Steel Coupons Research Articles

Terahertz Time-of-Flight Tomography Beyond the Axial Resolution Limit: Autoregressive Spectral Estimation Based on the Modified Covariance Method

We present a time-of-flight tomography method for exceeding the naive axial (i.e., depth) resolution limit of terahertz (THz) deconvolution by autoregressive spectral extrapolation (AR) based on the modified covariance method (AR/MCM). In contrast to Wiener filtering combined with wavelet denoising, AR/MCM does not discard any frequency components in the low signal-to-noise (SNR) regions of the measured data, and unlike the AR approach based on the Burg method (AR/BM), no peak splitting (single peaks in the impulse response function appearing as double peaks) as well as frequency bias (spectral peaks shifted with respect to their correct positions) is observed after deconvolution. After verifying the advantages of AR/MCM over Wiener filtering in conjunction with wavelet denoising as well as over AR/BM, using synthetic data, AR/MCM is employed to reconstruct a single layer of mill scale on a steel coupon from experimental THz time-of-flight tomography data. The reconstruction shows good agreement with the film thickness obtained from destructive cross-sectional measurements. In addition, unlike AR/BM, optimizing the parameters to obtain stable reconstruction is straightforward relying of Akaike’s information criterion suggesting that AR/MCM can be an easier to implement for THz nondestructive characterization of stratigraphy under noisy conditions, particularly when estimates of the stratigraphy may not a priori be available.

Thermal and non-thermal treatment effects on Staphylococcus aureus biofilms formed at different temperatures and maturation periods

The objective of this study was to investigate the effect of temperature and maturation period on the resistance of Staphylococcus aureus biofilms to thermal and non-thermal treatments. First, biofilm development was compared at three different temperatures (15, 25, and 37°C) for 5 days. The cell population at 15 and 25°C remained relatively consistent approximately at 6.3 log CFU/cm2, whereas 37°C resulted in the highest cell population on day 1 (7.6 log CFU/cm2) followed by a continual decline. Then, biofilm resistance to steam and sodium hypochlorite (NaOCl) treatments was evaluated. Obtained results highlighted that biofilms had different resistance to both treatments depending on development conditions. Specifically, steam treatment of 10 s eliminated 4.1 log CFU/cm2 of the biofilm formed at 25°C for 5 days. The same treatment inactivated over 5 log population of biofilms developed in other temperature and maturation period conditions. Treatment with NaOCl reduced approximately 1 log CFU/cm2 of biofilm cells developed at 25°C for 5 days. However, inactivation was found to be over 2 log CFU/cm2 under other development conditions. An extracellular polymeric substances (EPS) quantification using 96-well plates and stainless steel coupons was conducted. In the 96-well plate experiment, it was found that the highest amount of polysaccharide was secreted at 25°C (p < 0.05), while total biomass and protein contents were greatest at 37°C (p < 0.05). No significant difference in EPS content was observed for stainless steel, but the results displayed a similar trend to the 96-well plate. In particular, biofilms developed at 25°C tended to secret the highest amount of polysaccharide, which aligned with the current literature. This finding indicated that polysaccharide was the main contribution to the enhanced resistance of S. aureus biofilms. Overall, it was shown that biofilms formed at 25°C for 5 days exhibited the greatest resistance to thermal and nonthermal treatments due to the elevated exopolysaccharide secretion. This study demonstrates that temperature and maturation period significantly affect the resistance of S. aureus biofilms to thermal and non-thermal treatments.

Effective hydrogen diffusivities of AISI 304 stainless steel with Ni or Au coating

Abstract Metallic coatings which provide a hydrogen diffusion barrier are thought to reduce hydrogen assisted cracking on stainless steel. The influence of a metallic layer on the hydrogen migration of AISI 304 stainless steel was investigated using a commercial electroplating layer of Ni and Au on a thin stainless steel coupon. Phase identification was performed using an X-ray diffractometer to determine the average thicknesses, measured from back-scattered scanning electron images. Regarding the ASTM G148-97 practice, the effective hydrogen diffusivities of AISI 304 austenitic stainless steel, nickel and gold were measured as 7.07 × 10-13, 2.72 × 10-14 and 9.64 × 10-16 m2 × s-1, respectively. In this work, a gold layer was found to be most effective for the prevention of hydrogen diffusion when compared with untreated and Ni-plated 304 stainless steel.

