Carbon Steel Powder Research Articles

J0401-2-2 高炭素鋼/軟鋼混合粉末によるコールドスプレー皮膜硬さ制御([J0401-2]固相粒子成膜技術とその応用(2):溶射・コールドスプレー皮膜の特性評価)

In the case of cold spraying, small particles are accelerated to subsonic or supersonic velocity by high temperature and supersonic gas flow, and then impact onto a substrate. When particles impact onto a substrate, kinetic energy of the particles is converted to plastic deformation energy, namely plastic deformation is required for deposition. Because of requirement of plastic deformation, hard materials, such as high carbon steels, can be difficult to deposit on the substrate. And also, due to large plastic deformation, work hardening can be occurred. In this study, in order to develop an innovative repairing technique for high carbon steel by cold spraying, microstructures and hardness property of cold sprayed high carbon steel coatings using high carbon steel powders were evaluated. In order to improve and control the hardness of the coating, spray conditions were optimized and mixed powders of high carbon and mild steels were used. By applying mixed powders, a dense and thick coating with appropriate hardness was obtained.

Preparation and selective laser sintering of nylon‐coated metal powders for the indirect SLS process

PurposeThe purpose of this paper is to report a new method, the dissolution‐precipitation process, to prepare nylon‐coated metal powders for the indirect selective laser sintering (SLS) process.Design/methodology/approachThe nylon‐12 coated carbon steel powders were prepared by the dissolution‐precipitation process. The powder characteristics are examined by scanning electron microscope (SEM) and laser diffraction particle size analysis. The effect of the applied laser energy density on the three‐point bend strength and dimensional accuracy of the SLS specimens are studied. The influence of nylon‐12 content on the bend strength are also investigated.FindingsThe SEM and laser diffraction particle size analysis results indicate that the steel particles are well coated by nylon‐12 resin. The bend strength of the SLS specimens increases with increasing the applied energy density until it reaches a maximum value, and then further increasing energy density will cause the decrease in the bend strength. The bend strength of the SLS specimens increases with increasing the nylon‐12 content over the investigated range. The dimensional errors in the X‐Y‐and Z‐directions are all increased with the increase in energy density.Research limitations/implicationsThis paper only concerns the preparation and SLS of the coated powders. Further investigations are planned into post‐processing, such as binder decomposition and high‐temperature sintering, of the green parts made from the coated powders.Originality/valueThis paper provides a useful method for preparing nylon‐coated metal powders for making metal parts by the indirect SLS process.

Preparation and selective laser sintering of nylon-12 coated metal powders and post processing

A dissolution–precipitation process was successfully developed to prepare nylon-12 coated carbon steel powders. The SEM and laser diffraction particle size analysis results show that the metal particles are well coated by nylon-12 resin; therefore, an effective method for preparing nylon-12 coated metal powders is provided. Green parts were formed from the coated powders by selective laser sintering (SLS) process, and when the nylon-12 content in the coated powder was 1.0 wt% and the applied laser energy density was 0.06 J/mm 2, the SLS green parts had sufficient strengths for features as small as 0.1 mm to be built and post-processed, and relatively high dimensional accuracy. The SLS green parts were post-processed by binder decomposition and epoxy resin infiltration, and the obtained epoxy-infiltrated parts have the dimensional errors in the X, Y and Z directions of −0.30, −0.32 and −0.25% respectively, and the bend strength, bend modulus, tensile strength and impact strength of 93.4 MPa, 14.7 GPa, 70.3 MPa and 12.4 MPa respectively.

Specific features of the use of unconventional carbon-containing components in the technology of powdered steels: Report 2. The influence of unconventional carbon-containing components on the sintering processes in the technology of powdered steel

The processes of sintering powdered carbon steels with the introduction of unconventional carbon-containing components into the charge (special artificial low-ash graphite, pyrocarbon, and high-temperature coal-tar pitch) are considered. It is shown that the features of the chemical and granulometric compositions and the crystalline structure of these components (to a greater extent than the conventionally used pencil lead) determine the acceleration of material homogenization during sintering, improve its structural characteristics, and increase its mechanical properties.

Selective laser sintering of high carbon steel powders studied as a function of carbon content

Optimum conditions for laser irradiation to achieve fully dense high carbon steel SLS (selective laser sintering) specimens have been investigated as a function of carbon content in steel powders with the use of steel powders with different carbon contents in the range of 0.33–1.05 mass%C (corresponding to S33C, S50C, S75C and S105C in the JIS standard). Full densification is found to be easily achieved by SLS processing for all high carbon steel powders. The energy density during the SLS process required for full densification decreases as the carbon content increases from 400 J/mm 3 for 0.33 and 0.50 mass%C to 267 J/mm 3 for 0.75 and 1.05 mass%C. This is considered to be due to the increased wettability of molten Fe–C alloys for the higher carbon contents. The values of microhardness and yield stress of fully dense SLS specimens tend to increase as the carbon content in steel powders increases. At a given carbon content, the values of microhardness and yield stress of fully dense SLS specimens tend to be higher for those produced with a lower energy input (with higher laser scan speeds and larger scan spacings).

