Microstructure Of Iron Research Articles

Effect of Mo Co-Alloying on Microstructure and Properties of Gray Cast Iron Produced with Steel and Foundry Scrap

Effect of Mo Co-Alloying on Microstructure and Properties of Gray Cast Iron Produced with Steel and Foundry Scrap

Significance of Tool Coating Properties and Compacted Graphite Iron Microstructure for Tool Selection in Extreme Machining.

This study aims to determine the extent to which coating composition and workpiece properties impact machinability and tool selection when turning Compacted Graphite Iron (CGI) under extreme roughing conditions. Two CGI workpieces, differing in pearlite content and graphite nodularity, were machined at a cutting speed of 180 m/min, feed rate of 0.18 mm/rev, and depth of cut of 3 mm. To assess the impact of tool properties across a wide range of commercially available tools, four diverse multilayered cemented carbide tools were evaluated: Tool A and Tool B with a thin AlTiSiN PVD coating, Tool C with a thick Al2O3-TiCN CVD coating, and Tool D with a thin Al2O3-TiC PVD coating. The machinability of CGI and wear mechanisms were analyzed using pre-cutting characterization, in-process optical microscopy, and post-test SEM analysis. The results revealed that CGI microstructural variations only affected tool life for Tool A, with a 110% increase in tool life between machining CGI Grade B and Grade A, but that the effects were negligible for all other tools. Tool C had a 250% and 70% longer tool life compared to the next best performance (Tool A) for CGI Grade A and CGI Grade B, respectively. With its thick CVD-coating, Tool C consistently outperformed the others due to its superior protection of the flank face and cutting edge under high-stress conditions. The cutting-induced stresses played a more significant role in the tool wear process than minor differences in workpiece microstructure or tool properties, and a thick CVD coating was most effective in addressing the tool wear effects for the extreme roughing conditions. However, differences in tool life for Tool A showed that tool behavior cannot be predicted based on a single system parameter, even for extreme conditions. Instead, tool properties, workpiece properties, cutting conditions, and their interactions should be considered collectively to evaluate the extent that an individual parameter impacts machinability. This research demonstrates that a comprehensive approach such as this can allow for more effective tool selection and thus lead to significant cost savings and more efficient manufacturing operations.

Determining rational complex modifying and alloying additives to improve the mechanical characteristics of gray cast iron

The object of this study is the mechanical properties and parameters of the cast iron microstructure. The task to solve was to ensure high mechanical properties of cast iron for mechanical engineering part. To this end, a working hypothesis was put forward, which assumed the possibility of increasing mechanical properties by selecting complex additives based on modifiers and alloying ferroalloys. The effect of 4 groups of additives was investigated: group 1 – ferrochrome (FeCr025) and silicocalcium (SiCa-30), group 2 – ferrotitanium (FТі35) and ferroboral (FEB6), group 3 – ferrotitanium (FТі35) and ferrochrome (FeCr025), group 4 – ferroboral (FEB6) and silicocalcium (SiCa-30). They were introduced into the liquid metal in different percentages in the amount of 3 % of the mass of liquid cast iron. The following mechanical characteristics were selected: flexural strength (σ, MPa), tensile strength (UTS, MPa), deflection arrow (f, mm), hardness (HB), and whitening. It was determined that the strength characteristics of cast iron treated with ferroalloys of group 1 reach a maximum at about 40 % silicocalcium in the composition of the additive. The tensile strength of cast iron reaches about 320 MPa, the bending strength is about 710 MPa, the deflection arrow is 4.5 mm, and the hardness corresponds to the HB250 level. The fact of competition of hardness and other mechanical properties was established in the range of silicocalcium content in the modifier composition up to 40 %. Thus, it was established that it is the combination FeCr025+SiCa-30 with the ratio of components of 40:60, respectively, that is rational. The revealed regularities of changes in the amount of carbides, the size of graphite, and the amount of ferrite when using different additives allow us to explain patterns in the formation of mechanical properties of cast irons. Owing to this, it becomes possible to identify the mechanism of formation of properties, ensuring purposeful regulation of the quality of cast iron

Microstructure, Hardness, and Toughness Evolution in Nodular Cast Iron under 450°C Quenching and Tempering

