Carbon Steel Powder Research Articles

3D printing of low carbon steel using novel slurry feedstock formulation via material extrusion method

Conventional 3D metal printing methods, such as laser sintering and binder jetting are often associated with high initial capital costs that make them inaccessible to many consumers. In this article, an economical alternative approach to 3D metal printing is presented, which uses a slurry-based formulation with the material extrusion method. This method involves a novel slurry feedstock of metal powder and liquid binder, which can be printed at room temperature to form green samples without the need for equipment such as a laser source, binder jetting head, or heated nozzle. It is followed by a thermal treatment process to fuse the printed samples into a metal article. The slurry is prepared by blending carbon steel powder with a cellulose derivative binder and additives. Rheological behaviours of different metal contents and binder concentrations are being investigated to determine the optimum printable slurry formulation. It is found that the optimum slurry feedstock formulation comprises 45 vol% metal content, 54 vol% cellulose derivative binder solution at a concentration of 300 g/L, and 1 vol% defoamer. The resulting slurry has fast-drying shear-thinning behaviour and a high storage modulus of 4 × 107 Pa to sustain the printed article at room temperature. The printed articles exhibited an average linear shrinkage of 12.36%, with less than a 1% linear shrinkage difference between X, Y, and Z directions after thermal treatment. The measured densities of the sintered articles were 95% ± 2% compared to the ASTM B783 (material code F-0000). The sintered articles have a measured carbon content of 0.28 ± 0.02%, hardness of 64.15 ± 9 HV, ultimate tensile strength of 255.33 MPa and Young's modulus of 130.47 GPa. This work demonstrates the viability of this additive manufacturing method in producing metal parts with comparable properties to conventional manufacturing.

In-situ decarburization and deoxidation during laser powder bed fusion of water-atomized steel C35

Water atomization of low alloyed steels is a very cost-effective way to produce metal powders for laser powder bed fusion. In this study, water atomized C35 steel powder is used to 3D-print samples with different powder bed fusion machines. The porosity of the samples was analyzed. Chemical analysis of printed samples and the powder feedstock was carried out. The gas atmosphere during laser powder bed fusion process was measured to investigate changes in carbon and oxygen content of the samples. With optimal processing parameters, samples with a porosity of only 0.1% can be achieved. Gas atmosphere measurements have shown, that a reaction between carbon and oxygen in the melt pool occurs, leading to the formation of volatile carbon monoxide. By in-situ reduction of the oxygen and carbon level, negative effects caused by oxygen like balling of single melt tracks can be prevented to produce nearly dense parts. • Water-atomized C35 medium carbon steel powder was used for laser powder bed fusion • Samples with porosity of only 0.1% can be built using appropriate parameters • During LPBF, oxygen reacts with carbon inside of the melt pool • Volatile CO forms during LPBF to reduce carbon and oxygen content of samples • Excessive pore formation is prevented due to deoxidation during the process

Electrochemical Kinetic Analysis of Carbon Steel Powders Produced by High-Energy Ball Milling

This work reports on the electrochemical kinetic analysis of carbon steel powders produced during the milling of carbon steel chips for 2, 3, and 5 h under an air atmosphere in a high-energy ball miller. This work aims to fill the gap in the literature regarding the transformation processes that affect carbon steel powder production. This information can be crucial for specific powder metallurgy systems. The results obtained using the Rietveld refinement method showed a decrease in the crystallite size, an increase in the microstrain, and no changes in the lattice parameter with the milling process. The electrochemical results revealed a strong influence of anodic electroactivity with milling time in NaCl solution, in contrast with NaOH, where the influence of the milling process was not significant. These results clearly show the significant role of chloride ions in preventing the formation of a passive film in milling with NaCl solution and in contrast to the formation of a passive film that notoriously inhibits both the anodic and cathodic reactions in milling with NaOH solution. The novelty of this work lies in the experimental demonstration of milling’s influence on the surface properties of carbon steel powders that directly affect their electrochemical response.

