Carbon Steel Rods Research Articles

Study of the Tempcore Process for the Production of High Resistance Reinforcing Rods

The process known as Tempcore is used to produce high resistance rods by the formation of a surface layer of quenched and tempered martensite that surrounds a core made of ferrite and pearlite. Such a mixed structure is result of processing hot rolled rods through waters headers that reduce the temperature at the surface below that for the transformation into martensite. This structure is tempered by the heat flowing from the core of the rod, which transforms into ferrite and pearlite while the rod is in the cooling beds. Such processing produces a significant increase in yield and ultimate tensile strength, while maintaining adequate ductility. The economic advantages of this process are huge in comparison with those that require alloying elements or further metal working to improve mechanical properties. A series of experimental trials were carried out in a pilot plant in which parameters such as reheating temperature, water flow and processing time were varied to study their effect on the mechanical properties of carbon steel rods and on the structures formed in the bars. The study is being complemented by the thermal modelling by the finite element method.

Effect of warm cross-wedge rolling on microstructure and mechanical property of high carbon steel rods

High carbon steel rods with a microduplex structure was fabricated by warm cross-wedge rolling (WCWR) using fully lamellar pearlite starting material. The microstructures and mechanical properties at different locations over the cross-section of the rolled rod were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and mini-tensile tests. The results show that after WCWR, the microstructure from the surface to 1/4 R of the rod was refined, and the sizes of cementite particles and equiaxed ferrite grains were about 0.1–0.2 and 0.3–0.4 μm, respectively. The spheroidization/recrystallization of cementite/ferrite was non-uniform from the surface to the center, and the cementite/ferrite near the surface experienced more complete spheroidization/recrystallization. After WCWR, the change in strength and microhardness over the cross-section of the rod was not so distinct from the surface to the center. However, the elongation (EL) and the percentage of reduction in area (RA) of the rod decreased gradually from the surface to the center. This change can be linked to the non-uniform distribution of equivalent strain and strain rate, which also decreased from the surface to the center.

Examination of the influence of boron on the microstructure and properties of low C ferritic steels using NanoSIMS and TEM

In order to understand the influence of boron on the grain size and microstructure of a series of low carbon steel rods the imaging of elemental distributions of B, N and C has been undertaken using Cameca NanoSIMS 50. This instrument provides the high sensitivity, spatial and mass resolution required for the identification of small precipitates and segregation of light elements that are traditionally difficult to study by other micro-analytical techniques. However, the use of NanoSIMS to investigate metallurgical problems is complicated by matrix effects. This leads to changes in ionization yield and variable sputter rates due to the matrix composition. In order to help overcome this problem, the results from the sequential characterisation of exactly the same area of a sample using first transmission electron microscopy (TEM) and then NanoSIMS will be described. This permits the direct comparison of sensitivity and spatial resolution on precisely the same individual particles, which can help us determine the most efficient characterisation strategy.

Identification and formation of green rust 2 as an atmospheric corrosion product of carbon steel in marine atmospheres

AbstractGreen rust 2 (GR2(SO2−4 )) was detected amongst the products formed on a carbon steel rod exposed to atmospheric corrosion using X‐ray diffraction (XRD). The presence of green rust 2 has been related to sulphate reducing bacteria (SRB) in the sea spray. These were detected using test catch rods made out of inert material and posterior lab identification using Starkey culture. Likewise, after the exposure of said rods to sea environmental conditions, SRBs have been isolated from among the carbon steel corrosion products. The evolution of GR2(SO2−4 ) from GR1(SO2−4 ) was ruled out due to the tendency of this compund to produce GR2(SO2−4 ) in the presence of sulphate ions, as is the case here. Likewise, the evolution from GR1(Cl−) has also been ruled out since in such case as this compound should be formed (it has not been detected in any of the 39 stations studied), the enormous affinity of the GRs with divalent anions (such as is the case with SO2−4 ) as opposed to the monovalent ions (such as is the case of the Cl−) makes GR1(Cl−) transform into GR2 (SO2−4 ).

