Production Of Ductile Iron Research Articles

Production of Ductile Iron Using Inside-Mold Treatment Technique

Ductile Cast Iron is a widely used cast iron. Ductile iron applications are used in various sectors of modern mechanical industries. Ductile iron has wide uses in the field of car industry, military industries, agricultural equipment, construction and mines. The production of ductile iron faces many technical difficulties in our local factories due to the difficulty in providing equipment and technologies for its production by common methods. In this study, we resorted to applying one of the modern methods in the production of ductile iron, which is the treatment process for the molten iron in the sand mold. Magnesium alloys were added inside the sand mold within the casting stream and in the casting cavity for casting production. Specific weights were added and experiments were performed to determine the fusible chemical composition appropriate for preparing ductile cast iron. The study proved that adding magnesium alloys inside the sand mold, whether inside the mold cavity or in the casting channel, is both a successful method for producing ductile iron alloys. It is possible to produce different types of ductile iron by controlling the ratio of alloy additions to the molten metal content during casting.

Constructive Improvements in the In-Ladle Treatments

Nodular gray cast iron having properties superior to conventional gray cast iron can be produced by treating the molten iron so that, when cast, the graphite will be compacted rather than in flake form. One such treatment involves the introduction of magnesium (Mg) into a molten iron bath of such composition. It is the principal object of the present industrial experiments to provide an improved process for the ductile cast iron production. Another object is to provide a process which permits the efficient use of the nodulizing agents, which results in the efficient production of an improved homogeneous nodular cast iron. Essentially such treatments result in the retention by the cast iron of small amounts of nodulizing agents, for example magnesium (Mg). Conventionally these agents are added to cast iron, usually in the form of pre-alloys and the efficiency of the process is illustrated by the high assimilation of the added nodulizer’s constituents. Another object of this technological practice is to provide an improved method for introducing the nodulizing agents, using constructive improvements to the in-ladle equipment. Finding magnesium (Mg) using novel techniques is the first step to advance the understanding of the role of magnesium (Mg) in the formation of the nodular graphite, the mechanism behind nodular graphite formation due to the addition of Magnesium (Mg) being still relative unclear at present time. Moreover, this may advance new methods to improve the nodulizing treatment process. This study take into account the flexibility of the used technique, which describes the elasticity of the treatment process, by improvement or alternative to the existing one. As nodulizing agents magnesium-ferrosilicon (Fe-Si-Mg type) and cerium-magnesium-ferrosilicon (Nodulin type) are examples of materials containing nodulizing agents that have given excellent results in the mixture. This experiments relates to a process for the production of ductile iron (nodular gray cast iron) and particularly to a process for adding magnesium (Mg) to the melted iron.

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

The Impact of Process Factors on Creating Defects, Mainly Lustrous Carbon, during the Production of Ductile Iron Using the Lost-Foam Casting (LFC) Method

The purpose of this paper was to analyze the process factors affecting the occurrence of lustrous carbon defects in ductile cast iron castings when using the lost-foam casting (LFC) method. This phenomenon results in creating raw surface defects, which sometimes may even lead to cast iron scrapping. A series of trial melting batches were carried out for variable process assumptions. The analysis was performed to reflect, to the greatest extent possible, real foundry production conditions. Industrial tests were performed in Odlewnia Rafamet Sp. z o.o., Kuźnia Raciborska, Poland. The polystyrene patterns created by gluing components together, used in the tests, met the requirements of the high-tech lost-foam casting (LFC) process. The performed analysis allowed the obtaining of lustrous carbon defects in test castings as well as the determination of the process parameters with the highest impact on lustrous carbon inclusions in ductile iron castings. The test results were used to eliminate the possibility of creating a defect and thus directly improve the efficiency of the lost-foam casting (LFC) process used in the foundry.

