Showing papers on "Carbon steel published in 2019"

Stability and design of stainless steel structures – Review and outlook

Abstract: This paper provides a review of recent developments in research and design practice surrounding the structural use of stainless steel, with an emphasis on structural stability. The nonlinear stress-strain characteristics of stainless steel, which are discussed first, give rise to a structural response that differs somewhat from that of structural carbon steel. Depending on the type and proportions of the structural element or system, the nonlinear material response can lead to either a reduced or enhanced capacity relative to an equivalent component featuring an elastic, perfectly plastic material response. In general, in strength governed scenarios, such as the in-plane bending of stocky beams, the substantial strain hardening of stainless steel gives rise to capacity benefits, while in stability governed scenarios, the early onset of stiffness degradation results in reduced capacity. This behaviour is observed at all levels of structural response including at cross-sectional level, member level and frame level, as described in the paper. Current and emerging design approaches that capture this response are also reviewed and evaluated. Lastly, with a view to the future, the application of advanced analysis to the design of stainless steel structures and the use of 3D printing for the construction of stainless steel structures are explored.

Myristic acid based imidazoline derivative as effective corrosion inhibitor for steel in 15% HCl medium.

Abstract: There is a high demand of effective and eco-friendly corrosion inhibitor for industrial applications. In an attempt to prepare a benign and effective corrosion inhibitor for acidizing purpose, an imidazoline derivative, N-(2-(2-tridecyl-4,5-dihydro-1H-imidazol-1-yl)ethyl)tetradecanamide (NTETD) was synthesized from myristic acid and diethyleneamine. The characterization of the newly synthesized compound was done using 1H NMR, FTIR, and elemental analysis techniques. NTETD was examined as a corrosion inhibitor for low carbon steel in 15% HCl solution using weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), linear polarization (LPR), scanning electron microscope (SEM), energy dispersive spectroscopy (EDAX), atomic force spectroscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques. It was found that, the optimum concentration of NTETD is 300 mg/L. With this concentration, inhibition efficiency above 93% is achievable. Results from PDP show that, NTETD acted as a mixed type corrosion inhibitor but with principal effect on cathodic corrosion half reactions. The calculated value of the adsorption-desorption equilibrium constant (1.015 × 103) reveals a strong bonding between NTETD molecules and the steel surface. The EDAX, FTIR, and XPS results confirm the adsorption of NTETD molecules on the steel surface. SEM and AFM results agree with experimental findings that NTETD is effective in corrosion mitigation of steel in 15% HCl solution. The possible corrosion inhibition mechanism by NTETD has been proposed.

N, S co-doped carbon dots as effective corrosion inhibitor for carbon steel in CO2-saturated 3.5% NaCl solution

Abstract: N and S co-doped carbon dots (N, S-CDs) were synthesized and used as corrosion inhibitors for the first time in this study. The inhibition performance of N, S-CDs for carbon steel in CO2-saturated NaCl solution was investigated. Results showed that N, S-CDs can effectively protect carbon steel from corrosion and the inhibition efficiency increases as the concentration of N, S-CDs increases, reaching 93% at 50 mg/L. Even at the low concentration, such as 10 mg/L N, S-CDs, the corrosion current density reduces from 1.472 × 10−4 A·cm−2 in the blank condition to 2.99 × 10−5 A·cm−2 after 12 h immersion. N, S-CDs can adsorb on carbon steel through their functional groups and nanoparticles made up of N, S-CDs can form a hydrophobic film on the metal surface, whose thickness was about 40 nm. A theoretical model is established to describe the inhibition mechanism of N, S-CDs.

AEO7 Surfactant as an Eco-Friendly Corrosion Inhibitor for Carbon Steel in HCl solution

Abstract: The impact of AEO7 surfactant on the corrosion inhibition of carbon steel (C-steel) in 0.5 M HCl solution at temperatures between 20 °C and 50 °C was elucidated using weight loss and different electrochemical techniques. The kinetics and thermodynamic parameters of the corrosion and inhibition processes were reported. The corrosion inhibition efficiency (IE%) improved as the concentration of AEO7 increased. In addition, a synergistic effect was observed when a concentration of 1 × 10−3 mol L−1 or higher of potassium iodide (KI) was added to 40 µmol L−1 of the AEO7 inhibitor where the corrosion IE% increased from 87.4% to 99.2%. Also, it was found that the adsorption of AEO7 surfactant on C-steel surface followed the Freundlich isotherm. Furthermore, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements indicated that AEO7 was physically adsorbed on the steel surface. The surface topography was examined using an optical profilometer, an atomic force microscope (AFM), and a scanning electron-microscope (SEM) coupled with an energy dispersion X-ray (EDX) unit. Quantum chemical calculations based on the density functional theory were performed to understand the relationship between the corrosion IE% and the molecular structure of the AEO7 molecule.