Microstructural and Tribological Evaluation of Brake Disc Refurbishing Using Fe-Based Coating via Directed Energy Deposition

In this paper, the refurbishing of worn-out brake discs by coating with powder via direct energy deposition (DED) is evaluated. A medium carbon steel powder was used to coat cast-iron discs. Deposition of this steel was carried out directly on the disc surface or, alternatively, after a previous deposition of a buffer layer made of stainless steel. It was seen that the use of a buffer layer ensured a good coating adhesion, despite the formation of cast microstructures at the interfaces between the disc and the two different coatings (buffer and outer layer). Coated discs were tested against two different Cu-free commercial friction materials to evaluate their tribological properties. Very similar friction coefficients, specific wear rates, and total emissions were measured for both friction materials sliding against the coated disc. These tribological data are slightly higher with respect to those obtained in the case of an uncoated disc, suggesting that improvement of the top coating composition and surface finishing is necessary in order to achieve better performances.

Formation of Crystal Structure in Hot Forging of Powder Carbon Steels

The crystal structure acquired by powder steels produced from undoped iron powder and mixtures of iron with 1.0 or 1.5% graphite in hot forging was studied by X-ray diffraction and optical microscopy. The heating temperature of the samples to be forged was varied in the range 950–1150°C. The fundamentally different dependence of the lattice distortion on the heating temperature for forging of the outer and inner layers of the samples was found. The lattice imperfection increases with forging temperature in the outer layers of the hot-forged samples made of the undoped iron powder. The γ→α martensitic transformation occurs when the samples are heated above 1100°C and rapidly cooled down. The lattice imperfection decreases in the inner layers of the samples made of the undoped iron powder. In the case of carbon steel samples, the lattice distortion and hardness increase with heating temperature, reaching the maximum at 1100°C and thus characterizing the γ→α martensitic transformation. When temperature increases to 1150°C, the lattice imperfection reduces as carbon burns out more intensively at elevated temperatures, but the hardness and tensile strength decrease insignificantly. This is attributed to the quenching temperature of steel to form a ferritic cement mixture, whose structure is presented by sorbitol with a microhardness of 2700– 2900 MPa, troostite (3000 MPa), and bainite (4500 MPa).

Effect of nano and micro conductive materials on conductive properties of carbon fiber reinforced concrete

Abstract In this study, the pressure sensitivity and temperature sensitivity of the diphasic electric conduction concrete were investigated by measuring the resistivity using the four-electrode method. The diphasic electric conduction concrete was obtained by mixing nano and micro conductive materials (carbon nanofibers, nano carbon black and steel slag powder) into the carbon fiber reinforced concrete (CFRC). The results indicated that, with the increase of conduction time, the resistivity of CFRC decreased slightly at the initial stage and then became steady, while the resistivity of CFRC containing nano carbon black had a sharp decrease at the dosage of 0.6%. With the increase of compression load, the coefficient of resistivity variation of CFRC containing nano carbon black and steel slag powder changed little. The coefficient of resistivity variation increased with the increase of steel slag powder in the dry environment, and CFRC had preferable pressure sensitivity when the mass fractions of carbon fiber and carbon nanofiber were 0.4% and 0.6%, respectively. Besides, in the humid environment, the coefficient of resistivity variation decreased with the increase of steel slag powder, and the diphasic electric conduction concrete containing 0.4% carbon fibers and 20% steel slag powder had the best pressure sensitivity under the damp environment. Moreover, in the dry environment, CFRC containing nano and micro conductive materials presented better temperature sensitivity in the heating stage than in the cooling stage no matter carbon nanofiber, nano carbon black or steel slag powder was used, especially for the CFRC containing steel slag powder.

On Increasing Powder Carbon Steels Properties Using Activating Additives

In this paper, the possibility of increasing powder carbon steels properties by activation of carbon diffusion into the iron base during sintering process due to the introduction of the thermally split graphite (TSG), macromolecular compounds (MC) and sodium bicarbonate was investigated. It was found that the introduction of these additives allows obtaining homogeneous structures at a sintering temperature of 100–200 °C lower than that traditionally used for sintering of powder carbon steels. Such structures provide increased mechanical properties of powder carbon steels. The addition of sodium bicarbonate increases the diffusion rate of carbon into iron at a temperature of <i>950 C</i> by 1.8 times, at <i>1000 °C</i> by 1.5 times, and at 1100 °<i>C</i> by 1.2 times.

