Iron Specimens Research Articles

Exploring the wear mechanism of surface hardfacing Stellite 6 alloy on the cast iron over the wide temperature range

Abstract Cast iron is widely used as a heat-resistant material in the automotive industry, but it increasingly struggles to meet the demands of high-temperature friction applications. This study employs surface hardfacing with Stellite 6 alloy to improve the wear resistance of cast iron. By conducting sliding friction tests at various temperatures, we systematically investigate the friction behavior of both cast iron and hardfacing specimens over a broad temperature range. The results reveal that hardfacing-treated specimens exhibit exceptional wear resistance. At ambient temperatures, the hardfacing specimen shows a 65.5% reduction in wear loss compared to the cast iron specimen. This reduction increases to 83.8% at temperatures up to 600 °C. At room temperature, the wear mechanisms of cast iron include abrasive wear and fatigue wear. At medium temperatures, abrasive wear is the primary mechanism of cast iron. At high temperatures, the wear mechanisms of cast iron consist of abrasive wear, oxidative wear, and adhesive wear. In contrast, the wear mechanisms of the hardfacing specimens differ: at room and medium temperatures, abrasive wear is the predominant mechanism, while at high temperatures, the main mechanisms are abrasive wear and adhesive wear. The superior mechanical properties and enhanced resistance to high-temperature oxidation of the hardfacing specimens are the primary factors contributing to their improved friction performance across the temperature spectrum.

Friction and self-repairing behaviour of magnesium silicate hydroxide-MoS2 lubricant additives on gray cast iron with Cr-coated steel ball friction pairs

To improve the tribological performance of piston ring assemblies, this work studies the friction and self-repair behavior of magnesium silicate hydroxide(MSH)/MoS2 nanoparticles as PAO6 lubricant additives, whose friction condition is simulated piston ring-cylinder liner operating condition using a friction pair composed of chrome-plated steel balls and gray cast iron. By studying the effect of different concentrations on the friction reduction and anti-wear properties, it was found that the addition of MSH/MoS2 nano-powder to PAO6 could all play a role in the friction reduction and anti-wear effect, with the best friction reduction effect at 0.5 wt% addition. The self-repairing behavior of the lubrications with 0.5 wt% MSH/MoS2 nanopowders was found on grey cast iron specimens after 8 h of friction experiment.

A comparative study of flake graphite iron and compacted graphite iron in austempered condition for directional control valves

Demand for lighter materials with the right qualities is unavoidable in the present era of engineering. Compacted graphite iron is a type of cast iron gaining momentum nowadays in foundries due to its distinct characteristics that fall between gray cast iron/flake graphite iron and spheroidal graphite iron. It becomes the right candidate to replace flake graphite iron in many applications. In this research, flake graphite iron (FC −30) and compacted graphite iron-300 grades were studied to enhance its properties through austempering heat treatment process. Initially, the as-cast (non-austempered) flake graphite iron and compacted graphite iron were subjected to microstructural study and mechanical testing. Subsequently, the flake graphite iron and compacted graphite iron were subjected to austempering heat treatment. The various austempering temperatures selected are 270, 320, and 370 °C for different soaking time periods of 30, 60, 90, and 120 min. As cast flake graphite iron specimen (FC-30) exhibited lesser tensile strength (293 N/mm2) than as cast compacted graphite iron (528 N/mm2) and austempered compacted graphite iron (652 N/mm2). With respect to hardness measurement, austempered compacted graphite iron specimens yielded higher hardness of up to 415 BHN. However, the compacted graphite iron specimen austempered at 370 °C for 90 min measured an optimum hardness value of 373 BHN and tensile strength of 630 N/mm2 with less retained austenite (0.3%). This hardness value is considered to be more suitable in machining operation for making hydraulic directional control valves exposed to constant abrasion.

