Molten Cast Iron Research Articles

Investigation on Applicability of Lime as Desulfurization Agent for Molten Cast Iron

Investigation on Applicability of Lime as Desulfurization Agent for Molten Cast Iron

The time scale of nomadic steelmaking from molten cast iron

The time scale of nomadic steelmaking from molten cast iron

Industrial Ecotechnological Assessment of Lime as a Sustainable Substitute for Desulfurization of Cast Iron

This study comprehensively assesses the ecotechnological consideration and perspective of implementing a lime-based desulfurization process in the cast iron industry to replace the utilization of magnesium partially. By adopting an injection process to introduce the lime powder into molten cast iron, this research elucidated that the new alternative concept can successfully be integrated with daily operations without any disparities in cast iron quality, as proved by the production of cast iron products with vermicular graphite. A mixture of lime powder and carbon was utilized, and it was substantiated that the aim of a sulfur content lower than 0.015% can be reliably achieved. Furthermore, an ecological analysis was also conducted to justify the possible environmental advantages. The results indicated that considering the cradle-to-gate approach, the maximum amount of CO2eq connected to the lime-based desulfurization is approximately 43 g for 1 kg of desulfurized cast iron. This amount of calculated emission is still expected to be lower than the minimum calculated emission associated with the magnesium-based process, which can reach an amount of 76 g for a similar functional unit.Graphical

The Effect of Nodular Graphite on Hardness and Toughness in Permanent Molds Made of Ferro Casting Ductile

The permanent mold was made of Ferro Casting Ductile as a result of sand casting. Permanent mold is mold that can be used repeatedly. This permanent mold is used to produce tensile test specimens. Tensile test specimens are made of gray cast iron. This study aims to determine and analyze the effect of spheroidal graphite on the hardness and toughness of Ferro Casting Ductile in permanent molds to make tensile test specimens. The casting process starts by making patterns using Styrofoam, making molds with green-sand sand molds, followed by pouring molten cast iron into the molds. The next process is dismantling the castings and machining to get a permanent mold according to the dimensions. Specimens for testing the chemical composition were obtained from the results of castings into spherical dies. Meanwhile, the impact, hardness, and microstructure specimens were taken from the permanent molded product. The results of the chemical composition test showed that Ferro Casting Ductile contained several main elements, namely 92.14 %Fe, 3.681 %C, 3.715 %Si, 0.182 %Mn, 0.050 %Ni, and 0.034 %Mg which affected the percentage of nodular graphite. Nodular graphite will affect the hardness of the permanent mold. Validation was carried out by testing the hardness at 3 different points 167.70 VHN, 162.77 VHN, and 155.77 VHN. Toughness was obtained from the impact test using the Charpy method, the impact values were 0.048 Joule/mm2 0.046 Joule/mm2 0.037 Joule/mm2 on 3 different specimens. From the test results, the specimen has met the FCD 400 standard.

Experimental Study of a Representative Sample to Determine the Chemical Composition of Cast Iron.

In metallurgical practice, the material is considered of adequate quality if it meets the customer's expectations. It is necessary to take representative samples and perform quality testing to avoid financial and intangible losses. Sample contamination and matrix and surface quality play a significant role in the accuracy of chemical analyses. The purpose of this paper is to point out the advantages of specific methods of taking samples, such as immersion and spoon sampling of molten metal, and, in the experimental part, to assess the impacts of factors affecting the quality of the sampling. The influence of time of final sampling on determining the true amount of magnesium during a single melt and the influence of duration of mixing of molten cast iron on the accuracy of chemical analysis of the control sample were investigated. It is important that the time between the modification and casting of the liquid cast iron from the casting ladle be as short as possible. This is because the magnesium burns out and thus the chemical analysis of the sample taken is not accurate. Another important factor is ensuring the melt before sampling is homogenized and has the minimum prescribed temperature (1420 °C). Increasing sample collection time will cause changes in its chemical composition.

Analysis of the Penetration Behavior of Molten Cast Iron into the Sand Mold

An evaluation method for the initial penetration of molten cast iron into the sand mold was suggested based on the laboratory-scale penetration experiments for the cast iron. The horizontal penetration depth of the molten cast iron into the sand core was analyzed using the capillary model. The early stage of the penetration was discussed, and it was clarified that the penetration is not stopped by the solidification but is stopped by the decreasing of the equivalent pore radius. It was explained that the equivalent pore radius decreases with increasing the penetration depth, and the penetration is stopped when the critical pressure, i.e., the pressure required for the penetration, becomes higher than the pressure which is acting on the penetration front. Based on the analysis, an evaluation method of the penetration of depth at the early stage of the penetration was suggested. The analysis method was applied for the other type of metals (mercury and steel) as well, and reasonable results were obtained. A simplified finite-element model of liquid iron penetration into a sand core was developed, accounting for heat exchange between the melt and the porous medium, at different pore geometries.

