Carbon Content Of Steel Research Articles

Analysis of the influence of technological parameters of steel smelting in top blowing oxygen converters on metal oxidation

The article considers the influence of technological steelmaking parameters in an oxygen converter on the oxygen content in steel before tapping. Today, CELOX is an effective, but at the same time expensive method for measuring the oxygen content in steel. The information obtained using this device allows you to accurately determine the ferroalloys consumption for deoxidation of steel. Since the oxygen content in steel before production directly affects the ferroalloys and aluminum consumption, necessary for steel deoxidation, the aim of this work was to create a mathematical model that allows determining the oxygen content in steel before tapping, taking into account the controlled melting parameters. The object of the study was a top blowing oxygen converter of 60 t capacity. The following analysis was carried out for 3PS steel grade. To create a mathematical model, the factors that have the greatest influence on the oxygen content in steel before tapping were previously selected by the method of correlation analysis. Such factors included the carbon, manganese, sulfur and phosphorus content in steel before tapping, its temperature and specific consumption of oxygen. Using the method of multiple regression analysis, a mathematical model was determined, which allows determining the oxygen content in steel before tapping at the end of each melt. Comparison of the actual data on the oxygen content in steel before tapping with the results of calculation using the model showed their high convergence, which confirms the adequacy of the obtained model. The application of the developed mathematical model for predicting the oxygen content in steel before tapping in a real metallurgical enterprise will allow reduce consumption of ferroalloys and alumina for deoxidation of crude steel.

Calculation of heat transfer during the manufacture of railway wheels of increased hardness

The article is devoted to the study of temperature conditions in the tread of a railway wheel during the production of wheels with increased hardness of the rolling surface. It is shown that obtaining a metal structure on the wheel surface without martensite and with hardness of 360-390 HB required by technical conditions at a depth of 30 mm from the rolling surface is difficult to realize by varying technological parameters: the number of sprayers, changing the water supply to the rolling surface due to the switch on/off the sprayers. To achieve the highest cooling speeds in the mass of the wheel tread, including at a depth of 30 mm, it is necessary to use the largest possible rolling surface in the heat removal process. It is advisable to remove heat from the rolling surface according to a predetermined dependence of the specific heat flux on time. It was established by experimental studies that the required hardness at a depth of 30 mm was achieved with an increased carbon content in steel and with an increase in the temperature of heating of the wheel before cooling with water spayers of more than 900 °C. To optimize the cooling process, it is advisable to carry out additional theoretical studies with more correctly specified boundary conditions of heat transfer on the tread surface and with refinement of the boundaries of phase transformations. It is advisable to carry out experimental studies on cooling the wheel surface with the possibility of varying the heat removal when using a gas-liquid flow as a cooling agent.

Three Generations Micro-Allying Steel Processing: Thirty Years of Successive Work at CMRDI

The present article presents cumulative works, which were carried out in the field of micro-alloying steel processing at Central Metallurgical R&D Institute (CMRDI) and/or full scale trials in collaboration with the Egyptian steel industry.It was agreed upon defining three main generations of processing micro-alloying steel. The 1stgeneration starts officially on 1975 and continues up to 1995, where it deals with using Ti and V as micro-alloying elements for steel long products. On the year 1985, Central Metallurgical R&D Institute (CMRDI) succeeded to implement of HSLA V-micro-alloyed rebar steel grades at Delta steel mills instead of conventional rebar grades.The 2nd generation was starting on late 1995 and continued to 2005. It was dealing mainly with low carbon content steel (0.04-0.08 %) for flat products (plate and sheet). The most successfully used micro-alloying element was Nb. Beside its precipitate forming effect, Nb is working as substitution solid solution strengthener. Moreover, it raises the recrystallization temperature (Tr). Mainly, micro-alloyed flat steels were developed to fulfill the requirements of the American Petroleum Institute (API) specifications 5L- Product Specification Levels (PSL1) and (PSL2) for manufacturing oil and natural gas pipelines. Meanwhile, a newly born Compact Slab Processing (CSP)-hot strip direct rolling technology was created. On years 2002, the metal forming department in CMRDI succeeded to implement controlled rolling of hot strip Nb-steel sheet at the Compact Slab Process (CSP) Machine in Alexandria National Iron and Steel (ANSDK) Company. Controlled hot rolling schedules were used and followed by early and late cooling at the run out table (ROT). Both contracts were fruitfully succeeded to introduce the API X52 grade at ANSDK Company, followed by X60, and X70 steel grades at Ezz Flat Steel (EFS) Company. The essential mechanical properties of the processed API steel sheets were matched with the API 5L-PSL2 specifications.The 3rd generation was initially developed after 2005 and continued up to day. It deals with micro-alloying with special functional elements like Boron (B). Boron was favored as a micro-alloying element for bilateral effects. Boron carbide (B4C) precipitates are the hardest after diamond, which would be reflected on raising the mechanical properties of the steel. Moreover, Boron was favorably used because it delays the temper embrittlement phenomena. On year 2014, the National for Military Industrialization authority requested from CMRDI to collaborate with Military Factory 100 to develop a technology package for processing armor steel plates. Trials were started with a 3rd generation B-micro-alloyed steel alloy. Many other alloying elements were used beside Boron to develop extra high strength 6.0 mm thickness plates. Finish hot rolled plates were then subjected to a subsequent water quenching from 900 °C and followed by tempering at 250 °C for 20 min. Representation 50X50 cm2 steel plates were successfully passed after 3 bullets in front and 3 bullets rear shooting.

