Ductile Iron Materials Research Articles

Structural integrity and hybrid ANFIS-PSO modeling of the corrosion rate of ductile irons in different environments

Ductile iron (DI) samples were immersed in near-neutral, alkaline sodium hydroxide (NaOH), and sodium chloride (NaCl) environments for 180 days. The influence of microstructure on the corrosion resistance of three DI specimens was investigated. Microstructures, electrochemical measurements, and the characterization of the corroded surfaces were analyzed. The experimental results from this study were used to validate a model generated from hybrid adaptive neuro-fuzzy inferences system-particle swarm optimization (ANFIS-PSO) algorithms. The hybrid ANFIS-PSO modelling technique was improvised for a detailed evaluation of corrosion rate of ductile cast iron materials in different environments. The integrated hybrid ANFIS-PSO model revealed a sharp rise in localized corrosion caused by chloride-induced structural deterioration at the nanoscale for some of the grains. The performance results revealed that the fuzzy c-mean (FCM) clustering outperformed other clustering approach in the neuro-fuzzy model. Accuracy values of 92.9% and 93.7% were recorded for the training phase of ANFIS-FCM and ANFIS-PSO-FCM respectively for corrosion rates. The percentage error of the ANFIS-PSO predictions is significantly lower than the ANFIS-standalone prediction. This shows that the ANFIS-PSO with FCM approach is a better model for predicting corrosion rates. This will contribute to the body of knowledge for ductile iron, corrosion, and corrosion modelling using machine learning.

Optimization of car crankshaft strength with ductile iron material through Solidworks simulation

This study aims to provide crucial insights into the performance of crankshaft designs under various loads and operational conditions. The method employed in this research is finite element analysis, facilitated by SolidWorks software, utilizing Ductile Iron material. Crankshafts crafted from ductile Iron are typically employed in vehicle engines due to their commendable mechanical properties and cost efficiency. The force exerted by the piston on the crankshaft generally ranges from 4500 N to 7500 N. The Factor of Safety within the crankshaft denotes the ratio between its material strength and the maximum stress it experiences during operation. The findings of this research indicate that the highest recorded maximum von Mises stress utilizing ductile iron material is 4.658 MPa, with a corresponding Factor of Safety in the crankshaft of 118.4. Consequently, the resilience of ductile iron crankshafts under varying loads and operational conditions can be ensured through meticulous analysis of crankshaft geometry.

Investigation of Suitable Production Conditions of High Extension Cast Iron (EN-GJS-400-18)

EN-GJS-400-18 spherical cast iron materials are widely used in the automotive, construction, mining, metallurgy, and machinery manufacturing sectors due to their high strength, ductility, toughness, low melting point, good fluidity, and good machinability properties. There are various difficulties in always producing at the same standard under mass production conditions. The most important of these difficulties is the lack of availability of raw materials of the same purity. In this study, it is aimed to produce EN-GJS-400-18 ductile iron material, which is difficult to produce in terms of mass production practice in foundries, in accordance with serial conditions. For this purpose, the effects of Si, carbide-forming elements Cu and Mo, and casting material diameter on the microstructure and mechanical properties of EN-GJS-400-18 spherical graphite cast iron were examined. As a result of the experiments, it was seen that the 20 mm diameter sample with the content of %Si:3.10, %Mo:0.001, %Cu:0.03 was obtained with the highest elongation value of 22.38%. It has been determined that the minimum ferrite ratio in the microstructure of this material is 80% and the number of nodules per mm2 is 600, which will reveal superior mechanical properties.

Numerical study on erosion behavior of sliding sleeve ball seat for hydraulic fracturing based on experimental data

The sleeve sealing ball seat is one of the important components in the multistage fracturing process of horizontal wells. The erosion and wear of the surface will decrease the sealing performance of the fracturing ball and the ball seat. This leads to pressure leakage during the fracturing process and fracturing failure. In this paper, combined with the actual ball seat materials and working conditions during the fracturing process, the erosion tests of ductile iron and tungsten carbide materials under different erosion speeds, angles, and mortar concentrations are carried out. Then the erosion test results were analyzed by mathematical fitting, and a set of erosion models suitable for sliding sleeve setting ball seat materials were innovatively established. For the first time, this paper combines the erosion model obtained from the experiment and the computational fluid dynamics (CFD) with Fluent software to simulate the erosion of the ball seat. Based on the simulation results, the morphology of the sliding sleeve seat ball after erosion is predicted. Through analysis of the test and simulation results, it is showed that the erosion rate of tungsten carbide material is lower and the wear resistance is better under the condition of small angle erosion. This research can offer a strong basis for fracturing site selection, surface treatment methods, and prediction of failure time of ball seats.