Исследование влияния комбинированного модификатора из отходов кремниевого производства на свойства серых чугунов

Introduction. During the metallurgical production of silicon, waste is generated that accumulates in dumps, causing harm to the environment. Disposal and recycling of solid waste from silicon production is especially important because They contain important chemical compounds (silicon dioxide, silicon carbide, carbon nanotubes) that can be used in other industries, which will bring greater economic value. Considering the possibilities for extracting these useful components from silicon production waste, it is necessary to bring processing technologies to the stage of widespread practical application. Therefore, the development of a special waste processing technology to obtain a useful product in the form of a composition of silicon dioxide and silicon carbide remains an urgent problem. Purpose of the work: to study the formation of the morphological form of graphite with the introduction of nano-modifiers from silicon production waste. The work examined samples of gray cast iron after modification with a combined modifier obtained from silicon production waste. The research methods are mechanical tests for statistical tension, analysis of the chemical composition and metallographic studies. Results and discussion. It was revealed that the mechanical properties of gray cast iron increased by 30-50% after modification with a combined modifier, compared with witness samples. The morphology of graphite is an important parameter affecting the properties of cast iron. It has been established that during the modification process the morphology of graphite changes from lamellar to vermicular. Specimens of gray cast iron with vermicular form of graphite have high strength values compared to specimens of gray cast iron with lamellar form of graphite. The presented results confirm the promise of the developed approach aimed at obtaining new classes of modifiers and products made of gray cast iron with a high range of mechanical properties.

ANALYSIS OF CUTTING FLUID ON MASS LOSS OF CARBIDE INSERT IN THE MILLING PROCESS

The Machining process is manufacturing in the world industry that is widely used. The coolant in the machining process functions to lower the temperature and lubricate and clean the gram in the cutting process. The application of coolant in the cutting process is to maintain the quality of the workpiece during the cutting process and also serves to improve tool life so that the tool does not wear out easily. This study aims to determine the effect of a chemical-based coolant based on dromus oil and vegetable CPO on tool wear in the face milling process and to determine whether or not the liquid is effective in reducing and slowing down tool wear. In this research, the face milling process used a grey cast iron specimen as the workpiece specimen used and also used a carbide insert chisel cutting tool with the TPKN 22 VC2 type. The research was carried out by varying the engine speed and also the coolant variation, the engine speed variations used were 80, 360 and 720 Rpm. In the process of administering coolant using the method, it is sprayed directly onto the workpiece area which is cut continuously, in the milling process with a response variable that can be in the form of data or tool wear values that have been observed and tested using a microscope test tool, using the weight (mass) method to see the wear value. This research aims to see how effective the use of vegetable- based coolant (CPO) during experiments as a coolant in the machining process aims to ensure that the final value of tool insert wear must be smaller with (CPO) compared to chemical coolant (dromus).

Silybum marianum Extract: A green inhibitor for Iron Metal Corrosion and Bacterial Growth in Fresh and Marine Media

Egyptian Silybum marianum ethanolic-hexane crude extract efficiency was investigated as an inhibitor of bacterial growth and iron steel corrosion in fresh water and marine environment media. Iron steel corrosion inhibition rate was quantitatively measured by two methods: one as a concentration of iron released in the medium over time intervals at different inhibitor ratios against the control using Inductive Coupled Plasma Mass Spectrometry (ICP-MS), and the second was relative weight loss method. Meanwhile, the development of the adsorption layer of the inhibitor on the surface of the iron steel specimen was monitored qualitatively using scanning electron microscopy. The adsorption of the extract constituents was found to obey Langmuir adsorption isotherm. Bacterial growth inhibition was examined using a well-diffusion method. After three days, the percentage of corrosion inhibition in fresh and marine media was 95% and 91%, respectively at the ratio of 1.5 mg/mL of the crude extract, and a homogeneous adsorption layer was observed on the surface of the iron specimen. The same dose was enough to inhibit bacterial growth in both media. Natural ecofriendly inhibitor extracted from a wild native Egyptian plant was found to be anticorrosion and at the same time antibacterial in both fresh and marine water media.

Formation of Plasma-Nitrided Barrier Layers Against Hydrogen Absorption and Diffusion in Pure Iron

Hydrogen embrittlement is a serious problem for steels such as high strength steels. Reducing hydrogen absorption into steels is required for the prevention of hydrogen embrittlement. In order to improve the hydrogen absorption resistance into steels, a nitriding treatment is one of the effective ways among surface modifications because nitriding may increase the overpotential for the hydrogen evolution reaction on the surface and decrease hydrogen diffusivity in nitrided layers. In this study, the phase structure in the nitrogen compound layers for the pure iron specimens was controlled by plasma nitriding with different types of plasma gas and gas composition. The influence of ε-Fe2-3N and γ’-Fe4N phases on hydrogen absorption into the inside of the pure iron matrix through the nitrided layers was evaluated. During the hydrogen permeation tests, the plasma-nitrided specimens showed small permeation current values compared to the as-polished specimen when it reached the steady state. Especially, hydrogen absorption and permeation for the specimen with the compound layer containing ε-Fe2-3N were extremely inhibited. Hydrogen absorption and permeation behaviors in the nitrided pure iron specimens were discussed in terms of the catalytic activity and hydrogen diffusivity.

