Types Of Cast Iron Research Articles

Strength evaluation of flake and spheroidal graphite cast irons using diametral compression test

The diametral compression test also known as the Brazilian test is an old and unique method of measuring tensile strength of brittle materials owing to simple specimen geometry test conditions and quickness of testing. However, its practice in measuring the strength of the metals is quite limited. This work therefore attempts to apply diametral compression test with specimens of thickness to diameter ratio equal to 0.2, 0.4 and 0.6 in determining the tensile and compressive strengths of Flake Graphite (FG) and Spheroidal Graphite (SG) types of cast iron. Cracks developed in the FG and SG specimens indicate that the failures were caused by tensile and shear stress respectively. In case of FG cast iron specimens at lower t/d ratio, the stress state becomes biaxial and influence of tensile stress was found to be higher than the compressive stress. Whereas the biaxial stress condition violates in SG cast iron specimens. The present work concludes the suitability of diametral compression test at any t/d ratio of FG cast iron specimens and only at lower t/d ratios of SG cast iron specimens.

Effect of chill formation on the mechanical properties and microstructure of grey and nodular cast irons used in automotive industry

Cam shafts used in automobiles are produced by cast iron (grey cast iron, nodular cast iron) or steel. In this study, effect of chill formation on the surface of grey and nodular cast irons is investigated on the wear behavior, hardness, impact toughness and microstructure of grey and nodular cast irons. For this purpose, four types cam shaft made of grey cast iron with and without chill on the surfaces and nodular cast iron with and without chill on the surfaces, were casted. Mechanical tests were conducted after the camshafts have been produced by casting method. Surface hardness and wear resistance of grey and nodular cast irons have been improved by chill formation on the surfaces and it is concluded that the amount of wear on the surfaces of grey cast iron with chill and nodular cast iron with chill is almost the same. Maximum hardness value was obtained on the surface of grey cast iron with chill. The impact toughness has been found to decrease by chill formation. Maximum impact toughness value was obtained on nodular cast iron. Microstructures of grey cast iron with and without chill and nodular cast iron with and without chill were examined under optical microscope and worn surfaces of cast irons were examined by scanning electron microscopy (SEM). Wear mechanisms of the four types of cast iron were evaluated by SEM examination. Keywords: Cam shafts, Cast irons, Chill formation, Mechanical properties, Microstructure

Comparison of Numerical Analysis of Stress-Strain States of Cast Iron with Vermicular Graphite Shape and Globular Graphite Shape

Method of final elements is highly effective modern numerical method for solving technical and scientific tasks, which is nowadays more and more used. The report deals with comparison of analysis of stress conditions on microstructure of cast iron with vermicular graphite and with cast iron type with globular graphite. Briefly describes their chemical composition, mechanical properties and structure that we will serve us as input parameters for the creation of computational modeling and numerical analysis. Model of structure for the computer simulation was created in two-dimensional field by linear triangular elements for both types of graphitic cast iron. The size of elements was determined based on sensitivity analysis. According to the real structure of cast iron with vermicular shape of graphite and cast iron with globular graphite will be created model from which will be performed numerical analysis of voltage-strain states by finite element method – FEM software system ADINA 8.8.0. This calculation program helps to solve a very difficult task and has the advantage that the generated model can reflect very well the actual geometry of the object.

Эволюция нерегламентируемых форм графитных включений в графитизированных конструкционных чугунах

The evolution influence of the graphite form (from a platetype form to a globular one) upon structural cast iron properties was analyzed and grounded, there were also considered cast iron peculiarities and prospects of their commercial application is estimated. For castings production the expediency of rational application of unregulated graphitized cast iron with the intermediate transitional morphology of graphite inclusions instead of grey iron high grades with lamellar graphite (GI 30, GI 35) and malleable cast iron is shown. The appropriate use substantiation of mentioned cast iron types taking into account their peculi-arities is shown.

The Importance of a Surface Layer of a Cast Iron Casting in the Design of Technological Processes

The paper defines the scope and character of the surface layer of castings made of selected types of cast iron with special consideration of on spheroidal cast iron. The study also showed that on the basis of the distribution of hardness along the casting core, it is possible to define the distribution of structures and the reach of the surface layer of a cast iron casting.

