Surface Of Steel Specimens Research Articles

Study on corrosion performance and corrosion product composition of weathering steel and high‐performance steel in simulated C3 environment

AbstractWeathering steel (WS) and high‐performance steel (HPS) have been widely used in bridge engineering. Investigating the corrosion performances of WS and HPS is of great significance to the safety evaluation and maintenance of uncoated WS or HPS bridges, especially aging bridges. This study focused on the correlation between the corrosion performance and composition of the rust layer. Accelerated corrosion tests were conducted on Q345CNH and HPS 70 W to observe their corrosion performance under salt‐spray corrosive environment. Based on the results of corrosion test and the existing corrosion attack evaluation theories, the empirical formulae of uniform corrosion and pitting corrosion were derived. X‐ray diffraction experiments were performed to analyze the composition of the rust layer formed on the surface of steel specimens after various corrosion cycles. The relationship between the composition of the rust layer and the corrosion performance was established. The test corrosive environment was verified to be consistent with the C3 environment. The conclusions of this study could provide guidance for the corrosion evaluation in the following test or practical application.

Effect of Surface Pretreatment on Hot Press Lap joining of High Density Polyethylene to Stainless Steel Alloy AISI 304L

Hot press bounding technique was used to join a polyethylene sheet of 4mm thickness to stainless steel AISI 304L of 1mm thickness. Three different process parameters were used during the joining process: pressure of 4, 6, 8 and 10 bar, processing time of 1.5, 2, 2.5 and 3 min. and temperature of 115, 120, 125 and 130°C. The steel surface was treated with two methods: mechanical (scratch) and electrochemical (electro-polishing) treatment. A shear tensile, microstructure, scanning electron microscope and energy dispersive spectrometry tests were used to examine the joint specimens. The effect of process parameters on the joint properties was analyzed by the Minitab program. The scratched and electro-polished joint specimens exhibited a maximum shear force of 1112 and 1022N respectively. The tested joints were failed by an interfacial shear and necking in the polymer side with a ductile fracture. The joining process was occurred by a mechanical interlocking between the molten polymer and pores of the treated surface of steel specimen. The average thickness of the joining line for the scratched and electro-polished specimens was 5 and 4μm.

Development of functionalized SiO2–TiO2 reinforced cardanol and caprolactam modified diamine based polybenzoxazine nanocomposites for high performance applications

In the present work, three types of polybenzoxazines were synthesized using caprolactam-based diamine (CPA-NH2) and formaldehyde with different phenols, namely 4-fluorophenol, cardanol, and phenol, under appropriate experimental conditions. The molecular structure of the benzoxazine monomers was confirmed by FTIR, 1H, and 13C NMR spectroscopic techniques. Polybenzoxazines were obtained through ring-opening polymerization of benzoxazine monomers, and their formation was confirmed by FTIR spectroscopy. The elemental composition and morphological behavior of polybenzoxazines were characterized by SEM-EDAX and AFM techniques. The naturally occurring cardanol- and caprolactam-based diamine (CPA-NH2)-based benzoxazine was selected for detailed studies. The synthesized SiO2–TiO2 nanohybrid reinforcement was functionalized with 3-aminopropyltrimethoxysilane (3-APS) and reinforced with cardanol-based benzoxazine (CPBz) monomer. The resulted nanocomposites were studied for their corrosion protection behavior against mild steel surface along with thermomechanical (TGA and DMA) and morphological (SEM, XRD, and TEM) properties. The results obtained from electrochemical impedance analysis indicate that the 5 wt% of F–SiO2–TiO2 of reinforced CPBz exhibits an effective corrosion-resistant behavior toward surface of steel specimen than that of other samples.