Brazing of sintered iron to mild steel for wind turbine brake pad applications

The demand for renewable energy has prompted an increasing interest in wind turbine technology, where efficient and reliable brake systems play a critical role in ensuring safety and performance. This study investigates the brazing process to join sintered iron to mild steel for wind turbine brake pad applications. The sintered iron components were synthesized using iron powder with an average particle size of 30 µm and sintered at different temperatures under vacuum and hydrogen environments. Eutectic CuSil with added copper powder was employed as the brazing alloy to join the sintered iron and mild steel. The brazed joints were characterized using various techniques, including optical microscope, scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffractometer, and microhardness tester. The microhardness of the sintered iron was ∼580 HV for SICV and ∼620 HV for SICH due to oxide formation during processing. The microhardness of the braze joint was 72 HV, and mild steel exhibited 110 HV. Tribological testing was performed to analyze the wear behavior of the sintered iron specimens (before and after the brazing). SICH specimens showed a wear rate of 1.3 × 10−4 g/Nm, and SICV specimens exhibited a wear rate of 5.3 × 10−4 g/Nm. Brazing the sintered iron component (SICV) with mild steel using eutectic CuSil and a modified assembly method in a vacuum successfully achieved a satisfactory joint with improved wear resistance. The study emphasizes the potential of this approach for efficient and reliable brake pad fabrication for wind turbines.

Backscattering of Ultrasonic Waves as the Basis of the Method of Control of Structure and Physicо-Mechanical Properties of Cast Irons

Increasing the reliability of control of cast iron structure and its physical and mechanical characteristics is an important scientific and technical task of the machine-building industry. The paper studies the possibilities of controlling the structure of cast irons using structural noise created by ultrasonic scattering on graphite inclusions of different shapes. The subject of the present studies was such characteristics of structural noise as amplitude-temporal A(t) and as root mean square value of the amplitude of the ultrasonic waves backscattering field AN, compared with the data on ultrasonic velocity and strength or tensile strength of cast iron samples. As a result of the studies, a significant difference between the amplitude parameters of the AN structural noise obtained for samples with different shapes of graphite inclusions at 5 MHz was revealed for the first time. So, for example, for samples of gray cast iron (Russian: СЧ10, СЧ15, СЧ20, СЧ25), having predominantly plate-like form of graphite inclusions, the value of AN on 14–15 dB exceeds that measured in high-strength specimens of the cast iron with the prevailing form of spherical graphite inclusions ВЧ50 (Russian), etc. At the same time growth of longitudinal ultrasonic velocity amounted to 20–25 %. The method of rejection of gray cast iron from high-strength cast iron according to the data of amplitude parameters of structural noise AN at unilateral and local sounding of the object without using an additional reference signal reflected from its oppositional wall is suggested.

