Grades Of Cast Iron Research Articles

Design and Control of the Natural Frequency of Brake Discs in the Aspect of the Gray Cast Iron Production Process.

The results of research on the influence of the chemical composition of cast iron and its potential changes in the production cycle on the elastic properties and the correctness of numerical simulations of the natural frequency of ventilated brake discs are presented. The tests were carried out for three grades of gray cast iron with flake graphite with a eutectic saturation coefficient ranging from 0.88 to 1.01. A quantitative metallographic assessment of the pearlitic cast iron matrix and graphite precipitates was carried out, and the hardness and compressive/tensile strength of individual cast iron grades were determined, taking into account the limit contents of the alloying elements. Next, ultrasonic tests were performed, and the elastic properties of cast iron were determined. Based on the obtained data, a numerical modal analysis of brake discs was performed, the results of which were compared with the actual values of an FRF frequency analysis. The error of the computer simulations was estimated at approx. 1%, and it was found that the accuracy of the calculations of the first natural frequency did not depend on the dimensions (size) of the discs and the chemical composition of the cast iron from which they were cast. The functional relationships between the chemical composition of cast iron, its strength and elasticity and the first natural frequency of the disc vibrations were determined, and a database of the material parameters of the produced cast iron grades was developed. An implementation example showed the validation of the brake disc design with natural frequency prediction and demonstrated a high convergence of the experimental results with the simulated values. Using I-MR control cards, both the effectiveness of designing and predicting the natural vibrations of brake discs based on the implemented material database as well as the stability of the gray cast iron production and disc casting processes were confirmed.

The effect of silicon on the critical resolved shear stress of solid solution strengthened ferritic ductile iron

Solid solution strengthened ferritic ductile iron (SSFDI) exhibits improved mechanical properties compared to conventional ductile cast iron (DCI) grades, however, its potential widespread application is hindered by unpredictable brittle fracture which might be attributed to microstructural silicon segregation and associated superstructure formation. The aim of the present study is therefore to deepen the understanding on the effect of local silicon segregation on the mechanical properties of SSFDI, which is crucial especially for the common applications of DCI in cyclically loaded structures. Micropillar compression tests were carried out on three different casts to investigate the solution strengthening effect of silicon in the ferritic matrix. An almost perfect linear relationship between critical resolved shear stress (CRSS) and global silicon content was found. It was also found that the variation of CRSS with silicon content corresponds well to the variation of the macroscopic yield limits (under tension and compression) with global silicon content of different SSFDI alloys. This indicates that the ferritic matrix dominates the yield limit of the DCI alloys investigated in this study, while the morphology of the graphite nodules plays a minor role under monotonic loading conditions.

Improving the Abrasion Resistance of Nodular Cast Iron Castings by Remelting Their Surfaces by Laser Beam.

This paper presents the results of research conducted in the field of the technology of surface hardening of castings from unalloyed and low-alloy nodular cast iron using the laser remelting method. The range of studies included macro- and microhardness measurements using Rockwell and Vickers methods as well as metallographic microscopic examinations using a scanning electron microscope. Moreover, abrasive wear resistance tests were performed using the pin-on-disk method in the friction pair of nodular cast iron-SiC abrasive paper and the reciprocating method in the friction pair of nodular cast iron-unalloyed steel. Analysis of the test results shows that the casting surface layer remelting by laser for unalloyed nodular cast iron results in a greater improvement in its resistance to abrasive wear in the metal-mineral system, as compared to low-alloy cast iron. Additionally, carrying out the laser hardening treatment of the surface layer made of the tested grades of nodular cast iron is justified only if the tribological system of the cooperating working parts and allowable dimensional changes during their operation are known.

