

Effect of alternate corrosion factors on multiaxial low-cycle fatigue life of 2024-T4 aluminum alloy

Due to the seawater splash, rain water scouring and prolonged exposure, the aircrafts serviced in sea-coast or marine environment always suffered liquid corrosion effects under certain temperature. 2024-T4 aluminum alloy had been widely used in aircrafts fuselage. During service, the actual process was close to the alternate mode of “Ground Corrosion + Air Fatigue”, in which alternate corrosion factors had greatly effects on multiaxial fatigue life of 2024-T4 aluminum alloy. For the purpose of evaluating the influence of alternate corrosion time, corrosion temperature, corrosion solution flow rate and pH value on the fatigue performance, a multi-parameter regulated liquid corrosion device was designed. Multiaxial fatigue tests were performed under constant amplitude sinusoidal wave loading with constant tension-torsion ratio 3 in air. The fracture was observed by scanning electron microscope. The results indicated a reduction tendency of multiaxial fatigue life with the increase of alternate corrosion time, corrosion temperature and corrosion solution flow rate as well as the decrease of pH value. The influence order of relevant factors was: alternate corrosion time > corrosion temperature > corrosion solution flow rate > solution pH value. The effects of alternate time and temperature immersed in solution on corrosion resistance of 2024-T4 aluminum alloy are investigated by potentiodynamic polarization experiments and electrochemical impedance spectroscopy (EIS) tests. The observed mechanical behavior and associated phenomena were directly linked to microstructure characteristics such as corrosion pits and micro-cracks. The cyclic hardening appeared in both axial and tangential direction at the beginning stage. With the consideration of corrosion effect on the fatigue property, the equivalent corrosion life was proposed to characterize the influence of corrosion and to predict the alternate corrosion - fatigue life. Fine results were obtained with all data in 2× scatter band.

Multiaxial fatigue behaviors of 2024-T4 aluminum alloy under different corrosion conditions

In order to study multiaxial fatigue behavior of 2024-T4 aluminum alloy with an aircraft in-service environment, fatigue tests of multiaxial pre-corrosion and alternate corrosion are carried out. With the extension of pre-corrosion time, the multiaxial fatigue life decreases under the same equivalent stress. Pitting caused by corrosion is observed on the surface of specimens. While pre-corrosion time increases, the number and size of pits become larger and connection between adjacent corrosion pits becomes more obvious. For the multiaxial fatigue tests with alternate corrosion, for the same unit corrosion time, the fatigue life decreases with the increase of unit loading cycles. Under the same unit loading cycles, the fatigue life decreases as the unit corrosion time increases. The cyclic hardening appears in both axial and tangential directions at the initial loading stage. Cyclic softening trend becomes obvious as the number of alternation increases. It is shown that cracks initiate at specimen surface and gradually extend to inside. Exfoliation corrosion morphology can be observed on specimen surface. Based on Miner’s rule and data of pre-corroded multiaxial fatigue test, the alternate corrosion-multiaxial fatigue lives are predicted.

Effect of alternate corrosion and wear on the overall degradation of a dual phase and a mild steel

The present work investigates the alternate corrosion and wear effect on the overall degradation of a dual phase and a mild steel. In case of corrosion-wear, immersion corroded samples of both the steels in freely aerated 3.5wt% NaCl solution are subjected to reciprocating sliding wear at three different loads. In case of wear-corrosion, wear takes place first in the steel samples, which are then subjected to immersion corrosion. The wear volume and mean coefficient of friction have decreased for the corrosion-wear case as compared to only wear, and this attributes to the lubricating action of rust formed due to initial corrosion. In case of wear-corrosion, corrosion rates of both the samples have increased as compared to only corrosion situation, which attributes to the rough and strained surface created due to initial wear. Though both the trends are independent of types of steels, the overall wear of the dual phase steel is lower than that of the mild steel, whereas, corrosion rate of the dual phase steel is higher than the mild steel in both the corrosion-wear and wear-corrosion cases.