Chemistry of ancient materials of iron in India

India is acclaimed for its rich heritage of iron making at least since the protohistoric era. The ancient artisans were able to create iron artefacts possessing outstanding characteristics, which demonstrates the level of expertise they had attained in the field of chemistry and metallurgy. Numerous iron artefacts including iron pillar in Delhi, iron pillar in Dhar, iron beams at Sun temple in Konark, bear eloquent testimony to this. Therefore, it is fascinating to study the chemistry involved in the preparation and properties of these iron-based ancient materials. Several scholars have contributed to the study of iron artefacts discovered from various sites across India which belong to different periods, regions and dynasties. Across the scholarly spectrum, special attention has been paid to study the chemistry involved in the marvelous characteristics like super corrosion resistance of iron pillars, cannons, etc.This review, therefore, presents the recent insights into iron-based materials in ancient India.Our objective is to highlight (1) a brief historical background, (2) chemical composition, (3) preparation of the material, (4) surface microstructure and (5) the mechanism behind the special features, of iron artefacts. Analysis of antiquarian remains with the help of different characterization techniques like X-ray diffraction (XRD), Proton induced X-ray emission, Energy dispersive spectroscopy (EDS), Fourier Transform Infrared spectroscopy (FTIR), Mössbauer spectroscopy, High Resolution Transmission Electron Microscopy (HRTEM), micro particles induced X-ray emission (μPIXE), etc. have been focused upon. The ancient iron making process used for producing high quality wootz steel has been discussed too. A detailed analysis of the rust-free iron pillar of Delhi has been presented. In particular, the iron pillar at Dhar, Adi-Mookambika temple, Kodachadri, and iron beams at Sun Temple, Konark, Damascus swords made of wootz steel, cannon at Thanjavur and iron specimens of Gupta period at Eran (Madhya Pradesh) are the artefacts studied to understand the characteristics of iron objects produced in India during ancient times. This study can support the future making of metallic monuments and artefacts with outstanding characteristics. This review is expected to appeal across the disciplines, including but not limited to, materials science, chemistry, physics, metallurgy, chemical engineering and archaeology.

Improving the Properties of Gray Cast Iron by Laser Surface Modification.

Laser surface modification is a widely used technology to improve the properties of functional surfaces. In this study, the properties of gray cast iron are modified by laser surface modification, and the influence of laser quenching on the properties of cast iron in terms of frictional vibration and noise, friction and wear, internal structure, residual stress, hardness, and corrosion resistance is investigated. The experimental results show that, after high-power laser quenching, the frictional vibrations and noise of most gray cast iron specimens are decreased, but the coefficients of friction against a bearing steel counterface are increased and more stable. The surface and sub-surface hardness of all laser-quenched cast iron specimens is significantly increased. The residual stresses on the surface of the cast iron specimens are significantly increased and changed from tensile to compressive residual stresses. Experimental modal testing results show that the modal damping ratios of the laser-treated specimens are increased significantly, although their modal frequencies are not significantly changed. In addition, through the metallographic observation, XRD (X-ray diffraction) analysis, and TEM (transmission electron microscopy) observation, it is found that the microstructures of the cast iron specimen after high-power laser modification become fine-grained, and the pearlite and ferrite in the matrix become fine martensite, which leads to the improvement of the dynamical, tribological, and chemical properties of cast iron after laser modification.

Experimental and numerical investigation of thermal fatigue life in wedge specimens made of Ni-resist D5S cast iron

Thermal fatigue experiments were performed on a single-edge wedge specimen of Ni-resist D5S cast iron to reproduce the conditions to which exhaust manifolds are subjected during service. The leading edge temperature was cycled between 20°C and 850°C, and the temperature distribution on the specimen surface was measured with thermocouples during thermal cycling. Due to the complexity of the loads, a uncoupled thermomechanical computation of the problem was performed using the three-dimensional finite element code ABAQUS to evaluate the temperature, stress and strain distribution over a thermal fatigue specimen. The heat fluxes and forced convection coefficients generated by the thermal fatigue benchmark were optimized in both heating and cooling phases by reverse engineering to reproduce the experimental temperature-time profiles measured by thermocouples on the surface of the specimen. Then, an elastic-viscoplastic tow-layer model was used to simulate the mechanical behavior of the studied material. It was found that the maximum stress value was located in the center of the specimen at the edge of the wedge. This result was confirmed by experimental observations. The crack initiation zone is located in the edge zone and the direction of crack propagation is perpendicular to the edge line toward the thick part of the specimen. The saturation of the main crack propagation near the uniform specimen zone was mainly explained by the rapid decrease of the energy dissipated per cycle.

Research into the relationship of mechanical properties of grey cast iron through acoustic non-destructive testing

The following acoustic characteristics are measured in this study: the velocity of longitudinal waves Cl and the attenuation coefficient of ultrasound δ in samples of grey cast iron, which are obtained by centrifugal casting. The correlations between the mechanical properties, the acoustic non-destructive testing characteristics and the structure formation of the test specimens of cast iron with flaked graphite are studied. The study shows that data on the structure formation can be obtained, followed by the mechanical properties, hardness and tensile strength, by measuring the speed and attenuation of the ultrasound.