Ni-Cu Alloyed Austempered Ductile Iron Resistance to Multifactorial Wear

The paper provides a discussion on the results of studies of the effect exerted by combined degradation factors typical of four types of wear: abrasion, impact–abrasion, tribocorrosion, and impact–abrasion–corrosion, conducted for chain wheels made of Ni-Cu alloyed austempered ductile iron. The studies consisted of determining the content of retained austenite in the structure of the cast irons in question, establishing the measures of wear following wear testing, and identifying the basic surface degradation mechanisms observed in the chain wheels tested following multifactorial wear processes. The chain wheels made of ADI were found to have sustained the greatest damage under the impact–abrasion–corrosion (three-factor) wear scenario, while the wear was least advanced in the abrasion (one-factor) wear case. Another observation derived from the studies is that the combined effect of dynamic forces, corrosion, and quartz sand-based abrasives causes increased surface degradation in the cast iron grades taken into consideration compared to processes characterised by a reduced number of degradation factors (i.e., one- or two-factor wear processes). Additional hardness tests and XRD analyses revealed that a distinctive effect attributable to combined degradation factors on the surface hardness increased value and implied that bench testing was followed by phase transition.

Linking the microstructure with strain-life curves for improved utilization of the lightweight potential of thick-walled nodular cast iron

The assessment of the fatigue life of critical, highly stressed component areas is an important aspect in the design of thick-walled components for wind turbines made of nodular cast iron. With the demand for resource efficiency through lightweight design combined with a certain capability to withstand extreme loads and special events, this issue is becoming increasingly important. However, there are still gaps in the description of local strain-based material behaviour. For the design and local strain-based fatigue assessment of large cast components, possibilities to determine the fatigue life as accurately as possible must be provided by standards and guidelines. The paper aims to provide a wide range of material and fatigue data from one common source for general design interests. During research projects at Fraunhofer LBF, material properties for the PRAM-based fatigue life assessment and the elastic-plastic material behaviour have been derived from 9 nodular cast iron grades with 44 microstructural variations. To describe the influence of the technological size effect on cyclic stress-strain and PRAM-N curves the quasi-static parameters (tensile strength and elongation at break) and the microstructure (nodularity and graphite particle density) are considered. In addition, suggestions for scatter bands in the strain-based design approach are given to the designers of thick-walled GJS components.

Strain-life behavior of thick-walled nodular cast iron

Abstract For the design of thick-walled cast iron components used for wind energy turbines, large machines, presses, and engine parts made of nodular cast iron, the assessment of fatigue life of critical component areas is a crucial point to consider. Importance increases with the demand to safe resources by applying a lightweight design in combination with a certain resistance against extreme loads and misuse situations. Moreover, this gets more important when notches or deviations in the local microstructure are present. Nevertheless, due to accessibility, a lack in the description of the local strain-based material behavior still exists. Especially new cast iron grades such as ADI are not well investigated but offer an often-discussed potential for a lightweight design of the structure or to increase the highest admissible load on the structure. To determine the cyclic material behavior of nodular cast iron, different grades EN-GJS-400-18LT, EN-GJS-450-18, EN-GJS-500-14, EN-GJS-600-3, EN-GJS-700-2, and ADI in different wall thicknesses were investigated concerning their elastic–plastic material behavior under strain control. Moreover, new possibilities for the trilinear description of the strain-life and the stress–strain curve and the statistical and technological size effect are discussed in the following based on cyclic stress–strain and strain-life curves.

Yüksek Silisli Lamel Grafit Dökme Demir Kamyon Fren Disklerinin Sürtünme ve Aşınma Davranışı

In this study, the chemical compositions of high-silicon lamellar graphite cast irons commonly used in truck brake discs and the effects of applied heat treatments on their friction and wear behaviors were investigated. For this purpose, samples with two different chemical compositions (first with 2.43 C and 4.5 Si; second with 2.5 C and 4.2 Si) were produced, and homogenization annealing was applied at 900°C for 30, 45, and 60 minutes followed by air cooling. Hardness, tensile testing, and wear testing were performed on the heat-treated samples. Wear tests were conducted at room temperature and dry sliding conditions (20 N load, 250 mm sliding distance, and 200 mm/min sliding speed) using a ball-on-disk wear apparatus against 52100 bearing steel. The increase in homogenization heat treatment time resulted in an increase in hardness and tensile strength values for both lamellar graphite cast iron grades. The wear test results indicated that both the chemical composition and the duration of applied heat treatment influenced the friction coefficient and wear volume losses. Since high friction coefficient and low wear volume losses are desired in brake discs, it was determined that the best result among the compared samples was achieved in the sample produced with a chemical composition of 2.5 C and 4.2 Si, and then homogenized at 900°C for 30 minutes.