Study of Mechanical Properties and Wear Behaviour of Aluminium 6063 Matrix Composites Reinforced With Steel Machining Chips

The mechanical properties and wear behavior of Aluminium 6063 matrix composites reinforced with high carbon steel machining chips investigated. Aluminium 6063 was reinforced with 5 &10 wt. % of steel chips with an average size of 50-100 microns. Steel chips powder obtained by milling of high carbon steel are used. The conducting on Stir casting process of Aluminium 6063 reinforced with high carbon steel powder using of simple foundry melting alloying and casting rout. The mechanical properties (tensile and hardness), wear behaviour of aluminium 6063 and the composite is tested. The mechanical properties as well as the wear resistance were also observed to improve with the use of the high carbon steel machining chips as reinforcement. Another sample of aluminium 6063 is also taken along a side the composite. The results demonstrate the capability of high carbon steel machining chips to act as efficient reinforcing material and a reliable cost effective in the development of aluminium 6063 composites.

A Study on Austempering a Hıgh Carbon Powder Metal Steel

In this study, 1.5% by weight of natural graphite powders were added to NC 100.24 pure iron powders to obtain plain high carbon steel powder metallurgy specimens. After respectively uniaxial pressing at room temperature, 100 °C and 200 °C and under 700 MPa pressing pressure, the specimens were sintered in an atmospheric controlled furnace at 1150 ° C. The spec,mens were then austenitized at 950 ° C for half an hour in a salt bath at 300 ° C for austempering heat treatment. The structure transformations after the heat treatment were examined using optic microscope. Through pressing processes at different temperatures, the effects of densification rate on the hardness and bainitic transformation were investigated. It was seen that by increasing the densitity of high carbon powder metal materials, the bainitic structure transformation was improved and thus hardness value was effectively increased.

Waste steel scrap to nanostructured powder and superior compact through powder metallurgy: Powder generation, processing and characterization

The present paper reports fabrication of superior steel compact using nanostructured steel powder generated from industrial steel scrap. Extra low carbon and low carbon steel powders with size of submicron were generated from industrial waste by planetary milling for 5h. The milled powders are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and hardness. Finest particles are obtained after 3h of milling in both cases. In case of extra-low carbon steel, cold welding and agglomeration is observed after 5h of milling. However, in case of low carbon steel, no such phenomenon is visible after 5h of milling. The effect of ball to powder weight ratio (BPR) is studied using BPR of 12:1 and 6:1 for low carbon steel chips by milling for 3h. A higher yield of 94.29% is obtained when milling conducted at BPR 12:1 than 86.94% yield at BPR 6:1 after milling low carbon steel for 3h. Lower average particle size of 5–10μm is obtained when milling is carried out at BPR 12:1 than 15–20μm at BPR 6:1. In case of low carbon steel, % yield increases from 94.29% to 99.14% as milling time increases from 3 to 5h. Yttria free and 1wt% yttria dispersed both extra-low carbon and low carbon steel powders are cold compacted and conventionally sintered at 1100°C for 1h. Significant improvement in the hardness was achieved through addition of small amount of yttria with both the steel powder generated from the steel scrap.

