Gray Iron Research Articles

Coaxial laser cladding of cobalt-base alloy StelliteTM6 on gray cast iron/investigations on friction, wear versus commercial brake pad, and corrosion characteristics

Environmental legislation and the electrification of vehicles place increased requirements on brake disks in terms of wear and corrosion resistance. Departing from a preliminary study, the present investigation examined the friction and wear behavior as well as the corrosion properties of Stellite™ 6 coatings on gray cast iron, which were deposited by laser cladding. The friction and wear experiments were conducted on a pin-on-disk tribometer at contact pressures of 1.0 and 2.0 MPa as well as rotation speeds of 0.2, 0.4, 0.6, 0.8, and 2.0 m/s. The pins are manufactured from an automotive semi-metallic brake pad. The friction behavior of gray cast iron and Stellite™ 6 coatings is similar under changing test conditions. The tribological behavior is strongly influenced by the microstructural and mechanical properties of the coatings and the brake pad material. A third body layer of contact patches is formed on Stellite™ 6, which mainly consists of brake pad components. The transformation of the Co-matrix (fcc → hcp), subsurface fatigue, and tribo-oxidation are the main wear mechanism for Stellite™ 6. The electrochemical characteristics were analyzed by potentiodynamic polarization, and the corrosion rate was determined with Tafel plots in 3.5% NaCl solution, respectively. Compared to gray cast iron, Stellite™ 6 coatings have a pronounced corrosion resistance due to the formation of a protective passive layer of Co and Cr oxides. This corrosion resistance is mainly influenced by the microstructure. The corrosion rate of the coatings increases in parallel with the Fe dilution.

Risk Evaluation for Coating Thickness Conformity Assessment.

This paper presents the conformity assessment process of the epoxy coating thickness applied on water pipes made of gray cast iron with the specifications given for this kind of coating appliance. An epoxy coating was applied to prevent a special form of corrosion called the graphitization of cast iron. In order for the pipe to withstand its designed service life, it is necessary to ensure the required thickness of the applied coating. In accordance with the EN 877 norm, the thickness of the epoxy coating on the pipes for the projected corrosiveness of the environment C4 and the durability of 20 years is at least 70 μm and this indicates the required accuracy of the product. To achieve the desired product quality, statistical control of the coating application process was carried out and the impact of uncertainty associated with the measurement result was analyzed. Considering the quality of the coating application process and the quality of the measuring system, and to ensure the quality of products and to reduce consumer risk, the optimal thickness of the coating was determined.

A novel path towards limiting non-exhaust particulate matter emissions of a commercial friction material through the addition of metallurgical slag

Keeping recycling and the circular economy in mind, this study explores the reduction in emission of a highly optimized, commercially employed friction material formulation through the addition of metallurgical slags from a basic oxygen furnace in varying quantities from 6 to 38 wt%. The various compositions were paired with a pearlitic grey cast iron counterface and tested on a pin on disc tribometer. The friction coefficient and pin wear increased with the slag addition but were still within the permissible limit when compared to the original formulation. Specimens with higher slag content observed extremely compacted and extended secondary contact plateaus, which also recorded significant slag presence. The extended plateaus detached in the form of chunks from the mating surfaces, which settled on the equipment hardware and restricted the production of airborne particles. From an industrial symbiosis perspective, the addition of metallurgical slags proved to be a promising way of obtaining green friction materials with reduced emissions.

PRODUCTION OF DUCTILE CAST IRON BY RECYCLING GRAY CAST IRON SCRAP WITH ADDING VARIOUS LOCAL MATERIALS

Ductile cast iron is also called spheroidal graphite cast iron or nodular cast iron. It contains graphite in the semblance of nodules. Automobile scrap (i.e., the engine block) made from gray cast iron was used in this study. In this paper, the recycling of gray cast iron to ductile iron, and its influence on the microstructure and mechanical characteristics be studied. Four kilograms of scrap were put in a crucible and then heated up to 1400°C in an oil-fired crucible furnace. For desulfurization, 4% burnt lime with 0.5% fluorspar was direct tapped into the melt at 1400°C. Then, the additions were 3.5% nickel, 0.75% Ferro molybdenum, and 0.5% Ferro manganese of the scrap weighing. Also, 3.75% nodularizing alloy and 1% inoculating alloy of scrap weight were to treat the molten at 1450°C. Samples analyses have been achieved to determine their composition, tensile strength, impact strength, Brinell hardness, and microstructural. The microstructures revealed that the scrap sample possesses flake graphite, and the produced sample includes nodule graphite. It is observed that the ultimate tensile stress, elongation, and hardness of the scrap sample, which are 247.75 MPa, 6%, and 400.3 HB, respectively, increased in the product sample to 416.23 MPa, 8%, and 451 HB, respectively.