A strain energy density design approach for large cast iron components: From microstructural analysis to multiaxial fatigue response

A new criterion for predicting multiaxial fatigue in plain and V-notched specimens made of ductile cast iron is proposed. The criterion is based on volumetric strain energy density (SED) and separately accounts for the effect of normal and shear mean stresses with two material-dependent coefficients. The criterion also considers the impact of out-of-phase loading through a strengthening factor, assuming that fatigue damage is initiated by the total SED peak in the cycle. The criterion is validated using a large amount of independent multiaxial fatigue data, obtained from testing three different ductile cast iron grades.

Abrasive Wear Resistance of Ultrafine Ausferritic Ductile Iron Intended for the Manufacture of Gears for Mining Machinery.

The purpose of this study was to experimentally determine the abrasion wear properties of ausferritic ductile iron austempered at 250 °C in order to obtain cast iron of class EN-GJS-1400-1. It has been found that such a cast iron grade makes it possible to create structures for material conveyors used for short-distance transport purposes, required to perform in terms of abrasion resistance under extreme conditions. The wear tests addressed in the paper were conducted at a ring-on-ring type of test rig. The test samples were examined under the conditions of slide mating, where the main destructive process was surface microcutting via loose corundum grains. The mass loss of the examined samples was measured as a parameter characteristic of the wear. The volume loss values thus obtained were plotted as a function of initial hardness. Based on these results, it has been found that prolonged heat treatment (of more than 6 h) causes only an insignificant increase in the resistance to abrasive wear.

Improving technology for manufacturing casting case of truck clutch release cylinder

The object of research: Manufacturing technology of body castings for trucks using the example of a clutch release cylinder body made of gray cast iron with flake graphite EN-GJL-200.
 Investigated problem: Finding ways to reduce the weight and size characteristics of cast parts.
 The main scientific results: A mathematical model has been developed that has made it possible to determine the optimal compositions of alloying Cr/Ni – Cu/Ti complexes that ensure an increase in the grade of cast iron by increasing the tensile strength at elevated carbon contents. This makes it possible in the future to reduce the thickness of the walls of the castings, achieving a reduction in their weight and size characteristics
 The area of practical use of the results of the study: Automotive industry in terms of technology for manufacturing cast parts for trucks
 Innovative technological product: Improved technology for manufacturing the clutch release cylinder body due to optimization of melt technology and out-of-furnace processing allows for targeted selection of melt processing modes, ensuring an increase in the strength characteristics of cast iron for cast body parts, thereby moving from the EN-GJL-200 cast iron grade to the EN grade -GJL-250 and EN-GJL-300.
 The scope of the innovative technological product: Foundries of engineering enterprises, in particular those producing trucks, in which iron castings are produced

Waste-free processing of waste nickel slags

The paper considers one of possible options for the waste-free processing of dumped masses of nickel slags, accumulated over the years of operation of some enterprises. This process includes the use of hydroand pyrometallurgical processing, which results in three products: iron sulfate, ferrosilicon with a small admixture of aluminum, and slag from the ferrosilicon smelting. The slag has a hardness of 7-7.5 Mohs and can be used as an abrasive powder for sandblasting, or as a raw material for production of high alumina cement. The resulting iron sulfate can subsequently be purified from the copper, nickel, magnesium, and aluminum impurities and brought to the existing GOST compositional requirements. The resulting ferrosilicon, whose silicon content is similar to that of the marked ferrosilicon FS 75 with an aluminum admixture, can be used for deoxidation and silicon alloying of all existing grades of steels and cast irons. In this case, specifications drawn up with participation of a consumer enterprise can be a regulatory document for such ferrosilicon. The slag obtained during the ferrosilicon smelting can also be defined within the framework of these specifications for the abrasive powder producing enterprises.