This study investigated the evolution of microstructure, hardness, and toughness in nodular cast iron following quenching and tempering at 450°C. The research explored how the heat treatment process impacts these mechanical properties, to identify an optimal balance between hardness and toughness. Untreated nodular cast iron displayed a microstructure comprising ferrite, pearlite, and spheroidal graphite, resulting in moderate hardness (24.33 HRC) and toughness (0.082 J/mm²). Quenching at 850°C, followed by rapid cooling in water, induced the formation of martensite, a hard and brittle phase, which significantly increased hardness to 56.73 HRC but decreased toughness to 0.068 J/mm². Tempering at 450°C transformed the martensite into tempered martensite, reducing hardness to 41.37 HRC while improving toughness to 0.11 J/mm². These findings highlighted the importance of tempering in achieving a better balance between hardness and toughness, making the material suitable for industrial applications requiring both wear resistance and impact durability. The results offered valuable insights for optimizing heat treatment procedures to enhance the performance and durability of nodular cast iron components in various industries.

Investigation on the Effect of Water Quenching to Microstructure, Crystal Structure, Hardness, and Wear of Gray Iron

Gray cast iron has been one of the most widely used engineering materials since a long time ago. However, the development of casting techniques and methods to produce various models of cast iron products for the domestic market is not followed by improvements in product quality. The intriguing aspect of gray iron products is the diverse morphologies that graphite can assume, leading to distinct variations in mechanical and physical properties. Quenching is a typical heat treatment procedure performed to improve the mechanical properties of a material that entails the rapid cooling of the material from a high temperature to a low temperature. The aim of this study is to investigate the effect of water quenching effects on microstructure, crystal structure, hardness, and wear of gray iron, which undergoes quenching from the austenitizing temperature. Gray cast iron was obtained from the local foundry industry, then thermally treated at 900°C, held for 15 minutes, and rapidly quenched by water. The quenching procedure induces a significant alteration in the overall microstructure, where transition of most dendrite arms to the eutectic phase microstructure is observed. Moreover, the quenching process is attributed to the reduction of crystal size and growth of carbon crystal. The average crystal size of the sample was reduced from 47.833 nm to 17.97 nm, hence improving the hardness from 16.375 HRC to 48.04 HRC, which in turn improved wear resistance under high loading condition from 0.014 g/sec to 0.00042 g/sec.

Effect of purity on the tensile mechanical behavior of pure iron

The current work systematically investigated the microstructures, mechanical properties, textures, dislocation density and dislocation substructures of 3N2, 4N2 and 5N2 pure irons (3N2, 4N2 and 5N2 pure irons represent that the content of Fe are 99.9264 wt%, 99.9925 wt% and 99.9992 wt%, respectively) using SEM, EBSD, XRD and TEM. The results indicated that the recrystallization temperature decreased with increasing purity, and higher purity accelerated grain growth. 4N2 and 5N2 pure irons both presented equiaxed ferrite grains, while the microstructure of 3N2 pure iron was consisted of irregular polygonal ferrites and equiaxed ferrite grains. Low-density LAGBs were observed in annealed pure irons. The fraction of LAGBs increased significantly after deformation, and the LAGBs density decreased as the purity increased. The dislocation substructures of 3N2 and 4N2 pure irons were dominated by sub-grain boundaries with high dislocation densities and dislocation tangles, whilst 5N2 pure iron primarily consisted of fewer sub-grain boundaries and random dislocations. Work hardening was the primary strengthening contribution of pure irons. As the purity decreased, the capacity of work hardening increased, which resulted from the effective obstacles to dislocations by higher fraction of LAGBs, sub-grain boundaries with high dislocation densities and dislocation tangles. Therefore, the improved mechanical properties may be attributed to the increase of work hardening ability with the decrease of purity. 3N2 pure iron presented discontinuous yielding behavior, while 4N2 and 5N2 pure irons exhibited continuous yielding behaviors. The continuous yielding was attributed to the minimal interstitial atoms rarely segregated on mobile dislocations to form Cottrell atmosphere.

Experimental and Numerical Analysis of Thermal Fatigue of Grey Cast Iron Ingot Mould.