Application of silicon-based camera for measurement of non-homogeneous thermal field on realistic specimen surface

The high-cost low-resolution infrared cameras operating in middle infrared spectral ranges are widely used to detect the thermal fields. In this study, a low-cost high-resolution silicon-based sensor camera operating in near infrared spectral ranges is used to perform the observation of the thermal fields on the realistic steel specimen surface. In near-infrared spectral ranges, a small temperature variation led to a large modification in the sensor illumination, inducing acquired images with over saturation or poor dynamic range of gray levels. To address this problem, an algorithm was used to precisely adjust the exposure time to acquire images with constant gray level whatever the temperature evolution is, and then used in heating experiment of a steel specimen. Results showed that images with constant gray level could be acquired during the heating experiment. A special radiometric model was used to perform near-infrared thermography. Based on this radiometric model of steel specimen surface, the thermal fields on steel specimen surface were successfully reconstructed without measuring surface emissivity.

Study on integrally molded PA6/304 stainless steel by micro-nano pressing technology

With application of micro-nano pressing technology (MNPT) polyamide 6 (PA6) and 304 stainless steel were integrally molded, and the mechanical properties and structure on the interface of plastic and metal were investigated in the study. The micro structures on the stainless steel specimen surface were achieved by physical and/or chemical surface treatment techniques including polishing and etching methods, respectively. The tensile shear strength and work of fracture for the integrally molded specimen were influenced greatly by the surface treatment on stainless steel. The maximal tensile shear strength and the fracture work for the MNPT molded sample reached up to ca. 11 MPa and 17 KJ/m2, respectively. In addition, the interface fractography of the MNPT molded specimen was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). These results indicated PA6 melt flew into the micro and/or nano holes on the chemical etched metal surface during hot press molding to form micro mechanical interlock structure to prepare strong MNPT molded samples.

Effect of deformation twinning on dissolution corrosion of 316L stainless steels in contact with static liquid lead-bismuth eutectic (LBE) at 500 °C

This work addresses the effect of deformation twinning on the dissolution corrosion behaviour of 316 L austenitic stainless steels in contact with static liquid lead-bismuth eutectic (LBE). For this purpose, plastically deformed 316 L steel specimens with distinctly different deformation twin densities were simultaneously exposed to oxygen-poor (<10−13 mass%) static liquid LBE for 1000 h at 500 °C. The variation in deformation twin density was achieved by loading in uniaxial tension to similar degrees of plastic deformation (8–10%) specimens made of the same 316 L steel heat. Tensile loading was carried out at −150, 25 and 150 °C so as to affect the twin density, which increased as the temperature of plastic deformation decreased. Dissolution corrosion was the only liquid metal corrosion mechanism observed in the LBE-exposed steel specimens. The thickness of the dissolution-affected zone increased with the deformation twin density, which was highest in the 316 L steel specimen deformed at −150 °C and lowest in the one deformed at 150 °C. As deformation twin boundaries accelerated the LBE ingress into the steel bulk, their local orientation with respect to the steel specimen surface affected the thickness of the dissolution-affected zone.

Control of the Structure of Diffusion Layer in Carbon Steels Under Nitriding with Preliminary Deposition of Copper Oxide Catalytic Films

The effect of thin films of copper oxide deposited before nitriding on the phase composition and the kinetics of growth of diffusion layers in carbon steels is considered. The process of formation of an oxide film involves chemical reduction of pure copper on the surface of steel specimens from a salt solution and subsequent oxidation under air heating. The oxide film exerts a catalytic action in nitriding of low- and medium-carbon steels, which consists in accelerated growth of the diffusion layer, the nitride zone in the first turn. The kinetics of the nitriding process and the phase composition of the layer are controlled by the thickness of the copper oxide precursor, i.e., the deposited copper film.

Core/shell (ZnO/polyacrylamide) nanocomposite: In-situ emulsion polymerization, corrosion inhibition, anti-microbial and anti-biofilm characteristics