Optimization of product processing modes in modeling and programming of machining on machine tools with program control

Purpose. To solve a scientific and technical problem related to the technological support of high-performance machining of a cast iron part by optimizing and controlling its machinability with a hard-alloy tool on multi-axis CNC machines using CAD-CAM systems. The methods. The methodological basis of the work is a systematic approach and analysis of the study of the object of research, based on the use of: numerical and graphical-analytical research methods in order to establish a systematic relationship between turning parameters and the properties of the material being processed, tool geometry and its stability, parameters of cutting modes with the corresponding indication in the control program for the CNC machine. Findings. Numerical research results have been obtained for a scientifically based approach to solving the technical problem of high-performance turning of cast iron parts on multi-axis machining centers, which contains a set of adjusted methods and algorithms for predicting their machinability with ensuring the reliability of hard alloy cutting tools. The results obtained were compared with known works related to the study of machining processes of various grades of steels, alloys, and cast irons, the assessment of the reliability of cutting tools, the accuracy and roughness of the machined surface, and the results of measurements of cutting force parameters. The maximum relative error of the calculations did not exceed 6-8%. The originality. Establishment of a complete and systematic connection of machining parameters with the properties of the processed material, tool geometry and design and technological factors of the part for the calculation of an optimized automated production technology. In the mathematical and statistical processing of experimental data, which made it possible for the first time to obtain complex dependencies in a form convenient for calculation and analysis, which give a clear picture of the effect of each parameter of the turning process on its energy and time indicators when compiling a rational technology for machining a part of complex geometric shape in a CAM system. Practical implementation. It consists in selecting and justifying the optimal geometric parameters of cutting tools and equipment, establishing the nature of the influence of the conditions of turning cast iron on the main process parameters - machining time and operating parameters depending on the hardness of the part material and tool material. Practical recommendations are given on the optimal use of CAD-CAM systems, adjustment of process results and operating parameters to obtain optimal results at the stage of production preparation.

Dependence of hardness and other properties of gray iron on its carbon equivalent and degree of eutecticity

The chemical composition, carbon equivalent and properties of castings from unalloyed and low-alloyed gray irons with lamellar graphite of various grades from СЧ100 to СЧА400 were analyzed in accordance with DSTU 8833:2019. There is a reference to such cast iron in the technical conditions for brake pads made of composite materials (rubber mixtures), in particular, for the production of cast iron inserts. Other products for railway transport are also made from cast iron СЧ350, for example, the friction “Khanin wedge”. It is shown that in industrial batches of the “Khanin wedge”, cast from cast iron СЧ350, the hardness did not correlate either with the content of elements in the chemical composition of the cast iron, or with the carbon equivalent due to the narrow range of its values even within the cast iron of the same grade. According to DSTU 8833:2019, with an increase in the carbon equivalent in the possible regulated range of values (%) from 3.03 to 4.54, the Brinell hardness of HB monotonically decreases by approximately 1.54...1.57, and the coefficient of thermal conductivity increases by almost one and a half times. Reducing the sulfur content in the chemical composition from 0.20 to 0.05 % of CH350 cast iron significantly reduces the range of dispersion of the carbon equivalent. The parameters (mean values, mean square deviations and coefficients of variation) of the carbon equivalent and the degree of eutecticity of the chemical composition of cast irons with lamellar graphite of brands from СЧ100 to СЧА400 were determined by means of statistical tests using the Monte Carlo method. It is shown that due to the significant dispersion of the values of the carbon equivalent of the chemical composition, hardness, coefficient of thermal conductivity, strength, density, modulus of elasticity, linear shrinkage, heat capacity, coefficient of linear expansion of cast iron with lamellar graphite of grades from СЧ100 to СЧА400 according to DSTU 8833:2019, it is necessary from the specified list grades of cast iron to determine and regulate in the technical conditions for composite brake pads a specific grade of cast iron intended for the manufacture of inserts in such pads.

Technology for producing cast iron castings with compact graphite by top filling

The technology of ladle modification “top filling” has been tested and introduced to produce castings of parts from low grades of high-strength cast iron, in particular ChVG40, VCh50. The technology allows us to consistently achieve a degree of graphite spheroidization of at least 80%. For each of the mastered castings of the parts “Reduction gear axle casing”, “Front idler hub” and “Exhaust manifold”, the consumption of a spheroidizing modifier and a graphitizing modifier was selected. In the chemical composition of the castings, to obtain a predominantly ferrite-pearlite structure, the manganese content was adjusted from 0.4...0.5% to 0.3...0.4%.