Corrosion Behavior of S450EW Low-alloy Weathering Steel in Cyclically Alternate Corrosion Environments

Weathering steel is widely used in various fields due to its excellent mechanical properties and high corrosion resistance. The effect of chromium content on the S450EW weathering steel in cyclic immersion test was studied. The results indicated that the corrosion resistance of S450EW weathering steel is closely related to chromium content. The addition of chromium significantly inhibited the weathering steel corrosion. The corrosion rate of experimental steel after 96 h immersion was 1.101 g·m−2·h−1. The rust of S450EW weathering steel was mainly constituted of FeOOH and Fe3O4 phase, and the elevation of chromium content promoted the formation of α-FeOOH. The fine precipitates of the two phases contributed to the formation of dense dust layer of test steel. Furthermore, the increase of chromium is beneficial for the cure of original defects and cracks of the rust layer via the enrichment of chromium. The corrosion potential and the resistance of corrosion process were thus increased, protecting the experimental steel from further corrosion. A S450EW steel with corrosion resistance more than 1.5 times of Q450NQR1 steel was prepared.

Influence of Cyclic Action of Corrosion and Alternate Load on Fatigue Life of 2A12-T4 Aluminum Alloy

Tests of alternate corrosion and fatigue for 2A12-T4 aluminum alloy were performed in order to reveal the influence of factors related with corrosion environment and load on its fatigue life. The effect of the alternate frequency of corrosion/fatigue and the type of corrosion tests such as alternate immersion, salt spray and salt spray+hot and humidity corrosion on the degradation of 2A12-T4 aluminum alloy was analyzed. The results show that for a designated total time of corrosion, the alternate frequency of corrosion/fatigue has important influence on the fatigue life of the alloy. The fatigue life of the alloy increases gradually with the increasing alternate frequency. The total fatigue life of aluminum alloy for 2, 4 and 6 cycles were 16.9%, 30.7% and 50.3% respectively higher than that for the first cycle. Besides, the type of corrosion tests also has important influence on the fatigue life of the alloy, of which the impact intensity may be ranked in a descending order as follows: salt spray corrosionalternate immersion corrosionsalt spray+hot and humidity corrosion.

Differential Pressure Transducer for Corrosion Monitoring of Iron

In this study, differential pressure transducer (DPT) has been applied as an alternate corrosion monitoring device for monitoring corrosion of iron in atmospheric environment by measuring very small changes in the amount of oxygen. The result of corrosion current obtained from DPT method has been compared with that obtained from AC impedance method. The difference in the value of corrosion current obtained from these two methods was attributed to the error in choosing the value of proportionality constant k of the Stern-Geary equation.DOI: http://dx.doi.org/10.3126/ijasbt.v2i1.10112Int J Appl Sci Biotechnol, Vol. 2(1): 109-111

Investigation on corrosion behaviors of aluminum alloy in NaCl and EXCO solution

Purpose – The purpose of this paper is to investigate the corrosion behaviors of 2A12 aluminum alloy in NaCl and EXCO solution, and establish the relationship between the corrosion depth and the time. Design/methodology/approach – Alternate immersion corrosion test chamber was used to perform the corrosion test. The corrosion mediums were 3.5 percent NaCl solution and EXCO solution (NaCl 234 g/L, KNO3 50 g/L, 68 percent HNO3 6.8 mL/L). The surface morphology was studied using the digital microscope. Findings – The average corrosion rate of aluminum alloy in NaCl solution decreased gradually at the initial stage and then went to a plateau value. The average corrosion rate of aluminum alloy in EXCO solution increased first, then showed a downward trend. The empirical function D=At B was verified. Originality/value – The results could provide a reference for the establishment of accelerated environmental spectrum in the laboratory and give instructions on the application of aluminum alloy in alternated dry and wet environment.