This article presents the results of experimental studies and numerical calculations that were conducted to analyse the phenomena that occur during the operation of an ingot mould that is designed for casting steel ingots. The studies were conducted on an experimental stand in a foundry on an ingot mould that was designed to make ingots that weigh up to six tons; they consisted of determining the temperature of the ingot mould and measuring the displacements of its walls during filling with steel and cooling. These studies were used to create and verify a numerical model that was used to determine the temperatures, displacements, deformations, and stresses in ingot mould walls during the operating cycle using the FEM method. Microstructure studies of ingot cast iron that was subjected to thermal fatigue were also conducted on a laboratory stand; the temperature changes and test times were the same as those used under the normal operating conditions of the ingot mould. Cast iron samples were subjected to heating and cooling cycles within a range of 0 to 60 cycles; then, tensile tests were performed to determine their stress-strain curves. As a result of the conducted tests, a great influence was found of the number of cycles on decreases in the values of the modulus of elasticity and tensile strength-especially within a range of 0 to 10 cycles. A relationship was also found between the changes in these values and the image of the cast iron microstructure. Based on images of the cast iron microstructure after being subjected to different numbers of thermal fatigue cycles, the mechanism of the crack initiation and propagation was determined. The influence of the changes in the strength of the cast iron and the stress state that was determined by the FEM method on the durability of the tested type of ingot mould was analysed. The obtained research results will be useful for introducing design changes that are aimed at increasing the fatigue durability of ingot moulds.

A FEM-based model for failure initiation in the microstructure of gray cast iron under uniaxial compression

PurposeThe purpose of this study was to validate the feasibility of the proposed microstructure-based model by comparing the simulation results with experimental data. The study also aimed to investigate the relationship between the orientation of graphite flakes and the failure behavior of the material under compressive loads as well as the effect of image size on the accuracy of stress–strain behavior predictions.Design/methodology/approachThis paper presents a microstructure-based model that utilizes the finite element method (FEM) combined with representative volume elements (RVE) to simulate the hardening and failure behavior of ferrite-pearlite matrix gray cast iron under uniaxial loading conditions. The material was first analyzed using optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) to identify the different phases and their characteristics. High-resolution SEM images of the undeformed material microstructure were then converted into finite element meshes using OOF2 software. The Johnson–Cook (J–C) model, along with a damage model, was employed in Abaqus FEA software to estimate the elastic and elastoplastic behavior under assumed plane stress conditions.FindingsThe findings indicate that crack initiation and propagation in gray cast iron begin at the interface between graphite particles and the pearlitic matrix, with microcrack networks extending into the metal matrix, eventually coalescing to cause material failure. The ferritic phase within the material contributes some ductility, thereby delaying crack initiation.Originality/valueThis study introduces a novel approach by integrating microstructural analysis with FEM and RVE techniques to accurately model the hardening and failure behavior of gray cast iron under uniaxial loading. The incorporation of high-resolution SEM images into finite element meshes, combined with the J–C model and damage assessment in Abaqus, provides a comprehensive method for predicting material performance. This approach enhances the understanding of the microstructural influences on crack initiation and propagation, offering valuable insights for improving the design and durability of gray cast iron components.

Extracting ductile cast iron microstructure parameters from fracture surfaces: A deep learning based instance segmentation approach

This study investigates the deep-learning based microstructural analysis from SEM images of ductile cast iron fracture surfaces. A Mask R-CNN model was trained, achieving 70% precision and 75% recall in graphite particle detection. Combined with a fracture surface reconstruction using the.4-quadrant backscattered electron signal, key parameters, including the particle size, shape and distance were extracted accurately. Compared to micrograph analysis, following probabilistic simulations showed the impact of the higher microstructural variance for the fracture surfaces on crack initiation, leading to higher scatter and elevated crack resistance curves. This highlights the potential of deep-learning based analysis for comprehensive microstructural characterization.

Normalizing temperature influence on the microstructure characteristics, mechanical and wear performance of a novel high chromium cast iron

The microstructure, mechanical and wear behavior of a high chromium cast iron were studied at different normalizing temperatures (950 °C, 1000 °C, 1050 °C, 1100 °C). The martensite content was proportional to the normalizing temperature except at 1100 °C because of the appearance of retained austenite. As the temperature increased, the primary carbide downsized whereas the secondary carbide content first increased but then decreased, contributing to the superior mechanical properties observed tempered at 1050 °C. The superior hardness and strength improved the surface deformation resistance, including enhanced work-hardening in the matrix and stacking fault locks in carbides, hindering dislocation slipping and material spalling, thus achieving excellent wear properties when normalized at 1050 °C. Moreover, the wear mechanism changed from oxidative/fatigue to abrasive/adhesive wear as the temperature increased.