ПРОЕКТИРОВАНИЕ УСТАНОВКИ ПО ПЕРЕРАБОТКЕ МЕДИЦИНСКИХ ОТХОДОВ ТЕРМОХИМИЧЕСКИМ МЕТОДОМ

The article deals with issues related to the development of the design of a medical waste processing machine based on the thermochemical method, special attention is paid to the cutting equipment used in the machine. The problem statement is formulated as follows: to design a machine that allows realizing the possibility of processing medical waste by the thermochemical method; offer design options for the cutting equipment of the machine and justify the choice of knife material based on finite element modeling. The design of the machine is proposed, consisting of a base on which an electric motor is located, the movement from which is transmitted by means of a V-belt transmission to the tooling drive. Processing and disinfection of medical waste is carried out in a sterilization chamber. The sterilization chamber and the tank associated with it are structurally the most complex. The main structural elements of the tank are the base, the sterilization container and the lid. Direct processing of medical waste is carried out by rotating the rotary assembly with tooling. In the proposed machine tooling includes four movable horizontal and two vertical knives. During the processing of medical waste, the working surfaces of horizontal knives are exposed to a number of factors that lead to their intensive wear. The article offers several designs of knives to increase their durability. In order to check the correctness of the choice of material and the influence of operating conditions, a FE model was developed for the process of heating a knife under the action of a friction force caused by polyethylene chips descending along the front surface. Calculations were made for two knife materials: carbon steel and gray cast iron. The simulation results showed that, according to a number of criteria, gray cast iron is the most preferred knife material. The use of cast iron will ensure the rapid achievement of the required temperature in the sterilization chamber, and lower internal stresses will reduce the likelihood of knife breakage. To improve the reliability of the machine, design options for movable knives that are subject to the most intense wear are given.

Stress and deflection analysis of trench back-filling dozer blades using FEM

The objective of this paper is to improve the dozer's sharp edges in soil refilling applications based on limited component technique. The re-enactment strategy is achieved by involving computer-aided design programming for the pressure and redirection examination. The different terminology of dozer edges is mathematically obliged with the readiness of the model and the execution is successfully achieved from the real-time experimental conditions with given boundary conditions. The energy obliged for the dozer cutting edge applications with 35Hp power inlaying machine and assessed powers acting at the soil-instrument interface. The proposed work brings about recognizing adequate resilience in changing the elements of dozer edge segments and improving the overabundance of machine weight in a strong area. Furthermore, to raise the heaviness of the sharp edge for a solid strength different material such as EN24, Grey Cast Iron, Carbon Steel, and NIMONIC 80a were considered in this research. Based on the outcomes a recommendation is suggested as a suitable material.

Performance Analysis of EDM on Grey Cast Iron Using RSM and TOPSIS Method

Performance Analysis of EDM on Grey Cast Iron Using RSM and TOPSIS Method

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>

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.

Cortical Iron Accumulation as an Imaging Marker for Neurodegeneration in Clinical Cognitive Impairment Spectrum: A Quantitative Susceptibility Mapping Study.

Cortical iron deposition has recently been shown to occur in Alzheimer's disease (AD). In this study, we aimed to evaluate how cortical gray matter iron, measured using quantitative susceptibility mapping (QSM), differs in the clinical cognitive impairment spectrum. This retrospective study evaluated 73 participants (mean age ± standard deviation, 66.7 ± 7.6 years; 52 females and 21 males) with normal cognition (NC), 158 patients with mild cognitive impairment (MCI), and 48 patients with AD dementia. The participants underwent brain magnetic resonance imaging using a three-dimensional multi-dynamic multi-echo sequence on a 3-T scanner. We employed a deep neural network (QSMnet+) and used automatic segmentation software based on FreeSurfer v6.0 to extract anatomical labels and volumes of interest in the cortex. We used analysis of covariance to investigate the differences in susceptibility among the clinical diagnostic groups in each brain region. Multivariable linear regression analysis was performed to study the association between susceptibility values and cognitive scores including the Mini-Mental State Examination (MMSE). Among the three groups, the frontal (P < 0.001), temporal (P = 0.004), parietal (P = 0.001), occipital (P < 0.001), and cingulate cortices (P < 0.001) showed a higher mean susceptibility in patients with MCI and AD than in NC subjects. In the combined MCI and AD group, the mean susceptibility in the cingulate cortex (β = -216.21, P = 0.019) and insular cortex (β = -276.65, P = 0.001) were significant independent predictors of MMSE scores after correcting for age, sex, education, regional volume, and APOE4 carrier status. Iron deposition in the cortex, as measured by QSMnet+, was higher in patients with AD and MCI than in NC participants. Iron deposition in the cingulate and insular cortices may be an early imaging marker of cognitive impairment related neurodegeneration.