MICROSTRUCTURAL CHARACTERISTICS, MECHANICAL AND WEAR BEHAVIOUR OF ALUMINIUM-ALLOYED DUCTILE IRONS SUBJECTED TO TWO AUSTEMPERING PROCESSES

The effect of aluminium addition and austempering processes on the microstructures, mechanical and wear properties of rotary melting furnace processed ductile irons was investigated. Ductile irons containing 1−4 wt.% Al were produced and subjected to single and two-step austempering processes. Optical microscopy was used to characterize the graphite features and estimate the volume fraction of the matrix phases present, while the x-ray diffractogram was also carried out to analyse the samples. Mechanical and wear properties of the alloys were equally evaluated. From the results, it was observed that both the as-cast and austempered ductile iron microstructures contained nodular graphite, and the matrix structure for the as-cast ductile irons consisted predominantly of pearlite and ferrite, while that of the austempered grades, contained principally, ausferrite. The microstructure and intermetallic compound obtained played dominant role on the properties of the alloys. The aluminium addition and austempering processes had a significant influence on the mechanical properties and wear resistance of the alloys. The austempered ductile irons exhibited superior strength and wear resistance compared to the as-cast samples, albeit ductility values were lower in the composition group. Austempering increased the strength by over 100% while the addition of Al further enhanced the strength. The improved properties were linked to the refined microstructure, increased proportion of ausferrite phase and intermetallic compound formed. For all properties evaluated, the two-step austempering yielded better properties combination than the single step process. The rotary melting furnace processing adopted was found viable for ductile iron production.

Influence of Charge Composition on EN-GJS-500-7 Ductile Iron Properties in Foundry Operating Conditions

Worldwide production of ductile iron castings reached in year 2017 26,428,148 metric tons, which is 34% of the total weight of all castings made from cast iron. The most significant increase in ductile iron castings was recorded in Slovakia, up to 78.6%. Castings from ductile iron have a very huge utilization thanks their very good foundry and mechanical properties. The current economic situation in all industries forces entrepreneurs and producers to rationalize production and reduce production costs, with a worldwide trend to increase the share of steel scrap, a technology for the production of ductile cast iron. The paper describes the results of research focused on the effect of charge composition, mainly the share of scrap steel on the final properties and structure of ductile iron EN-GJS-500-7 under the operating conditions of foundry. Six melts with different charge composition were made. The samples from all melts were taken and chemical analysis, microstructure analysis and testing on mechanical properties were made on them. The mechanical properties of produced globular cast irons were according with the relevant standard. It is important to mention that there has been a significant increase in strength characteristics in melts in which the carbon content exceeded 4% (CE = 4.7 and 4.8%, respectively).

Influence of Carbide-Promoting Elements on the Microstructure of High-Silicon Ductile Iron

Because of its low cost, steel scrap is one of the most important raw materials for the production of ductile iron (DI). The amount of carbide-promoting elements in steel scrap, such as chromium, manganese, molybdenum, niobium and vanadium, is expected to increase in the future. Most of these elements have a negative impact on the microstructure and mechanical properties of DI. The solubility of carbide-promoting elements in solid solution-strengthened DI materials, standardized in DIN EN 1563:2011, is modified by the high silicon content. For these new materials, the tolerance limits for carbide-promoting elements and their mutual influence must be known to ensure a sustainable production process. To investigate the individual and combined impact of carbide-promoting elements on the carbide content in high-silicon ductile iron EN-GJS-500-14, experimental investigations and thermodynamic–kinetic microstructure simulations were carried out. Microstructure was characterized using metallographic analysis, and quantitative relations between chemical composition and microstructure were developed by means of regression analysis. Besides this quantitative analysis, it was found that the formation of grain boundary carbides can be detected via thermal analysis. Furthermore, experiments and simulations showed that vanadium promotes the formation of chunky graphite in high-silicon DI castings.