Effect of Sample Geometry on Regression Rate of the Melting Interface for Carbon Steel Burned in Oxygen

Abstract Promoted-ignition testing on carbon steel rods of varying cross-sectional area and shape was performed in high pressure oxygen to assess the effect of sample geometry on the regression rate of the melting interface. Cylindrical and rectangular geometries and three different cross sections were tested and the regression rates of the cylinders were compared to the regression rates of the rectangular samples at test pressures around 6.9 MPa. Tests were recorded and video analysis used to determine the regression rate of the melting interface by a new method based on a drop cycle which was found to provide a good basis for statistical analysis and provide excellent agreement to the standard averaging methods used. Both geometries tested showed the typical trend of decreasing regression rate of the melting interface with increasing cross-sectional area; however, it was shown that the effect of geometry is more significant as the sample's cross sections become larger. Discussion is provided regarding the use of 3.2-mm square rods rather than 3.2-mm cylindrical rods within the standard ASTM test and any effect this may have on the observed regression rate of the melting interface.

A FEM model of conventional hot dipping coating process by using a fluidized bed

A FEM model of a conventional hot dipping fluidized bed (FB) coating process on a low carbon steel rod using a PPA thermoplastic powder was developed. Two computational domains, the former for the metal substrate and the growing coating and the latter for fluidized bed emulsion nearby the metal substrate were set. A novel recursive procedure was employed to solve the ‘coupled’ thermal problem. Besides, realistic values of polymer thermal properties according to temperature as well as the whole curve of polymer enthalpy were input to the model so as to increase its reliability. As a result, consistent trend of coating thickness and growth rate according to dipping time with experimental data and theoretical considerations were calculated. Moreover, the calibration procedure of FEM model took to realistic values of heat transfer coefficient according to preheating temperature of substrate as the comparisons with available experimental data confirm. At last, dimensionless analysis stated once more the FEM model reliability by comparing the numerical findings with those of pioneer models available in literature.

Effect of cassava fluid on corrosion performance of mild steel

PurposeThe cheapest and most rapidly available metal for agro‐processing equipment fabrication in Nigeria is plain carbon steel. However, there are some aggressive ions present in raw agricultural and food products, which may attack the steel components of these processing machinery, resulting in their untimely failure in service. The present study investigates the effect of fluid squeezed from cassava tuber on the corrosion behaviour of mild steel.Design/methodology/approachThe investigation involved periodic weight loss measurements of 0.8 per cent carbon and 0.36 per cent carbon steel rods as they were exposed to cassava fluid. The relationships between loss in weight of the exposed samples and exposure period were determined. Models were developed to relate corrosion rate in each environment with total surface area and exposure period.FindingsThe results show that 0.36 per cent carbon steel was less affected by corrosion than 0.18 per cent carbon steel, with corrosion intensity in both cases, increasing with duration of immersion. Generally, there was low level of corrosion resistance (high corrosion rate) by the two steel materials. The correlation coefficient between the experimental values of corrosion rates and predicted values (using the developed models) was high.Originality/valueIn food and agricultural industries, product quality, health and sanitation issues are the major concerns. The industries cannot tolerate corrosion deposits in the manufactured products. Hence, material selection for machinery fabrication is essential. In line with this, the results of this study indicate that mild steel materials are unsuitable for use in cassava processing without some forms of surface treatment.

Microstructure characteristics in high carbon steel rod after warm cross-wedge rolling

Abstract An ultrafine ( α + θ ) structure is successfully produced through warm cross-wedge rolling at the outer layer of high carbon steel rod where equiaxed α grains and fully spheroidized θ particles are in submicron scale. In the central region of the rod, original lamellar θ is fragmented but the spheroidization is not complete.