Detailed macro-/micro-scale exploration of the excellent active corrosion inhibition of a novel environmentally friendly green inhibitor for carbon steel in acidic environments

Abstract: An environmentally friendly green inhibitor based on Clove seed aqueous extract was applied for corrosion mitigation of mild steel (MS) surface in 1 M HCl solution. Applying integrated experimental (electrochemical combined with surface morphological) and theoretical (molecular simulation connected with density functional theory) techniques the Clove seed aqueous extract inhibition properties were examined. Through EIS and polarization methods the electrochemical characteristics were probed. Using scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle test the surface morphology of the un-inhibited and inhibited metal specimens was characterized. EIS analysis disclosed notable corrosion inhibition degree (93%) using 800 ppm Clove seed extract after 2.5 h metal immersion, which was ascribed to the inhibitor adsorption on the MS surface as evidenced by SEM micrographs. According to the polarization test results, the corrosion suppression occurred via retardation of combined cathodic and anodic reactions with small cathodic prevalence. The AFM photographs depicted that introducing 800 ppm Clove seed extract into corrosive media gave rise to more smooth steel surface. By following Langmuir adsorption isotherm the Clove seed extract molecules reacted with steel surface, resulting in steel coverage by a monolayer. To complement the experiments, detailed theoretical explorations at microscopic electronic and atomic levels were accomplished employing Monte Carlo (MC) in conjunction with molecular dynamics (MD) and electronic-structure density functional theory (DFT) to fundamentally examine the adsorption possibility and the reactive atomic regions of organic compounds of Clove seed extract playing crucial roles in metallic inhibition manner.

Epoxy pre-polymers as new and effective materials for corrosion inhibition of carbon steel in acidic medium: Computational and experimental studies.

Abstract: Present study is designed for the synthesis, characterization and corrosion inhibition behavior of two diamine aromatic epoxy pre-polymers (DAEPs) namely, N1,N1,N2,N2-tetrakis (oxiran-2-ylmethyl) benzene-1,2-diamine (DAEP1) and 4-methyl-N1,N1,N2,N2-tetrakis (oxiran-2-ylmethyl) benzene-1,2-diamine (DAEP2) for carbon steel corrosion in acidic medium. Synthesized DAEPs were characterized using spectral (Nuclear magnetic resonance (1H NMR) and Fourier transform infrared-attenuated total reflection (FTIR-ATR)) techniques. Viscosity studies carried out at four different temperatures (20–80 °C) increase in temperature causes significant reduction in their viscosities. The anticorrosive properties of DAEPs differing in the nature of substituents, for carbon steel corrosion in 1 M HCl solution was evaluated using several experimental and computational techniques. Both experimental and computational studies showed that inhibitor (DAEP2) that contains electron releasing methyl (-CH3) showed higher protectiveness as compared to the inhibitor (DAEP1) without substituent (-H). Electrochemical results demonstrate that DAEPs act as reasonably good inhibitors for carbon steel in 1 M HCl medium and their effectiveness followed the sequence: DAEP2 (92.9%) > DAEP1 (91.7%). The PDP results show that the diamine aromatic epoxy pre-polymers molecules (DAEPs) act as mixed type inhibitors. Electrochemical study was also supported using scanning electron microscopy (SEM) method were significant improvement in the surface morphology of inhibited (by DAEPs) metallic specimens was obtained. Results derived from computational density functional theory (DFT) and molecular dynamics (MD) simulationsand studies were consistent with the experimental results derived from SEM, EIS and PDP electrochemical studies. Adsorption of the DAEPs obeyed the Langmuir adsorption isotherm model.