Evaluation of metallurgical behavior of oxygen and sulfur in base iron for ductile iron production based on thermal analysis

Evaluation of metallurgical behavior of oxygen and sulfur in base iron for ductile iron production based on thermal analysis

Structural characterization and mechanical properties of rotary melting furnace processed aluminium alloyed ductile irons

ABSTRACTThe microstructural characteristics and mechanical properties of rotary melting furnace processed aluminium alloyed ductile irons were investigated in this study. This was aimed at developing high performance – low material and processing cost ductile irons, suitable for the production of automobile components. Different compositions of the alloys were processed containing 1–4 wt.% aluminium. X-ray diffractometry, optical, scanning electron microscopy and mechanical properties measurements, were used to characterize the alloys. The results show that the ductile irons consists essentially, nodular and vermicular graphite-type distributed in a predominantly pearlite – ferrite matrix structures which attest to the viability of rotary furnace melt processing for ductile iron production. The nodule count were observed to increase with increase in Al wt.% but nodule sizes and degree of sphericity decreased with increase in Al wt.%. The mechanical properties of the ductile irons increased with increase in Al wt.%, except the ductility which decreased slightly with increase in Al wt.%.

Principles of construction and identification of a multilevel system for monitoring parameters of technological cycle of casting

For the creation of a multi-level system of integrated control and operational management of physical-chemical and technological casting processes, deterministic causality of technological objects was determined. These objects are involved in the processes of melting, ladle and heat treatment in the production of ductile iron castings. This made it possible to develop a block diagram of selection and optimization of key technological parameters, geometry of gating systems for the lost-foam casting.In order to ensure continuous control over a set of parameters of technological processes, equipment and environmental safety, key factors of influence of technological parameters were determined. To this end, the Ishikawa diagram was used to evaluate the effectiveness of the parameters and casting objects influence during lost-foam casting on the casting quality and environment. The expediency of using the Ishikawa diagram for the theory and practice of casting production was determined. Methods using the Ishikawa diagram were developed, which allow identifying and defining the deterministic influence of factors of the first, second, third order on technological processes and casting objects, as well as environment. They also provide an opportunity to determine the effectiveness of using the Ishikawa diagram in the production of high-quality cast products of iron-carbon alloys, including ductile iron.Basic data on the identification of casting objects and processes as the full cycle of production of ductile iron and castings of it by lost-foam casting were obtained. This will allow constructing a multi-level system for controlling the parameters of the full technological cycle using modern computer information technologies, as well as monitoring the environmental condition of casting objects and determining their environmental impact.

Production of Ductile Iron from Waste Sleeve Scraps for Automobile Applications

There is continuous demand for local production of quality automobile spare parts in the country nowadays. The current economic condition of the nation has placed more challenges on the indigenous foundry to improve on their technology to make automobile spare components accessible and affordable to the nation. This study examined the possibility of converting the indiscriminately dumped sleeve scraps from state of waste to ductile iron useful products thereby adding value to it. The mechanical properties of ductile iron produced from the sleeve scraps using local technology were determined and found comparable to that of international standard (ISO). Sleeve scraps were charged with graphite and FeSi into a rotary furnace and melted. Nodularization was achieved ising MgFeSi as an indigenous technology of the production process. The hypotheses of the study were tested and compared with the ISO standard of the grade of ductile iron and the findings revealed that Ductile iron that corresponds with the standard was successfully produced from solid waste (automobile sleeves scraps). It was recommended among others that the effort be made towards the conversion of sleeve scraps to ductile iron automobile components, in order to minimize the menace of environmental pollution which leads to numerous health hazards and mortality. Also, making automobile spare parts available to the end users and reduce its importation

Influence of Carbide-Promoting Elements on the Pearlite Content and the Tensile Properties of High Silicon SSDI Ductile Iron

Steel scrap is one of the most important raw materials for the production of ductile iron (DI) because of its low cost. Most low alloyed steels contain carbide-promoting elements such as chromium, manganese, molybdenum and niobium and are currently not used for the production of DI because of their negative impact on the mechanical properties. The solid solution strengthened DI grades (SSDI) exhibit an increased tolerance toward carbide-promoting elements and thus allow the production of ferritic DI using low alloyed steel scrap. Therefore, the tolerance limits of these elements need to be identified. The following article shows the influence of low contents of Cr, Mn, Mo and Nb on the microstructure and the tensile properties of the SSDI grade EN-GJS-500-14. The results indicate that even low levels of chromium and molybdenum have a negative impact on tensile properties, whereas manganese and niobium are tolerable up to much higher levels.