Mechanical properties of low-temperature gaseous carburizated layer in 316L stainless steel based on nano-indentation and four-point bending tests

Low-temperature gaseous carburization (LTGC) is an effective method to generate a surface carburized layer with gradient carbon content in austenitic stainless steels. In the present paper, optical microscopy (OM), X-ray diffractometry (XRD), electron probe microanalysis (EPMA) and scanning electron microscopy (SEM) were employed to characterize the surface carburized layer in 316L stainless steel. The gradient mechanical properties of surface carburized layer were investigated by four-point bending and nano-indentation tests. The results show that the mechanical properties of the carburized layer, such as initial yield strength (σy), strain hardening exponent (n) and elastic modulus (E), increase with the increase of solid solution carbon atoms and plastic deformation. Because of huge carbon content and plastic deformation, the surface of carburized layer become very brittle and the fracture strain is only about 1.4%. In the paper, we also show that four-point bending test and nano-indentation test are both useful methods to evaluate the mechanical property distribution in a gradient surface layer such as carburized layer.

Effect of decarburisation and nitriding on the carbon content, precipitates, microstructure and texture of Nb-bearing grain-oriented silicon steel

ABSTRACTThe decarburisation annealing processes of Nb-bearing grain-oriented silicon steel under different conditions were conducted. The effect of nitriding and decarburisation annealing time on the carbon content, precipitates, microstructure and texture of Nb-bearing grain-oriented silicon steel were investigated by the various analysis methods. The results show that the carbon content in the steel decreases as decarburisation time increasing, and decreases below 0.003% eventually. Larger number density and smaller size of precipitates were obtained in the sample treated by nitriding before decarburisation annealing process, leading to fine and uniform microstructure, which is beneficial to obtain excellent magnetic properties for Nb-bearing grain-oriented silicon steel. The main texture types of the experimental samples were γ-fibres with a peak at {111}<112 >. The nitriding before decarburisation annealing process makes little effect on texture evolution during decarburisation annealing process.

Study of TiC Interaction and its Reaction Products with the Different Carbon Content Steels

Study of TiC interaction with low-and high-carbon steel is presented in this article. Was carried out interaction thermodynamic modeling in the temperature range of 900-1800 °C, which showed that titanium carbide would dissolve in melts with these compositions, regardless of melt’s carbon content at given parameters. The obtained thermodynamic results were verified by conducting an experiment with high-temperature complex in order to study substances interaction processes. The obtained experimental samples were studied with scanning microscope as well as structure and compounds composition, obtained as a result of experiment mentioned above.