Polyacrylamide nanoparticles of 20nm were prepared using emulsion polymerization technique. Core/shell nanocomposites of functional core of zinc oxide nanoparticles surrounded by a shell of polyacrylamide were also prepared using in-situ emulsion polymerization technique. Potentiodynamic polarization and Electrochemical impedance parameters for corrosion of carbon steel in absence and presence of ZnO/PAM.NCs indicated that, as the ZnO nanoparticles ratio increased, the corrosion inhibition efficiency increased; 50%, 80% and 94% for 1, 5 and 10% ZnO; respectively. Scanning electron micrographs of carbon steel specimen surface immersed in HCl in absence and presence of ZnO/PAM.NC10 indicated that carbon steel surface is less damaged in presence of ZnO/PAM.NC10 which confirms the observed high inhibition efficiency. ZnO/PAM.NC10 was found to display a broad spectrum antimicrobial activity with the inhibition zones in the range of 15–22mm. ZnO/PAM.NC10 demonstrated a higher antibacterial activity for the Gram-positive than for the Gram-negative bacteria and exhibited lower minimum inhibitory concentrations and minimum bactericidal concentrations for the Gram negative bacteria than the Gram positive bacteria. Moreover, it showed MICs/MFCs against yeast and fungal strains at concentrations (250/250ppm). Additionally, ZnO/PAM.NC10 exhibited antibiofilms activity against the standard bacterial strains; Bacillus subtilis and Escherichia coli as confirmed by SEM imaging.

Automated Determination of Nanocoating Cracking and Fragmentation Sites

Features of using a zirconium nanocoating as a surface sensor during steel plastic deformation are analyzed. Brightness distribution for a crack–surface system is considered on the example of electron-microscope images, and the form of cracks in question within a nanocoating is studied. The surface of steel specimens with a zirconium nanocoating is examined by defectometry and analysis results are summarized for the form and dimensions of the crack-like defects identified.

A new multi-component composite with gamma polyglutamic acid as corrosion and scale inhibitor

A new multi-component composite corrosion and scale inhibitor γ-gamma polyglutamic acid (10 mg L−1)/hydrolysed polymaleic anhydride (6 mg L−1)/benzotriazole (4 mg L−1) was developed. Its scale and corrosion inhibition performances were evaluated by bubble experiments, rotary hanging-piece corrosion tests, electrochemical, dynamic simulation test and scanning electron microscope. The rates of scale inhibition and corrosion inhibition were 94·8 and 85·4%, respectively. Further, scanning electron microscope morphology displayed complete and smooth carbon steel specimen surface, which was taken from dosing system. These results demonstrated that the water treatment agent possessed excellent scale and corrosion inhibition performance, so it can protect equipment and piping in the industrial circulating cooling water system.

Synergized Action of CuCl on Recycled Cigarette Butts as Corrosion Inhibitor for N80 Steel at 90 °C in 15% HCl

One of effective ways to reduce pollution from cigarette butts is introduced by recycling the cigarette butts. Inhibitor from recycled cigarette butts shows good inhibition properties, but we do not know whether CuCl can help to improve the inhibition efficiency. So, in this study, the impact of CuCl on recycled cigarette butts as corrosion inhibitor for N80 steel at 90 °C in 15% HCl is studied by weight loss, electrochemical noise, polarization, impedance, and X-ray photoelectron spectroscopy. All the results show that the inhibition efficiency of water extracts from cigarette butts in the presence of CuCl is higher than in absence of CuCl, and it can reach 95.3% when 9% water extracts with copper added is used. The X-ray photoelectron spectroscopy results indicate that the N80 steel specimen surface is undamaged and covered with a protective coat formed by copper-added water extracts from cigarette butts. CuCl has synergizing action on recycled cigarette butts as a corrosion inhibitor for N80 steel at 90 °C in 15% HCl.

Effect of alloying elements on the cracking resistance of structural steels intended for low-temperature application

The cracking resistance of structural chromium-nickel-molybdenum steels are analyzed under delayed fracture conditions. The fracture surfaces of steel specimens and the effect of molybdenum and impurities (phosphorus, tin) on their cracking resistance are investigated by Auger electron spectroscopy and emission spectral microanalysis. The positive influence of molybdenum on an increase in the cracking resistance is shown to increase as its content increases to 0.6%; molybdenum does not influence the cracking resistance at its content of 0.6–0.98%, and this effect decreases at a molybdenum content higher than 0.98%.

