Showing papers on "Carbon steel published in 2012"

Schinopsis lorentzii Extract As a Green Corrosion Inhibitor for Low Carbon Steel in 1 M HCl Solution

Abstract: The corrosion inhibition of low carbon steel in 1 M HCl solution with different concentrations of Schinopsis lorentzii extract was studied using Tafel extrapolation, linear polarization, and electrochemical impedance spectroscopy (EIS). It was found that Schinopsis lorentzii extract acted as slightly cathodic inhibitor and inhibition efficiencies increased with the increase of extract concentration. The adsorption of the molecules of the extract on the low carbon steel surface was in accordance with the Temkin adsorption isotherm. The results showed that Schinopsis lorentzii extract could serve as a corrosion inhibitor of the low carbon steel in hydrochloric acid environment.

The continuous strength method for structural stainless steel design.

Abstract: Current stainless steel design standards are based on elastic, perfectly plastic material behaviour providing consistency with carbon steel design expressions, but often leading to overly conservative results, particularly in the case of stocky elements. More economic design rules in accordance with the actual material response of stainless steel, which shows a rounded stress–strain curve with significant strain hardening, are required. Hence, the continuous strength method (CSM) was developed. The CSM replaces the concept of cross-section classification with a cross-section deformation capacity and replaces the assumed elastic, perfectly plastic material model with one that allows for strain hardening. This paper summarises the evolution of the method and describes its recent simplified form, which is now suitable for code inclusion. Comparison of the predicted capacities with over 140 collected test results shows that the CSM offers improved accuracy and reduced scatter relative to the current design methods. The reliability of the approach has been demonstrated by statistical analyses and the CSM is currently under consideration for inclusion in European and North American design standards for stainless steel structures.

Steel Corrosion Characterization Using Pulsed Eddy Current Systems

Abstract: A pulsed eddy current (PEC) system has been used to characterize atmospheric corrosion on steel samples. International Paint has supplied coated and uncoated mild steel (S275) samples with marine atmospheric corrosion (exposure time between 1 and 10 months). The PEC response due to corrosion is a complex mix of many factors, including conductivity, permeability and material thickness variation, which are all taken into account through experimental studies and the extraction of signal features. Considering the conductivity and permeability variation in the corrosion layer or the actual rust region, two time-domain features, each representing the conductivity and permeability, are extracted and used to characterize corrosion. The relationship between PEC features and exposure time has been derived, which can be useful for corrosion rate measurement and early-stage corrosion evaluation and prediction. In conclusion, PEC testing has the potential for corrosion characterization and monitoring in areas such as the marine industry.

Dual phase structure formed by partial reversion of cold-deformed martensite

Abstract: Effect of prior deformation and heating rate on the dual phase (DP) structure formed by partial reversion of cold-rolled martensite was investigated in a low carbon steel (0.15%C–1.0%Mn). The steel plate was quenched after austenitization to obtain full martensitic structure and then cold-rolled with varying reductions. The cold-rolled specimens were continuously heated at a slow (0.083 K/s) or fast (100 K/s) heating rate up to a temperature above A1 point to partially form reversed austenite. Increasing rolling reduction rate or lowering heating rate enhanced recrystallization on heating before the onset of reversion, while the undeformed martensite never caused recrystallization irrespective of heating rate. The matrix of DP structure was changed from tempered martensite to equiaxed ferrite through the recrystallization, which resulted in a large difference in the distribution of fresh martensite (reversed austenite). Tensile testing revealed that the excellent strength-elongation balance was obtained in the DP steel produced from undeformed martensite, while higher strength was realized in the steel with prior deformation. With increasing the rolling reduction and the heating rates, the grain size of recrystallized ferrite becomes finer and the tensile strength is more increased. It was also suggested that the competition between recrystallization and reversion during continuous heating could be predicted by the modified tempering parameter.