ВПЛИВ ВУГЛИЦЮ НА КОРОЗІЙНУ ПОВЕДІНКУ ТЕРМІЧНО ЗМІЦНЕННОГО ПРОКАТУ

In this work, we studied the corrosion behavior of hot-rolled and heat-hardened rolled products made of carbon steel with different carbon content in order to select the optimal conditions for its heat treatment to obtain a satisfactory combination of strength and corrosion resistance during the development of processes of general corrosion with hydrogen depolarization. The studies were carried out on samples of carbon steel (0.14-0.8% C) in hot-rolled and heat-hardened states. It has been established that the corrosion rate (K) in specimens made of steels in the quenched state is lower than in the hot-rolled state; however, even in this state, with an increase in the carbon content within the studied limits, it increases 40 times. An increase in the corrosion rate with an increase in the carbon content in hot-rolled steel is explained by an increase in the amount of pearlite and an increase in the length of the ferite-cementite interphase boundaries. It was determined that in quenched hardened steel in the carbon content range from 0.14 to 0.80 % C, an increase in the corrosion rate is apparently due to an increase in microstresses (accumulation of excess internal energy) associated with an increase in the tetragonality of the martensite lattice and the appearance of concentration inhomogeneity in the solid solution. It was found that during the course of corrosion with hydrogen depolarization, the dependences of the general corrosion rate of thermally hardened structural steels on the tempering temperatures are described by extreme dependences with a maximum corrosivity in the temperature range of 350-500 oC, while, with an increase in the carbon content in steel, rental increases. It was determined that at the tempering temperature corresponding to the maximum K, the corrosion rate is 1,5-3,6 times higher than in the quenched state, and 1,4-2,6 times higher than in hot-rolled, and with an increase in the carbon content this difference is growing. An increase in the rate of corrosion with hydrogen depolarization in the tempering temperature range of 350-450 oC is apparently associated with the process of carbide formation and the appearance of coherent stresses during the release of dispersed particles. An increase in corrosion losses in this interval with an increase in carbon content is due to an increase in the volume fraction of fine particles of the carbide phase and an increase in the level of elastic microdistortions of the crystal lattice (Δa/a).

Effect of Heat Treatment on the Microstructure and Corrosion Resistance of Stainless/Carbon Steel Bimetal Plate

In order to research the effect of heat treatment on the microstructure and corrosion resistance of stainless/carbon steel bimetal plate, the annealing process at 700°C with different times was carried out for stainless/carbon steel bimetal plate. Because the carbon content of carbon steel was higher than that of stainless steel, the carbon would diffuse from carbon steel to stainless steel in the bimetal plate during the annealing process. The carbon diffusion would cause the thickness of the decarburized layer in carbon steel and the carbon content of stainless steel to increase. The carbon diffusion would be ongoing with the annealing process until the carbon content of stainless steel reached 0.08%. The higher carbon content could help in the formation of more chromium‐depleted regions in the stainless steel surface, causing the stainless steel in the bimetal plate to have a poorer surface corrosion resistance than that of stainless steel under the same annealing conditions.

Study on the Mechanism of Carbon Steel Sparks

Abstract Spark testing is an effective and convenient method that can be used be identify general classification of the steel material by observing the sparks projected by the grinding wheel. In order to more accurately identify the type of spark, the spark streams of carbon steels are described and illustrated by a high-speed camera. The appearance and phase analysis of the residues collected from the spark streams are studied separately by scanning electron microscope and X-ray diffractometer. Results show that the spark streams are the trajectory of the movement of carbon steel wear debris. The luminescence of the debris is provided by the heat released by the iron oxidation reaction. The carbon burst is caused by the explosion of carbon monoxide (CO) on the surface of carbon steel wear debris, and CO is produced by the reduction reaction of carbon and iron oxides. The main shape of the residues is flaky and spherical. There are some holes caused by carbon burst on the surface of the spherical residues. For the qualitative phase analysis of the residues, the main phase is composed of iron, ferrous oxide (FeO), ferric oxide (Fe2O3), and ferroferric oxide (Fe3O4). As the increase of the carbon content of steel, the quantity of iron phase is greatly reduced, and the quantity of Fe2O3 and Fe3O4 phase is gradually increased. Moreover, the amount and density of carbon burst is increased, and the number of the holes in the spherical residues are also increased.