Electrostatic fluidized bed deposition of a high performance polymeric powder on metallic substrates

The electrostatic fluidized bed deposition of a single-layer PPA 571 coating onto low carbon steel rods is reported.A full factorial experimental design was developed in order to study the influence of several operative variables on the effectiveness of the coating process and on the coating thickness and uniformity. The operative variables included exposure time, air flow, the applied voltage, attitude, and the radial and vertical location of the work-piece in the fluid bed. After the experimentation, several process maps were developed as a support to identify the best way to lead the coating process. Finally, by using a statistical approach, the reliability and repeatability of the coating process was also established.Experimental trends were consistent with theoretical expectation. A significant growth in achievable coating thickness was obtained by increasing voltage and air flow. Furthermore, at higher values of exposure time and applied voltage, relevant back ionization phenomena occurred, which simultaneously caused a top limit in coating thickness and a worsening of surface finishing.Process characteristics, leading mechanisms, and some practical aspects are also discussed in detail.

Inverse Heat Transfer Solution of the Heat Flux Due to Induction Heating

The explicit finite difference formulation of an inverse heat transfer model to calculate the heat flux generated by induction is developed. The experimentally measured temperature data are used as the input for the inverse heat transfer model. This model is particularly suitable for a workpiece with low cross section Biot number. Induction heating experiments are carried out using a carbon steel rod. The finite difference method and thermocouple temperature measurements are applied to estimate the induction heat flux and workpiece temperature. Compared to measured temperatures, the accuracy and limitation of proposed method is demonstrated. The effect of nonuniform temperature distribution, particularly in the heating region during the induction heating, is studied. Analysis results validate the assumption to use the uniform temperature in a cross section for the inverse heat transfer solution of induction heat flux. Sensitivity to the grid spacing, thermocouple location, and thermophysical properties are also studied.

Prediction of temperature distribution and phase transformation on the run-out table in the process of hot strip rolling

In this paper a mathematical model based on the finite element method and the Scheil additivity rule is presented for predicting the temperature distribution and phase transformation behavior on the run-out table during the hot strip rolling of a low carbon steel. The model considers the austenite to ferrite and pearlite transformations, the temperature-dependent material properties of the cooling austenite as well as the austenite work hardening effect on the kinetics of austenite transformation. To determine the validity of the model predictions, the time-temperature histories of a low carbon steel rod in different cooling media were measured and also hot rolling experiments were performed. Good agreement between the predictions and the experimental results indicates the reliability of the model.

416 鋼の残留オーステナイトを利用した磁気記録法

Intelligent actuators have contributed to constructing machines, robotic systems, factory automation and more. The stroke detection mechanism by using magnetic scales is small, simple and durable. But the magnetic scaling rod is made of expensive special stainless steel. Therefore the magnetic scaling rod by general carbon steel was tried experimentally. The carbon steel rod was masked by turns with copper coating, and was carborized. The coating part transformed martensite (ferromagnetic), on the other hand, non-coating part changed to retained auastenite (nonmagnetic). So the magnetic scaling rod was made using this method and the magnetic sensor detected this waveform successfully.

Innovative sample preparation for GDOES analysis of decarburized layers in cylindrical metal specimens

AbstractGlow discharge optical emission spectrometry (GDOES) is a technique widely used for depth profile analysis but there are two significant limitations: samples must have planar surfaces and profile analysis generally cannot go beyond a depth of 100 µm. A new method of sample preparation has been developed to overcome both of these limitations, consisting of plastic deformation of the curved sample by pressing it until a planar surface is obtained. Furthermore, after profile analysis, the surface surrounding the glow‐discharged zone of the sample is ground to obtain a uniform layer levelled down to the bottom of the crater. Repeated grinding operations and profile analyses allow analysis of samples with practically unlimited thickness. An application of this method to determine the entity of the decarburized layer on a carbon steel rod sample is described in this paper. Copyright © 2001 John Wiley & Sons, Ltd.

