Effect of microstructure and surface features on wetting angle of a Fe-3.2 wt%C.E. cast iron with water

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

In this paper, sliding friction and wear behaviors of gray cast iron A35 and white cast iron manufactured by quenching from the same cast iron in water were studied and compared by employing pin-on-disk wear tests. Microstructure of the worn surfaces before and after the wear tests were investigated by optical microscope observations. These images show that flakes separated from the surface in gray cast iron due to delamination process, while in white cast iron, the separation of materials from its surface is in the form of powder. In addition, the gray cast iron had higher graphite volume fraction with Type-A graphite flake morphology. The results show that white cast iron has less rate of wear than gray cast iron due to the higher hardness. However, gray cast iron because of presenting graphite flakes in its surface (lubricant property) has lower average coefficient of friction.

Grinding is one of the most common finishing processes used in the manufacture of metal components that require a combination of both smooth surface finish and tight tolerances. Despite the abundant knowledge concerning this process, specific literature is still scarce regarding the grinding of different cast iron grades. These materials have a wide application in the automotive industry, notably in the manufacture of gears, crankshafts, and valve control shafts. In this sense, this paper presents an experimental study of the peripheral surface grinding of three grades of cast iron grades (gray, nodular, and compacted graphite) with two SiC abrasive grinding wheels. The input variables tested were two values for depth of cut (15 and 30 μm) and two worktable speeds (5 and 10 m/min). The output variables analyzed were surface roughness, microhardness, microstructures, and SEM images of the ground surfaces. The results showed that gray cast iron provided the best performance concerning surface and sub-surface integrity among the three cast iron grades tested, whereas the nodular cast iron exhibited both worst finishing and superficial texture. No microstructural changes were observed in the samples of gray and compacted graphite cast iron grades, irrespective of the cutting conditions investigated, unlike for the nodular cast iron grade in which microstructural change was detected. The ranking order for the grindability of the three cast iron grades in terms of roughness, microhardness and surface texture investigated in this paper is gray cast iron, compacted graphite iron and nodular cast iron.

Wear resistance of cast irons used in brake disc rotors

Cast iron, especially ductile iron, is being used more and more in most countries of the world due to its excellent mechanical properties, castability, and good price. Cast iron alloys can be given a wide range of properties by changing the alloy composition, inoculation, and treatment, heat treatment, or cooling conditions. On a weight basis, most castings are made in gray cast iron. Some examples of gray and ductile iron products are shown in Fig. 1 [1]. The main factors for the high usage are good casting properties, low price, good cutability, and unique properties like damping and good tribology. Lamellar gray cast iron has very good damping capacity. This property is used in many components where damping of sound and vibration is important. Gray iron, also called lamellar graphite iron, is an iron–carbon–silicon alloy with different alloying elements. To understand the microstructure formations and to model them and other important phenomena, both the solidification and the solid-state transformations must be considered. These phase transformations are, to a large extent, affected by nucleation and growth kinetics which are dependent on, for example, handling of the melt, charge material, melting method, metal treatment, inoculation, pouring method, casting process and mold material, cooling power of the mold, and other factors. Many of these important material and process factors and combinations of them are still not fully understood today. Consequently, it is necessary that a foundry producing cast iron components has very strict process control in order to avoid unpredictable problems in production. When this is the case, it will also be possible to use simulation tools for predicting solidification sequence, microstructures, mechanical properties, as well as formation of defects.

Two types of cast iron were employed in this work. Grey cast iron was the first type, and ductile was the second one. Two specimens of the grey cast iron sample were used; one was kept without heat treatment, and the second was completely heat-treated by ferritisation regime. The two specimens of ductile cast iron were used similarly; one was kept without heat treatment grey and the second was ferritised by heat treatment. Potentiodynamic technique was applied for collecting corrosion data of the above four metal specimens in HCl solutions in the absence and presence of thiourea as an inhibitor. The measurements were performed in different concentrations of HCl (0.05, 0.2, 0.5, and 1 M) at 20?C and in the absence of an inhibitor, on the other hand, corrosion parameters were collected in 0.2 M HCl at different temperature levels (20?C, 30?C, 40?C, and 50?C). Thiourea was added in different concentrations to 0.2 M HCl at 25?C, then corrosion data was deduced. An optical microscope was used to investigate the microstructure of grey and ductile cast iron before and after heat treatment. Corrosion resistance and corrosion rates were collected directly from potentiostat, where Tafel lines were applied to the software. The above raw data was used to deduce activation thermodynamic parameters (Ea*, &#916H?, and ΔS?) of dissolution processes in the absence of thiourea by applying Arhenius equation. Adsorption parameters, in the presence of thiourea, were deduced using the kinetic model and the Flory-Huggins isotherms were used as inhibition mechanisms for the investigation before and after treatment.