THE INFLUENCE OF BORON IN THE SURFACE LAYER ON THE STRUCTURE AND THE TRIBOLOGICAL PROPERTIES OF IRON ALLOYS

This paper presents two methods of introducing boron into the surface layer of iron alloys, namely diffusion boronizing by means of the powder method and laser alloying with a TRUMPF TLF 2600 Turbo CO2 gas laser. Amorphous boron was used as the chemical element source. As regards diffusion drilling, the influence of temperature and time on the properties of the layer was tested. During the laser alloying, the influence of the thickness of the boriding paste layer as well as the power and laser beam scanning velocity was determined. How the carbon content in steel and alloying elements in the form of chromium and boron influence the structure of the surface layer was tested. To achieve this object, the following grades of steel were used: C45, C90, 41Cr4, 102Cr6, and HARDOX boron steel. The microhardness and wear resistance of the obtained boron-containing surface layers were tested. A Metaval Carl Zeiss Jena light microscope and a Tescan VEGA 5135 scanning electron microscope, a Zwick 3212B microhardness tester, and an Amsler tribotester were used for the tests. The structure of the diffusion- borided layer consists of the needle-like zone of FeB + Fe2B iron borides about 0.15 mm thick, with a good adhesion to the substrate of the steel subjected to hardening and tempering after the boriding process. After the laser alloying, the structure shows paths with dimensions within: width up to 0.60 mm, depth up to 0.35 mm, containing a melted zone with a eutectic mixture of iron borides and martensite, a heat affected zone with a martensitic-bainitic structure and a steel core. The microhardness of both diffusionborided and laser-borided layers falls within the range of 1000 – 1900 HV0.1, depending on the parameters of the processes. It has been shown that, apart from the structure and thickness of the layer containing boron and microhardness, the frictional wear resistance depends on the state of the steel substrate, i.e. its chemical composition and heat treatment. The results of testing iron alloys in the borided state were compared with those obtained only after the heat treatment.

Effects of carbon content and hardness on rolling contact fatigue resistance in heavily loaded pearlitic rail steels

To reproduce the rolling contact fatigue (RCF) damage of rail steel used in heavy haul railways and to clarify its possible mechanism, the RCF characteristics of pearlitic steel with different carbon content and initial hardness values are evaluated using a two-disk-type machine. The results indicate that the number of spalls and the crack depth decrease with increasing carbon content of pearlitic steel even when the initial hardness is almost the same level. Furthermore, an increase in the carbon content increases the hardness of the rolling contact surface, resulting in the suppression of the plastic flow development. Results also indicate that the crack inclination angle varies depending on the carbon content. According to these results, a possible mechanism for the suppression of fatigue crack propagation in higher carbon pearlitic steel is proposed on the basis of the fracture mechanics approach.

Pengaruh Hardening dengan Media Quenching Fluida Getah Pohon Pisang terhadap Struktur Mikro dan Komposisi Kimia Baja Karbon Sedang

The purpose of this study was to determine how the chemical composition and microstructure formed in medium carbon steel hardened with banana tree sap fluid compared to oil and water. The process of carbon steel hardening is being heated to the austenite area (850oC ) then held for 10 minutes after which it is cooled quickly (quenching). During the cooling process, it is also measured the cooling rate of the three cooling media. Hardening process material is carried out by microstructure observation using an optical microscope with 400x magnification and also chemical composition testing with SEM-EDX. The results for measuring the cooling rate of banana fluid have a fast cooling rate of 36.9oC/s while water is 16.6oC/s and oil is 7.0oC/s. In observing the microstructure of water it has an unstable micro structure that is still the structure of pearlite, this is because the temperature of the cooling media is too high during quenching. And for oil microstructure and banana fluid get a homogeneous structure, namely martensite and bainite. From the results of testing the chemical composition, it was seen that there was an increase in carbon content in steel after hardening and quenching with the three cooling media. Conclusion The hardening process by quenching oil and banana fluids has a homogeneous micro structure compared to water. Water cooling process has the highest carbon content increase of 1.53 %C from before 0.52 %C.

