Low Carbon Steel Samples Research Articles

Effect of Ceramic Powder Coatings on Low Carbon Steel

Effect of ceramic powder coating on low carbon steel samples was presented. Electrostatic deposition method was used to produce ceramic coatings on low carbon steels. The coatings were fabricated over a range of temperatures (100℃ - 400℃). Detailed investigation on the corrosion behaviour, the hardness property and electrode potential of the fabricated and uncoated samples are reported. The ceramic materials used are locally available in Ondo-State Nigeria. The coating temperatures affect the rate of corrosion, the hardness property and the electrical resistivity of the coated steel sample. The sample coated at 300℃ with ceramic powder Y showed the best corrosion resistance in 0.5 M NaCl solution. The highest resistivity occurred in the sample coated at 300℃ with ceramic powder Z. All the samples coated with ceramic powder Y had better corrosion resistance in 0.5 M NaCl than the one coated by sample Z.

Stress state evaluation in low carbon and TRIP steels by magnetic permeability

Magnetic permeability is an indicative factor for the steel health monitoring. The measurements of magnetic permeability lead to the evaluation of the stress state of any ferromagnetic steel. The magnetic permeability measurements were conducted on low carbon and TRIP steel samples, which were subjected to both tensile and compressive stresses. The results indicated a direct correlation of the magnetic permeability with the mechanical properties, the stress state and the microstructural features of the examined samples.

Investigation of the Laser-Powder Cladding Effect on Steel Surface Hardening

The investigation was carried out in the laser-technological complex with the power up to 8 kW, ITAM SB RAS. An inert-gas jet was supplied coaxially with the beam. A protective nozzle from which gaseous Ar was injected was used to protect the hardening joint. The parameters of the laser hardening process with the surface alloying was optimized on the samples of low-carbon steel 20, construction steel 45, and spring steel 65G.Special cladding powders containing carbon, manganese, nickel, chromium, molybdenum, tungsten, silicon, boron, and nitrogen were chosen for laser-powder cladding. They are intended for cladding wear-resistant layers onto machine parts, tools and equipment operated under abrasion-wear conditions with moderate shock loading.It was found that an optimal radiation power was 2 kW. Extra water cooling of treated parts is unpractical during laser hardening because it did not improve the hardening effect. The best effect of surface alloying was reached when the powder of rapid tool steel Р6М5 was injected in the liquid metal pool. High hardness of the clad layer remained at further heating up to 550°C. The use of laser thermal treatment and laser-powder cladding provides thermal hardening and enables increasing hardness and hence wear resistance of low-carbon steel parts by 3 - 4 times, whereas the base part remains viscous.

Ultrasonic Investigation of the Effect of Carbon Content in Carbon Steels on Bulk Residual Stress

Formation of residual stress as a result of welding process is a familiar fact, but its relation with material composition is unknown. This study aims to investigate the effect of carbon content on welding residual stress in carbon steels. For this purpose, samples of ultra-low carbon interstitial free, low carbon and medium carbon steels are selected. Welding is performed as a beam on plate in spite of a joining process. Weld grooves are prepared at center of the rectangular samples. Automated submerged arc technique is preferred for welding process in order to ensure same welding parameters at each sample. Ultrasonic sound waves are used to determine residual stress. This non-destructive technique provides bulk residual stress which is average of shear and normal stresses through thickness of a material. A new approach is practiced to verify experimentally determined bulk residual stress with finite element simulation results. The model geometry of numerical analysis is divided into equivalent parts and average of shear and normal stresses is calculated. Non-destructive ultrasonic technique seems to be in good agreement with finite element analysis.

CO2 Corrosion in the Region Between the Static and Turbulent Flow Regimes

This paper discusses the influence of the flow of a fluid from the static regime to the turbulent in CO2 corrosion experienced by low carbon steel. A more comprehensive approach to CO2 corrosion implies taking the free flowing velocity and shear stress of the fluid and the surface roughness of the material into consideration. Low carbon steel samples in two different superficial finish conditions were used as the rotating cylinder electrode. The corrosion rate were determined by linear polarization at 25 °C in a 0.5 mol/L NaHCO3 solution purged with CO2 at 1 atm pressure in pH 7.5. The effect of superficial finish on CO2 corrosion in flow conditions was studied. The results obtained showed that the corrosion rate increases with flow velocity and is influenced by surface roughness.