Microstructure and mechanical properties of ultrafine-grained aluminum consolidated by high-pressure torsion

Coarse-grained aluminum powder with 99.5wt% purity was consolidated by high-pressure torsion (HPT) technique at room temperature using a low carbon steel powder holder. In this process, the powder experiences a semi-constrained condition because the internal wall of the powder holder can expand under the load applied during HPT. After 4 turns of HPT a relative density of 99.83% was achieved. The microstructure was characterized by electron backscatter diffraction and X-ray line profile analysis. It was found that the grain size decreased while the dislocation density increased with both increasing the distance from the disk center and the number of HPT turns. The smallest grain size and the maximum dislocation density with the values of 0.41μm and 6.8×1014m−2, respectively, were achieved at the periphery of the disks processed for 4 turns. Tensile tests showed that the consolidation of this Al powder by 4 turns of HPT yielded a high ultimate tensile strength and a good ductility (~373MPa and ~22%, respectively). It turned out that the yield strength versus grain size relationship obeys the Hall-Petch equation. This study demonstrates the capability of HPT technique for processing consolidated Al powder with high strength and good ductility.

Influence of dispersed microadditives on the structure and properties of powder carbon and high-chromium steels

The influence of dispersed different nature microadditives on structure formation and volume changes during sintering, and strength of powder carbon and high-chromium steel is investigated. Mechanisms of the effect of additives on the formation of their structure are described. It is shown that the introduction of sodium bicarbonate provides the largest strengthening of carbon steel, while the introduction of boron nitride provides that of high-chromium steel. The level of increasing the strength depends on the sintering temperature and amount of additive.

A Metallurgical Evaluation of the Powder-Bed Laser Additive Manufactured 4140 Steel Material

Using laser powder bed fusion (PBF-L) additive manufacturing (AM) process for steel or iron powder has been attempted for decades. This work used a medium carbon steel (AISI 4140) powder to explore the feasibility of AM. The high carbon equivalent of 4140 steel (CEIIW ≈ 0.83) has a strong tendency toward cold cracking. As such, the process parameters must be carefully controlled to ensure the AM build quality. Through an orthogonally designed experimental matrix, a laser-welding procedure was successfully developed to produce 4140 steel AM builds with no welding defects. In addition, the microstructure and micro-cleanliness of the as-welded PBF-L AM builds were also examined. The results showed an ultra-fine martensite lath structure and an ultra-clean internal quality with minimal oxide inclusion distribution. After optimizing the PBF-L AM process parameters, including the laser power and scan speed, the as-welded AM builds yielded an average tensile strength higher than 1482 MPa and an average 33 J Charpy V-notch impact toughness at −18°C. The surface quality, tensile strength, and Charpy V-notch impact toughness of AM builds were comparable to the wrought 4140 steel. The excellent mechanical properties of 4140 steel builds created by the PBF-L AM AM process make industrial production more feasible, which shows great potential for application in the aerospace, automobile, and machinery industries.

Influence of Dispersed Microadditives on the Structure and Properties of Powder Carbon and High-Chromium Steel

The influence of dispersed microadditives of different nature on bulk changes during sintering and strength of powder carbon and high-chromium steel is investigated. Mechanisms of the influence of additives on their structure formation are described. It is shown that the largest hardening of carbon steel is provided by the introduction of sodium bicarbonate, while of high-chromium steel – of boron nitride additives. The level of hardness increase depends on the sintering temperature and additive amount.

Rapid evaluation of temperature distribution of coatings during atmospheric plasma sprayed process

This study presents the experimental results of coating AISI 1045 steel substrate by low alloyed carbon steel powder using atmospheric plasma spraying (APS). Thermocouples were used to monitor the temperature history at specified positions during the spraying process. A simplified thermal finite element model of APS coating is presented. The transient temperature field is calculated first. An appropriate numerical filter implementing the thermal time response of the thermocouple is created and applied to the raw FEM results. Agreement between experiment and numerical model for temperature were deemed promising despite the simplifications adopted in the numerical model.

Influence of processing factors on the structure and properties of carbon steel powder obtained by sintering and hardening of electropulse nanoparticles

In the article the study of the effect of temperature electropulse sintering of powder on the properties of steel. The optimal conditions for obtaining medium-carbon steels, cold brittleness threshold is defined, which allows to judge about the possibility of powder steel for use with impact loads at low temperatures.