The effect of thermal-cycle treatment parameters on the mechanical properties of hot-stamped powdered steel

In order to improve the properties of powdered carbon steels and grain refinement, thermal-cycle treatment was performed with the use of both induction and furnace heating. This resulted in an extra-fine-grain structure and it increased the values of strength, plasticity, and impact strength. The optimum number of cycles is 3–10.

Three Filter Beds for Arsenite and Chromate Removal

Arsenic (As) and chromium (Cr) are two of the most toxic pollutants introduced into natural waters from a variety of sources, and they cause various adverse effects on living bodies when their concentrations exceed permissible limits. Laboratory experiments have been conducted to investigate the sorption of As and Cr on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of As and Cr species for iron/iron carbide (Fe/Fe3C) sites is the key factor in controlling the removal of the elements. The method is based on the use of powder carbon steel, powdered block carbon, and ball ceramic in the ion‐sorption columns as a cleaning process. The presence of carbon steel in a system that contains As3+ and Cr6+ might have a potential effect.

Selective Laser Sintering and Subsequent Gas Nitrocarburizing of Low Carbon Steel Powder

Optimum conditions for laser irradiation to achieve fully dense SLS (Selective Laser Sintering) specimens have been investigated for S15C steel, in order to check the industrial feasibility of the SLS process. The mechanical properties of SLS processed S15C steel as well as the surface hardenability have also been investigated. The volume fraction of pores in S15C steel decreases as the scan speed, scan spacing and layer thickness decrease and as the laser power increases, so that the density of SLS specimens increases as the energy density increases. The specimens sintered at an energy density of 800 J/mm3 exhibit very low porosity and, hence, very high density, comparable to those of the corresponding wrought material. Complete elimination of pores is indispensable for the ductility and strength of SLS specimens. Excellent wear resistance can be provided with the surface of S15C steel produced by the SLS process by gas nitrocarburizing because of the formation of Fe2-3N nitride with a very high value of microhardness on the surface.

TRACE ELEMENTS REMOVAL FROM WATER USING MODIFIED ACTIVATED CARBON

This paper present the possible alternative options for the remove of trace elements from drinking water supplies in the trace. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causing various adverse effects on living bodies. The performance of three filter bed methods was evaluated in the laboratory. Experiments were conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe3C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon, powder carbon steel and ceramic spheres in the ion‐sorption columns as a cleaning process. The modified powdered block carbon is a satisfactory and economical sorbent for trace elements (arsenite and chromate) dissolved in water due to its low unit cost of about $ 23 and compatibility with the traditional household filtration system.

Removal of selected metals from drinking water using modified powdered block carbon

This paper presents the possible alternative removal options for the development of safe drinking water supply in the trace elements affected areas. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causes various adverse effects on living bodies. Performance of three filter bed method was evaluated in the laboratory. Experiments have been conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe3C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon (PBC), powder carbon steel and ball ceramic in the ion-sorption columns as a cleaning process. The PBC modified is a satisfactory and practical sorbent for trace elements (arsenite and chromate) dissolved in water.

Effect of Elastic and Plastic Deformations on the Coercive Force of Porous Ferromagnetic Materials

The effect of elastic and plastic deformations accompanying uniaxial strain on the coercive force of powder carbon steel 50H2M was studied. Regularities of variations in the longitudinal and transverse coercive forces of a specimen in the elastic- and plastic-deformation ranges were determined.

Ferritic Fine Structure Characteristics in Hot Die Forged Powder Steels. I. Effect of Heating Temperature during Die Forging on Ferritic Fine Structure in Specimens of Powder Technical Grade Iron and Carbon Steels

We have studied the effect of the composition and heating temperature during die forging on the microstructure and fine structure of ferrite in powder iron and powder carbon steels. From the structural characteristics obtained for different planes of the blank, we used harmonic analysis of the x-ray line shape to establish the nonuniformity of deformation over the volume. We have established the heating temperature during die forging of powder technical grade iron and carbon steels, for which the deformation is close to uniform over the die forging volume: 1050 °C for technical grade iron and low-carbon steel, 1100 °C for carbon steel.