Susceptibility to interfacial failure mode in similar and dissimilar resistance spot welds of DP600 dual phase steel and low carbon steel during cross-tension and tensile-shear loading conditions

Abstract: The paper investigates the failure mode transition from interfacial to pullout in similar and dissimilar combinations of DP600 dual phase steel and low carbon steel (LCS) under tensile-shear (TS) and cross-tension (CT) loading conditions. In both CT and TS loading conditions, a transition in the failure mode from interfacial to pullout was observed with increasing fusion zone size beyond a critical value (DC). The tendency to fail in interfacial mode during the CT loading was increased in the order of LCS/LCS, DP600/LCS and DP600/DP600. It was shown that interfacial to pullout failure mode transition during the CT test is governed by the fracture toughness of the fusion zone and strength of the pullout failure location (i.e. heat affected zone). It was shown that increasing carbon equivalent of the fusion zone promoted interfacial failure mode in CT loading condition. The high carbon equivalent of DP600 steel led to formation of hard and brittle martensite, which in turn promotes crack propagation through fusion zone. In DP600/LCS combination, decreased carbon equivalent and fusion zone hardness through dilution with the LCS promotes pullout failure at smaller weld sizes. DC during the TS loading is increased in the order of DP600/LCS, LCS/LCS and DP600/DP600. No correlation between fusion zone carbon equivalent and the tendency to fail in IF mode during TS loading was found. Failure mode transition during the TS loading is controlled by hardness of fusion zone and stiffness of the joint. The lowest DC for DP600/LCS is a function of its high fusion zone hardness (in comparison to LCS/LCS combination) and its low stiffness (in comparison to DP600/DP600 combination).

New Amines for CO2 Capture. IV. Degradation, Corrosion, and Quantitative Structure Property Relationship Model

Abstract: Degradation of 22 compounds was evaluated in stainless steel batch reactors at 140 °C for 14 days under a pressure of 0.5 MPa (mixture of 75% CO2, 20% N2, and 5% O2). For each run, two corrosion coupons, one carbon steel (XC38) and one stainless steel (304Ti), were immersed in aqueous solutions of amines to determine corrosion due to degraded solutions. Two additional coupons were put in the vapor phase above solutions. At the end of the run, corrosion rates were evaluated through weight-loss measurements. The amounts of remaining starting material were determined with a quantitative gas chromatography method. Corrosion and degradation data were compared with those of a benchmark molecule (MEA, monoethanolamine), tested under the same conditions. Results indicate that some molecules are less corrosive and have a better chemical stability than MEA. In addition, a quantitative structure property relationship (QSPR) model was built that can be applied to predict compound degradation.

The effect of explosive welding parameters on metallurgical and mechanical interfacial features of Inconel 625/plain carbon steel bimetal plate

Abstract: Like all cladding methods, interfacial features dominate the ultimate mechanical and metallurgical behavior of explosive cladded samples. Therefore, knowing the effect of explosive welding parameters on interfacial characteristics can be helpful in adjusting the welding parameters to obtain final desired properties. The present study aims to relate the load ratio and standoff distance as two main explosive welding parameters to interfacial features of explosive cladded Inconel 625/plain carbon steel bimetal plate such as interfacial structure, interfacial local melting phenomenon, localization of plastic strain, hardness variation across the interface and adhesion strength. As the results indicate, low impact energies are accompanied by linear interfacial structure, and increasing the impact energy initiates the waves at the interface. However, excessive impact energies lead to spoiling the wavy structure locally. Moreover, by raising the impact energy through increasing the load ratio and standoff distance, the locally melted zones appear in the Inconel side in vicinity of the interface. Higher impact energies promote the continuity of these interfacial cast layers. Though chemical elements of two materials are mixed together in these regions, no sign of intermetallic compounds formation is observed. According to the obtained results, raising the impact energy localizes the plastic deformation of steel side, resulting in the formation of adiabatic strain bands (ASB). The microhardness profiles reveal the hardening effect of collision in the vicinity of the interface with the exception of samples where the localization of strain in steel side hinders the hardening effect. Furthermore, the results of the shear test show that adhesion strength possesses an optimum value versus the increment of impact energy. By raising the load ratio and the standoff distance, the adhesion strength improves, but applying excessive collision energies drops this value significantly.

Explosive welding of stainless steel–carbon steel coaxial pipes

Abstract: Bi-metallic corrosion resistant steel pipes were produced through explosive welding process. The weldability window of the stainless steel pipe (inner pipe) and the carbon steel pipe (outer pipe) was determined by the use of available semi-empirical relations. The impact velocity of the pipes as the most important collision parameter was calculated by the finite element simulation. Direct effect of the explosive mass reduction on the bonding interface of the pipes was studied. Optical microscopy study showed that a transition from a wavy interface to a smooth one occurs with decrease in explosive load.