On selective laser melting of ultra high carbon steel: Effect of scan speed and post heat treatment

AbstractSelective laser melting is a laser‐based additive manufacturing process applying layer manufacturing technology and is used to produce dense parts from metallic powders. The application of selective laser melting on carbon steels is still limited due to difficulties arising from carbon content. This experimental investigation aims at gaining an understanding of the application of the process on ultra high carbon steel, which is a special alloy with remarkable structural properties suitable for different industrial applications. The feedstock ultra high carbon steel (2.1% C) powder, 20 μm to 106 μm was prepared by water atomizing technique. This powder was used for the selective laser melting to build specimens 10×10×40 mm in dimensions. To decrease the thermal stresses during layer by layer building, laser scanning was done through 5×5 mm random island patterns while layer thickness was 30 μm. Laser beam diameter, maximum power output, layer thickness and scan speed range were 0.2 mm, 100 W, 30 μm and 50–200 mm/s respectively. The process was done inside high purity nitrogen environment, with less than 0.5% oxygen content. The results illustrate the influence of scan speed from 50 to 200 mm/s on product geometry and dimensions, surface roughness, internal porosity and cracks, microstructure and surface hardness. The effect of post heat treatment by heating and holding for one hour (annealing) at different temperatures of 700°C, 750°C, 950°C is studied. The results indicate that selective laser melting is able to produce near to 95% density of ultra high carbon steel parts with acceptable geometry and surface quality. Porosity cracks, and microstructure formed during the process could be controlled through proper selection of process parameters and post heat treatment. Industrial ultra high carbon steel products can be rapidly fabricated by selective laser melting.

Some aspects of barreling in sintered plain carbon steel powder metallurgy preforms during cold upsetting

The present research establishes a relationship of bulged diameter with densification and hydrostatic stress in forming of sintered iron (Fe) powder metallurgy preforms cold upset under two different frictional conditions, namely, nil/no and graphite lubricant condition. Sintered plain carbon steel cylindrical preforms with carbon (C) contents of 0, 0.35, 0.75 and 1.1% with constant initial theoretical density of 84% and aspect ratio of 0.4 and 0.6 were prepared using a suitable die-set assembly on a 1 MN capacity hydraulic press and sintered for 90 minutes at 1200 °C. Each sintered preform was cold upset under two different frictional constraints. It is seen that the degree of bulging reduces with reducing frictional constraints at the die contact surface. Further, it is found that the bulging ratio changed as a function of relative density and hydrostatic stress, respectively, according to the power law equations.

Synthesis of fullerene-containing phases in nickel powder steels depending on dispersity of nickel powder

The influence of nickel powder dispersity on the synthesis of the fullerene-bearing phase in powder carbon steels is investigated. It is established that the synthesis of fullerenes takes place the most actively at the temperatures 600 and 800°C. As the temperature of sintering increases in the interval of 800–1200°C, the activity of fullerene synthesis damps. The synthesis activity damps in steels alloyed with electrolytic and carbonyl nickel at a temperature of 1200°C. The synthesis in steels with nanosized nickel does not take place at all. It is established that the increase in stability of austenite of nickel leads to slowing down of fullerene synthesis.

炭素鋼とチタン箔の拡散接合と表面窒化同時処理の検討

The purpose of this study is the development of simultaneous processing of diffusion bonding and surface nitriding. Carbon steel was used as the base material. The surface was nitrided to a 20-μm-thick titanium foil. The sample was arranged in the order of carbon steel, titanium foil, and Al2O3 powder (diameter=1 μm) and placed in N2 gas in a furnace to undergo simultaneous diffusion bonding and surface nitriding. These processes were carried out at a processing temperature T of 1100~1250 K and processing pressure P of 0.5 MPa (processing time=4.8 ks). Because no defect was observed in the bonded interface, it was confirmed that a sufficiently suitable joint can be obtained under these processing conditions. The surface hardness was observed to increase with the increase in processing temperature; it reached approximately HV1600 at 1250 K. The surface of the titanium foil, which had been simultaneously processed at 1250 K, consisted of a single phase of TiN. The results of the ball-on-disc-type wear test revealed that the surface, which had been processed at 1250 K, was hardly worn by the TiN layer.