Spheroidal Iron Research Articles

Production of reduced iron from mill scale waste using tilting rotary furnace

The production of steel in steel mills generates undesired scales of oxidized iron on the surface of the hot steel. Although several attempts have been made to transform mill scale into valuable products, the low porosity of the oxides and the presence of oil contamination have been the main limitations in pelletizing the scales. In our recent research, we were able to produce reduced iron in the form of spheres with a 93% metallization degree using only mill scale as a source of iron without the need for any agglomeration or cleaning steps. The main equipment used in the production process was a tilting rotary furnace. We also examined the relationship between fuel consumption and the metallization degree of the reduced iron, as well as the effect of furnace RPM on the cross-sectional diameter of the produced spheres. By adjusting the process parameters, we were able to produce spheroidal iron with a cross-sectional diameter ranging from 10 mm to 400 mm. This high-quality reduced iron can be directly used as a replacement for DRI or scrap in traditional steel production methods.

Green synthesized iron nanoparticles by green tea and eucalyptus leaves extracts used for removal of nitrate in aqueous solution

Since water pollution associated with high concentrations of nitrate poses serious threats to aquatic ecosystems and can eventually lead to eutrophication, the removal of nitrate, particularly in a large scale context is still a challenge. To address it, this study proposed that iron nanoparticles (Fe NPs) synthesized by green tea (GT-Fe) and eucalyptus leaves (EL-Fe) extracts, which regarded as cleaner productions can be used for the efficient removal of nitrate. Scanning electron microscopy (SEM) and X-ray energy-dispersive spectrometer (EDS) confirmed the successful synthesis of spheroidal iron nanoparticles. Meanwhile, X-ray diffraction (XRD) and Fourier Transform Infrared spectrometer (FTIR) indicated the formation of Fe0-iron oxide core-shell NPs with polyphenols as a capping/stabilizing agent. Batch experiment showed that 59.7% and 41.4% of nitrate was removed by GT-Fe and EL-Fe NPs, compared to the 87.6% and 11.7% that was removed using zero-valent iron nanoparticles (nZVI) and Fe3O4 nanoparticles, respectively. Nevertheless, reactivity of nZVI decreased 2.1-fold after being aged in air for two months, whilst GT-Fe and EL-Fe NPs almost remain the same. Additionally, the kinetics study indicated that the nitrate removal process better fitted to the pseudo-second-order adsorption model, where the qe was 13.06 mg/g for GT-Fe and 9.698 mg/g for EL-Fe NPs. Based above, a removal mechanism dominated by adsorption and co-precipitation process with subsequently reduction was proposed. Finally, applications of these as-prepared green Fe NPs in swine wastewater demonstrated a promising environmental pollution management option for large scale eutrophic wastewater treatment.

Matematic Model of the Use of Raw Spheroidal Iron Casts

The paper determines the range and the form of the surface layer of the spheroid iron cast. It presents the possibility of forming the surface layer of the mold of the exploitation surface of the final product in the range of the transverse section.

Green synthesis of Fe nanoparticles using eucalyptus leaf extracts for treatment of eutrophic wastewater

Iron nanoparticles were firstly synthesized through a one-step room-temperature biosynthetic route using eucalyptus leaf extracts (EL-Fe NPs). Scanning electron microscopy (SEM) and X-ray energy-dispersive spectrometer (EDS) confirmed the successful synthesis of the spheroidal iron nanoparticles. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared spectrometer (FTIR) indicated that some polyphenols are bound to the surfaces of EL-Fe NPs as a capping/stabilizing agent. Reactivity of EL-Fe NPs was evaluated for the treatment of swine wastewater and results indicated that 71.7% of total N and 84.5% of COD were removed, respectively. This demonstrated the tremendous potential of EL-Fe NPs for in situ remediation of eutrophic wastewater.

Surface integrity generated by oblique machining of steel and iron parts

In this study the surface integrity produced by oblique turning of a range of iron-based materials including C45 carbon, 41Cr4 low-alloy hardened, X6CrNiTi18-10 stainless steels and EN-GJS-500-7 spheroidal iron was quantified by means of 2D and 3D surface roughness parameters, strain-hardening effects and associated residual stresses. Surfaces were produced by a special straight-edged cutting tool with large inclination angle of 55° equipped with carbide and mixed Al2O3–TiC ceramic cutting tool inserts. It was documented that oblique machining performed with relatively higher feed rate allows obtaining lower surface roughness and, in general, better bearing characteristics. Moreover, compressive stresses with the maximum value located close to the machined surface and parabolic profile can be induced into the surface layer. The magnitude of stresses depends on the strain-hardening rate of the surface layer.

