Search results

The purpose of this paper is to present a laboratory accelerated periodic immersion wet/dry cyclic corrosion test, reflecting the alternate wet/dry process during the atmospheric exposure of metallic materials, which can be applied to evaluate the atmospheric corrosion resistance (ACR) of weathering steels in a very short period.

This test method uses 0.01 M sodium bisulfite aqueous solution with pH 4.4 as the immersion medium, simulating the notable characteristics of sulfur dioxide pollutant in industrially polluted atmospheres. During the test process, the tested specimens are immersed into the solution for 12 minutes, immediately followed by the subsequent drying process for 48 minutes, and such alternate process consists of a cyclic period, i.e. 1 hour. As a result of this procedure, a relative corrosion rate is defined to determine the ACR. To determine a preferred test period, different test periods including 72 and 200 hours were compared.

Compared with several other commonly used test methods, it was confirmed that the relative ACR of various steels can be determined after testing for only 72 hours. The constituent of the corrosion products, i.e. the rust layer, was consistent with that formed after long-term exposure in a typical outdoor atmospheric environment.

The test method enables comparative testing for ranking the ACR of weathering steel during the development of new weathering steels.

This paper aims to investigate the atmospheric corrosion mechanism of structural materials to develop more advanced corrosion-control technologies and cost-reduction strategies. As a second phase in steels, the non-metallic oxide inclusions are considered to not only affect the mechanical properties of steel but also the corrosion resistance of steel. So, an important research goal in this paper is to investigate the indoor accelerated corrosion kinetics of Q450NQR1 weathering steel, analyzing the galvanic polarity of different inclusions in electrochemical corrosion microcell between the inclusion and steel matrix and then elucidating the influence mechanism of inclusions on corrosion resistance of weathering steel.

Two methods of inclusion modification are usually used to improve the properties of weathering steel: one is calcium treatment on aluminum killed steel and the other one is rare earth (RE) modification. Wet/dry cyclic immersion corrosion test field emission scanning electron microscopy (FE-SEM) metallographic optical microscope.

The indoor accelerated corrosion kinetics of Q450NQR1 weathering steel could be divided into two stages with different log (thickness loss, D)-log (time, t) fitting functions, and the effect of inclusions on the corrosion resistance of Q450NQR1 weathering steel was only reflected in the initial stages of corrosion. The inclusions of CaS in Ca-modified test steel and RE oxides and sulfides in RE-modified test steel were preferentially dissolved in acid media, slowing down the corrosion rate of steel matrix, but the non-metallic inclusion Al₂O₃ may accelerate the corrosion rate of the steel matrix as a form of differential aeration corrosion.

The effects of inclusions on corrosion resistance of Q450NQR1 weathering steel was investigated by dry–wet cycle immersion test and FE-SEM. The effect of inclusions on the corrosion resistance of Q450NQR1weathering steel was only reflected in the initial stages of corrosion. The inclusions of CaS in Ca-modified test steel and rare earth (RE) oxides and sulfides in RE-modified test steel were preferentially dissolved in acid media, slowing down the corrosion rate of steel matrix, but the non-metallic inclusion Al₂O₃ may accelerate corrosion rate of the steel matrix as a form of differential aeration corrosion.

This paper aims to study the effect of ultraviolet (UV) light on the corrosion behavior of BC550 weathering steel in simulated marine atmospheric environment.

The effect of UV light on the corrosion behavior of BC550 weathering steel in simulated marine atmospheric environments were investigated by the corrosion weight gain experiment, in situ electrochemical noise, scanning electron microscope and X-ray diffraction.

UV light accelerated the corrosion process of BC550 weathering steel in the simulated marine atmospheric environment during the first 168 h. The maximum influence factor of UV light was 0.32, and it was only 0.08 after 168 h of corrosion process.

As the extension of corrosion time, the thickness and density of the corrosion product layer increased, which weakened the acceleration effect of UV light.

This study aims to study the effect of Sn on the corrosion behavior of weathering steel (WS) in a simulated tropical marine atmosphere.