Mechanical properties investigations of the plasma sprayed coatings based on alumina powder

In this paper Al2O3 + 13 wt% TiO2 ceramic coatings manufactured by Atmospheric Plasma Spraying (APS) have been investigated. The commercial feedstock materials, Metco 6221 (top coat) and Amdry 4535 (bond coat) have been deposited on stainless steel coupons. The main goal of researches was to determine the influence of critical plasma spray parameters (CPSP) on structure and properties of the coatings. In present studies, the electrical power was a variable parameter. Coatings have been characterized by in the terms of microstructure, topography, bond strength adhesion, fracture toughness and wear resistance. As a result, it was observed, that coatings sprayed with higher value of the electrical power exhibit higher mechanical properties due to better cohesion as well as higher melting degree.

Chitosan/Lignosulfonate Nanospheres as "Green" Biocide for Controlling the Microbiologically Influenced Corrosion of Carbon Steel.

In this work, uniform cross-linked chitosan/lignosulfonate (CS/LS) nanospheres with an average diameter of 150–200 nm have been successfully used as a novel, environmentally friendly biocide for the inhibition of mixed sulfate-reducing bacteria (SRB) culture, thereby controlling microbiologically influenced corrosion (MIC) on carbon steel. It was found that 500 µg·mL−1 of the CS/LS nanospheres can be used efficiently for the inhibition of SRB-induced corrosion up to a maximum of 85% indicated by a two fold increase of charge transfer resistance (Rct) on the carbon steel coupons. The hydrophilic surface of CS/LS can readily bind to the negatively charged bacterial surfaces and thereby leads to the inactivation or damage of bacterial cells. In addition, the film formation ability of chitosan on the coupon surface may have formed a protective layer to prevent the biofilm formation by hindering the initial bacterial attachment, thus leading to the reduction of corrosion.

Marine bacterial community analysis on 316L stainless steel coupons by Illumina MiSeq sequencing.

In order to evaluate the corrosive action of microorganisms on 316L metal exposed directly to a marine environment, a system was designed to immerse coupons in seawater. After periods of 30, 60 and 90days, the coupons were recovered, the corrosion rates evaluated and the biofilm samples on their surface were analyzed by 16S rRNA gene sequencing. The results of the corrosion rate showed an acceleration over the entire experimental period. Alpha diversity measurements showed higher rates after 60days of the experiment, while abundance measurements showed higher rates after 90days of exposure to the marine environment. The beta-diversity results showed a clear separation between the three conditions and proximity in the indices between replicates of the same experimental condition. The results of 16S rRNA gene sequencing showed that after 30days of exposure to seawater, there was massive representativeness of the pioneer bacteria, Gamma and Alphaproteobacteria, with emphasis on the genera Alcanivorax, Oceanospirillum and Shewanella. At the 60-day analysis, the Gammaproteobacteria class remained dominant, followed by Alphaproteobacteria and Flavobacteria, and the main representatives were Flexibacter and Pseudoalteromonas. In the last analysis, after 90days, a change in the described bacterial community profile was observed. The Gammaproteobacteria class was still the largest in diversity and OTUs. The most predominant genera in number of OTUs were Alteromonas, Bacteriovorax and, Nautella. Our results describe a change in the microbial community over coupons directly exposed to the marine environment, suggesting a redirection to the formation of a mature biofilm. The conditions created by the biofilm structure suggest said condition favor biocorrosion on the analyzed coupons.

Changes in microbial community in the presence of oil and chemical dispersant and their effects on the corrosion of API 5L steel coupons in a marine-simulated microcosm.