Cold-curing mixtures based on biopolymer lignin complex for casting production in single and small-series conditions

<abstract> <p>This study proves that lignin-based biopolymer materials can be employed as starting materials for the synthesis of novel casting binders that fulfill the current level of characteristics. The optimal concentration of the binder in the mixture was experimentally determined to be 5.8%–6.2%. It has been demonstrated in practice that the employment of ammonium salts as a technical lignosulfonate (TLS) modifier can result in the provision of cold (room temperature) curing of a mixture based on them. It was proposed to use as a technological additive that boosts the strength characteristics of a mixture of substances carboxymethyl cellulose (CMC). In a variety of adhesive materials, it is utilized as an active polymer base. The concentration limits for using CMC in the mixture are set at 0.15%–0.25%. To improve the moldability of the combination, it was suggested that kaolin clay be used as a plasticizing addition. The concentration limits for using a plasticizing additive are set at 3.5%–4.0%. The produced mixture was compared to the analog of the alpha-set method in a comparative analysis. It was discovered that the proposed composition is less expensive, more environmentally friendly, and enables the production of high-quality castings. In terms of physical, mechanical, and technological properties, the created composition of the cold curing mixture is not inferior to analogs from the alpha-set method. For the first time, a biopolymer-based binder system containing technical lignosulfonate with the addition of ammonium sulfate and carboxymethyl cellulose was used in the production of cast iron castings on the case of a cylinder casting weighing 18.3 kg from gray cast iron grade SCh20. Thus, it has been proved possible for the first time to replace phenol-based resin binders with products based on natural polymer combinations. For the first time, a cold-hardening mixture based on technological lignosulfonates has been developed without using hardeners made of very hazardous and cancer-causing hexavalent chromium compounds. But is achieved through a combination of specialized additives, including kaolin clay to ensure the mixture can be manufactured, ammonium sulfate to ensure the mixture cures, and carboxymethyl cellulose to enhance the strength properties of the binder composition. The study's importance stems from the substitution of biopolymer natural materials for costly and environmentally harmful binders based on phenolic resins. This development's execution serves as an illustration of how green technology can be used in the foundry sector. Reducing the amount of resin used in foundry manufacturing and substituting it with biopolymer binders based on technological lignosulfonates results in lower product costs as well as the preservation of the environment. Using lignin products judiciously can reduce environmental harm by using technical lignosulfonates, or compounds based on technical lignin. The combination is concentrated on businesses with single and small-scale manufacturing because it is presumable that this is merely the beginning of the investigation. This study confirms the viability of creating a cold-hardening combination based on technical lignosulfonates in practical applications and supports this with the castings produced, using the creation of a gray cast iron cylinder casting as an example.</p> </abstract>

Computational and experimental determination of parameters of laser hardening zones of cast iron

The paper presents the results of metallographic studies and tribotechnical tests of samples of special cast iron of the "C" brand for passenger train brake pads. Regression equations for determining the depth and width of laser quenching zones were obtained using a full factorial experiment. The response surfaces of the system are constructed and the patterns of change are determined the size of the quenching zones depends on the processing modes. It is shown that the greatest influence on the depth and width of the hardening zones was exerted by the radiation power and the scanning speed of the beam. The use of transverse vibrations of the laser beam increased the productivity of the processing process. The microhardness in the zones of laser quenching from the liquid state was significantly higher than the zones of hardening from the solid state in all the studied processing modes. Tribotechnical tests were carried out according to the scheme "plane (wide side of a flat sample of special cast iron grade "C") – the annular surface of the sleeve of the counter-tile (wheel steel grade 2) with the use of semi-liquid lubricant "PUMA". The load and sliding speed varied discretely. The wear resistance of laser–hardened samples was 2.4 - 2.9 times higher than the base material, depending on the area of the hardened tracks. The friction coefficients paired with the wheel steel of the samples with laser hardening decreased slightly, which will allow the use of laser hardening for passenger train brake pads without changing their design.