Processing and the Effect of Nb–Mo on the Microstructure, Mechanical and Tribological Behavior of High-Cr Cast Iron

Processing and the Effect of Nb–Mo on the Microstructure, Mechanical and Tribological Behavior of High-Cr Cast Iron

Microstructure, hardness, and wear resistance of high-carbon hypereutectic high chromium irons containing W for use as roller sleeves

High chromium irons (HCI) have rarely been investigated the impact of varying W content on the microstructure and performance of high-carbon irons by scholars. In this study, after calculating by Java-based Materials Properties software (JMatPro), the casting alloying method was applied to explore the effect of adding W (0-15 wt%), Mo 3 wt%, and C 6 wt% on HCI to prepare highly wear-resistant and hard materials. The results showed that the maximum volume fraction of carbide was 38% at C 6 wt%. The addition of W promoted the formation of M6C with a maximum volume fraction of 21%, which increased the hardness to 64.5 HRC and reduced the weight loss to 0.062 g. Since W10 (the iron with W 10 wt%) and W15 (the iron with W 15 wt%) exhibited similar wear resistance but lower impact resistance, the W10 samples were heat-treated. W10 after QT550 (quench and temper heat treatment at 550 °C) sample developed a large number of M6C-type carbides and martensite in the matrix, which improved the properties of the matrix by diffusion strengthening, leading to a hardness of 70.0 HRC and a reduction in weight loss to 0.035 g. Compared to the Cr20 reference iron, W10 after QT550 was 22.8% higher in hardness and 76.8% lower in abrasion. Concurrently, an experiment was conducted on the production of roller sleeves. With the use of W10 after QT550, the lifetime of the roller sleeve was increased by 1.6 times.

Microstructure Characteristics and Mechanical Properties of Grey Cast Iron at Varied Ferrosilicon Addition

Inoculation is an essential metallurgical route for controlling solidification conditions of cast iron, consequently, in this study, the influence of varied percent ferrosilicon (FeSi) addition on microstructure and mechanical properties of grey cast iron (GCI) was investigated. A 50Kg capacity rotary furnace was used to melt the charge (Auto engine block scrap, graphite, ferrosilicon (FeSi) and limestone). The casting was produced in a greensand mold with wooden rectangular pattern of length 50 mm and breadth 30 mm. Chemical compositions and carbon equivalent values (CEVs) of the samples were determined, using Optical emission spectrometry (AR 4 metal analyzer) and the expression respectively. Microstructures of the samples were obtained, using metallurgical microscope (model number NJF-120A). The tensile and hardness properties were measured, using Universal tensile tester and Rockwell hardness tester respectively. From the results, C and Si were the major elements. Other trace elements were Mn, P, S and Al. CEVs of both the control and inoculated samples were less than 4.3%. Microstructure of the control sample was comprised of primary dendrites and graphite flakes, while those of the inoculated samples were characterized by varied amount of more developed primary dendrites, longer graphite flakes and austenite dendrites. Also, a number of small MnS particles were observed in relative amount within the microstructures. Tensile and hardness properties of the FeSi inoculated samples were superior to the control sample. Highest tensile strength and hardness values of 76.62 MPa and 99.89 HRB respectively were obtained at the optimum inoculation of 1.5 wt. % FeSi.

Effect of Cerium Addition on Microstructure and Mechanical Properties of the Ductile Iron

The effect of the cerium addition on the microstructure and properties of the ductile iron is investigated. The ferrocerium is added to obtain ductile iron samples with cerium contents of 10–750 ppm. In the ductile iron with a cerium content of 60 ppm, the amount and the spheroidization rate of graphites are the highest. The tensile strength of the ductile iron is 488 MPa and the elongation rate reaches 20.17%. For the ductile iron with a high toughness demand, it is necessary to add 60 ppm Ce in the ductile iron to increase the number density and spheroidization rate of graphites. The formation of CeS inclusions effectively promotes the heterogeneous nucleation of graphites, increasing the amount of graphites. The stronger carbon diffusion during the eutectic process increases the ferrite formation in the ductile iron, leading to a lower tensile strength and a higher elongation rate. When the cerium content exceeds 460 ppm, the precipitated Ce2C3 significantly reduces the performance of the ductile iron.