The influence of crude oil and chemical dispersant was evaluated over planktonic bacteria and biofilms grown on API 5L steel surfaces in microcosm systems. Three conditions were simulated, an untreated marine environment and a marine environment with the presence of crude oil and a containing crude oil and chemical dispersant. The results of coupon corrosion rates indicated that in the oil microcosm, there was a high corrosion rate when compared with the other two systems. Analysis of bacterial communities by 16S rRNA gene sequencing described a clear difference between the different treatments. In plankton communities, the Bacilli and Gammaproteobacteria classes were the most present in numbers of operational taxonomic unit (OTUs). The Vibrionales, Oceanospirillales, and Alteromonadales orders were predominant in the treatment with crude oil, whereas in the microcosm containing oil and chemical dispersant, mainly members of Bacillales order were detected. In the communities analyzed from biofilms attached to the coupons, the most preponderant class was Alphaproteobacteria, followed by Gammaproteobacteria. In the control microcosm, there was a prevalence of the orders Rhodobacterales, Aeromonadales, and Alteromonadales, whereas in the dispersed oil and oil systems, the members of the order Rhodobacterales were present in a larger number of OTUs. These results demonstrate how the presence of a chemical dispersant and oil influence the corrosion rate and bacterial community structures present in the water column and biofilms grown on API 5L steel surfaces in a marine environment. KEY POINTS: • Evaluation of the effects of oil and chemical surfactants on the corrosion of API 5L. • Changes in microbial communities do not present corrosive biofilm on API 5L coupons.

Preliminary Investigation of Utilization of a Cellulose-Based Polymer in Enhanced Oil Recovery by Oilfield Anaerobic Microbes and its Impact on Carbon Steel Corrosion

Water injection increases reservoir pressure in enhanced oil recovery (EOR). Among other oilfield performance chemicals, an EOR polymer is added to the injection water to provide the viscosity necessary for effective displacement of viscous crude oil from the reservoir formation. However, these organic macromolecules may be degraded by microbes downhole, causing undesirable viscosity loss. The organic carbon utilization by the microbes promotes microbial metabolism, thus potentially exacerbating microbiologically influenced corrosion (MIC). In this preliminary laboratory investigation, 3,000 ppm (w/w) carboxymethyl cellulose sodium (CMCS), a commonly used EOR polymer, was found to be utilized by an oilfield biofilm consortium. This oilfield biofilm consortium consisted of bacteria (including that can degrade large organic molecules), sulfate-reducing bacteria (SRB), and other microorganisms. A 30-day incubation in 125 mL anaerobic vials was conducted with an artificial seawater medium without yeast extract and lactate supplements at 37°C. The polymer biodegradation led to 16% viscosity loss in the broth and a 30× higher SRB sessile cell count. Slightly increased MIC weight loss and pitting corrosion were observed on C1018 carbon steel coupons. Thus, the use of CMCS in EOR should take into the consideration of microbial degradation and its impact on MIC.

Anti-corrosive properties of two epoxy primer systems applied to steel surfaces prepared with various mechanical abrasive treatments

The present study evaluates an anticorrosive system of epoxy primers applied on carbon steel coupons under different surface preparation techniques: dry abrasive blasting up to Sa 2½, wet abrasive blasting up to Sa 2½ and mechanical treatment up to SSPC SP-11. The epoxy primers were pigmented with zinc phosphate, commonly used in offshore structures, on which intermediary and anti-scaling paints are applied. The components of this primers system were analyzed through Fourier transform infrared spectroscopy (FTIR) while the corrosion protection was analyzed by electrochemical impedance spectroscopy (EIS) and potential monitoring, as well as the adhesion to the coupons’ surface immersed in 3.5%w/v NaCl solution (3.5 g of NaCl in 100 mL of solution). The results showed a better epoxy system adhesion to coupons surface prepared by dry abrasive blasting to Sa 2½. According to the electrochemical results, better corrosion protection was observed in samples prepared by wet abrasive blasting up to Sa 2½.

Simulated Sunlight Rapidly Inactivates SARS-CoV-2 on Surfaces.

Previous studies have demonstrated that SARS-CoV-2 is stable on surfaces for extended periods under indoor conditions. In the present study, simulated sunlight rapidly inactivated SARS-CoV-2 suspended in either simulated saliva or culture media and dried on stainless steel coupons. Ninety percent of infectious virus was inactivated every 6.8 minutes in simulated saliva and every 14.3 minutes in culture media when exposed to simulated sunlight representative of the summer solstice at 40°N latitude at sea level on a clear day. Significant inactivation also occurred, albeit at a slower rate, under lower simulated sunlight levels. The present study provides the first evidence that sunlight may rapidly inactivate SARS-CoV-2 on surfaces, suggesting that persistence, and subsequently exposure risk, may vary significantly between indoor and outdoor environments. Additionally, these data indicate that natural sunlight may be effective as a disinfectant for contaminated nonporous materials.