Intermetallic compounds (IMCs) formation during dissimilar friction-stir welding of AA5005 aluminum alloy to St-52 steel: numerical modeling and experimental study

Abstract: In this research, AA5005-O aluminum-magnesium alloy and St-52 low carbon steel sheets were friction-stir welded in a butt-dissimilar joint design. Effects of different processing parameters including tool rotational speed (w), traverse velocity (v), plunge depth, and offset distance on the solid-state weldability of these dissimilar materials were assessed in terms of formation of intermetallic compound (IMC) layer at the interface. A 3D thermo-mechanical finite element modeling procedure was employed to predict the nucleation and growth of IMC layer. Formation of various FeAl, FeAl3, and Fe2Al5 IMCs at the interface, layer morphology, and thickness were experimentally studied as well, by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis techniques. A good agreement between the simulated thermal results and experimental data was noticed. The results showed that the thickness of IMC layer at the interface as the main controlling parameter in transverse tensile property and fracture behavior of produced dissimilar joints can be varied extremely as a function of processing parameters. By decreasing the heat input and suppressing the kinetics of IMCs layer formation, the tensile performance of dissimilar welded joints is improved, considerably. However, the soundness of these dissimilar welds played another main role as a restriction mechanism against this trend. The maximum joining efficiency is attained around 90% at an optimized working window of w = 1200 rpm, v = 90 mm/min, and a plunge depth of 0.3 mm with an offset distance of 0.5 mm toward the Al side. The hardness of this optimized dissimilar weld is enhanced even more than the steel base metal caused by the formation of IMC layer at the interface as well as the dispersion of reinforcing intermetallic particles (IMPs).

Experimentally validated predictions of thermal history and microhardness in laser-deposited Inconel 718 on carbon steel

Abstract: Process−property relationships in additive manufacturing (AM) play critical roles in process control and rapid certification. In laser-based directed energy deposition, powder mass flow into the melt pool influences the cooling behavior and properties of a built part. This study develops predictive computational models that provide the microhardness of AM components processed with miscible dissimilar alloys, and then investigates the influence of varying process parameters on properties in experiments and modeling. Experimentally-determined clad dilution and microhardness results of Ni-based superalloy Inconel 718 clads deposited onto 1045 carbon steel substrates are compared to the values from a computational thermo-fluid dynamics (CtFD) model. The numerical model considers the fluidic mechanisms of molten metal during powder deposition and the resulting transient melt pool geometry changes. The model also handles the change in thermo-physical properties caused by the composition mixture between the powder and substrate materials in the melt pool. Based on the computed temperature and velocity distributions in the melt pool, cooling rate, dilution of the melt pool and microhardenss are evaluated. The capability to predict thermal histories in such models is calibrated and validated with experimental thermal imaging and microstructures of additive manufactured clads. In addition, the roles of cooling rate and alloy composition on the microhardness are examined. The results show that variation in microhardness is dominated by composition mixture between the powder and substrate materials, rather than cooling behavior or dendrite arm spacing at liquid-solid interface in laser deposited Inconel 718 on AISI 1045 carbon steel.

An Investigation into Quantum Chemistry and Experimental Evaluation of Imidazopyridine Derivatives as Corrosion Inhibitors for C-Steel in Acidic Media

Abstract: The corrosion inhibition performance of two imidazopyridine derivatives, namely 6-nitroso-2-phenylimidazo[1,2-a]pyridine-3 carbaldehyde (C1) and (2-phenylimidazo[1,2-a]pyridin-3-yl)methanol (C2) for carbon steel in 1.0 M hydrochloric acid solution, was evaluated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and quantum chemical calculations. The surface morphology was examined using Scanning Electron Microscopy (SEM). Imidazopyridine derivatives adsorbed onto the carbon steel surface via mixed types of adsorption with predominantly chemisorption obeying Langmuir adsorption isotherm. DFT computational chemistry at B3LYP/6-31G(d,p) basis set level was applied in order to correlate some electronic properties of tested molecules to the inhibition efficiencies obtained from experimental data. The computed Fukui functions have been useful to predict the reactive sites of nucleophilic and electrophilic attacks.

Comparative Corrosion Behavior of Five Microstructures (Pearlite, Bainite, Spheroidized, Martensite, and Tempered Martensite) Made from a High Carbon Steel

Abstract: The present work discusses the comparative corrosion behavior of five microstructures of steels, namely, pearlite, bainite, spheroidized, martensite, and tempered martensite, which have been processed, respectively, by air cooling, isothermal transformation, spheroidizing, quenching, and tempering of a steel with composition 0.70C, 0.24Si, 1.12Mn, 0.026P, 0.021S, 0.013Nb, 0.0725Ta, and 97.7Fe (all are in wt pct). Dynamic polarization and alternating current (AC) impedance spectroscopic tests in freely aerated 3.5 pct NaCl solution show that the corrosion resistance of the steel specimens consisting of the preceding five microstructures decreases in the following sequence: pearlitic – bainitic – spheroidized – martensitic – tempered martensitic steels. The variation in the corrosion rate has been attributed to the shape, size, and distribution of the ferrite and cementite.