WEAR RESISTANCE OF DIFFERENT TYPES OF CAST IRON USED IN GLASS BLOW MOULD

The aim of this work is to study the wear characteristics of different cast iron types which might be used as mould materials in glass blow molding. Wear testing rig was designed and developed to carry out the wear tests. Three types of gray cast iron with different chemical compositions were cast and heat treated, as well as samples taken (for comparison) from another two existing mould already being in use.Samples for wear testing were taken from the prepared materials and abraded against an automobile friction brake pads. Sliding velocity, friction pressure and contact time were taken as test variables. Weight loss of the tested samples was measured after conducting the wear tests at 600 & 800 0C.Cast iron with (2.98% C, 5.117% Si, and 1.39% Cu) showed the highest hardness in its as cast condition compared to the other types. It showed the best wear resistance after heat treatment (stress relief annealing).Results also showed that some of the tested materials gave a good wear resistance at low temperature (up to 600 0C) but they lost their resistance at high temperature (up to 800 0C). It was concluded that hardness is not the only parameter that controls the wear resistance at high temperature.

Analysis of tapping process in three types of cast iron

The main objective of this work is to investigate the tapping operation of cast iron when varying the cutting speed and the method of application of cutting fluid, monitoring tool wear, torque, and axial force during the operation. Two types of gray cast iron were evaluated: CrCuSn alloy, FC 250; CrCuSnMo alloy, FC 300, and compacted graphite iron machine tool, FV 350. Tests were performed at two lubrication/cooling conditions: in the first one, it was applied an emulsion of water and oil; in the second one, the fluid was applied in minimal quantity (MQF), at pressure of 6.0 bar and intermittent spray at a frequency of 1 pulse/s, resulting in a flow rate of 30 ml/h. For MQF condition, a vegetable oil was used. Torque, axial forces, and tool wear were measured during the operation. Statistical analysis showed that the cutting speed was the parameter that most influences the torque, followed by the cutting fluid and the material hardness.

Electrochemical dissolution of cast iron in NaNO3 electrolyte

The electrochemical dissolution of three cast iron types in NaNO3 electrolyte was investigated by cyclic voltammetry, chronoamperometry, and numerical simulations. The measurements were performed with commercially available materials with different iron matrix compositions and graphite particle shapes: lamellar graphite particles in a ferritic/perlitic matrix, spheroidal graphite particles in a ferritic matrix, and spheroidal graphite particles in a ferritic/perlitic matrix. With regard to electrochemical machining (ECM) applications, the measurements were performed in different kinds of flow cells which realize the high electrolyte flow of an ECM experiment. It could be shown that the electrochemical dissolution was especially influenced by the microstructure of the cast iron and the pH of the electrolyte. Electrochemical measurements as well as numerical simulations show that the graphite geometry and the matrix structure are responsible for inhomogeneities of the electric field in the outer sample surface region which were formed during the dissolution process. The resulting shape of the electric field is responsible for different dissolution mechanisms. The kinetics of the dissolution reaction was influenced in the same manner. Finally, it was found that an alkaline electrolyte pH impedes the dissolution process, whereas no significant difference can be observed between acidic and neutral electrolytes.

The Reliability of the Results of the Modified Low-cycle Fatigue Test for Cast Iron Evaluated by Metallographic Studies

Abstract This study discloses the characteristic features of the modified low-cycle fatigue test used for the determination of the mechanical properties of two types of cast iron, i.e. EN-GJL-250 and EN-GJS-600-3. For selected materials, metallographic studies were also conducted in the range of light microscopy and scanning microscopy.

Pulse electrochemical machining of cast iron: a layer-based approach for modeling the steady-state dissolution current

In this paper, a new layer-based simulation method for predicting the steady-state current of a pulse electrochemical machining (PECM) process is described. The basic concept of the method is a simple two-layer model consisting of a porous oxide and an adsorption layer. The oxide layer of PECM-machined samples, characterized by Raman spectroscopy and electron microscopy measurements, shows a similar structure as the oxide layer formed in electrochemical impedance spectroscopy (EIS) measurements. Therefore, the electronic equivalent circuit developed according to EIS results was used as analogy for the description of the overall impedance of the PECM model. The difference between the assumed layers of a PECM and EIS measurement is modeled with a material-dependent adjustment function. In this way, the calculated values of the equivalent circuit elements can be directly derived from experimental PECM data. It could be shown that the procedure allows the calculation of the steady-state current of PECM processes for different work conditions (e.g., pulse on-times, pulse frequencies). The procedure is applied to the electrochemical dissolution of three different types of cast iron in NaNO3 electrolyte on realistic machining conditions. All samples were characterized according to their chemical composition, graphite particle morphology/structure, and their anodic dissolution behavior.