Inactivation of Pseudomonas aeruginosa Biofilms by 405-Nanometer-Light-Emitting Diode Illumination.

Biofilm formation by Pseudomonas aeruginosa contributes to its survival on surfaces and represents a major clinical threat because of the increased tolerance of biofilms to disinfecting agents. This study aimed to investigate the efficacy of 405-nm light-emitting diode (LED) illumination in eliminating P. aeruginosa biofilms formed on stainless steel coupons under different temperatures. Time-dependent killing assays using planktonic and biofilm cells were used to determine the antimicrobial and antibiofilm activities of LED illumination. We also evaluated the effects of LED illumination on the disinfectant susceptibility, biofilm structure, extracellular polymeric substance (EPS) structure and composition, and biofilm-related gene expression of P. aeruginosa biofilm cells. Results showed that the abundance of planktonic P. aeruginosa cells was reduced by 0.88, 0.53, and 0.85 log CFU/ml following LED treatment for 2 h compared with untreated controls at 4, 10, and 25°C, respectively. For cells in biofilms, significant reductions (1.73, 1.59, and 1.68 log CFU/cm2) were observed following LED illumination for 2 h at 4, 10, and 25°C, respectively. Moreover, illuminated P. aeruginosa biofilm cells were more sensitive to benzalkonium chloride or chlorhexidine than untreated cells. Scanning electron microscopy and confocal laser scanning microscopic observation indicated that both the biofilm structure and EPS structure were disrupted by LED illumination. Further, reverse transcription-quantitative PCR revealed that LED illumination downregulated the transcription of several genes associated with biofilm formation. These findings suggest that LED illumination has the potential to be developed as an alternative method for prevention and control of P. aeruginosa biofilm contamination.IMPORTANCEPseudomonas aeruginosa can form biofilms on medical implants, industrial equipment, and domestic surfaces, contributing to high morbidity and mortality rates. This study examined the antibiofilm activity of 405-nm light-emitting diode (LED) illumination against mature biofilms formed on stainless steel coupons. We found that the disinfectant susceptibility, biofilm structure, and extracellular polymeric substance structure and composition were disrupted by LED illumination. We then investigated the transcription of several critical P. aeruginosa biofilm-related genes and analyzed the effect of illumination temperature on the above characteristics. Our results confirmed that LED illumination could be developed into an effective and safe method to counter P. aeruginosa biofilm contamination. Further research will be focused on the efficacy and application of LED illumination for elimination of complicated biofilms in the environment.

Effective hydrogen diffusivities of AISI 304 stainless steel with Ni or Au coating

AbstractMetallic coatings which provide a hydrogen diffusion barrier are thought to reduce hydrogen assisted cracking on stainless steel. The influence of a metallic layer on the hydrogen migration of AISI 304 stainless steel was investigated using a commercial electroplating layer of Ni and Au on a thin stainless steel coupon. Phase identification was performed using an X-ray diffractometer to determine the average thicknesses, measured from back-scattered scanning electron images. Regarding the ASTM G148-97 practice, the effective hydrogen diffusivities of AISI 304 austenitic stainless steel, nickel and gold were measured as 7.07 × 10-13, 2.72 × 10-14 and 9.64 × 10-16 m2 × s-1, respectively. In this work, a gold layer was found to be most effective for the prevention of hydrogen diffusion when compared with untreated and Ni-plated 304 stainless steel.

Corrosion study of pipeline material for seabed sediment in tropical climate

Corrosive environments such as marine sediments can cause corrosion to steel pipelines at any time when certain conditions are met. Seabed sediment could cause severe corrosion damage due to its corrosiveness to the pipelines buried under it. Many consequences could take place in case if there is incident in oil/gas pipelines. Successfully identifying elements of corrosion in marine sediment would enhance the future of steel structure protection and monitoring systems. This article focuses on the behaviour of corrosion rate of steel located near shore environment and the aim is to determine the effect of sediment on corrosion of steel. To investigate that, simulated near shore sediment conditions have been used where the steel coupons buried in sediments which have different characteristics. Weight loss technique has been implemented to determine the weight loss rate of the steel specimens. Based on the results of this study, metal weight loss increases as the duration of exposure to seabed sediment environment become longer. The sea sediment simulated condition has given significant levels of corrosion. Conclusively, the corrosion rate of steel in seabed sediment located in tropical region is complicated and further studies are suggested.

