Ductile Iron Research Articles

Reaction Behavior at the Contact Interfaces between High-Manganese Cast Steel or High-Manganese Spheroidal Graphite Cast Iron and Molten Aluminum Alloys

Reaction Behavior at the Contact Interfaces between High-Manganese Cast Steel or High-Manganese Spheroidal Graphite Cast Iron and Molten Aluminum Alloys

Mechanism and machinability in novel electroplastic-assisted grinding ductile iron

Mechanism and machinability in novel electroplastic-assisted grinding ductile iron

Vermicular and Chunky Graphite Nucleation during Chill Casting: Study on the Dynamics of Ductile Iron Recycling

AbstractThis investigation provides alternative insight into the dynamic behavior of spheroidal graphite structures throughout the remelting process during ductile cast iron recycling. Specifically, this study systematically analyzed the impact of the remelting process on graphite nucleation. Two approaches are included in this research: thermal analysis and the copper–mold chill casting method. Based on these results, different graphite structures nucleate in cast iron in response to the remelting and recasting processes, which correlate with the melting temperature, the cooling method, and the fading effect. Furthermore, it is indicated that the dissolution rate of spheroidal graphite is relatively slower than lamellar graphite, substantiated by the detection of residual graphite nodules in the case of low melting temperature applied during the remelting process. In addition, the formation of vermicular and potentially chunky graphite structures can also be observed to a certain extent during this set of investigations, thus providing further insight into their relation to the ductile cast iron production process. Graphical Abstract

Enhanced erosion-corrosion resistance of monolithic ENP coating on ductile cast iron by using electrochemical pretreatment and heat treatment

This research aims to enhance the erosion-corrosion durability of monolithic ENP coating used on ductile cast iron. The ENP coating does not usually adhere well to the cast iron surface due to the special characteristics and innertness of the graphite sphere so an electrochemical surface pre-treatment containing a cathodic treatment was implemented to ensure proper adhesion of the coating to the surface. A slurry pot erosion-corrosion test was performed at a linear velocity of 10 m/s for 16 h, and it verified the efficacy of the treatment. Three different heat treatments were carried out on coated samples at 200 °C, 400 °C, and 600 °C. The sample heat-treated at 600 °C exhibited a pseudo-passivation behavior and displayed the best corrosion resistance of 0.1407 μA/cm2. Nonetheless, in erosion-corrosion tests, it was outperformed by other coatings due to the removal of its oxide layer. The heat treatment at 400 °C resulted in the highest hardness of 871 Vickeres and the best erosion-corrosion resistance of 8.8 mpy compared to 11.74 mpy for the as-plated sample and 381.3 mpy for the cast iron substrate.

Coupling effects of loading rate and temperature on mode I dynamic fracture characteristics of ductile cast iron

Engineering structures made of ductile cast iron (DCI) have a potential risk of failure due to extreme service environments such as high velocity impacts and sub-zero temperatures. Therefore, it is of great importance to investigate the dynamic fracture behavior of DCI under the coupling effect of rate and temperature. In this paper, two sets of impact velocities (5 m/s and 13.5 m/s), and four sets of temperatures (20 °C, −40 °C, −60 °C, and −80 °C) were specially designed to investigate the coupling effect on the mode I dynamic fracture toughness (DFT). The results show that DFT is positively correlated with impact velocity at 20 °C, −40 °C and −60 °C. However, at −80 °C, the rate effect is reversed. Moreover, DFT decreases with decreasing temperature regardless of impact velocity. With microscopic analysis, the phenomenon of ductile–brittle transition (DBT) was observed in the failure of the material, and it’s verified by dynamic tensile tests. The ductile–brittle transition temperature (DBTT) of DCI is determined as −39.7 °C by comparing the DFT with the strain energy density (SED) characterization method.