Conversion of Mill Scale Waste into Valuable Products via Carbothermic Reduction

Mill scale is one of waste materials which is produced as a result of hot rolling of steel in all steel companies. On the other hand, mill scale is considered a rich iron source with minimum impurities. This work aims at conversion of mill scale by adjusting smelting processes to produce different valuable products. The smelting processes were carried out using carbothermic reduction in a submerged arc furnace. Two carbonaceous reducing agents and different fluxing materials have been used to adapt optimum smelting process condition. A maximum iron recovery of 83% was obtained by using graphite compared with 76% obtained by using coke. Low sulphur content (≤0.02 wt% S) can be attained by using graphite as a reducing agent in amount that equals or exceeds the stoichiometric molar ratio. By using coke, the highest degree of desulfurization of 97.8% and much lower content of sulphur in the castable metal (0.0028 wt% S) were obtained by controlling the type and quantity of the flux. The results reveal that mill scale waste can be converted into valuable products such as high purity iron as alternative to Sorelmetal used in ductile iron production, low carbon steel, and free cutting steel.

World Crisis of Rare Earth – Inoculants Enhancer Solution for Ductile Iron Production

The unique properties of rare earth elements (REE) have resulted in their being crucial to a growing number of emerging technologies. As the demand for REE currently exceeds annual production, the present worldwide crisis for REE will probably continue for the foreseeable future. Hence, it is highly likely that the availability of REE used in the metallurgy of cast iron will be significantly reduced and alternatives to REE usage may have to be developed. Graphite nodules nucleate heterogeneously on particles formed in the melt, having a duplex structure (sulphide as a core and oxide/silicate as a shell). Mg, Ca and REE appear to act in the nucleation first stage, while Si, Al, Mg, REE, Ca, Sr and Ba act predominately in the second stage. Generally, REE are employed in ductile irons to accomplish the following tasks: (a) neutralize tramp elements such as Ti, Pb, Bi, As etc; (b) assist in nodulizing or provide a supplementary effect to Mg to promote spheroidal graphite shapes; (c) assist in nucleating graphite. When anti-nodularising Thielman control factors (K) are less than 0.8, REE are usually not required since there are no trace elements to neutralize. REE are useful for K factors between 0.80 to 1.20 and are mandatory for K factors greater than 1.20. Theilman factors greater than 2.0 will always require REE. When Theilman factors are less than 0.80, REEreslevels of 0.01% are usually more than sufficient for ductile iron production. Three ductile iron inoculation alloys were selected for this research: (a) a conventional Ca bearing 75% FeSi inoculant (Ca-FeSi), used at a high consumption level; (b) an improved conventional Ca-FeSi alloy that incorporated active inoculating elements, such as Ba or REE, used at a medium consumption level, and (c) a combination of a commercial inoculant, such as Ca-FeSi alloy, used with a separate oxy-sulphide inoculant enhancer alloy addition. The last inoculation variant provided the best structural parameters and the lowest consumption level.

The Continuing Evolution of MgFeSi Treatments for Ductile and CG Irons

Production of ductile iron has been linked to the use of Mg and Mg-alloys since its invention. In the early history of ductile iron production, pure or high Mg containing alloys were needed due to the higher S level in the base iron. With the introduction of basic slag cupolas and low S base iron, the high Mg containing alloys were replaced with materials with lower Mg-content providing a calmer reaction with less slag generation and more predictable results and tighter control of the final Mg level. MgFeSi was recognized early as an excellent material to introduce Mg into the cast iron melt. MgFeSi offered the possibility to design both chemical composition and sizing to accommodate needs such as reaction control for different treatment processes, trace element control, packing density, and boosting of Mg-level. One of the main goals with MgFeSi treatments is to minimize the overall addition of Mg to tight reproducible low levels to reduce the shrinkage tendency observed with high final Mg levels. This can be achieved through a combination of optimization of the MgFeSi composition as well as improvement of the treatment process. A well designed MgFeSi-treatment can reduce fume and flare, slag generation, and the need for subsequent inoculation. The history and evolution of MgFeSi treatment along with relevant recent case studies will be presented in this paper. Examples of how the MgFeSi material can be optimized will be presented both in terms of theory and case studies. Focus of case studies will be on the recent evolutions focusing on maximizing Mg-yield through delayed and calm reaction.