Material properties and membrane residual stresses of S690 high strength steel welded I-sections after exposure to elevated temperatures

This paper reports a thorough experimental investigation into the material properties and membrane residual stresses of S690 high strength steel welded I-sections after exposure to seven levels of elevated temperatures ranging from 30 °C (room temperature) to 950 °C. The experimental programme included heating, soaking and cooling of S690 high strength steel coupons and welded I-section specimens as well as post-fire material tensile coupon tests and membrane residual stress measurements, with the experimental rigs, procedures and results fully reported. The key post-fire material properties were then carefully analysed together with the test data collected from the existing literature, and a new set of retention factor curves of simple multi-linear shapes was proposed and shown to result in accurate predictions of post-fire yield and ultimate stresses for S690 high strength steel after exposed to elevated temperatures. Regarding post-fire membrane residual stresses, the measured distribution pattern and peak amplitudes in S690 high strength steel welded I-section after exposed to an elevated temperature of 300 °C generally remained unchanged in comparison with those in S690 high strength steel welded I-section at room temperature. However, for higher elevated temperatures ranging from 600 °C to 950 °C, the peak values of both compressive and tensile membrane residual stresses dramatically decreased, and moreover the discrepancy between the peak compressive and tensile membrane residual stress values became smaller and the transition regions (where the peak tensile residual stresses are changed to the peak compressive residual stresses) became narrower; this can be attributed to the fact that prominent elastic strain redistribution and residual stress relaxation of steel starts from around 500 °C–600 °C. A membrane residual stress predictive model was proposed for S690 high strength steel welded I-sections after exposed to elevated temperatures, and shown to well represent the measured membrane residual stress patterns and amplitudes over the full temperature range from 30 °C to 950 °C.

Experimental Study on Microbial Fouling Inhibition Performance of Ni‐P‐NanoTiO2 Composite Surfaces

AbstractMicrobial fouling of heat exchangers causes serious issues including increased fuel consumption, flow resistance, and maintenance cost expenditure. Composite Ni‐P‐nanoTiO2 coatings were prepared for inhibiting and mitigating the heat exchanger microbial fouling deposition. The surface energy components and wall adhesion work of microbial fouling medium had a significant effect on the microbial fouling deposition process. Compared with carbon steel coupons, the microbial fouling deposition on Ni‐P‐nanoTiO2 coatings was reduced by about 90 % and the wall adhesion work and microbial fouling deposition rate of these coatings were less. The Ni‐P‐nanoTiO2 coatings might not only be advantageous for controlling the initial microbial adhesion, but also effective for reducing the fouling deposition rate.

Investigating coating liquefaction and solidification of furnace-heated Al-Si coated 22MnB5 steel using laser reflectance

As part of the hot stamping process, aluminum-silicon (Al-Si) coated 22MnB5 steel blanks are austenitized using a roller hearth furnace, but the coating melts at ~577 °C, creating an intermediate liquid phase which, among other issues, shortens the lifetimes of the ceramic rollers and complicates blank transfer. Little is known about how this liquid regime is related to furnace process parameters, and how these parameters should be adjusted to minimize the impact of the liquid phase on hot stamping operations. This study pioneers laser reflectance measurements to infer the surface state of furnace-heated Al-Si coated steel coupons in situ. Time-resolved spectral reflectance measurements reveal multiple peaks, the first of which indicates the moment at which the coating liquefies. While the temperature corresponding to the start of the first peak is insensitive to heating rate, as the set-point of the furnace increases, the later peaks in the signal occur quicker but shift towards higher temperatures. These measurements are connected to the evolving surface microstructure via ex situ scanning electron microscopy and energy-dispersive X-ray spectroscopy of coupons extracted from the furnace at intermediate heating times.