Hydrazine and Hydrogen Coinjection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors (VII)—Effects of Bulk Water Chemistry on ECP Distribution inside a Crack

Water chemistry in a simulated crack (crack) has been studied to understand the mechanisms of stress corrosion cracking in a boiling water reactor environment. Electrochemical corrosion potential (ECP) in a crack made in an austenite type 304 stainless steel specimen was measured. The ECP distribution along the simulated crack was strongly affected by bulk water chemistry and bulk flow. When oxygen concentration was high in the bulk water, the potential difference between the crack tip and the outside of the crack (ΔE), which must be one motive force for crack growth, was about 0.3V under a stagnant condition. When oxygen was removed from the bulk water, ECP inside and outside the crack became low and uniform and ΔE became small. The outside ECP was also lowered by depositing platinum on the steel specimen surface and adding stoichiometrically excess hydrogen to oxygen to lower ΔE. This was effective only when bulk water did not flow. Under the bulk water flow condition, water-borne oxygen caused an increase in ECP on the untreated surface inside the crack. This also caused a large ΔE. The ΔE effect was confirmed by crack growth rate measurements with a catalyst-treated specimen. Therefore, lowering the bulk oxidant concentration by such measures as hydrazine hydrogen coinjection, which is currently under development, is important for suppressing the crack growth.

Hydrazine and Hydrogen Coinjection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors (VII) —Effects of Bulk Water Chemistry on ECP Distribution inside a Crack

Water chemistry in a simulated crack (crack) has been studied to understand the mechanisms of stress corrosion cracking in a boiling water reactor environment. Electrochemical corrosion potential (ECP) in a crack made in an austenite type 304 stainless steel specimen was measured. The ECP distribution along the simulated crack was strongly affected by bulk water chemistry and bulk flow. When oxygen concentration was high in the bulk water, the potential difference between the crack tip and the outside of the crack (ΔE), which must be one motive force for crack growth, was about 0.3V under a stagnant condition. When oxygen was removed from the bulk water, ECP inside and outside the crack became low and uniform and ΔE became small. The outside ECP was also lowered by depositing platinum on the steel specimen surface and adding stoichiometrically excess hydrogen to oxygen to lower ΔE. This was effective only when bulk water did not flow. Under the bulk water flow condition, water-borne oxygen caused an increase in ECP on the untreated surface inside the crack. This also caused a large ΔE. The ΔE effect was confirmed by crack growth rate measurements with a catalyst-treated specimen. Therefore, lowering the bulk oxidant concentration by such measures as hydrazine hydrogen coinjection, which is currently under development, is important for suppressing the crack growth.

Accumulation of uranium on austenitic stainless steel surfaces

The surface contamination by uranium in the primary circuit of PWR type nuclear reactors is a fairly complex problem as (i) different chemical forms (molecular, colloidal and/or disperse) of the uranium atoms can be present in the boric acid coolant, and (ii) only limited pieces of information about the extent, kinetics and mechanism of uranium accumulation on constructional materials are available in the literature. A comprehensive program has been initiated in order to gain fundamental information about the uranium accumulation onto the main constituents of the primary cooling circuit (i.e., onto austenitic stainless steel type 08X18H10T (GOSZT 5632-61) and Zr(1%Nb) alloy). In this paper, some experimental findings on the time and pH dependences of U accumulation obtained in a pilot plant model system are presented and discussed. The surface excess, oxidation state and chemical forms of uranium species sorbed on the inner surfaces of the stainless steel tubes of steam generators have been detected by radiotracer (alpha spectrometric), ICP-OES and XPS methods. In addition, the passivity, morphology and chemical composition of the oxide-layers formed on the studied surfaces of steel specimens have been analyzed by voltammetry and SEM-EDX. The experimental data imply that the uranium sorption is significant in the pH range of 4–8 where the intense hydrolysis of uranyl cations in boric acid solution can be observed. Some specific adsorption and deposition of (mainly colloidal and disperse) uranyl hydroxide to be formed in the solution prevail over the accumulation of other U(VI) hydroxo complexes. The maximum surface excess of uranium species measured at pH 6 (Γsample = 1.22 μg cm−2 U ≅ 4 × 10−9 mol cm−2 UO2(OH)2) exceeds a monolayer coverage.