DISTRIBUTION OF METAL DROPLETS BETWEEN GAS AND SLAG PHASES DURING BUCKET BATH BLOWING

Losses of metal with slag falling from the surface of the molten cast iron at the loading plants after the end of the ladle desulfurization process and losses with metal drops leaving the ladle bath when gas bubbles exit and break on its surface affect the cost and energy efficiency of the operation. Blowing a mixture of dispersed magnesium with lime into the ladle bath in the conditions of cast iron desulphurization plant PrJSC "KAMET—STEEL" leads to an increase in both the viscosity and the mass of the ladle slag, with an increase in the metal content in the form of balls in the ladle slag to 65— 80 %.
 The purpose of the work is to study the peculiarities of the removal of metal drops into the surrounding space, which are formed after the bursting of gas bubbles, when they fall on the surface of the ladle bath. To realize the set goal, a series of high—temperature experiments with simulation of bath purging during bucket desulfurization of cast iron were conducted in the laboratory conditions of the Department of metallurgy of ferrous metals and pressure metal processing of DSTU. A study of the features of removal and loss of cast iron with drops during overflows of the latter shows that some of the drops explode in flight with the release of brown smoke and the formation of drops of smaller sizes than the "mother" drop. Despite favorable conditions, part of the drops reach the surface of the bath or fly beyond it without exploding. Using the obtained experimental data, a model of the release of gas bubbles on the surface of the bath and an algorithm for calculating the indicators of the movement of metal drops formed from a metal film on the surface of gas bubbles after their rupture are proposed. It was determined that the most probable condition for blowing out the bath in a 230-ton bucket is the departure of metal drops from the surface of the bath at angles in the range of 35...45 degrees. The decisive role of the physicochemical properties of the slag cover and the expediency of further improvement of the blowing mode and slag regime of ladle desulphurization of processing cast iron have been confirmed.

Investigation of shell mold casting technique in Ghana using indigenous materials

Shell mold casting processes are more cost-intensive in terms of equipment, raw materials, and skills than the sand-casting technique. Sand casting is practiced in Ghana to cast mainly corn mill plates and occasionally vehicle and machine parts that lack good surface finish, better dimensional accuracy, and require a lot of effort/energy to bring the cast to the actual specification. As a result of the limitations of the sand-casting technique, the shell mold casting technique was adapted in this work. Indigenous clay chemically composed of 69.8% silica; 15.7% alumina was used. Washed and unwashed Silica from the Yakor River were investigated. The combination of clay, silica, and water was used to form a mold for the casting of a machine component. Of all the mixtures that were fired, the best mixture ratio was the sample which has the composition of 70% Mfensi clay, 10% silica sand, and 20% water selected from sixty-six samples. The mixture was tested based on its compressive strength and other parameters such as Acid Demand Value, pH Value, and Grain Fineness Number. Chemically, the final mold had a thickness of 16 mm which was able to withstand the high temperature (1450 °C) of the molten cast iron without the shell mold collapsing. A shell core made exhibited better core properties such as collapsibility, thermal stability, and permeability when the molten cast iron was poured into the mold for solidification.

Comparative Study on the In-Ladle Treatment Techniques for Nodulizing the Iron’s Graphite

The objectives of this research is to study and understand the nodulizing of ductile iron using in-ladle treatment process. Among the more common nodulizing agents is magnesium (Mg) which is conventionally added to the cast iron by combining suitable alloys of one or both of these elements with molten cast iron. Depending on the characteristics of each master alloy used as nodulizer, different treatment methods and techniques are used, among these, the most widely used being in-ladle, in-mould, and flow-through, the first being the most used. This research deals with the parameters, that affect the quality of ductile iron produced using in-ladle treatment process. The parameters involved are the percentage of magnesium–ferrosilicon (Fe–Si–Mg) used and the nodulizing technique. In-ladle treatment used consists of a deep pocket into the bottom of ladle, in which magnesium–ferrosilicon is placed into it together with a steel scrap barrier (steel sheets) or calcium carbide. This study, take into account, the degree of assimilation of magnesium, which shows the performance of the chosen process, depending on the nodulizer used and the temperature of the treatment.