The use of papain for the removal of biofilms formed by pathogenic Staphylococcus aureus and Campylobacter jejuni

Papain is a cysteine protease isolated from Carica papaya that has been used for various purpose in the food industry. The aim of this study was to investigate the effects of papain on Staphylococcus aureus (S. aureus) and Campylobacter jejuni (C. jejuni) biofilms. Papain did not affect the viability of cells, even at the highest tested concentration (5 μg/mL). However, biofilm formation by S. aureus 7, S. aureus 8, C. jejuni NCTC 11168, and C. jejuni Y23-5, as determined by crystal violet staining assays, was inhibited by 32.8%, 42.2%, 23.9%, and 22.2%, respectively, following treatment with 5 μg/mL papain. In addition, mature biofilms on stainless steel coupons were reduced by 2 Log CFU/coupons after treatment with 5 μg/mL papain, and the morphological changes in the biofilm were assessed by scanning electron microscopy. These results confirmed that although papain does not exert antibacterial effects, it has anti-biofilm effects against S. aureus and C. jejuni. This study suggests the potential of papain as an anti-biofilm agent in the food industry.

Microbiologically Influenced Corrosion of Stainless Steel by Sulfate Reducing Bacteria: A Tale of Caution

The influence of different experimental media composition and air purging on the potential for microbiologically influenced corrosion (MIC) of Type 304 stainless steel with sulfate-reducing bacteria (SRB) was investigated. Modified Baar’s (MB) medium, MB medium without iron ions and supplemented with sodium chloride (MBN), and air purged MBN medium (MBO) were used. Pitting corrosion attack was found on the surface of the coupons for all of the conditions tested including the abiotic tests, and detailed statistical analysis showed no significant difference between the pitting results. General corrosion and maximum pit penetration rates also showed no difference between the coupons exposed to different test conditions. Interestingly, the pits found on the surface of the coupons in all of the tested conditions were comparable in size/shape and depth to that of the inclusions present on the surface of the stainless steel coupons. These findings suggest that (i) the test conditions studied do not lead to increased corrosion rates of stainless steel with SRBs and (ii) care needs to be taken to avoid the pitfall of misinterpreting the corrosion of inclusions present on the surface of stainless steels, which can occur as a result of cleaning of the coupons, as MIC pits.

Antibody-Based Capture and Behaviour of Endothelial Cell Lines on Pre-Surface Modified Medical Grade Steel

Coronary artery disease is one of the major causes of morbidity and mortality worldwide. Coronary stents, tube-shaped medical implants that are placed in narrowed coronary arteries, have been used successfully in the management of this condition. However, re-narrowing (i.e. restenosis) of the artery can occur which is instigated by an immune response towards the implanted ‘foreign’ material. A new approach to prevent restenosis and reduce the stent-induced immune response has been proposed previously, which involves re-endothelialization of the implanted stent. In the present study a proof-of-concept experiment involving surface-modified medical grade steel was employed in order to examine the best surface chemistry for in vitro cell capture. Steel coupons were coated with a silanized adlayer, followed by attachment of whole antibodies, followed by culturing of human umbilical vein endothelial cells (HUVECs) or human aortic endothelial cells (HAECs or HAoECs). With regard to the adlayer-antibody configuration, HUVECs adhered and grew with normal morphology, and a significantly increased number of HUVECs proliferated on the coupons compared to the ‘bare’ surface. Similar effects were observed with HAECS grown on adlayer-antibody modified substrates, with a significantly higher number of cells proliferating. These results demonstrate a successful strategy for re-endothelialization of the steel surface that may prevent immune response with respect to the behaviour of steel-based stents in vivo.

Rapid, Noninvasive, and Nondestructive Method for Biofilm Imaging on Metallic Surfaces Using Active Thermography.

A simple, rapid, low-cost method was proposed for the imaging of Pseudomonas aeruginosa biofilms on metallic surfaces using an infrared camera. Stainless steel coupons were cooled to generate a thermal gradient in relation to biofilm for active thermography (AT). Both cooling and image acquisition times were optimized and the images obtained with AT were compared with those from scanning electron microscopy. A free software (Thermofilm) was developed for image processing and the results were compared with the software ImageJ, with good agreement (from 87.7 to 103.8%). Images of coupons treated with sanitizer (peracetic acid) were obtained to show the applicability of the proposed method for biofilm studies. All analytical steps could be performed in 3 min in a noncontact, nondestructive, low-cost, portable, and easy-to-use way.