Localized Surface Modification on 1018 Low-Carbon Steel by Electrolytic Plasma Process and its Impact on Corrosion Behavior

Electrolytic plasma process (EPP) was applied on 1018 low-carbon steel sample surfaces and tested in a 3.5% NaCl solution. The treatment details of the EPP were described, and the test results indicate the improvement in corrosion rate, and localized corrosion was due to the unique surface features resulting from the EPP treatment. The corrosion protections show a sustainable consistency for EPP-treated samples in a 48 h immersion test. SEM (with FIB) and XRD were used to characterize the surface features. Potential polarization and cyclic voltammetry were performed for corrosion evaluations.

Microstructure and texture evolution in low carbon steel deformed by differential speed rolling (DSR) method

The study examined the microstructural and textural evolution of low carbon steel samples fabricated using a differential speed rolling (DSR) process with respect to the number of operations. For this purpose, the samples were deformed by up to 4-pass of DSR at room temperature with a roll speed ratio of 1:4 for the lower and upper rolls, respectively. The DSR technique applied to low carbon steel samples resulted in a microstructure composed of ultrafine ferrite grains, approximately 0.4 µm in size, after 4-pass with a high-angle grain boundary fraction of ~65 %. The microstructural features of the ferrite phase indicated the occurrence of continuous dynamic recrystallization, beginning with the formation of a necklace-like structure of ultrafine equiaxed grains around the elongated grains, which were formed in the early stages of deformation, and ending with ultrafine recrystallized grains surrounded by boundaries with high angles of misorientations. In the pearlite phase, the microstructural changes associated with DSR deformation were presented by the occurrence of bending, kinking, and breaking of the cementite lamellar plates. In addition, the evolution of texture after DSR processing was affected by shear deformation and rolling deformation, leading to the formation of a texture composed of fractions of components with shear texture orientations such as {110} 〈001〉 (Goss) and orientations close to {112} 〈111〉, in addition to rolling texture components consisting mainly of α-fiber and γ-fiber.

Crack Healing in a Low-Carbon Steel Under Hot Plastic Deformation

The behavior of internal crack healing in low-carbon steel samples undergoing hot plastic deformation was investigated using the MMS 200 thermo-mechanical simulator. The characterization of cracks after plastic deformation was analyzed using scanning electron microscopy under different heating temperatures, reduction ratios, numbers of deformation passes, strain rates, and holding time durations. It was found that the degree of crack healing increases with increasing heating temperature, reduction ratio, and holding time duration, and with decreasing number of deformation passes and strain rate.

Characterization of Hybrid Sol-Gel Coatings Doped with Hydrotalcite-likeCompounds on Steel and Stainless Steel Alloys

Hybrid sol-gel organic-inorganic coatings have been extensively studied to their active properties to protect different metal surfaces. Incorporation of non-hydrolysable groups in conjunction with different molar ratio of sol-gel precursors dissolved in distinct solvents lead to an increment of better protective barrier properties. Different hybrid silica sol-gel coatings were prepared changing the type and content of solvent (2-propanol, ethylacetate, ethanol). Coatings were deposited by dip-coating method on AISI 304 stainless steel and low carbon steel. Incorporation of ethyl acetate in the sol-gel formulation provided the best results on low carbon steel whereas 2-propanol resulted adequate for stainless steel by means of electrochemical impedance (EIS) characterization. In addition, EIS showed a marked improvement of the corrosion resistance when hydrotalcite particles were incorporated into the coating. Scanning electron microscopy (SEM) revealed homogeneous coating deposition for low carbon steel samples. However, stainless steel samples developed cracks along the sol-gel coating.

Application of CGP-cross route process for microstructure refinement and mechanical properties improvement in steel sheets

A modified method of severe plastic deformation (SPD) entitled constrained groove pressing-cross route (CGP-CR) was introduced for imposing a high magnitude of equivalent strain of about 2.32 per pass on the sheet form samples. The major benefit of this improved route compared to previous common route was the more homogeneity of strain in the rolling (RD) and transverse (TD) directions of sheets. In this study, low carbon steel samples were used for examination of evolutions in microstructure and mechanical properties during SPD via CGP-CR process. Mechanical properties improvement were measured by tensile and macro hardness tests. The results indicate that CGP-CR process can effectively improve tensile strength; and also, yield stress and hardness of as-received low carbon steel samples were improved up to about 100% after two deformation passes. Also, high magnitude of inhomogeneity can be observed in hardness distribution through first pass of the process which diminishes in the subsequent passes. Microstructural evolutions during process were monitored by optical microscopy observations and X-ray diffraction analysis. The results demonstrate that initial ferritic microstructure with grain size of about 30μm was refined to a 225nm cell structure after two passes of CGP-CR process.