Investigations into the Mould Variability of Process Parameters in Green Sand Moulds for Mould Characterization in the Casting Process

In this study, the time-temperature behaviour of selected process parameters is established. The paper describes a new approach to understanding the defect generation phenomena in castings by considering the uniqueness of individual green sand moulds. It also explains the changing values of process parameters by experimental investigation. Foundry is the science of experiments. The aim is to achieve the right quality, quantity, and cost with minimum rejections. The casting quality results from several interconnected, dynamic, and complicated processes that are part of a foundry operation. Quality castings are produced by exercising proper control over several process parameters involved in the casting process. Despite taking several control measures regarding proper casting design, methoding and processing, casting defects are still observed. Defect reduction continues to be the primary goal in sand casting foundries due to the same. This paper investigates the essential parameters of the Green Sand casting process for understanding the influence over the generation of the casting defect in green sand moulding grey cast iron components. This study also adopts the time series method of recording the process parameters and finding the values of process parameter sets for individual moulds. The results showed a systematic predictive behaviour of the selected process parameters. By recording the process parameters under given conditions, it is found that they are time and temperature-dependent. Values can be obtained by building regression equations. It has been found that values of per cent moisture and green compressive strength reduce, whereas permeability and mould hardness increase.

ПОРОШКОВЫЕ ПОКРЫТИЯ, ПОЛУЧЕННЫЕ ЭЛЕКТРОКОНТАКТНОЙ ПРИВАРКОЙ

Most often, for electrocontact welding when restoring worn parts of machines, a steel tape with a thickness of 0.5...1.0 mm is used as a filler material. Powder filler materials for electric welding are rarely used due to the loss of expensive powder during welding and the difficulty in cooling the welding zone. However, the use of powder materials makes it possible to obtain a variety of coating properties and increase the adhesion strength of the powder coating to the base metal of the part. The paper presents the properties of coatings obtained by electrocontact welding of metal powders, namely, the adhesion strength of the powder coating to the base metal of the part, the surface hardness of the powder coatings and wear resistance. The purpose of the research: to evaluate the effect of the composition of the powder and powder compositions on the hardness, adhesion strength and wear resistance of coatings obtained by electrocontact welding. For electrocontact welding, metal powders of grades FBH-6-2, PG-С1, PG-С27М, "Sormite", PGR3.200.28, PRNH17СR4, PG1С were used. The adhesion strength was determined by the shear method on a P-125 press. The hardness was determined by the standard Rockwell method on a TK-2 hardness tester. Wear resistance was determined using an SMC-2 friction machine. It was found that the highest adhesion strength with the base metal of the part (steel 45) is observed in the powder coating of powder grade PG-С27М during electric contact welding in "hard" modes. The highest hardness was recorded for the powder coating from the Sormite powder. The least wear was observed for coatings obtained by electrocontact welding of powder compositions: PGR3.200.28+Sormite and PGR3.200.28+ВК8, however, wear of the counterbody (pads made of gray cast iron) when working with a coating of PGR3.200.28+VK8 had catastrophic wear after 3 hours wear tests. The use of powder filler materials for obtaining coatings on machine parts by electrocontact welding makes it possible to obtain coatings that are superior to coatings obtained by electrocontact welding of steel tapes. Thus, the adhesion strength of steel strips welded by electrocontact welding in "soft modes" is about 100...200 MPa, which is 1.2...1.4 times less than the adhesion strength of powder coatings. The hardness of steel tape and wire coatings reaches HRC60, and powder coatings up to HRC65.

Assessment of hydraulic efficiency and duration of residual service life of metal water supply pipelines

Substantiation of the necessity to develop projects of reconstruction of non-wood metal water supply pipelines, which have been in operation for a long time, including in the far north regions. Development of methodology of estimation of hydraulic efficiency and duration of residual service life of metal pipes depending on the thickness of the actual layer of deposits on their inner walls. Methods. It is proposed to estimate the period of residual use of steel and gray cast iron pipes by the value of the coefficient of efficiency of their operation. Outcomes. The study allows us to determine the values of the coefficient of efficiency of the use of the pipeline, assembled from steel and gray cast iron pipes, characterizing the residual duration and hydraulic efficiency of its operation. We obtained a formula for determining the coefficient of hydraulic efficiency of metal water supply pipelines, which is the ratio of values of actual characteristics of the hydraulic potential of non-metal pipes at the moment of evaluation to the values of these characteristics for steel and gray cast iron pipes. Practical Relevance. The developed methodology is recommended for use in determining the possibility of extending the period of further use of worn metal water supply pipelines, as well as for predicting the duration of their residual operating life.