Analysis of the Ductile Iron Production on the Steel Scrap Base

Removed at authors request

Analysis of ductile iron production on steel scrap base

The cast iron production (melting) process is commonly based on pig iron. However, economic and ecological factors necessitate that the melting process is more often based on steel scrap (with no pig iron at all). This kind of cast iron is called synthetic cast iron. This approach may, however, cause a decrease in the quality of the alloys obtained, particularly when ductile iron (DI) is produced. The following article presents an analysis of the product and some aspects of ductile iron produced exclusively on a base of steel scrap. The experiments and the charging materials are described. The results of the chemical analysis of the produced DI, the carburisation efficiency and microstructure of the obtained material are presented as well. The results of cast iron melted on a pig iron base are presented for comparison. A quantitative microstructure analysis is also presented.

Production of Ductile Iron Using Indigenously Manufactured Rotary Furnace

Production of ductile iron using an indigenous 100kg rotary furnace was achieved using the ladle treatment/sandwich cover ladle method. Powdered Ferrosilicon magnesium of 400g was used as a nodularizer together with powdered Ferrosilicon of 20g was used as innoculant. The nodularizer was put in a cylindrical pocket at the base of the ladle with a circular fitting steel plate cover welded to a handle which was removed immediately after tapping the molten metal from the rotary furnace. The resulting melt was subsequently poured into the mould after the violent reaction between the molten metal and the nodularizer. Samples of the as-cast were subjected to metallographic process and characterized using a Nikon Eclipse metallurgical microscope and a Hilger Analytica atomic mass absorption spectrometer for percentage elemental analysis. The average percentage element weight of the samples and microstructures of 200X and 400X compared favourably with the ductile iron produced from standard procedure.

Using Cored Wire Injection Method in the Production of Austenitic High Ni-Alloyed Ductile Iron Castings

Abstract Below are described results of the analysis concerning the use of two cored wire injection method (2PE- 9) and the unique application of a drum ladle as a treatment, transport and casting one, instead of a vertical treatment ladle. Parameter optimization, like: length of nodulariser wire, residual magnesium content, treatment and pouring temperature have been shown. Influence of various treatment temperatures, magnesium-cored wire velocities (Mg-treatment times) and weights of molten alloy on magnesium recovery are demonstrated. Moreover, graphite nodule content in relation to different raw materials in the charge mix are presented. Typical microstructure, mechanical properties and treatment costs are given as well. Using specific industrial conditions for tests and optimal, low scrap production of austenitic nodular cast iron (EN-GJSA-XNiSiCr35-5-2 Grade, according with EN 13835), makes this innovative method very credible. Injection of two Ø 9 mm wires; cored in FeSi + Mg nodulariser mixture and inoculant master alloy into a drum ladle is a treatment method that can be used for the production of ductile iron melted in a coreless induction furnace.

Using Cored Wires Injection 2PE-9 Method in the Production of Ferritic Si-Mo Ductile Iron Castings

Abstract The results of studies on the use of modern two cored wires injection method for production of ferritic nodular cast iron (ductile iron) with use of unique implementation of drum ladle as a treatment / transport and casting ladle instead vertical treatment ladle was described. The injection of length of Ø 9mm wires, cored: in FeSi + Mg nodulariser mixture and inoculant master alloy is a treatment method which can be used to produce iron melted in coreless induction furnace. This paper describes the results and analysis of using this method for optimal production of ductile iron under specific industrial conditions. It means, that length of nodulariser wire plus treatment and pouring temperatures were optimized. In this case, was taken ductile iron with material designation: EN-GJS-SiMo40-6 Grade according EN 16124:2010 E. Microstructure of great number of trials was controlled on internally used sample which has been correlated with standard sample before. The paper presents typical ferritic metallic matrix and nodular graphite. Additionally, mechanical properties were checked in some experiments. Mean values of magnesium recovery and cost of this new method from optimized process parameters were calculated as well.