Cast a different iron: Grey and mottled cast iron production in early China

The issues related to the essence of the concepts of carbon equivalent, an indicator of the degree of eutecticity and the ratio of carbon content to silicon content for characterizing the chemical composition and properties of gray cast iron were analyzed. The results of studies of the carbon equivalent value, the degree of eutecticity and the C/Si ratio of the chemical composition of synthetic cast iron, which is used for the manufacture of brake pads and the «Khanin wedge» of railway rolling stock, are presented. Examples of different approaches and formulas for determining the limits and methods of using the carbon equivalent of the chemical composition of cast iron to characterize the weldability of steels, coefficient of friction, wear, other operational indicators of cast iron brake pads, and evaluation of the quality of cast iron as a whole are given and analyzed. Within the standards-regulated ranges of the content of chemical elements in cast iron, the value of its carbon equivalent in individual smelting batches of products can differ significantly (by 30 %). With certain ratios of the main elements in the chemical composition of cast iron, the values of the carbon equivalent can be the same, but the mechanisms of crystallization of cast iron and its properties do not coincide. The parameters of the distribution of the content of carbon, silicon, manganese, phosphorus, sulfur, carbon equivalent, and the degree of eutecticity in cast iron СЧ350, from which the friction «Khanin wedge» for railway rolling stock is made, were analyzed. Cleaning the factory arrays of indicators of chemical composition, hardness, carbon equivalent, degree of eutecticity of cast irons intended for the production of brake pads and the friction «Khanin wedge» from gross erroneous values practically did not affect the general characteristics of the statistical analysis, which indicates the reliability of the results. It is shown that when smelting in induction crucible furnaces gray synthetic cast iron intended for the production of brake pads and the «Khanin wedge», the ranges of variation in the content of C, Si, Mn, P, S are much narrower than those regulated by the standards for these foundry products. The fundamental possibility of introducing appropriate clarifications to the requirements of the standards regarding the content of chemical elements in synthetic gray cast iron intended for the production of brake pads of the «M» type and the friction «Khanin wedge» for railway rolling stock was noted, in particular, reducing the sulfur content to 0,05 % to increase stability of its quality. Keywords: cast iron, chemical composition, carbon equivalent, degree of eutecticity, properties, castings, brake pads, operational characteristics.

It is shown that one of the promising directions for improving the quality and serviceability of rolling rolls due to the improvement of the structure and properties of all zones of massive castings used for their production is the modification of cast iron. A significant improvement in the structure and properties of white cast iron is ensured by modifying them with rare-earth metals (REM), and gray ones by REM and magnesium. There is information that. REM and complex modifiers on their basis are increasingly used in rolling production. The need for studies of the influence of complex modifiers on the preparation of forming tools with a stable structure and inclusions of globular graphite was noted. The effect of complex modifiers on the structure and properties of cast irons was studied. The methodology of research is outlined. Investigation of the influence of the amount of complex modifier introduced on the structure of cast iron (from 0,94-1,01% Si) and gray (with 1,58-1,66% Si) cast iron. It is established that the modification of REM allows a wide variation in the structure, hardness, and physico-mechanical properties of white and half-rolled cast iron. The metallographic studies performed show that the optimal amount of the complex modifier with a content of at least 40,6% REM in the treatment of cast iron is 1,5-2,0%, which corresponds to the assimilability of 0,25-0,30% ΣREM. In gray cast iron, the amount of cementite is in the range 25,3-27,2% when casting into a chill. In bleached pig iron, the amount of cementite increases from 29,0 to 31,4%, and there is no graphite. In the structure of bleached cast iron casted in sandy-argillaceous forms, the proportion of cementite is in the range from 27,7 to 30,0%. It has been established that the use of Ce and La in the modification of the pre-eutectoid cast iron of the working layer at a content of 0,064-0,105% ΣREM promotes the formation of graphite of the vermicular form. With a content of 0,122-0,315% ΣREM, a compact and vermicular graph is formed. It is shown that modifying the REM does not ensure the production of graphite of a spherical shape for gray iron in the core, as in the case of magnesium modification

Engine castings are made in grey iron which has UTS (ultimate tensile strength)around 250 MPa. Requirement is to make grey cast iron with higher strength without loosing grey cast iron properties namely thermal conductivity and damping capacity. Objective is to develop high grade cast iron by adding alloying elements. Base iron was made in medium frequency induction furnace. Furnace was charged with medium carbon steel and foundry returns as charge materials. Carbon and silicon percentage in base iron was raised by adding petroleum coke and ferro silicon alloys during melting stage. Hot liquid metal was taken into ladle and alloy tin (Sn) addition had been done into the same metal Alloyed liquid metal was poured into a drys and mould in the bar form. Inoculation (ferrosilicon) had been done before pouring into sample mould. Base grey iron was alloyed with tin in the range 0.010–0.100 wt %.Four numbers (nos.) of test bar samples had been made in the different tin percentage range keeping copper constant in the range 0.45–0.5 wt %. Tin(Sn) was added in grey iron to study mechanical and microstructural properties. Tensile, hardness and impact test had been performed for mechanical properties study. Microstructural properties had been studied on optical microscope for the same tin varied samples. UTS was found upto 253–376.11 MPa, hardness upto 173–222.33 BHN and impact strength upto 3.33–4 J.

