Showing papers on "Carbon steel published in 2016"

Electrochemical and surface characterizations of morus alba pendula leaves extract (MAPLE) as a green corrosion inhibitor for steel in 1 M HCl

Abstract: Recently the researchers' attention has been directed toward using environmentally friendly corrosion inhibitors extracted from plant leaves for corrosion protection of steel structures against acidic environments. The objective of this study is using morus alba pendula leaves extract (MAPLE) as a new green corrosion inhibitor for carbon steel in 1 M HCl solution at different concentrations(0.1–0.4 g/L) and temperatures (25–60 °C). In addition, the effect of addition of potassium iodide (KI) to the MAPLE was studied. Electrochemical investigations were performed by electrochemical impedance spectroscopy (EIS) and polarization test. Also, surface characterizations were done on the steel panels exposed to 1 M HCl solutions containing MAPLE by atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FT-IR). The inhibitor adsorption/desorption behaviors in the 1 M solution was studied by UV–visible analysis. Results obtained from electrochemical measurements revealed that a high inhibition efficiency value of 93% was achieved in the presence of 0.4 g/L MAPLE at room temperature (25 °C). A synergistic effect was observed between KI and MAPLE with optimum concentration of 0.4 g/L MAPLE+ 10 mM KI. Adsorption of extract on the steel surface in the presence of KI resulted in an inhibition efficiency of 96%. The presence of flavonoids such as morusin, kuwanonC and kuwanonG, phenolic acids and pyrrole alkaloids in the MAPLE is responsible for its high inhibition efficiency in 1 M HCl solution on the steel surface. It was found that MAPLE acted as a mixed type corrosion inhibitor and the inhibition efficiency was increased by increasing the inhibitor concentration obeying a Langmuir adsorption isotherm.

Corrosion of steel in concrete structures

Abstract: At potentials and pH levels normally measured in the concrete, a protective passive layer forms on the surface of carbon steel. It is believed that this layer is an ultrathin (<10 nm) protective oxide or hydroxide layer that decreases the anodic dissolution rate to negligible levels. However, the partial or complete loss of the passive layer, known as depassivation, leads to active corrosion of steel bars. Loss of passivation of steel bars in concrete is caused by either chloride ions or carbonation exposure. The corrosive products of iron are expansive, and their formation can cause cracking and further deterioration in the concrete. This chapter discusses the basic and essential mechanisms of the corrosion of the reinforcing steel bars in a concrete environment.

Enhancing the Mechanical Properties and Formability of Low Carbon Steel with Dual-Phase Microstructures

Abstract: In the present study, a special heat treatment cycle (step quenching) was used to produce a dual-phase (DP) microstructure in low carbon steel. By producing this DP microstructure, the mechanical properties of the investigated steel such as yield stress, tensile strength, and Vickers hardness were increased 14, 55, and 38%, respectively. In order to investigate the effect of heat treatment on formability of the steel, Nakazima forming test was applied and subsequently finite element base modeling was used to predict the outcome on forming limit diagrams. The results show that the DP microstructure also has a positive effect on formability. The results of finite element simulations are in a good agreement with those obtained by the experimental test.

Cladding of low-carbon steel to austenitic stainless steel by hot-roll bonding: Microstructure and mechanical properties before and after welding

Abstract: The aim of this contribution was to study the performance of cladded low-carbon steel (ASTM A283 Grade C) to austenitic stainless steel (ASTM A240 type 316/AISI 316) using hot-roll bonding. The mechanical and metallurgical properties of the cladded steel have been investigated before and after welding. Three weld samples with different configurations are prepared from cladded materials and, then, these joined metals were studied. Results on the microstructure, microhardness and mechanical strength were reported. Experimental studies showed that austenitic stainless steel AISI 316 (clad layer) could be cladded to low-carbon steel A283 (parent metal) with a good quality of bonding by hot-roll bonding. The bond interface of the cladded metals indicated that there is an intermediate zone between the clad layer and parent metal with heterogeneous microstructures due to the carbon diffusion. It was also found that microhardness measured from the clad layer to the parent metal showed an abrupt change adjacent to the interface due to a coarse grained soft ferritic band near the interface with larger microhardness than the adjacent metals. Tensile results revealed that the bonding was acceptable in all weld samples. It was also observed in bending tests that interfaces of bonded samples were safely carried out for some welding configurations. Toughness strength of the cladded metals at a given test temperature was found significantly higher than that of parent plate alone because of the high impact toughness of austenitic stainless steel layer. Consequently, mechanical properties of the low-carbon steel can be improved by hot-roll bonding with austenitic stainless steel.

A Close-up of the Effect of Iron Oxide Type on the Interfacial Interaction between Epoxy and Carbon Steel: Combined Molecular Dynamics Simulations and Quantum Mechanics

Abstract: In the present study, the effect of different types of iron oxides, which naturally exist on steel substrate, on the interfacial interaction between an epoxy coating and a carbon steel substrate was studied at the molecular/atomic level by employing molecular dynamics (MD) simulations and quantum mechanics (QM) calculations. Three types of iron oxide, that is, ferrous oxide (FeO), ferric oxide (Fe2O3, hematite), and ferrous ferric oxide (Fe3O4, magnetite), were considered for modeling, and their binding energies were calculated and compared by altering the concentration of hydroxide groups on the surface. To probe the effect of curing agent on interfacial interactions, computations were performed for either uncured or aminoamide-cured epoxy resins. The effect of the acid–base properties of the iron oxide on the molecular bonding was theoretically investigated by imposing diverse iron hydroxide/oxide termination groups. Noticeably, MD and QM calculations confirmed rather well earlier experimental evaluatio...

A Fe-C Coated Long-Period Fiber Grating Sensor for Corrosion-Induced Mass Loss Measurement

Abstract: This Letter reports a Fe-C coated long period fiber gratings sensor with a grating period of 387±0.1 μm for corrosion monitoring of low carbon steel in a 3.5 wt. % NaCl solution. An LPFG sensor was first deposited with a 0.8 μm thick layer of silver (Ag) and then electroplated with a 20 μm thick Fe-C coating. The chemical composition of the Fe-C coating was designed to include the main elements of low carbon steel. The resonant wavelength of the coated sensor was correlated with the mass loss of steel over time. Test results indicated a corrosion sensitivity of 0.0423 nm per 1% mass loss up to 80% Fe-C mass loss and 0.576 nm per 1% mass loss between 80% and 95% Fe-C mass loss. The corrosion sensitivity of such a Fe-C coated LPFG sensor was a trade-off for the service life of the sensor, both depending on thicknesses of the inner silver layer and the outer Fe-C coating.