Effect of Heat Treatments on Corrosion of Welded Low-Carbon Steel in Acid and Salt Environments

Effect of heat treatment on the corrosion of welded low-carbon steel in 0.3 M and 0.5 M of hydrochloric acid and sodium chloride environments at ambient temperature (25oC) has been investigated. Arc welded low-carbon steel sample of known composition were subjected to the corrosion reagents for 21 days (504 hours). pH and weight loss values were taken at interval of 3 days. Thereafter, weight loss method was used to measure therate of corrosion attack on the heat treated samples at ambient temperature. Results obtained showed that at low concentration, the annealed sample exhibits better corrosion characteristic as compared to the normalized and quenched samples. However, at higher concentration the normalized sample exercised better service performance over the annealed and quenched samples. Thequenched sample was found to have relatively low corrosion performance over the annealed and normalized samples at both low and high concentrations of the media.

Hall–Petch and dislocation strengthening in graded nanostructured steel

The structure and strength of low carbon steel samples have been analyzed after plastic deformation by shot-peening and cold-rolling. The fine scale surface microstructure caused by shot-peening extends to ∼50μm below the surface. The structure is graded and subdivided by dislocation boundaries and high angle boundaries showing a clear resemblance to the lamellar structure, which evolves during conventional rolling of bulk metallic materials from medium to high strain. As the surface is approached, the boundary spacing decreases to ∼50nm at the surface. In parallel, the misorientation angle across boundaries increases to ∼65% of high angle boundaries. The cold-rolled steel shows a low hardening rate at high strain and by assuming additive strength contributions from Hall–Petch and dislocation strengthening, the flow stress has been expressed by the relationship σ-σ0=k2Dav-0.5, where Dav is the average spacing between the low and high angle boundaries which subdivide the microstructure, σ0 is the friction stress and k2 is a number which is expressed in terms of structural parameters which have been determined by electron backscattered diffraction. It is found that calculated k2 values are in accord with an experimental value of 310MPaμm0.5. In the shot-peened steel the increase in Dav with increasing distance from the surface is transformed into a stress profile based on the σ-Dav relationship established for cold-rolled bulk samples. The calculated stress profile is validated by comparison with the experimental profile based on hardness measurements, and good agreement is found. This result points to a wider application of the suggested method to derive the local flow stress in a deformed microstructure based on a measurement of the local boundary spacing and the stress–structure relationship for the bulk material in the deformed state.

Coated Steel Surfaces with WC by Lasers Action

In this work low carbon steel samples were coated by tungsten carbide (WC), and then the properties of the obtained coatings were evaluated, such as morphology, hardness, phase composition and dimension of the layer. The results indicate the formation of a new phase, composed of iron carbide in the base metal, a more dense coating has been obtained when the WC powder was sprayed directly on to the steel and then irradiated with the laser beam.

Conducting polyaniline based paints on low carbon steel for corrosion protection

Conducting polyaniline powder was synthesized chemically and paints containing conducting polyaniline powder were applied on low carbon steel samples. The conducting polyaniline powder was characterized by UV-Visible absorption spectroscopy and the morphology of paint coating on low carbon steel was studied by scanning electron microscopy. The corrosion protection performance of the coating was evaluated by using potentiodynamic polarization techniques and electrochemical impedance spectroscopy. It has been found that the 2 wt % polyaniline-hydrochloric acid based paint coating offers maximum corrosion protection to low carbon steel in chloride medium.