Seed Extract of Psidium guajava as Ecofriendly Corrosion Inhibitor for Carbon Steel in Hydrochloric Acid Medium

The anticorrosion characteristics of the seeds of Psidium guajava (P. guajava) fruits on carbon steel in acid medium were examined with weight loss data and subsequently thermodynamic factors such as heat of adsorption of the inhibitor on the metal surface (Q), change in entropy (ΔS), change in free energy of the reaction (ΔG), corrosion rate (CR) and energy of activation for corrosion reaction of carbon steel (E) were also evaluated. Adsorption isotherm was plotted to study the adsorption of the inhibitor on the metal surface with increasing concentration of the inhibitor. The functional groups responsible for inhibition were investigated using Fourier transform infrared (FT-IR) spectra. Electrochemical parameters were evaluated through the potentiodynamic Tafel polarization and impedance spectral studies. Scanning electron microscopy (SEM) micrographs were recorded to investigate the change in surface morphology. The complete study reveals the efficiency of seed extract of P. guajava as a safe, ecofriendly and alternate corrosion inhibitor for carbon steel in acid medium.

STUDY ON THE RUSTING EVOLUTION AND THE PERFORMANCE OF RESISTING TO ATMOSPHERIC CORROSION FOR Mn-Cu STEEL

The rust evolutions of the corrosion mass gain, the corrosion rate, the chemical composition, and the cross-section of the rust layer versus cycles of dry/wet alternate corrosion test were summarized on the basis of the study progress on the rust layer of Mn-Cu weathering steel. The validity of the cyclic dry/wet corrosion acceleration test simulating the atmospheric corrosion has also been discussed. Moreover, we have described the principle of synergistically improving the corrosion resistance of the rust layer resisting to both coastal atmospheric corrosion and industrial acidic rain atmospheric corrosion through adding alloying elements Cu, Mn and P. Meanwhile, the mechanism of P in the rust layer and the relationship of the ion-selectivity of Mn-Cu steel rust layer and its structure have been discussed.

The application of microstructural fracture mechanics to various metal surface states

The application of microstructural fracture mechanics to various metal surface states

The influence of the sulfur/oxygen ratio in the environment on the creep and creep damage behavior of a heat-resistant steel

Investigations have been carried out on the creep behavior of a 32Ni-27Cr-0.07Ce heat-resistant steel in several S-O bearing environments at 700 °C. It was found that the creep strength is reduced if severe corrosion, as was found in the case of the highest S/O ratio, causes a reduction of load-bearing cross section. Deformation-induced fingerlike corrosion paths along grain boundaries, which form an alternate corrosion pattern, were less damaging, even when the penetration was deep. Creep ductility was strongly reduced in all environments regardless of the S/O ratio. The formation of sulfide-oxide corrosion products causes rapid crack initiation at the surface and promotes crack propagation.

The ASCOR Test: A Simple Automated Method for Stress Corrosion Testing of Aluminum Alloys

Abstract Alternate immersion stress corrosion testing according to ASTM G 44, Practice for Alternate Immersion Stress Corrosion Testing in 3.5% Sodium Chloride Solution, has proves to be representative for alumimum alloys in natural environments resembling the actual eavironmental conditions for aircraft. A simple automated stress corrosion testing method called the ASCOR (automated stress corrosion ring) test was developed to test aluminum alloys according to ASTM G 44 and using direct stressing as in ASTM G 49. Recommended Practice for Preparation and Use of Direct Tension Stress Corrosion Test Specimens. The method involves testing cylindrical or pin-loaded flat tension test specimens in a loading sing provided with strain gages to measure the load. Initiation of a stress corrosion crack (SCC) results in a small load decrease. During the test the load is measured periodically and stored in a data acquisition system controlled by a personal computer. A specific load decrease is used as the criterion for SCC initiation. The main advantages of the method are that a large number of specimens can be tested simultaneously in a climate chamber and that SCC initiation lives can be determined according to a clearly defined criterion without time consuming and subjective inspections, and without disturbing the test procedure.

Effect of alternate corrosion and abrasion on some ferrous metals : J. Dearden and J. D. Swindale. Iron and Steel Institute, journal, v. 185, Feb. 1957, P. 227–234

Effect of alternate corrosion and abrasion on some ferrous metals : J. Dearden and J. D. Swindale. Iron and Steel Institute, journal, v. 185, Feb. 1957, P. 227–234