Removal of chromate from drinking water using powder carbon steel

This paper presents the possible alternative removal options for the development of safe drinking water supplies in areas affected by hexavalent chromium. Chromate is a matter of great environmental concern due to its extensive contamination and carcinogenic toxicity. In this study, the conventional adsorption with various types of adsorbent method were used for chromate removal, but only powder carbon steel was compatible with household water treatment and can be designated based on high removal efficiency and affordable cost. Home powder carbon steel with granular activated carbon (PCS–GAC) treatment systems are quite simple. Water needing treatment passes through the cartridge or filter candles contacting PCS–GAC on its way to the faucet. This method is based on the use of powder carbon steel, ML 90 Bombril S.A, as a cleaning agent. Granular activated carbon filters have been employed in home water purification systems essentially for the removal of taste, odor, and color. The effect of pH, redox potential, time, and adsorbate concentration on the uptake carbon steel were observed. The lack of desorption suggests that anion chromium is irreversibly sorbed by the powder carbon steel.

Phase Transformations in Carbon Steel Powders Subjected to Ball Milling

The tool carbon steel powder, containing 1.1 % C, was subjected to heavy cold working by ball milling in a Fritsch P5 planetary ball mill. XRD studies showed that ball milling results in a dissolution of cementite and formation of nanoferrite. The crystallite size and lattice strain of ferrite, calculated by applying Williamson-Hall method, were 10 nm and 1%, respectively. Mössbauer spectroscopy measurements confirmed the formation of a phase called “distorted ferrite”, characterized by the values of hyperfine field of 28.5 T and isomer shift of 0.15 mm/s, different from ones of ferrite (32.9 T and 0.00 mm/s, respectively). DSC investigations revealed two heat effects recorded during heating the sample after 100 h of ball milling: exothermic effect at 360oC and endothermic one at 580oC. The first one was attributed to the dramatic decreasing of lattice strain (from 1% after milling down to 0.1%, as showed XRD studies) and slightly increasing of crystallite size (from 10 to 25 nm).The formation of Fe3C was not observed in this temperature and the structure of nanoferrite was preserved. The second observed heat effect was reversible and probably related to the eutectoid transformation, shifted by ball milling to lower temperature range, comparing to equilibrium conditions.

Superplastic Densification of Ultrahigh Carbon Steel Powder Compacts

Superplastic Densification of Ultrahigh Carbon Steel Powder Compacts

An experimental design approach to selective laser sintering of low carbon steel

This paper is an outcome of the application of statistical design of experiments to the process of selective laser sintering (SLS) on low carbon steel powder using pulsed Nd:YAG laser of max. average power 100 W. It is intended to investigate the effects of variation of sintering parameters: layer thickness and hatching distance (side step) on the density, hardness and porosity of the sintered products. Experiments have been done according to second order central composite rotatable design and response surfaces of the outputs are plotted after regression analysis. It has been observed that increasing layer thickness and hatching distance results in an increase in porosity that diminishes the hardness and density.

Effect or Porous Billet Forging Temperature on Parameters of the Fine Structure of the Ferritic Phase in Powder Carbon Steel

The effect of forging temperature for a porous billet made of SP90 steel on the fine structure parameters of the ferrite phase crystal lattice is studied. Harmonic analysis of the form of x-ray lines is used to establish the sharp reduction in material structural defects in surface layers at the punch ― compact interface compared with core material and the nonuniform nature of the dependence of the levels of defects on deformation temperature.

Special features of the ? ? ? transformation in powder carbon steels

The structural state of powder steels after sintering depends on the technological regimes of their production and can markedly affect the transformations in subsequent heat treatment. The effect of the technological regimes on the nature of the α → γ transformation is investigated.

Optimization of properties of water atomized carbon steel powder by experimental design: G-H. Shiau et al (China Steel Corp).

Optimization of properties of water atomized carbon steel powder by experimental design: G-H. Shiau et al (China Steel Corp).

Structure formation mechanisms and properties of powdered carbon steels during laser thermal modification. II. Properties of modified steels

When low and medium carbon steel surfaces are thermally modified with a CO 2 laser [i], the fusion zone is typified by a low-carbon martensitic structure, the hardness of which increases as the tetragonality level increases. Ferrite and martensite are present in the original ferritic and ferriticpearlitic structure in the laser-affected zone; the former are developed at the original pearlitic colony site and retaintheir identity. Pearlitic colonies present in the laser-affected zone are typically nonuniform in composition. Apparently, this structure is formed when the steel is quenched from the two-phase (~ + ~)region. It may also be a condition of its formation that there is inadequate austenite homogenization of the carbon content due to the rapid heating rate above the point at which the phase-transformations begin.