Effect of bimodal distribution in ferrite grain sizes on the tensile properties of low-carbon steels

In order to understand the effect of grain size bimodality on the tensile properties, low-carbon steel samples having bimodal ferrite grain size distributions, with different coarse-grain sizes (15–54 μm), fine-grain sizes (2.4–13.0 μm) and coarse-grain fractions (0.10–0.45) have been tensile tested. Samples having bimodal grain structures showed lower strength (UTS: 395–744 MPa), better tensile ductility (eu: 8.5–19.4%) and lower YS to UTS ratio (0.63–0.84) than the ultra-fined grained steel (UTS = 900 MPa, eu = 5%, and YS:UTS = 0.93). In case of mixed grain structures, effective grain size (Deff), numerical average grain size (Davg) and the average grain size in the fine-grain regions (Df) showed better correlation with strength (i.e. strength ∝ D−1/2) than the weighted average grain size (Dwt). Coarse-grain sizes in the range of 15–35 μm and fraction of the coarse-grain regions in the range of 15–35% can be recommended for achieving the best tensile ductility. Measurement of micro-hardness and the change in grain aspect ratios from the coarse- and fine-grain regions indicated that the bimodal grain structure can be considered as a composite structure, where stress and strain vary between the coarse- and fine-grain regions. Lower nucleation and higher growth of the voids in the carbide-depleted, coarse-grain regions (than carbide-rich, fine-grain regions) allow higher plastic deformation till fracture and improve the total-elongation of the steels.

Strain Localizations in Ultra Low Carbon Steel

Ultra low carbon (ULC) steel samples were deformed in near plane-strain compression mode with different strains, strain rates and temperatures. Different aspects of microstructural developments, for deformed γ (ND//) and θ (ND//) fibre grains, were investigated using X-ray line profiles and high resolution electron diffraction. The study clearly showed increase in grain interior strain localizations and in-grain misorientation at the intermediate deformation temperature. This effect was more apparent in γ-fibre and can best be explained through orientation sensitive recovery. γ-fibre also demonstrated higher potential for increase in dislocation density. This was observed experimentally and simulated through discrete dislocation dynamic simulations. Higher textural softening with stronger increase in dislocation density and possible effects of orientation sensitive recovery appears to define the orientation dependent recovery in low carbon steels.

Influence of cold deformation and aging on the relaxation of strengthened low-carbon steel

Attention focuses on relaxation phenomena, including the rate of stress relaxation in the uniaxial extension of low-carbon steel samples strengthened by cold deformation (extension and torsion) with subsequent aging to 400°C. The relaxation effects that arise with identical and different loading configurations in the strengthening treatment and in relaxation tests are discussed.

The Surface Weak Magnetic Signals of Low Carbon Steel under Cyclic Loads

The magnetization induced by applied cyclic stresses on low carbon steel samples was studied through experiments by using a high sensitive magnetic sensor. The stress-magnetic coupling under cyclic tensile stress was researched during static, cyclic and fatigue loading process respectively. The results indicate the consistency and also some contradiction with existing conclusions of metal magnetic memory theory or magneto-mechanical researches. It is put forward that the stress induce magnetization is dependent on both applied stress and micro structure abnormality in ferromagnetic materials. Then the potential applications of the stress-magnetic coupling behavior were proposed.

Effect of coal slurry on the corrosion of coal-mine equipment

The corrosion of coal mine equipment immersed in coal slurry is addressed. The corrosion of low carbon steel samples immersed in coal slurries of different concentrations (80, 130, and 180 g/L) prepared from coals of different rank (long-flame coal, meager lean coal, and anthracite) and different granularity (0.25–0.5 mm, 0.074–0.25 mm, and less than 0.074 mm particle size) was studied by the electrochemical method of polarization curve measurement, controlled potential sweeping, and continuous scanning. The results show that the corrosion rate in an anthracite slurry, where the coal has high coalification, is far greater than corrosion in a long-flame or a meager lean coal slurry. Furthermore the corrosion current, polarization current, and corrosion rate of low carbon steel become larger, and the polarizability becomes smaller, as the coal particle size decreases. The same trend is seen as the concentration of the coal slurry increases.

An alternative to kinematic hardening in classical plasticity

In this work, an approach is proposed for the description of the plastic behavior of materials subjected to multiple or continuous strain path changes. In particular, although it is not formulated with a kinematic hardening rule, it provides a reasonable description of the Bauschinger effect when loading is reversed. This description of anisotropic hardening is based on homogeneous yield functions/plastic potentials combining a stable, isotropic hardening-type, component and a fluctuating component. The latter captures, in average, the effect of dislocation interactions during strain path changes. For monotonic loading, this approach is identical to isotropic hardening, with an expanding isotropic or anisotropic yield surface around the active stress state. The capability of this constitutive description is illustrated with applications on a number of materials, namely, low carbon, dual phase and ferritic stainless steel samples.