Influence of processing variables on the mechanical behavior of spheroidal graphite cast iron

The mechanical properties achievable from spheroidal iron castings are adequate for a very wide range of applications. Apart from mechanical properties, a number of other characteristics such as density, thermal expansion, thermal conductivity, specific heat, electrical conductivity, magnetic properties, and acoustic properties are also of considerable importance. Efforts are being made to improve all these properties. In the present investigation, five melts of SGI castings (M1 to M5) were prepared by standard foundry procedure and practices. The mechanical behavior of spheroidal graphite iron (SGI) castings was studied as a function of processing variables. It is found that the mechanical properties (viz. Tensile strength, Yield strength, Elongation, Impact resistance, etc) for a given chemical composition are highly dependent on processing variables (i.e. pouring temperature, preconditioning of base iron, inoculation practice, and molding materials). SGI castings are produced and tested as per ASTM 395 specifications. From the results, it is found that with varying processing conditions, the mechanical properties have been improved to a great extent; that is, the UTS (Ultimate Tensile Strength), YS (Yield Strength), EL(Elongation), and impact strength (at −20°C). The UTS has improved to 475·41 MPa; YS is also enhanced to 316·94 MPa; elongation has increased to 18%, but there is reduction in impact strength.

Evolution of Texture in Ultra-Fine Grained Ferrite through Warm-Rolling and Intercritical Annealing

The ferrite grain size refining is the unique mechanism for increasing both mechanical strength and formability of steels. Steel with an ultra-fine ferrite grained structure must show a good relation between mechanical strength, ductility and toughness, while the low carbon content enhances good welding characteristics. The objective of this work is to investigate the influence of warm rolling on the evolution of texture in a microalloyed low carbon-manganese (0.11%C, 1.41%Mn, 0.028%Nb and 0.012%Ti) steel with ultra-fine grains produced through out quenching, warm rolling, followed by sub and intercritical annealing. The evolution of restoration process - recovery and recrystallization - was followed by optical and scanning microscopy. After subcritical annealing, the microstructure was formed by spheroidal iron carbides and a ferritic recovered matrix. Otherwise, after intercritical annealing, the microstructure was composed mainly by ultrafine grain polygonal ferrite, MA (martensite-austenite) constituent and carbides. The mechanical behaviour of the steel was evaluated using tensile tests. The mechanical properties have been correlated with the evolution of texture in the ultra-fine grained ferrites.

To Study the Effect of Austempering Temperature on Fracture Behaviour of Ni-Mo Austempered Ductile Iron (ADI)

Austempered Ductile Iron (ADI) can be as twice as strong as standard spheroidal iron at the same level of toughness. It responds to work-hardening surface treatments and exhibits excellent fatigue and wear property. There is extensive work done on the fracture of steel with ferrite or/and austenite structure, but little on fracture behaviour of ADI whose microstructure also comprises austenite and ferrite but with graphite nodules in the matrix. The present work is aimed in this direction. The fracture behavior of Ni-Mo ADI is studied. It is found that the crack always originates from graphite nodules and the matrix affects the propagation path.

The Effect of Restoration Process on the Mechanical Behavior of Ultra-Fine Grain Size Nb-Ti Steel Processed by Warm Rolling and Sub and Intercritical Annealing

The ferrite grain size refining is the unique mechanism for increasing both mechanical strength and toughness of steels. Steel with an ultra-fine ferrite grained structure must show a good relation between mechanical strength, ductility and toughness, while the low carbon content enhances good welding characteristics. The objective of this work is to investigate the influence of restoration process on the mechanical behavior of a microalloyed low carbon-manganese (0.11%C, 1.41%Mn, 0.028%Nb and 0.012%Ti) steel with ultra-fine grains produced through out quenching, warm rolling, followed by sub and intercritical annealing. The evolution of restoration process -recovery and recrystallization - was followed by optical and scanning microscopy. The x-rays diffraction was employed to evaluate the degree of restoration after subcritical annealing. The mechanical behavior of the steel was estimated using microhardness tests. After subcritical annealing, the microstructure was formed by spheroidal iron carbides and a ferritic recovered matrix. Otherwise, after intercritical annealing, the microstructure was composed mainly by ultra-fine grain polygonal ferrite, MA constituent and carbides. The hardness after processing has shown a 20% increase compared with the steel under hot rolling condition.