The nitriding process can be effectively applied to steel with alloying elements. The higher the alloying element in the steel maximizes the mechanical properties, including hardness. However, the raw material can be costly, therefore using cheap materials (without alloys) is a challenge in increasing surface hardness through iron nitride formation. Furthermore Grey and nodular cast iron have different properties and characteristics in the structure. This research focuses on the ability of the cast-iron structure to affect the nitride layer formation. Gas nitriding was conducted in a fluidized bed reactor with a 550°C in 20 % N2 and 80 % NH3 atmosphere at a flow rate gasses of 0.7 m3/hr process temperature and holding for 2, 4, and 6 hours. Tests are conducted by observing the depth of hardening, SEM, and EDAX. According to the results, the nitriding process increases the surface hardness of cast iron. The highest hardness value is nodular cast iron with a holding time of 6 hours (345 HV) and a hardening depth of up to 20-micron meters. The compounds formed in the nitride layer include FeN, Fe2-3N, Fe4N, and Fe2N. The compound formed is strongly influenced by the treatment time. Furthermore, the comparison of nitriding treatment on gray and nodular cast iron was influenced by the flake and nodule structure. In general, the nodule structure is responsible for maximum hardness. The longer treatment time allows the nitrogen atoms to diffuse more to the surface, while the flake structure limits the absorption of nitrogen atoms into the surface of the cast iron. Characterization of Nodular Cast Iron shows that The hardening depth distribution trend due to the nitriding process in nodular cast iron was not much different from gray cast iron.

ASTM specification A 48 classifies gray irons in terms of tensile strength. The usual microstructure of gray iron is a matrix of pearlite with graphite flakes dispersed throughout. Section sensitivity effects are used in the form of a wedge test in production control to judge the suitability of an iron for pouring a particular casting. Mechanical property values obtained from test bars are sometimes the only available guides to the mechanical properties of the metal in production castings. Gray iron castings are used widely in pressure applications such as cylinder blocks, manifolds, pipe and pipe fittings, compressors, and pumps. Where high impact resistance is needed, gray iron is not recommended. The machinability of most gray cast iron is superior to that of most other cast irons of equivalent hardness, as well as to that of virtually all steel. Gray iron is used widely for machine components that must resist wear.

Investigation of effects of boron additives and heat treatment on carbides and phase transition of highly alloyed duplex cast iron

Test samples of grey and compacted graphite cast irons with pearlitic matrix were shot-peened to different surface conditions using twelve different combinations of shot size, peening intensity and peening coverage percentage. Relatively high surface compressive residual stresses varying between 245 to 565 MPa were observed and the compressive residual stresses reached a depth between 280 µm and 770 µm. Within the range of peening parameters used, the compacted graphite cast iron with its vermicular graphite showed a somewhat better response to the same shot-peening treatment than the grey cast iron containing flake graphite, giving a larger peening affected zone with higher compressive residual stresses. For both the cast irons, an increase in peening coverage percentage, shot size or peening intensity led often to a lower surface compressive stress. However, peening using a higher intensity greatly increased the degree and extent of plastic deformation and therefore increased the magnitude and penetration depth of the subsurface compressive residual stresses, while the effect of increasing shot size also depends on the peening intensity. On the other hand, measurements on the grey cast iron samples showed that the peening coverage has little effect on the depth profile of residual stress.

The objective of the study reported in this paper was to determine the effect of structure on thermal power of cast-iron heat exchangers which in this case were furnace chambers constituting the main component of household fireplace-based heating systems and known commonly as fireplace inserts. For the purpose of relevant tests, plate-shaped castings were prepared of gray iron with flake graphite in pearlitic matrix (the material used to date typically for fireplace inserts) as well as similar castings of gray cast iron with vermicular graphite in pearlitic, ferritic-pearlitic, and ferritic matrix. For all the cast iron variants of different structures (graphite precipitate shapes and matrix type), calorimetric measurements were carried out consisting in determining the heat power which is quantity representing the rate of heat transfer to the ambient environment. It has been found that the value of the observed heat power was affected by both the shape of graphite precipitates and the type of alloy matrix. Higher thermal power values characterize plate castings of gray iron with vermicular graphite compared to plates cast of the flake graphite gray iron. In case of plates made of gray cast iron with vermicular graphite, the highest values of thermal power were observed for castings made of iron with ferritic matrix.