Self-ion irradiation effects on nanoindentation-induced plasticity of crystalline iron: A joint experimental and computational study

In this paper, experimental work is supported by multi-scale numerical modeling to investigate nanomechanical response of pristine and ion irradiated with Fe2＋ ions with energy 5 MeV high purity iron specimens by nanoindentation and Electron Backscatter Diffraction. The appearance of a sudden displacement burst that is observed during the loading process in the load–displacement curves is connected with increased shear stress in a small subsurface volume due to dislocation slip activation and mobilization of pre-existing dislocations by irradiation. The molecular dynamics (MD) and 3D-discrete dislocation dynamics (3D-DDD) simulations are applied to model geometrically necessary dislocations (GNDs) nucleation mechanisms at early stages of nanoindentation test; providing an insight to the mechanical response of the material and its plastic instability and are in a qualitative agreement with GNDs density mapping images. Finally, we noted that dislocations and defects nucleated are responsible the material hardness increase, as observed in recorded load–displacement curves and pop-ins analysis.

Plasticity Resource of Cast Iron at Deforming Broaching

The contact interaction mechanics of deformation broaching in low-plasticity materials is studied. Particular attention is paid to the study of the stress–strain state parameters and the plasticity margin in the deformation zone during the machining of gray cast iron EN-GJL-200. The stress–strain state was analyzed using a finite-element model of the deforming broaching process for each area of the deformation zone. The model parameters of the machined material were determined experimentally by compressing specimens of gray cast iron EN-GJL-200. The changes in the parameters of accumulated strain, stress tensor components, stress triaxiality ratio, hydrostatic stress, and plasticity margin at different deformation zones along the machined specimen depth are analyzed. It is shown that there is a zone of local plastic deformation in conditions of critical contact stresses. This leads to the appearance of tensile stresses that reduce the plasticity margin in the surface layer. The impact of tool geometry on the stress–strain state of the surface layer is also discussed, and recommendations for the optimal working angle of the deforming element are provided based on plasticity margin minimization.

Modelling of ductile fracture in pure iron considering the ductile–brittle transition at very high strain rate

At different deformation rates, a ductile material may fail by isothermal deformation fracture, thermoplastic shear instability, or even brittle fracture. The failure mode transition at sound speed deformation rate has not been well described. This paper aims to establish a new fracture model which considers the strain rate embrittlement effect (SREE) at the sound speed deformation rate, and can be used to predict the failure of the material in a large range of strain rate. Taking pure iron DT 8 as the experimental material, impact tests of pure iron specimens under different stress states, strain rates, and temperatures were carried out. Fracture strains under different stress states, strain rates, and temperatures were obtained. The strain rate was increased to 227450/s (5.36/s in log10) to obtain the ductile–brittle transition point. A new fracture model is proposed to describe the evolution of fracture strain over the wide range of strain rate. The new proposed model is experimentally validated and compared with the J-C failure model. It shows the new proposed fracture model can predict the ductile fracture behavior of a ductile material in the full strain rate range, and capture the failure mode transition at the sound speed deformation rate of a material.

Improvement of Nodularity Value of Graphite in Ductile Iron and Its Effect on Mechanical Properties

AbstractDuctile iron is becoming popular in many industrial applications due to its comparatively high strength and a considerable amount of ductility, which is because of the presence of spheroidal graphite in the microstructure. An effort has been made to improve the nodularity value of graphite in ductile iron by varying the fineness of inoculant, that is, ferro‐silicon (Fe‐Si) and section thickness of the casting. Further, the effects on mechanical properties are also studied. The spheroidal graphite iron specimens for different inoculant treatments, such as without any inoculation, in‐mold inoculation with coarse, and fine Fe‐Si, are prepared. The results have shown that the nodularity increased with in‐mold inoculation with Fe‐Si, and for the same amount of inoculated Fe‐Si, the nodularity is higher for fine Fe‐Si. Ultimate tensile strength is also found to increase with the increase in nodularity, and maximum strength of ≈460 MPa is recorded for a specimen having in‐mold inoculation with fine Fe‐Si. Stepped bar specimens of different thicknesses are also prepared by casting with the same composition for studying the effect of section thickness, and nodularity value is found to be higher for the thinnest section and is about ≈48%.