Multi-objective optimization of high carbon steel (EN-31) and low carbon steel (SAE-1020) using Grey Taguchi method in rotary friction stir welding

PurposeNowadays, a rotary friction welding method is accepted in many industries, particularly for joining dissimilar materials as a mass production process. It is due to advantages like less material waste, low production time and low energy expenditure. The effect of the change in carbon contents in steel is studied experimentally in the rotary friction welding process, and a statistical model is developed. The Grey Taguchi method gives the single parameters optimization for all output responses. The paper aims to discuss these issues.Design/methodology/approachAn experimental setup was designed and produced to achieve the multi-response in single optimum parameters through Grey relational analysis. A continuous/direct drive rotary friction welding process is chosen in which transition from friction to the forging stage can be achieved automatically by applying a break. In this experimentation, high carbon and low carbon work-pieces with different carbon percentage were welded with rotary friction welding. Response tensile strength and micro-hardness of the design of the experiment are used to analyze the results.FindingsThe optimization of parameters has been performed with Grey relational analysis, and optimum parameters are friction pressure 40 kg/cm2, forging pressure 100 kg/cm2 and speed 1,120 rpm. GRA optimum parameters give 56.04 and 82.16 percent improvement in Tensile strength and micro-hardness, respectively.Practical implicationsHigh carbon steel (En-31) and low carbon steel (SAE-1020) are used in so many industrial applications. These materials are mostly used in the process like manufacturing, metallurgy, machinery, agricultural, etc. These practical applications have brought forward definite and notable economic benefits.Originality/valueIt provides a new framework to investigate the problems where multiple input machining variables and various output responses are obtained in single optimized parameters.

Effect of Carbon Content on Abrasive Impact Wear Behavior of Cr-Si-Mn Low Alloy Wear Resistant Cast Steels

The effects of carbon contents on wear resistance were investigated for Cr-Si-Mn low alloy cast steels. The abrasive impact wear behavior was also analyzed. The results showed that, with the increase of carbon content in steels, the metallographic structure partly transformed from lath martensite to acicular martensite gradually, the hardness increased and the impact toughness decreased distinctly, furthermore, wear resistant first increased and then decreased, that was mainly caused by the wear mechanism changed form plastic fatigue wear to brittle fracture wear.

Preventing Wetting Between Liquid Copper and Solid Steel: A Simple Extraction Technique

Copper contamination of end-of-life steel scrap is the main barrier to high-quality recycling. Preferential melting of copper from solid steel scrap is a potential extraction technique, which could be integrated into conventional scrap re-melting with little additional energy. However, previous investigations show removal of liquid copper is limited by its adherence to solid scrap. Preventing wetting between liquid copper and steel is essential to enable separation. The carbon content of steel, initial surface oxidation, and applied coatings effect wetting behavior, but have not been systematically studied. In this study, the individual and combined effects of these parameters on wetting behavior in an inert gaseous environment are observed with a heating microscope. Carbon content appears to be the most significant factor: blistering of the oxide scale on medium-carbon steels causes liquid copper to flow rapidly between the oxide and steel substrate. Liquid copper exhibited a stable droplet on low-carbon steel, regardless of the initial level of oxidation. The tested coatings did not consistently improve nonwetting behavior, but impaired the connection between the scale and steel substrate. This study confirms the potential of the preferential melting technique, but further investigation is needed to determine the most robust process conditions to handle diverse, fragmented scrap at an industrial scale.

Influence of the Casting Conditions on the Position of the Structural Boundaries in Continuous-Cast Ingots

Comparison of experimental data regarding the structure of continuous-cast ingots yields complex linear regression equations for predicting the position of the boundaries between structural zones of the ingot on the basis of parameters such as the ingot thickness, the casting rate, and the carbon content in the steel.

TESTING THE STRUCTURE AND PROPERTIES OF STEELS AFTER HARDFACING AND LASER TREATMENT

This paper analyses the structure, hardness, and frictional wear resistance of surface layers formed on steels after hardfacing by means of the SSA arc method with self-shielded flux cored welding wire, with a content of carbon 5% and chromium 30% as well as boron alloying with the CO2 laser. S355J2 steel after being hardfaced with one up to three layers is characterized by the martensitic structure with chromium carbides and its surface hardness is 50–55HRC. In the weld deposit zone, with a thickness of up to approx. 2 mm, there is a constant distribution of hardness with the average value of 700 HV0.1, and then the hardness decreases to approx. 160 HV0.1 in the steel substrate. After hardfacing, the carbon content in S355J2 steel (0.23% wt.) increases to a similar content as in steel C90U in the initial state (0.96% wt.). After laser alloying with boron and after rapid cooling, C90U steel obtains distinctive paths with a zone structure and thickness reaching up to approx. 380 μm. In the remelted zone, there is a eutectic structure consisting of a mixture of iron borides and martensite with a hardness of approx. 1200–1800 HV0.1, and beneath it, there is heat affected zone with a martensitic-bainite structure with a hardness of approx. 700HV0.1. Hardfacing and laser heat treatment significantly decrease the frictional wear of the tested steels.