Investigation of elastic property relationships for flake and spheroidal cast irons using Raman spectroscopy

The deformation micromechanics of flake and spheroidal graphitic cast irons have been studied for the first time using Raman spectroscopy. It has been found that the Raman band peak positions of the graphite shift to a lower wavenumber during tensile deformation, and to a higher wavenumber in compression. The elastic properties of the cast irons have been investigated using various theoretical models. It has been shown for flake iron that the Young’s modulus is in close agreement with the models for disk-shaped inclusions, and with models for spherical inclusions for the spheroidal iron. In the case of the graphite stress at 1% strain, the same models underestimate the stress reached in the graphite possibly due to breakdown of the interface between the graphite particles and the iron matrix. It has been shown further that Raman spectroscopy can follow the elastic recovery of the cast iron and can pinpoint the onset of permanent plastic deformation by comparing the peak positions of the Raman before and after unloading.

Magnetic and mechanical properties of molded iron particle cores

Using high performance soluble imide polymer as a binder, it was possible to accomplish a substantial mechanical strength in iron particle cores molded under uniaxial compacting pressure which was much lower than that was commonly applied by others in the past. The directional ordering of oblate spheroidal iron particles occurred despite the low compacting pressure resulting in strong anisotropy in the magnetic properties and mechanical strength in the fabricated cores. The low molding pressure, however, resulted in a low density of core which, in turn, caused the low permeability.

The dry sliding wear behaviour of an austempered spheroidal cast iron

Dry sliding pin-on-disc wear tests have been carried out on an austempered spheroidal cast iron. The wear resistance was found to be orders of magnitude greater than the parent as-cast spheroidal iron and a much harder steel. The study of the wear behaviour was conducted as a function of sliding velocity between 0.5 m s −1 and 2.0 m s −1 at a load of 2 MPa. A distinction in the wear behaviour was found with severe wear at low speeds and mild wear at high speeds. This distinction has been related to oxide formation, microstructural and surface-hardening characteristics.

Seismic, bathymetric and photographic evidence of widespread erosion and a manganese-nodule pavement along the continental rise of the Southeast Cape Basin

The Southeast Cape Basin is flanked by the extensive Cape Town Slump at the foot of which is a widespread zone of erosion. Southward-dipping reflectors that intersect this surface of erosion are truncated and the surface itself contains channels up to 35 m deep and 2 km wide. An extensive moat, up to 100 m deep and over 20 km wide, runs along the northern edge of the subdued (< 1000 m relief) eastern section of the Agulhas Ridge. A pavement of well-exposed, large, spheroidal, botryoidal manganese nodules, embedded in sandy mud, was photographed and grab-sampled in a depth of 4517 m, south of the Cape Town Slump and southwest of the Argentina Seamount. The nodules are polynucleate and have increasing proportions of silicate detritus towards the outer edge. It is suggested that the inner layer may be of Early to Middle Pleistocene age because the nodules lie on a regional unconformity eroded into Palaeogene, Neogene and, in places, Early Pleistocene sediments. In contrast, the outer layer is probably Middle Pleistocene to Holocene and contains ice-rafted detritus. A camera-grab station in 4749 m near the major erosional channels revealed evidence of southeastward-flowing contour currents scouring a veneer of foraminiferal muddy sand draping a pavement of manganese nodules. More powerful bottom currents in the Agulhas Ridge Moat have formed westward-moving current ripples of glauconitic muddy sand. Small, friable, spheroidal iron nodules in the troughs between the ripples have nuclei of glauconitic sandy mud and are probably goethite-encrusted intraclasts derived from erosion of the underlying Early Pleistocene glauconitic pelagic clay.

球状黒鉛鑄鐵の車輛用制輪子への應用

Spheroidal graphite cast iron has many good properties as an industrial material, because of its special type of graphite. Wear resisting properties of this material has been expected to be excellent since advent of spheroidal graphite cast iron. Especially, in a dry wear condition spheroidal iron is said to be superior to other types of cast iron. Much research on the wear properties this material has been made by many investigators in Japan but their opinions about wear properties of spheroidal iron differed from each other and various experimental results were obtained. Naturally, complexity of substantial wearing mechanism and diversity of experimental conditions of wearing tests caused these discrepancies. Accordingly, to permit the wearing properties of the spheroidal graphite iron to be clear, experiments should be made in practical conditions. In this report the authors compared the life of spheroidal iron brake shoes with grey iron brake shoes which had been attached to electric tram cars The results were obtained in which the wear loss by grey iron brake shoe was about three times as spheroidal iron. The authors also made brake tests with the same tram car using two types of cast iron brake shoes which were used in the wearing tests. In brake tests retardation curves were recorded by using a self-recording acceleration meter. From these retardation curves the friction coefficients between brake shoes and tires were calculated in various experimental conditions. Thus the brake·effects of these two types of cast iron brake shoes could be compared. The results were such that the friction coefficient of spheroidal iron brake shoe was larger than that of the grey iron shoes when car velocity was raised up to more than 43 kilometers per hour.