An Investigation of Electrochemical Dechlorination of Wrought Iron Specimens from the Marine Environment

The research shows the benefits provided by the use of electrochemical treatment, with the application of impressed current combining the use of a porous medium for the dechlorination of large iron structures removed and/or located in the marine environment. Considering the previous work for the dechlorination of the paddle wheel of the shipwreck “Patris”, located in the Aegean Sea, this study aims to determine the optimum parameters of the amount of current density, the time and the use of the porous medium to stimulate the chloride ion diffusion into an alkaline solution. Specimens of wrought iron coming from the shipwreck were electrochemically treated and the efficiency of the method was verified by the determination of the chloride concentration removal using a chloride ion selective electrode. Samples of corrosion products before and after treatment were analyzed for chloride content using SEM-EDX analysis. The results found that changing the porous medium every 24 h with replenished alkaline solution and using a stainless steel mesh is the best approach for the dechlorination of the specimens. This electrochemical method, is economical and fast, and can be applied to the conservation of large iron structures in situ, coming from and/or located near a marine environment with less waste than the traditional dehlorination methods.

A comparative analysis of the effect of laser surface treatment on the dry sliding wear behavior of ductile cast irons with different microstructures

In this study, the wear behavior of ferritic (GJS 400) and pearlitic (GJS 700) ductile cast iron (DCI) specimens after laser surface hardening were investigated comparatively. In general, multi-pass laser applications are inevitable in a laser surface treatment (LST) applied for surface hardening because the laser spot diameter is quite small compared to the applied surface area. This situation may cause a decrease in wear resistance due to residual stress formation because of the thermal gradient and softening effect due to the overlap ratio. In this study, a single-pass laser surface hardening (LSH) process with a laser pulse area of 20 × 5 mm2 compatible with the laser energy density (6.28 J/mm3) used in the literature, was applied to overcome these limitations. Thus, it is aimed to make it possible to evaluate the comparative analysis more reliably. After LSH processes, hardness values of DCI samples increased approximately 4.3 times compared to untreated ones due to the transformation hardening effect. In the microstructure of the laser-treated pearlitic DCI samples, martensite was present as the dominant phase in addition to a small amount of residual austenite. As for the ferritic DCI samples, the ledeburite and martensite phases were detected. Dry sliding wear tests were performed using different loads (5 N, 10 N) and sliding speeds (10 mm/s, 20 mm/s, 30 mm/s). As a result, the wear volume loss values of laser-treated ferritic and pearlitic DCI samples could be reduced by approximately 26.6% and 30.7%, respectively, compared to untreated ones. The COF values of the untreated samples increased with increasing load, while those of LSHed decreased. Severe plastic deformation and delamination were observed for untreated samples, while mild plastic deformation and micro-grooves were observed for samples with LSHed.

Initial grain orientation controls static recrystallization outcomes in cold-worked iron: Insight from coupled crystal plasticity/vertex dynamics modeling

Recrystallization of metallic materials is an important metallurgical treatment to bring cold-worked alloys to a usable state. Static recrystallization (SRX) occurs after deformation, once the material has built up sufficient plastic strain energy to trigger grain boundary motion. However, we have very limited knowledge about the combined effects on recrystallization kinetics of temperature, amount of cold working, triple junction mobility, and level of recovery in the deformed microstructure. In particular, little is still known about the microstructural factors that control the onset of SRX. Here we develop a comprehensive physical model based on coupling crystal plasticity and grain boundary kinetics utilizing curvature and differential plastic strain energy as driving forces for SRX in polycrystalline iron. The model links finite-element polycrystal plasticity simulations with a two-dimensional vertex dynamics approach, and is used to probe the large parameter space influencing static recrystallization. Our main finding is that the initial texture (defined by the polycrystal’s grain orientation and size distribution) is the dominant feature triggering and controlling SRX kinetics. We find a direct correlation between the degree of dislocation density buildup and the relative grain orientation across a grain boundary at the beginning of the deformation phase. Indeed, analysis of our results points to the maximum Schmid factor of a grain as the best predictor for activation of its grain boundaries during the recrystallization phase. We also find that the amount of post-deformation recovery only has a limited effect on the evolution of the recrystallized microstructure. Finally, using a definition based on the rate of transformation of the material, we find a recrystallization temperature of 600 ∘C, consistent with experimental observations in high-purity iron specimens.