Interface Formation Mechanism of Cemented Carbide Dipped in Molten Cast Iron

Interface Formation Mechanism of Cemented Carbide Dipped in Molten Cast Iron

RESEARCH OF THE RATE OF COOLING AND SELECTION OF THE MATERIAL FORM FOR THE MECHANICAL CHARACTERISTICS OF CAST IRON CASTINGS

The structure and properties of cast iron castings depends not only on the chemical composition of molten cast iron and the technology of its smelting, but also on many other conditions such as cooling and crystallization of castings, especially on further solidification of castings in casting molds. The article presents the established dependences of the influence of the cooling rate of castings on the mechanical properties of the obtained parts, the investigated microstructures of experimental samples from the selected molding materials and it is established that the thermal conductivity of materials affects the structure of graphite in cast iron castings. Computer models of dependencies and regression equations of the processes are proposed.

Investigation of the Nodularisation Propensity of Calcined Cashew-Nut Shell-Ash in Cast-Iron Melt Graphite

Production of ductile iron using ferrosilicon-magnesium master alloy in melt treatment is currently fraught with challenges bothering on cost and availability. In this study the suitability of cashew nut shells ash (CNSA) as a viable alternative to magnesium master alloys employed in the treatment of molten cast iron for enhanced mechanical properties was studied. The carbonized CNSA used varied from 2-10 wt. % to treat different heat batches; CA1-CA5 containing varied amount of CNSA, CaO and FeSi in the molten cast iron. The cast samples were subjected to both mechanical characterisation (tensile, hardness and impact) and microstructural analysis using Instron electromechanical machine, impact tester and scanning electron microscope (SEM) coupled with energy dispersive spectroscope (EDS). Results show that the 8 wt. % CNSA addition demonstrated the best mechanical properties comparable to ASTM A536 ferritic ductile cast iron. Specifically, the 8 wt. % CNSA cast samples exhibited 433 MPa tensile strength, 144HRC hardness and ductility of 14.7%. Contributions to improved mechanical properties may be attributed to the development of sufficient fractions of graphite nodules during melt treatment with CNSA. These outcomes are a boost both to the production of quality ductile irons and a cleaner environment.
 Keywords: Nodularisation, ductile-iron, cashew-nut, ferrosilicon-magnesium alloy, mechanical properties

Cast Iron Cooling Rate Variation Using Cooling Channels: A Numerical Approach

The cooling rate of molten cast iron can make or mar it. The cooling rate plays a significant role in the resulting mechanical properties of cast iron. It determines the grain growth and size. The mechanical properties of cast iron variation along its length are achieved either with the use of different mold materials or by sectioning to ensure varied cooling rates. Mechanical properties can, however, also be varied along its length without any of these adopted methods by the incorporation of cooling channels in the mould. This study seeks to expand the frontier of this concept with the use of different cooling fluids and fluid flow rate, and numerically investigate the impact on the cooling rate of gray cast iron (class 40). The cooling curve for the cast iron was impacted by the use of different cooling fluids with the attainment of the desired mechanical properties with the selection of an appropriate cooling fluid. Also, the flow rate of the cooling fluid has an impact on the cast iron cooling rate.

High-temperature erosive wear characteristics and bonding requirements of hard carbides cast-in insertion multi-component white cast iron

This research investigated wear resistance characteristics of hard carbide cast-in insertion cast iron by high-temperature erosive test. Moreover, good bonding conditions between cast iron and hard carbide alloy were examined by using casting simulation CAE. Two types of multi-component white cast iron with Cr, Mo, W, V, and Nb for base metal, tungsten carbide (WC) and titanium carbide (TiC) for insert were prepared. High-temperature erosion tests were conducted using alumina ball (average diameter: 1.16 mm, hardness: 1140 HV) with impact angle of 30, 60, and 90 deg. at 873 K.The air velocity of 100 m/s (particle velocity about 30 m/s). The total particle loading was 8 kg. The mass of the test specimen was measured before and after each test to evaluate the erosive wear property by erosion rate which is volumetric removal divided by the total feed of impact particles.As a result of erosion tests, WC cast-in insertion multi-component white cast iron showed good wear resistance characteristics compared with TiC one. TiC cast-in insertion multi-component white cast iron increased wear amounts due to cracking on insert surfaces that occurred by heat shock when pouring.Temperature history of interfacial molten cast iron and insert on solidification process were acquired by using solidification analysis to compere condition of molten steel and insert at the bonding interface. To longer liquid phase contact time is the thicker diffusion and reaction layer of each cast-in insertion sample. Both diffusion and reaction layers were created in the bonding interface of WC cast-in insertion sample. On the other hand, only diffusion layer was created in TiC cast-in insertion sample. These differences in bondability are due to diffusion coefficient of insert elements and gibbs standard free energy of carbides.