The Study of a New Type of Cast Iron Material Used in the Glass Mould

Develop a new type of alloy cast iron material.Design experimental scheme and research method, choose low tin vermicular cast iron as raw materials, to determine the main alloying element and trace alloying elements, formulate the necessary particularizing alloy. On the basis of strict technology and process, to complete the cast iron smelting, produce vermicular cast iron that has a good comprehensive performance. To observe the metallographic structure of cast iron under a microscope. Finally，test the stretchability of the developed vermicular cast

Monitoring Methods the Properties and Structure of Grey Iron Castings

Flake graphite cast irons are very used construction materials, which are characterized by good sliding and damping properties. Graphite and character matrix affects the properties of cast iron. It is also important to the size distribution of the graphite. Compressive strength graphite cast iron with lamellar graphite is very good , is 3 to 4 times greater than the tensile strength. The various types of cast iron with lamellar graphite is possible only in the tensile strength. Flake graphite cast iron are widely used in mass production where they use their good casting properties. With sophisticated sand moulds can produce a very complex shape castings with excellent mechanical properties and relatively low production costs. For this reason, cast iron with lamellar graphite are constantly used in the automotive industry for blocks, heads, engines, brake drums and discs, insertion loss cylinders, piston rings. At our department of Engineering Technology, Technical university of Liberec (Czech Republic - Europe) has long been focused on prediction methods of production quality castings for the automotive industry.

The Effect of Heat Treatment of Gray and Nodular Cast Iron with Ferrite Matrix on Mechanical Properties and Corrosion Rate Compared with Medium Carbon Steel

In this work, the influence of heat treatment process and quenching in different quenchant media of medium carbon steel, gray and nodular cast iron with ferrite matrix on the hardness, ductility and corrosion rate of has been investigated. During this type of operations, the specimens were Austenizing at 900°C for one hour. Therefore, the specimens were quenched in different kind of oil as quenched medium (oil 20-50, oil 40, oil 90, and water as reference). The hardness , impact energy to measure the ductility, corrosion rate and microstructures were studied. From result of steel 0.47% carbon was clear increasing in hardness and decreasing in ductility with close varying values in oil quenchant kind comparing with as received specimen and water quenched one, corrosion rate decreased with heat treatment and quenching process due to formation of single face instead of double phase before heat treatment process which created galvanic cell. For gray and nodular cast iron it is noticeable that no changing in microstructure within heating for one hour at 900°C because the matrix in both cast iron types is ferrite, therefore no changing in mechanical properties under heat treatment process with time of one hour which is not sufficient to decomposition of graphite, but with comparison the hardness of gray cast iron is more than nodular one due to distribution of graphite flacks which increase the hardness and decrease the ductility as well as increasesing the corrosion rate compared with nodular cast iron. Microstructure of both types of cast iron have been studied after subjected the specimens to heat treatment at 1000°C and for 10 hours, the microstructures shown clear diffusion of some carbon in ferrite matrix around the graphite phase and under quenched some of martensite formed.

Gray Cast Iron Behavior in Cavitation Erosion

The paper presents the cavitation stand used, the work methodology, the trials realized on specimens of gray cast irons, with flake graphite and spheroidal-graphite, which were tested for cavitation erosion during different periods of time of the cavitation attack. Finally, the conclusions were interpreted on the basis of comparative graphics realized at the macro and microstructures level obtained for these two types of cast iron. Of the two types of gray cast iron, the nodular cast iron presents a better cavitation erosion resistance.

The Abrasive Wear Resistance of Chromium Cast Iron

Abstract The resistance of cast iron to abrasive wear depends on the metal abrasive hardness ratio. For example, hardness of the structural constituents of the cast iron metal matrix is lower than the hardness of ordinary silica sand. Also cementite, the basic component of unalloyed white cast iron, has hardness lower than the hardness of silica. Some resistance to the abrasive effect of the aforementioned silica sand can provide the chromium white cast iron containing in its structure a large amount of (Cr, Fe)7C3 carbides characterised by hardness higher than the hardness of the silica sand in question. In the present study, it has been anticipated that the white cast iron structure will be changed by changing the type of metal matrix and the type of carbides present in this matrix, which will greatly expand the application area of castings under the harsh operating conditions of abrasive wear. Moreover, the study compares the results of abrasive wear resistance tests performed on the examined types of cast iron. Tests of abrasive wear resistance were carried out on a Miller machine. Samples of standard dimensions were exposed to abrasion in a double to-and-fro movement, sliding against the bottom of a trough filled with an aqueous abrasive mixture containing SiC + distilled water. The obtained results of changes in the sample weight were approximated with a power curve and shown further in the study.