Effect of HCl on the corrosion and wear of in-bed tubes in a laboratory simulated bubbling fluidized bed

Heat-exchanger tubes in fluidized bed combustors (FBCs) often suffer material loss due to combined corrosion and erosion. The effect of chlorine on in-bed tube wastage and its possible mechanism are being studied using the EPRI/LBNL FBC wastage simulator. This test rig was designed to simulate dense particle impacts on tube bottoms with well-controlled parameters, and has been proven to closely reflect situations found in operating bubbling FBCs. In this study, HCl gas was chosen to be the Cl source and was introduced into the fluidizing air with a 50-ppm concentration. Tests were performed at temperatures ranging from ambient to 400°C using 1018 low carbon steel rods in a bed of commercial SiO 2 sand that had an average size of 800 μm. The wear profile after each test was measured using a profilometer. Results showed an increase in material wastage rates in the presence of HCl, and that the rate was significantly higher with higher test temperatures. Microstructural and chemical analysis of the wear surface and corrosion products are reported. It is concluded that the dominating effect of HCl on the wastage rates is due to an enhanced oxidation and a reduced scale adherence.

Verification and application of beam-particle model for simulating progressive failure in particulate composites

Two physical experiments are performed to verify the effectiveness of beam-particle model for simulating the progressive failure of particulate composites such as sandstone and concrete. In the numerical model, the material is schematized at the meso-level as an assembly of discrete, interacting particles which are linked through a network of brittle breaking beams. The uniaxial compressive tests of cubic and parallelepipedal specimens made of carbon steel rod assembly which are glued together by a mixture are represented. The crack patterns and load-displacement response observed in the experiments are in good agreement with the numerical results. In the application respect of beam-particle model to the particulate composites, the influence of defects, particle arrangement and boundary conditions on crack propagation is approached, and the correlation existing between the cracking evolution and the level of loads imposed on the specimen is characterized by fractal dimensions.

Neural-network feedback control of an extrusion

This work is concerned with the feedback control of microstructure during one of the simplest metal forming operations: round-to-round extrusion. Physically based semiempirical models of the microstructural dynamics are available, but they require flow variables such as strain, strain rate, and temperature as inputs. Direct measurement of these quantities inside the deforming material is not feasible, so such models alone do not define a feedback controller. In the study presented, the mapping from the temperature of the material flowing through the die to the ram load is estimated via finite-element simulation. The ram load can be measured, and so this mapping, composed with the microstructural model, does close the loop, but the simulation is far too slow for real-time implementation. This problem is addressed by training an artificial neural network to represent the simulation output. This approach is demonstrated on the simulated extrusion of a plain carbon steel rod.

Surface modification of poly(tetrafluoroethylene) by excimer laser processing: enhancement of adhesion

The adhesion of the PTFE substrate whose surface was modified upon ArF excimer laser irradiation under a hydrazine atmosphere was examined by a tensile test for the sample prepared by jointing the laser-treated PTFE substrate and a carbon steel rod through chemical adhesives. The tensile strength at breaking point was over 12 MPa almost comparable to that of PTFE itself. The modified layer formed as a result of laser processing had a strong intimacy with PTFE itself and possessed mechanical properties comparable to that of PTFE. The degree of modification was gradual from the upper layer to the inner layer of PTFE.

Radionuclide Sorption on Well Construction Materials

AbstractLaboratory experiments were conducted to measure the extent to which trace concentrations of radioactive materials would sorb on well construction materials and to assess the rapidity with which sorption would occur. The radionuclides employed in these studies were tritium, Cs‐137, and Co‐57, Solutions with trace concentrations of these radionuclides were contracted with casings of PVC, fiberglass‐epoxy, stainless steel, carbon steel, and steel rods coated wtih expoy. The PVC showed no interaction with the tritium or Cs‐137 during contact times of two hours to these weeks; however, it did sorb Co‐57. The fiberglass‐epoxy also interacted only with the cobalt. The stainless steel sorbed cesium and cobalt. The carbon steel (or the ferric hydroxide forming on its surface) also sorbed both cesium and cobalt. The epoxy‐coated steel rods did not interact measurably with day of the radio‐nuclides so long as the coating was intact. The sorption reactions generally were apparent after a few days of contact: in the case of carbon steel, they were detectable in a few hours.