Influence of Silicon on Solidification Behavior, Microstructure and Oxidation Resistance of Gray Iron for Cookware Applications

Gray iron, a widely used engineering material, is favored for its desirable properties such as good damping capacity, thermal conductivity, and corrosion resistance. However, when exposed to elevated temperatures over time, issues like oxidation and graphite depletion can impact its durability. High-silicon gray iron, with elevated silicon content exceeding 3.0%, is known for its ability to withstand heat and oxidation, making it suitable for many applications, including cookware. This study investigates the impact of varying silicon levels (2.00-4.56%Si) on the solidification behavior, microstructure, and oxidation resistance of gray iron. Three heats with different silicon concentrations were produced and analyzed. Results indicated that higher silicon content increases the eutectoid temperature, stabilizes the ferritic structure, and introduces Type-D graphite in the microstructure. Graphite depletion was observed only in samples with 2.00%Si. The oxidation resistance improved with higher silicon content, as evidenced by a decrease in weight gain after exposure to 800 °C for 4 hours. This suggests the potential of using lower silicon levels in gray iron for cookware applications, balancing material cost with good impact resistance.

Effect of Bismuth on Microstructure and Properties of Ductile Iron

Effect of Bismuth on Microstructure and Properties of Ductile Iron

Influence of Casting Materials on the Microstructure and Mechanical Properties of Gray Cast Iron for Cylinder Liners

Influence of Casting Materials on the Microstructure and Mechanical Properties of Gray Cast Iron for Cylinder Liners

Effect of tempering temperature on microstructure and properties of low silicon hypereutectic high chromium cast iron

Effect of tempering temperature on microstructure and properties of low silicon hypereutectic high chromium cast iron

Investigation of microstructure, corrosion and mechanical properties of iron and holmium modified Sn-3.0Ag0.5Cu solder alloy with ultrasonic treatment

This research investigated the microstructure, corrosion behavior and mechanical properties of iron and holmium modified Sn-3.0Ag-0.5Cu solder alloy with ultrasonic treatment. The results demonstrated that the distribution of the phases in the ultrasonically treated solder alloys became homogeneous and the microstructure of ultrasonically treated solder alloys were more refined. The average grain size of ultrasonically treated solder alloys was reduced from 206.7 μm to 184.1 μm. A significant increase in the tensile strength from 38.75 MPa to 47.38 MPa was found in the ultrasonically treated solder alloys. The polarization curves results indicated that the solder alloys treated with ultrasound possessed lower corrosion current density and the results of atomic force microscopy suggested that roughness of corrosion products morphology was reduced. Furthermore, the electrochemical impedance spectroscopy (EIS) results indicated that the ultrasonically treated solder alloys had larger diameter of the semicircular loops and higher total impedance values.

The influence of trace vanadium on the solidification process, microstructure, and mechanical properties of gray cast iron

This study employed optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) to investigate the impact of vanadium (V) on the microstructure and mechanical properties of gray cast iron (GCI) HT250. Additionally, Thermo-Calc software was employed to explore the influence of V on the solidification process. The results indicate that adding trace amounts of V in GCI forms a face-centered cubic VC phase, with the precipitation temperature of the VC phase gradually increasing. When the V content reaches 0.28 wt%, the VC phase begins to precipitate during the eutectic reaction. The incorporation of V consumes carbon, reducing the graphite content and promoting the formation of type D graphite. As the V content increases, there is an enlargement in the pearlite area ratio, a decrease in the pearlite layer spacing, and a reduction in the size of eutectic cells. These microstructural alterations lead to enhanced mechanical properties. The tensile strength peaks at 336 MPa with a V content of 0.77 wt%, representing a 29% increase compared to samples without added V. Similarly, the Vickers hardness increases with increasing V content, reaching a peak of 373 HV at 0.92 wt% V, a 27% increase compared to samples without V addition. However, at this point, the tensile strength decreases to 322 MPa.