Criteria of shape recognition for cast iron

The aim of this study was to determine the criteria for recognising cast iron types by calculation of areas of graphite images. For this purpose, graphites are discretised from images of six different shapes given in the standard TS EN ISO 945-1 and processed with the developed software. Binary images of graphites were obtained with the developed image processing software. Different criteria are tested on binary images. The most acceptable criterion is evaluated for the determination of the types of cast irons. The criterion is defined as the ratio of graphite area to the large circle area (GA/LCA). The calculation of the large circle area is made by drawing a circle from the gravity centre of graphite. The radius of the circle is the farthest point of the graphite image. GA/LCA ratio is always smaller than 0.3 for grey cast iron and greater than 0.7 for ductile iron. Ratios between 0.3 to 0.7 are for malleable cast irons. Average GA/LCA values are calculated as 0.0540 for shape I, 0.1354 for shape II, 0.2578 for shape III, 0.4394 for shape IV, 0.5410 for shape V and 0.8368 for shape VI respectively.

An approach for the fatigue estimation of porous cast iron based on non-destructive testing results

Big cast iron components made of spheroidal cast iron allow constructing big structures such as stone mills, engine blocks or wind mills with acceptable expenses. Thus, in economically optimized cast processes pores cannot be always prevented in thick walled cast iron components and these components are often rejected because of safety reasons. On the one hand the fatigue performance of high loadable spheroidal cast iron components is reduced significantly by the presence of local porosities which has been pointed out in the past. On the other hand concepts for the fatigue estimation based on fracture mechanics which take the size and localization of the defect into account can lead to erroneous estimations because the defect is modelled as a crack. The challenge of an estimation method is to derive a fatigue life without the necessity to perform component tests. In the contribution an estimation method is presented which is able to determine the fatigue strength of a material volume taking the pores into account. The method can be applied based on data from computer tomographic X-ray (CT) or Sampling Phased Array (SPA) ultrasonic analyses. The method is presented for three spheroidal cast iron types: ferritic GJS-400-18, ferritic GJS-450-15 with high silicon content and perlitic GJS-700-3.

Analysis of the Structure and Abrasive Wear Resistance of White Cast Iron with Precipitates of Carbides

Abstract The resistance of castings to abrasive wear depends on the cast iron abrasive hardness ratio. It has been anticipated that the white cast iron structure will be changed by changing the type of metal matrix and the type of carbides present in this matrix, which will greatly expand the application area of castings under the harsh operating conditions of abrasive wear. Detailed metallographic analysis was carried out to see the structure obtained in selected types of white cast iron, i.e. with additions of chromium and vanadium. The study compares the results of abrasive wear resistance tests performed on the examined types of cast iron.

Machinability Studies of Peripheral Milling on Pearlitic Cast Iron

Cast Iron with high carbon content is the most commonly used material for machine tool components such as slide guide ways, tables and columns etc, due to its excellent vibration damping characteristics and easy to cast part features. Although it is very easy to cast, cast iron with high carbon content is extremely hard thus making it very difficult to machine. Normally Poly Crystalline Boron Nitride (PCBN) or diamond tipped tools are used for machining these types of Cast Iron to get good surface finish with less tool wear. Unfortunately, cost of these cutting tools is high. Hence it leads to high production cost. In this direction, an attempt has been made to explore the feasibility of machining cast iron with K20 carbide milling cutter with peripheral milling on two different work pieces, one is with heat treated and another one is without heat treated. Tempering process was carried out for heat treatment. Result shows that heat-treated work piece performs well in all aspects compared to non-treated work piece.

Hydrogen-Induced Ductility Loss in Cast Irons

Effect of hydrogen-charging was investigated with respect to the tensile properties of three types of cast irons: JIS FCD400, FCD450 and FCD700. In this study, hydrogen charging led to a marked ductility loss in all the cast irons. The thermal desorption spectroscopy and the hydrogen microprint technique revealed that, in the hydrogen-charged specimens, most of solute hydrogen was diffusive and mainly segregated at graphite, graphite/matrix interface zone and pearlite. In the fracture process of non-charged specimen, neighboring graphites were interconnected with each other mainly by ductile dimple fracture. On the other hand, in the fracture process of hydrogen-charged specimen, the graphites were interconnected by cracks. The difference in the fracture morphology between the non-charged and the hydrogen-charged specimens is attributed to the presence of diffusive hydrogen in graphite and graphite/matrix interface. During early stage of fracture process in hydrogen-charged specimen, the interspace between graphite and matrix is filled with hydrogen gas, which leads to the ductility loss of matrix in the vicinity of graphite. Even after the initiation of crack from graphite, hydrogen is continuously outgassed from graphite and supplied to the crack tip. Therefore, concerning the hydrogen effect on the strength of cast irons, a role of subsurface graphite as a “local hydrogen supplier” should be taken into consideration.