Precipitation Mechanism and Reduction of Amount of Primary Carbides During Electroslag Remelting of 8Cr13MoV Stainless Steel

The precipitation and growth of primary carbides in 8Cr13MoV steel during electroslag remelting (ESR) were studied. The effects of melting rate and fill ratio of ESR on the reduction of primary carbides were clarified. Primary carbides M7C3 precipitated from liquid steel at the final stage of solidification, which is attributed to an enrichment of carbon and chromium in liquid steel. The carbon content in the residual liquid steel was the determining factor for the formation of primary carbides. The growth of primary carbides was affected mainly by the chromium-concentration and temperature-field gradients. An appropriate melting rate facilitated the nucleation and growth of dendrites, which caused dendrite closure and prevented the further enrichment of carbon atoms. Primary carbides were refined and their amount was reduced when using a lower ESR melting rate. The fill ratio can affect the uniformity of the temperature field in the liquid metal pool and heat transfer from the slag pool to the liquid metal pool, and an optimal fill ratio resulted in a minimum mushy zone and less primary carbides. The volume fraction of primary carbides was reduced by 23 pct when the melting rate decreased from 150 to 133 kg/h and the fill ratio increased from 0.23 to 0.33.

Synergistic strengthening effect induced ultrahigh yield strength in lightweight Fe[sbnd]30Mn[sbnd]11Al-1.2C steel

In the past decades, high MnAlC lightweight steels have been extensively studied due to their excellent mechanical properties. However, the yield strength is usually less than 1.2 GPa for relative lower carbon content (≤1.2 wt %) steels after the general strengthening process. This study was intended to enhance the yield strength of the steel. For this purpose, a novel heterogenous lamellar microstructure was introduced in lightweight steel with the nominal component of Fe30Mn11Al-1.2C (wt. %), which could provide extra back stress strengthening. The microstructure consists of the lamellar fully recrystallized austenite matrix and the small volume fraction (<2%) submicron-sized ferrite which merely distributed in the fine grain layer. The formation process and the underlying strengthening mechanism of the lamellar microstructure were analyzed. Due to the synergistic strengthening of back stress, grain refinement and aging strengthening, ultrahigh yield strength (∼1.4 GPa) and greatest specific yield strength (∼220 MPa g−1 cm3) with good elongation (∼27%) were realized in the present alloy.

Thermodynamics and Industrial Trial on Increasing the Carbon Content at the BOF Endpoint to Produce Ultra-Low Carbon IF Steel by BOF-RH-CSP Process

Abstract Thermodynamic analysis was performed to obtain the relation between the carbon content at the BOF endpoint and the dissolved oxygen content in liquid steel and the (FeO + MnO) content in the slag with the help of thermodynamic calculation software FactSage. It finds that both the [O] and (FeO + MnO) content increase with decreasing the carbon content at the BOF endpoint and the increasing rate is larger when the carbon content is lower. In addition, in the case of the higher temperature at the BOF endpoint the [O] in liquid steel increase and the (FeO + MnO) in the slag increase as well. The consumption of O2 for decarbonization at the BOF endpoint is much more than that in RH degasser since the majority of the blowing O2 at the BOF endpoint will produce FeO into the slag, thus it increase the metal loss and deteriorate the steel cleanness during the consequent refining process. As a result, the carbon content at the BOF endpoint should be properly increased within the RH decarbonization ability. At last, industrial trials were carried out and confirmed that total oxygen consumption decrease obviously and the (FeO + MnO) of final BOF slag decline as well with increasing carbon content at BOF endpoint from 0.042% to 0.081%. In addition, it almost does not slow down the RH process and the carbon content in final steel all met the demand of the ultra-low carbon steel. In addition, mechanical properties of IF steel with higher carbon content at the endpoint of BOF are almost all more superior to those of heat with lower carbon content at BOF endpoint.