Procedure for selecting a rational technological mode for the processing of cast iron melt on the basis of graph-analytical processing of the data of serial smeltings

The object of research: cast iron grade DSTU EN 1561 (EN-GJL-200), used for the manufacture of body parts for mechanical engineering.
 Investigated problem: the choice of the technological mode of the process of producing cast iron under conditions of multifactorial influence on the formation of its microstructure.
 The main scientific results: A procedure for truncation of the influencing factors on the formation of the microstructure is proposed, which is a consistent reduction of data from serial smeltings to uniform conditions allowed by the actual data set. Common conditions mean the closeness of the chemical composition of the melt, which makes it possible to compare the effectiveness of the applied modifiers in combination with microalloying in terms of cast iron microstructure indicators. The proposed data truncation procedure made it possible, by creating conditions for comparing the efficiency of FeSi75 and FeSi65CaBaSr2 modifiers, to develop a rational technological regime for melt processing.
 It has been established that the compared modifiers have the same effect on the size of graphite – its content is (50–51) μm, however, the use of FeSi65CaBaSr2 in combination with an alloying complex (0.27 %Cr+0.083 %Ni+0.048 %Ti+0.155 %Cu+0.018 %V ) makes it possible to obtain an average amount of pearlite of 96 % in the microstructure.
 The area of practical use of the results of the study: the results obtained can be used in foundries or metallurgical shops of industrial enterprises as part of a general technology for producing cast iron of various grades, developed for cases of incomplete control of the quality of charge materials. Such a situation occurs, for example, when the charge is formed from dismantled armored vehicles that cannot be restored due to destruction on the battlefield.
 Innovative technological product: iron smelting technology that allows the possibility of minimizing the cost of smelting in terms of the use of modifiers and alloying ferroalloys
 The scope of the technological innovative product: technological regimes for the production of cast iron.

ACO EUROBAR EN-GJL-250C (5.1203)

Abstract ACO Eurobar EN-GJL-250C (5.1203) is an intermediate-tensile-strength gray cast iron that is produced by the continuous casting process. Compared with the lower strength gray cast iron grade, EN-GJL-200C (5.1202), it possesses superior wear resistance, while still maintaining good thermal conductivity, damping capacity, and machinability. Brinell hardness values in Table 3 corrected September 2022. This datasheet provides information on composition, physical properties, microstructure, hardness, and tensile properties. It also includes information on heat treating and machining. Filing Code: CI-94. Producer or source: ACO Eurobar GmbH (a subsidiary of ACO Guss GmbH).

Influence of Microstructure on Static and Cyclic Fracture Toughness of EN-GJS-600-3 Nodular Cast Iron

In this paper, the effect of microstructure of a thick-walled rotor shaft for wind turbines on fracture toughness properties has been investigated. The relevant nodular cast iron grade EN-GJS-600-3 was processed using chill casting technology. Due to different solidification conditions over the wall thickness, heterogeneous microstructures were formed. To illustrate the influence of the microstructure gradient caused by chill casting technology, specimens were taken from different sample positions in the cross section of the casting component. A detailed metallographic analysis revealed essential differences in microstructure. The crack growth resistance under quasi-static loading conditions and the fatigue crack propagation under cyclic loading conditions were measured. The results of the static fracture mechanics investigations revealed that fracture toughness is strongly influenced by the microstructure of this pearlitic ductile iron grade. On the other hand, cyclic fracture mechanics analysis showed that the complex formation of the microstructure has only a minor effect on the fatigue threshold value, but microstructure has a significant effect on the stable crack growth. For the assumed load cases, it was shown that microstructure can be a dominant factor on the mechanical and fracture toughness properties.

CEN EN-GJL-200 (5.1300)

Abstract CEN EN-GJL-200 is an intermediate-tensile-strength gray cast iron that has a predominantly pearlitic matrix, and a tensile strength of 200–300 MPa (29–44 ksi), when determined on test pieces machined from separately cast, 30 mm (1.2 in.) diameter test bars. Compared with the lower strength gray cast iron grades, CEN EN-GJL-200 contains lower carbon and silicon contents and exhibits superior wear properties, while still maintaining good thermal conductivity, good damping capacity, and good machinability. This datasheet provides information on composition, physical properties, tensile properties, and bend strength. It also includes information on casting, heat treating, and machining. Filing Code: CI-96. Producer or source: European Committee for Standardization (CEN).