Optimization and machinability evaluation for WEDM of austempered ductile iron

Abstract Wire electrical discharge machining (Wire EDM) is a non-contact CNC machining that removes material from a workpiece with electrical sparks. Optimization of parameters involved in wire EDM is essential for better operational economics and energy usage. The major goal and objective of this research are to assess the machining parameters, like surface roughness Ra, material removal rate MRR, and hardness HV by experimental investigation utilizing the wire cut EDM machine and austempered ductile iron (ADI) as the work material. An artificial neural network (ANN) has been employed to create a prediction model using experimental data. The Aquila optimization approach is then used to obtain the ideal operating parameters. With Aquila optimization, the predicted optimum values for MRR, Ra, and Hardness are 3.529 mm3/min, 1.966 µm, and 367 HV, respectively, when the input parameters are pulse ton 16 µs, pulse-toff time toff 14 µs, servo voltage 50 V, and current 3 A. Finally, SEM and 3D roughness analysis have been carried out to study surface morphology and material removal mechanism.

Toward Continuous Electrochemical Synthesis of Ferrate

AbstractFerrate (Fe(VI)) is of great interest in energy storage solutions, organic synthesis, and wastewater treatment due to its decent oxidation potential and non‐toxic end‐product formation, making it a green oxidizer. The electrochemical generation of ferrate in NaOH at current densities of j ≥ 100 mA cm−2 is presented using low‐cost sacrificial iron anodes, mild steel, and spheroidal graphite cast iron (ductile iron). Under optimized reaction parameters with 40 wt.% (14 m) NaOH and a ZrO2‐based diaphragm, spheroidal graphite cast iron shows no signs of passivation in 5 h experiments even at j = 150 mA cm−2. The results are used in a novel electrolysis cell with a combined geometric anode surface area of 230 cm2, incorporated in a mini‐plant suitable for continuous synthesis. This setup produces a peak ferrate concentration of 10.1 g L−1 (84 mm) after 5 h in 1.6 L anolyte volume, resulting in a total ferrate mass of 16.2 g. Optimal electrolysis temperatures are between 35 and 50 °C. The highest current efficiency is 63.0%, and the lowest specific energy consumption is 9.2 kWh kg−1 ferrate. The presented work is an essential step toward the continuous electrochemical synthesis of ferrate using sacrificial anodes under basic conditions.

Effect of Intercritical Austenitization and Starting Matrix on Martensite Start Temperature and Austenite Carbon Concentration in Ductile Iron

AbstractIn this work, the effect of the intercritical austenitization temperature and time, Ni + Cu concentration and starting matrix (fully ferritic or fully pearlitic) on the volume fraction of austenite (fγ), martensite start temperature (Ms) and carbon concentration of the parent austenite (C0) in ductile iron was investigated using standard metallographic techniques and high-resolution dilatometry. The results showed that a fully pearlitic starting matrix gives higher fγ and C0 and lower Ms than a fully ferritic starting matrix at the same austenitization temperature under continuous heating. On the other hand, the austenitization time has an effect on the parameters under study only during the first minutes of intercritical austenitization. Finally, at the same intercritical austenitization temperature, the addition of Ni + Cu increases the volume fraction of austenite.

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.

Morphological and Corrosion Characterization of Electroless Ni-P Coatings Deposited on Ductile Iron

Morphological and Corrosion Characterization of Electroless Ni-P Coatings Deposited on Ductile Iron

Assessment of the Functional Properties of the Surfaces of Ductile Cast Iron Parts