445 火災加熱による建築部材の温度上昇抑制手法に関する研究(S40-2 火災科学とその応用(2),S40 火災科学とその応用)

It is very important to consider and plan the fire safety design of building components exposed to fire. Especially, the public often believe that timber buildings are unsafe in fires, because wood burns readily. This paper was focused on control of temperature rise within wooden elements during fire to limit the fire collapse risk of timber buildings. First of all, the incident heat flux to surface of steel specimen from a radiation panel was investigated. Next, the control effect of charring rates within wooden specimen by using the sprinkler system was examined. As a result, thickness and velocity of water film, charring rates under the condition that the surface of wooden specimen was covered with water film and so on were clarified.

Wear reduction mechanism of graphite and MoS 2 in epoxy composites

In order to overcome the shortcomings of present switch slide baseplates, a kind of epoxy composite was designed as lubricating coatings for switch slide baseplates. The wear tests of epoxy composite specimens paired with A36 steel specimens under air-lubricated condition were carried out on a ring–block wear tester typed M200. After the wear tests, the worn surfaces of steel specimens were examined by XPS and SEM. Furthermore, the wear reduction mechanism of graphite and MoS 2 was discussed. The results showed that the graphite in epoxy composite can reduce the friction coefficient effectively, and increase the wear resistance of the epoxy composite greatly. MoS 2 in epoxy composite is translated to MoO 3 during the wear tests. Consequently, the friction coefficient of the pair cannot be decreased because MoO 3 has not a layer structure. But MoS 2 can effectively improve the wear resistance of the composite through restraining the epoxy transfer from the surface of composite to the surface of A36 steel.

Tribochemical Conversions of Zinc Dialkyldithiophosphate (ZDDP) Under Extremely Different Pressure Conditions

The authors performed ball-on-disk and four-ball tests. The former gave much less severe conditions than the latter. A ZDDP-containing package, blended with a mineral base oil, was tested. Completely different mechanisms of ZDDP conversions were observed. During ball-on-disk tests, ZDDP undergoes partial tribochemical decomposition. It results in a modification of the surface of test specimens—organic compounds are produced and zinc atoms diffuse into the surface. During four-ball tests, advanced structural decomposition of ZDDP takes place—S and P take part in tribochemical reactions. Probably inorganic compounds are produced, whereas there is a lack of a layer of organic ones adsorbed on the surface. The generation of inorganic compounds results from chemical reactions of decomposed ZDDP with the surface of steel specimens as well as diffusion of some elements (e.g. S) into the surface. Good antiseizure properties of such inorganic structures help to improve the tribological characteristics under severe test conditions.

Stereoscopic Measurements of the Stretched Zone as an Independent Method for Metal Fracture Toughness Control

Methods and results of stereoscopic measurements of the geometrical parameters of the so-called "stretched zone" on the fracture surface of steel specimens tested for crack resistance are discussed. It has been found that in the temperature range of brittle fracture there is a linear correlation between the height of the stretched zone and the crack resistance. The main unique properties of the stretched zone are reported. It has been shown that statistical spread of results of measuring the geometrical parameters of the stretched zone are comparable to and even lower than the spread of results of determining steel crack resistance by standard methods.

Selective surface preoxidation to inhibit the corrosion of AISI type 316L stainless steel by liquid Pb17Li

This paper describes the formation of a ternary oxide coating on 316L stainless steel from the reaction of Pb17Li with the preoxidized surface of steel specimens. The preoxidized surfaces were prepared by heating 316L stainless steel specimens to 800°C in a controlled H 2/H 2O atmosphere (ratio 1000:1). The oxide layer before reaction with the Pb17Li was characterized as Mn 1.5Cr 1.5P 4. Analysis after reaction with Pb17Li indicated a LiMn 2O 4 structure with some of the manganese sites occupied by chromium. 316L specimens prepared with different oxide layer thicknesses, along with uncoated specimens, were corroded in the isothermal hot legs of two Pb17Li filled thermal convection loops. Post-test analysis of the specimens indicated that the oxide coated specimens had, on average, a thinner ferritic corrosion layer than the uncoated specimens. The coated specimens also showed areas with no ferritic corrosion layer.