Carbide formation in titanium coatings deposited on carbon steel

During the last few years, the use of coatings as a material treatment, in particular for cutting tools, has shown extensive development. The prime interest of this technique is that the treated surfaces exhibit great mechanical and chemical resistance [1~4]. Most of the transition-metal carbides and nitrides of the fourth to sixth group of the periodic table have extremely high melting points, great hardness, very good chemical and thermal stability and typically metallic electrical, magnetic and optical properties [5]. These unusual properties make transition-metal carbides and nitrides both interesting and useful. The aim of the present work is to describe the results of a study concerning carbide phase formation and characterization of titanium coatings on high carbon steel substrates. The material used for the substrate is in the form of discs (15 mm diameter, 10 mm thick) cut from plain carbon steel rods. The chemical composition in weight is: 1.34% C, 0.11% Si, 0.21% Mn, 0.06% Cr, 0.10% Ni, 0.02% A1, 0.10% Cu. The specimens were polished with emery paper and finished with alumina pastes (0.25#m). The discs were then ultrasonically degreased and cleaned with trichloroethylene, acetone and methanol for 10min each. Prior to titanium deposition, the substrates were sputter etched using an argon pressure of 1 Pa, 100mA current and 1 0 0 0 V voltage for 15 min and a base pressure of 10 -4 Pa. During deposition, the experimental conditions were as follows: applied power to magnetron 2000 W; magnetic field 0.05 T; target polarization 4 0 0 V; current intensity 5 A; maximum temperature 150 °C; base pressure 0.3 Pa. After deposition, the samples were exposed for 1 h to vacuum annealing in the temperature range from 500 to 1100 °C in steps of 100 °C (every specimen was annealed only once). The rate of heating to the desired temperature and the rate of cooling after annealing was about 20 °C/min. The structure of the layers before and after annealing was then investigated using a HZG-3 powder diffractometer with Bragg-Brentano focusing and monochromatic Co (Ka) radiation, and compared with that after deposition. The titanium films were deposited to a thickness of about 4 #m. The morphology of the sample surface was studied by a Neophot 21 optical microscope. The surface hardness was measured with a Zwick 3212 microhardness tester at a load of 50g. Finally, the adhesion is evaluated using a scratch tester similar to the Revetest-LSRH; the radius of curvature of the diamond tip was about 0.1 mm. The data in Table I show that in the as-prepared state only the reflections from polycrystalline a-Tl films were obtained. The spectra of samples annealed at 600 and 700°C for 1 h are nearly identical with those of samples as-deposited. After annealing at higher temperatures (above 700 °C) a new phase gradually appears and is assigned to a TiC phase (Fig. 1). Simultaneously the a-Ti compound becomes unstable and changes completely to TiC phase at 1100 °C and all their reflections disappear. The growth and stability o f the TiC

Dynamic Strain Aging and the Wire Drawing of Low Carbon Steel Rods.

The dynamic strain aging behaviour of low carbon steel wire rod was examined at room temperature to 450°C using tensile testing at strain rates of 10-4 to 10-1 s-1 The effects of temperature and strain rate on the yield stress, flow stress, UTS, fracture stress, and fracture strain were investigated in detail. In agreement with previous studies, work hardening peaks, minima in ductility, and negative strain rate dependences of the flow stress were observed between 100 and 400°C, the positions of which depended on the strain rate. A model for dynamic strain aging is employed to predict whether or not it will occur at the strain rates and temperatures involved in commercial wire drawing. For a steel containing 32 ppm N, a temperature higher than about 315°C must be attained for dynamic strain aging to occur; this is higher than the temperatures usually encountered in drawing. However, the model also predicts that if the N content is increased to 115 ppm, the minimum temperature for dynamic strain aging decreases to about 250°C, which can be attained if the die and capstan cooling are not adequate. The negative rate dependence of the flow stress attributable to dynamic strain aging is considered to promote flow localization and, therefore, to be a possible cause of wire breaks during drawing.