Modern technology allows ductile cast iron parts to be efficiently machined while ensuring a relatively long tool life. One of the basic indices describing the susceptibility of ductile cast irons to change in volume, shape, and dimensions under machining conditions is their machinability. Machinability can be expressed directly in terms of the values of basic quantities such as periodic cutting speed and roughness. At the same time, machinability is a relative quantity evaluated alternatively. This means that the machinability of ductile cast iron can be good, allowing high cutting speeds to be achieved, but it can also be poor, expressed in terms of poor surface quality. In the experimental research carried out, an attempt was made to determine the limit values of the cutting speed, beyond which one should not exceed, in order to increase the efficiency of the machining process. The surface roughness, unlike the periodic cutting speed, is a quantity defined in the product design documentation, so its limits must be observed. In addition to the usual indices of surface geometric texture, the research analysed alternative indices for determining the condition of surface geometric texture and the influence of periodic cutting speed on their values. In the conclusions, valuable recommendations are given for designers and technologists on the purpose and functionality of product surfaces and how to define them. Methods of specifying tribological characteristics, hydrophobic or hydrophilic properties, as well as the ability to retain fluids and maintain protective coatings of ductile cast iron parts after machining are described, for which relative values, depending on the machining parameters used, can vary from about 10 to even 30%.

Efficient phosphate removal from water using ductile cast iron waste: a response surface methodology approach.

Water scarcity is a critical issue worldwide. This study explores a novel method for addressing this issue by using ductile cast iron (DCI) solid waste as an adsorbent for phosphate ions, supporting the circular economy in water remediation. The solid waste was characterized using XRD, XRF, FTIR, and particle size distribution. Wastewater samples of different phosphate ion concentrations are prepared, and the solid waste is used as an adsorbent to adsorb phosphate ions using different adsorbent doses and process time. The removal percentage is attained through spectrophotometer analysis and experimental results are optimized to get the optimum conditions using Design Expert V13. The pseudo-second order (PSO) kinetics model and Langmuir isotherm were fitted with the experimental results with maximum adsorption capacity (qmax = 0.28mg/g). The thermodynamic analysis indicated that this adsorption process was spontaneous based on the negative value of Gibbs free energy (∆G). Additionally, the positive values of enthalpy (∆H) indicated the endothermic nature of this adsorption system. It was able to reach the highest adsorption percentage of 98.9 (%) for phosphate ions from aqueous solutions using response surface methodology (RSM) with optimum conditions of 10mg/L phosphate ion concentration, pH = 8, normal room temperature, 9min adsorption, and 0.5g/L adsorbent dosage.

Microstructure and Various High Temperature Properties in a Small Amounts of Aluminum Added High Silicon Spheroidal Graphite Cast Iron

Microstructure and Various High Temperature Properties in a Small Amounts of Aluminum Added High Silicon Spheroidal Graphite Cast Iron

Comparison of microstructure and tribological behavior for ductile iron with quench-tempered and intensive quench-tempered

In recent years, the intensive quenched process has gained significant attention due to its low energy consumption and absence of pollution. The tribological behavior of traditional quenched and tempered ductile iron (DI_QAT) and an innovative intensive quenched and tempered ductile iron (DI_IQAT) was investigated. Both DI_QAT and DI_IQAT consist of graphite, ferrite and cementite particles. Compared to DI_QAT, DI_IQAT exhibits higher hardness, impact toughness, and yield strength. Wear tests indicate that the friction coefficient of DI_IQAT is lower and the wear resistance of DI_IQAT surpasses that of DI_QAT, it is mainly related to its enhanced wear-resistant structure. Examination of the wear surface morphology reveals that the primary wear mechanisms for DI_QAT and DI_IQAT involve adhesive and abrasive wear.

Transformation-induced plasticity (TRIP) in ductile iron and resultant exceptional strength-plasticity synergy

This study produces a Ni-containing ductile iron with a matrix consisting of lamellar α and γ phases, along with nanoscale Mg6Si7Ni16 phases. The interface of fine α and γ phases and the nanoscale Mg6Si7Ni16 phases impede dislocation mobility, contributing to high yield strength. During the tensile test, the transformation-induced plasticity (TRIP) phenomenon is etected because Ni addition effectively endows appropriate carbon concentration in γ phase of ductile iron. The TRIP effect significantly augments the strain-hardening capacity of ductile iron, resulting in an excellent plasticity with an elongation of ∼21 % and a considerable ultimate tensile strength of ∼900 MPa. Consequently, the ductile iron achieves an exceptional strength-plasticity synergy, characterized by the product of tensile strength and elongation (PSE) of 19 GPa%.