Indoor alternate immersion tests, electrochemical measurements and real-time current-monitoring technology based on the galvanic corrosion principle were used and the scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and electron probe microanalyzer were used to analyze the morphology and component of the rust layer.

The results indicated that Sn has a positive influence on the corrosion process. Sn participated in the composition of the rust layer in the form of SnO₂ and is enriched in the inner rust layer. SnO₂ participated in the coprecipitation process with iron oxides and oxyhydroxides, which promoted further transformation of γ-FeOOH to α-FeOOH. As a result, the rust layer of Sn-containing steel was continuous, compact and effectively blocked the invasion of aggressive Cl⁻. Therefore, the additive of Sn enhanced the corrosion resistance of WS in a simulated tropical marine atmosphere.

The corrosion behaviors of WS were researched by the real-time current-monitoring technology which was rarely used.

Introduction From the range of engineering materials, steel finds wide application in the building construction industry. The majority of steel used is for structural purposes but thinner gauge coil and sheet products in the form of coated mild steel or stainless steel are increasingly used for cladding and roofing.

The problems involved in the choice of priming paint for galvanized steel are discussed in this article and explained on a chemical basis. Case histories are given of the successful use of metallic lead primer together with photographs which show the result of cross hatch tests on a variety of primers.

Recherches sur la Corrosion de la British Iron and Steel Research Association.

The purpose of this paper is to draw up an atmospheric corrosion map for an industrial zone to determine the best coating system for each location.

The outdoor atmospheric corrosion rate was measured at eight locations distributed in an oil refinery during a year. Corrosion rates were measured by weight loss of carbon steel coupons, according to ISO Standard 9223. Weathering conditions, including temperature, time of wetness, and atmospheric pollution such as chloride precipitation and sulfur content also were measured. The results were analyzed using “Surfer 8” software and the corrosion map of the refinery was derived.

An atmospheric corrosion map was derived for the oil refinery. By this approach, coating system for equipment can be selected based exactly on where the plant item is located.

Exterior coating systems for equipment now can be selected based on their application, regardless of their position in any refinery. In this article, an atmospheric corrosion map was developed for a refinery for the first time. The position of equipment on the corrosion map is a new parameter that should be considered for coating system selection.

This paper aims to explore the transformation process and transformation mechanism of carbon steel under the marine environment.

In this paper, the transformation and rust layers corrosion products on 0Cu2Cr carbon steel with different cycles coupon test was investigated and deeply explored by scanning electron microscope, energy dispersive spectrometer, X-ray diffraction.

The results showed that the thickness of rust layers grew from 71.83 µm to 533.7 µm with increasing duration of corrosion. The initial corrosion product was γ-FeOOH, then part of the γ-FeOOH continued growing, and under the capillary action, the other part of the γ-FeOOH transformed to α-FeOOH.

To the best of the authors’ knowledge, this paper puts forward for the first time a new viewpoint of the development of corrosion products of low-carbon steel in two ways. This discovery provides a new idea for the future development of steel for marine engineering.

The purpose of this study is to explore the corrosion behaviors of tube pile steel with the addition of 0.2 per cent Cu and 0.2 per cent Cu-0.2 per cent Cr in half-immersion environment.

The electrochemical corrosion behaviors of tube pile steel with different alloy-elements addition were identified using the polarization curve method and electrochemical impedance spectroscopy technique. Corrosion product and its morphology were analyzed by X-ray diffraction, optical microscope and scanning electron microscopy.

Results indicate that the most serious corrosion occurred in the liquid-air interface zone due to the higher oxygen and water concentration. With the addition of Cu and Cu-Cr, pits were getting smaller and denser, transforming the corrosion type from pitting corrosion to uniform corrosion gradually. Rust layer containing Cu/Cr tended to compact and inhibited the anodic process, while the enrichment of Cu/Cr in rust layer decelerated the dissolution of substrate, thus the expanding of pits was suppressed.

This paper studied the corrosion behaviors of liquid-air interface zone of tube pile steel and verified the transformation of corrosion type with adding Cu, Cu/Cr elements.