Interface Formation Mechanism of Cemented Carbide Dipped in Molten Cast Iron

Interface Formation Mechanism of Cemented Carbide Dipped in Molten Cast Iron

Investigation of Influence of Silicon Carbide Phase and Chemical Composition on its Recovery

When employing the cast iron manufacturing technology involving the use of silicon carbide, it was discovered that recovery of silicon carbide and that of its individual elements, viz., carbon and silicon varied. Based on the results obtained from a diffraction analysis and electron microscope investigation with electron microprobe analysis, the genuine structural and chemical features of industrial-grade silicon carbide were described. The phase composition of silicon carbide is inhomogeneous and consists of particles of the a-SiC crystalline silicon carbide and oxidized non-crystalline silicon carbide whose basis is a solid solution “carbon-silicon”. Recovery of silicon carbide by molten cast iron determined by the increase in the contents of carbon and silicon during the melting process is inversely on the content of the a-SiC phase.

Effect of Strontium Addition in Graphite Morphology and Nodularization of Hypoeutectic Cast Iron

Nodular graphite cast iron or known as spheroidal graphite cast iron structurally has a spherical graphite morphology with a matrix consisting of a ferrite-pearlite phase. In general, cast iron has a main alloy consisting of carbon and silicon where both elements have an influence on the potential of graphitization and castability. In this work, the influence of strontium (Sr) added to molten cast iron with a composition of 0, 0.04, 0.06 and 0.08 wt% to graphite morphology were studied. The sample obtained will be carried out a characterization process by observing macro and microstructures using optical microscope equipped with image data processing software that displays graphite fraction, size, form and nodularity. Analysis showed that Sr addition increase in nodularization of graphite from 19.6 % to 31.5% at 0.08 wt% Sr addition.

Cellular SiC/Iron Alloy Composite

Cellular SiC/iron alloy composite with a spatial structure of mutually intersecting skeletons created with a porous ceramic preform has not been obtained before, despite promising spectrum of potential uses. We tested the possibility of obtaining such material using a SiC material with an oxynitride bonding and grey cast iron. Porous ceramic preforms were made by pouring the gelling ceramic suspension over a foamed polymer base which was next fired. The obtained samples of materials were subjected to macroscopic and microscopic observations as well as investigations into the chemical composition in microareas. It was found that the minimum width of a channel in the preform, which in the case of pressureless infiltration enables molten cast iron penetration, ranges from 0.10 to 0.17 mm. It was also found that the ceramic material applied was characterized by good metal wettability. Were the channels are wide enough for the metal penetration we observed that the ceramics/metal contact area always has a transition zone in which mixing of both components takes place.

Nodulization of graphite in cast iron by addition of plastic resin

An addition of active metals such as magnesium and cerium to molten cast iron gives rise to solidified spheroidal graphite. Such alloys are called nodular cast iron, spheroidal graphite cast iron or ductile cast iron. However, the manufacturing of nodular cast iron has some issues including a difficulty in process control, a hazardous working environment and the unstable price of rare earth metals. To build an alternative way to produce nodular cast iron, this study examined the feasibility of nodulizing graphite by using plastic resin instead of active metals. It is presumed that the contact of plastic resin with molten cast iron results in its thermal decomposition, generating gas and carbon clusters that act as nuclei for precipitation of nodular graphite. Laboratory tests demonstrated a partial nodulization of graphite precipitating into cast iron that came in contact with a polyethylene sheet during the process of solidification. This result suggests an application potency of waste plastics for controlling microstructure of ferrous alloys, contributing to promotion of their recycling.

Influence of Inoculant Type on the Microstructure Characteristics and Mechanical Properties of Ductile Iron

The inoculation process of molten cast iron defines the final microstructure of the produced castings. The current study is concerned with the microstructure and mechanical properties of ductile iron castings as influenced by the type of inoculant. Inoculation treatment was done through one step and double step processes with different types of inoculants. The most efficient inoculant was that containing (1.0% Sr, 0.1% Ca, 0.5% Al) when used in single step or double step with (1.0% Sr, 0.5% Al) containing inoculant. As-cast tensile strength of 580 and 550 MPa at 20 mm thickness was achieved when this inoculant was used in single and double inoculation treatments, respectively. On the other hand, inoculation using the inoculant containing up to 2.0% Ce showed the lowest tensile strength of about 340 MPa. Though the nodule count (at 20 mm) was 100/mm2 for (1.0% Sr, 0.1% Ca, 0.5% Al) inoculant compared to 280/mm2 for the Ce containing inoculants, the pearlite content was higher in case of treatment by the former inoculant which resulted in higher tensile strength.