Effect of Austenitization Time on Corrosion and Wear Resistance in Austempered Ductile Iron

Effect of Austenitization Time on Corrosion and Wear Resistance in Austempered Ductile Iron

Corrosion potential and theoretical studies of fabricated Schiff base for carbidic austempered ductile iron in 1M H2SO4 solution

In this body of work, a chemical known as 2-cyano-N-(4-morpholino benzyl dine) acetohydrazide (CMBAH) is explored for its ability to suppress the carbidic austempered ductile iron (CADI) corrosion in 1M H2SO4. Density functional theory was used in experiments and theoretical investigations to investigate the inhibiting impact. The corrosion of CADI alloys in 1M H2SO4 produced a corrosion resistance superior to that of CADI heat treatment (H.T.). As-cast carbidic ductile iron (CDI) 4 alloy with 1.5%t Cr-Nb has a corrosion rate (C.R.) of 11.69 mm/year, which drops to 5.31 mm/year at HT-275 °C and 6.13 mm/year at HT-375 °C. When describing the adsorption of inhibitors, the Langmuir adsorption isotherm is the most effective method. The findings of the Gads show that the inhibition was induced mainly by the physisorption on the surface CADI alloys. In addition to this, it was found that the results of the experiments and the hypotheses were largely harmonious with one another. The formation of protective layers on the CADI surfaces is also visible in the images captured by the SEM. In 1M H2SO4, these Schiff base inhibitors effectively prevent corrosion caused by CADI. However, the combination of inhibitors leads to a fine microstructure with ausferrite and narrow ferrite needles, promoting corrosion resistance. The CADI needles rated an upper ausferritic microstructure with wide ferrite needles.

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.

The load-transfer method as a tool for determining the load-displacement curve of piles

The paper presents two applications (software packages) in which the load-transfer method is used for axially loaded Kelly drilled bored piles and displacement ductile iron piles. In the first, the ultimate friction is related to the effective stress via the so-called β method. The β method is refined into three stages to cover the variety of soils typical of Central Europe. For the driven piles, a different approach is presented in which the ultimate shaft friction is related to the reference hammering time. The recorded hammering time profile is fed directly into the software based on the load-transfer method. Analyses of five loading tests are presented proving that the load transfer method in combination with the β method or the recorded hammering time profile is able to compute the load-displacement curve of both replacement and displacement piles with a reasonable accuracy in various geological conditions.

Numerical simulation and experimental study on nonlinear ultrasonic characterization of graphite size in nodular cast iron

Graphite morphology has a significant influence on mechanical properties such as tensile strength and hardness in nodular cast iron (NCI). Compared to the detection of graphite nodularity, there is relatively less ultrasonic simulation and detection experiment research on the graphite size. Therefore, it is of great importance to study rapid nondestructive testing methods for the internal graphite size of NCI. This study establishes a simulation model of nonlinear ultrasonic penetration longitudinal wave detection for graphite size. The acoustic nonlinearity parameter (ANP) is used to characterize the graphite size. Nonlinear ultrasonic detection experiments on the internal graphite size are conducted to verify the reliability of the nonlinear ultrasonic simulation model. The simulation and experimental results show that the ANP of penetrating longitudinal waves decreases with the increase of average graphite diameter. The relationship between ANP and internal graphite size is established. Moreover, the experimental results verified the accuracy of the numerical model. The decrease in ANP may be related to the decrease in the number of grain boundaries. Therefore, the nonlinear ultrasonic technique is an effective method for characterizing the internal graphite size. The establishment of a nonlinear ultrasonic simulation model for graphite size in NCI lays the research foundation for nonlinear ultrasonic microstructure characterization experiments.