Welding Effect at the Heat Affected Zone by Joining a Gray Cast Iron with Stainless Steel E308-16

Welding Effect at the Heat Affected Zone by Joining a Gray Cast Iron with Stainless Steel E308-16

Optimization of Sea Beach Sand Composition for Cast Iron Foundry Applications

The increasing demand and exorbitant use of river bed sand in foundries over the years have led to its depletion at an alarming rate. Consequently, many states in India have imposed severe restrictions on the mining of riverbed sand. Therefore, an effort is made to explore the potential use of sea sand for cast iron foundry applications. Experiments were performed for optimizing the composition of molding sand with respect to functional properties namely, strength, mold hardness, and permeability. The optimum composition of molding sand comprised of 8.33 wt% bentonite and 3.12 wt% moisture, and 88.54 wt% sea sand. Trials were conducted in a local foundry to ascertain the suitability of using a mixture of sea sand, bentonite, and water for producing defect-free gray iron casting. The trial was successful and parts were accepted for production purposes.

Microstructure investigation of cast irons with nodular and flake graphite via nanoindentation

The paper investigates and compares the local mechanical properties of microstructure components in grey iron EN GJL -300 and ductile iron EN GJS -500-7. The microstructure of both cast irons is analysed by LOM, and then certain microstructure components found and their local mechanical properties are investigated. Finally, the resulting nanohardness and reduced Young modulus of the components are discussed and compared between the two cast irons used. A Hysitron TI -950 gauge with Triboscan software is used to perform experiment measurements.

EMISSIVITY OF METAL SURFACE COATINGS

As it is known, emissivity is paramount for accurate temperature measurement using IR thermography. The emissivity of metals is particularly interesting due to its variability in relation to surface conditions (surface roughness and oxidation state), viewing angle, temperature, and wavelength. In the frame of this paper, knowledge regarding metal surface coatings and its effect on emissivity has been gained in an effort to improve risk assessment of workplace burns arising from hot metal surfaces. The present study examined the emissivity of two-component polyurethane metal covering coat on steel and grey cast iron depending on temperature and coating thickness. It was concluded that metal coating leads to moderated metal heating and increases constancy of emissivity compared to uncoated metal surfaces.

Influence of silicon and cobalt laser alloying on the microstructure and nanomechanical properties of the gray cast iron surface layer

Influence of silicon and cobalt laser alloying on the microstructure and nanomechanical properties of the gray cast iron surface layer

The Effect of Cutting Speed on the Wear and Tear of Dormer A100 Brazil Drill Bit Applied to Gray Cast Iron

Drilling is the process of making holes by pressing a rotating drill bit on the workpiece. During the machining process there is interaction between the drilling bit and the workpiece in the drill bit of the workpiece with a hole while the drill bit undergoes friction. Such a friction comes from the chipped surface that flows on the surface of the workpiece that has been cut; as a result, the tool wears out. The wear of the drill bit that occurs due to friction between the drill bit and the workpiece needs to be examined so that the extent of the wear and tear is known. The purpose of this study was to determine wear on the Dormer A100 Brazil drill bit with size (8 mm), rotation speed (260 rpm, 375 rpm and 710 rpm). Tool wear data was collected using a microscope with a magnification of 20x. Tool wear is seen three times during the drilling and the machining process. The result obtained is that the higher the cutting speed, the bigger the wear occurs. Keywords: Dormer A100, gray cast iron, drilling process

Mechanical behavior of bimetallic stainless steel and gray cast iron repairs via directed energy deposition additive manufacturing

The utility of gray cast iron in engine components remains tied to the mechanical performance and cost. Repair and remanufacturing of castings offer economical and sustainable benefits; however, high thermal input from traditional fusion-based welding is unable to restore the original mechanical quality owing to brittle microstructures and porosity formed in situ. Directed energy deposition (DED) is an additive manufacturing method that has received considerable interest for repairs owing to the highly controllable nature of the process. Despite this, few works have connected the effect of DED parameters on actual interfacial strength. Consequently, distinct DED parameter combinations were identified to maximize the strength and fatigue life of the repaired cast iron. High speed melt pool imaging and residual stress measurements are provided to aid in the understanding of the metallurgical quality and strength seen in these structures. In general, higher scanning speeds and lower thermal gradients promoted comparable tensile strength to that of the original gray cast iron. The results presented here provide a foundation to tune in the DED process to generate the required mechanical quality as a starting point for future process advancements.