Effects of Vermiculariser, Inoculant and Copper Addition on Microstructure and Corrosion Properties of Vermicular Graphite Cast Iron

In this study, the microstructure and corrosion properties of Vermicular Graphite Cast Iron (VGCI) produced via different methods and parameters were investigated. VGCI was produced from a base ductile iron material using different proportions of vermiculariser and inoculant. Copper was added to a group of samples as an alloying element. The microstructures and corrosion properties of samples were investigated in saltwater media. The effects of production parameters on the microstructure and corrosion behavior were determined. It was observed that as the ratio of vermiculariser applied was increased, the vermicular graphite ratio and vermicularity was also increased. The matrix grain size decreased while the inoculant and pearlite phase ratio increased due to the addition of copper. In electrochemical corrosion studies, VGCI was superior in corrosion resistance compared to SGCI and addition of vermiculariser, inoculants and copper was found effective in improving the corrosion resistance of the VGCI material.

Study of Surface Roughness of Cutting Isothermally Hardened Ductile Iron in Tosa Knife Forging Technique Based on Intelligent Calculation

With a long history of more than 600 years of development, the Achang Tosa knives have always been handmade and made in strict accordance with tradition and absorbing the essence of foreign cultures. It is not only a tool or a gift, but also a “knife culture” and a local “folk culture” with local ethnic characteristics in Yunnan. In this paper, we begin our research on the Achang Tosa knives by compiling literature and conducting field research to investigate the “knife culture” jointly created by the Achang and neighboring ethnic groups by studying the forging process of the Achang Tosa knives. Three sets of specimens were prepared and the mechanical properties were determined by combining the existing isothermal quenched ductile iron (ADI) material production, and a high-speed cutting test was carried out with a CC650 ceramic tool to investigate the relationship between the machined material, tool material, and cutting dosage-surface roughness during high-speed cutting of ADI; based on the particle swarm algorithm, a theoretical model between surface roughness and cutting parameters was established to provide theoretical guidance for the optimal production process of ADI in high-speed cutting. It provides more valuable experience for the protection of intangible cultural heritage of ethnic minorities and also provides reference for the development and protection of unique crafts of other ethnic minorities.

On Scaled Normal Stresses in Multiaxial Fatigue and Their Exemplary Application to Ductile Cast Iron

The approaches used to calculate the fatigue life of components must inevitably consider multiaxial stresses. Compared to proportional loading, the calculation of nonproportional loading is particularly challenging, especially since different materials exhibit the effects of nonproportional hardening and shifts in fatigue life. In this paper, the critical plane approach of scaled normal stresses, first proposed by Gaier and Dannbauer and later published in a modified version by Riess et al., is investigated in detail. It is shown that, on the one hand, compatibilities exist or can be established with known proportional strength criteria that can account for the varying ductility of different materials. Furthermore, it is demonstrated that the scaled normal stress approach can be formulated in such a way that different strength criteria can be used therein. As an example, the generally formulated approach for scaled normal stresses is applied to test results from ductile cast iron material EN-GJS-500-14. Different correction factors accounting for nonproportional loading are investigated. Through appropriate parameterization of one of the studied corrections, proportional and nonproportional test results were observed to fall within one common scatter band.

Process Optimization for an Energy Efficient Heat Treatment of ADI*

Abstract Austempered ductile iron (ADI) materials show a good combination of mechanical properties, with high tensile strength levels (800-1600 MPa) and an elongation at fracture of up to 10 %. Due to its high fracture toughness as well as high fatigue resistance, ADI is a very attractive material group for applications under cyclic loads. However, the material properties are very sensitive to the applied process conditions during heat treatment. The basis for a substantial increase in the application of ADI materials in the industry requires the establishment of a predictable and robust process design. Here, an integrated process simulation of the heat treatment process coupled to required information about the as-cast quality of the component would aid in understanding process dependencies and defining a robust process window. For the austenitization step, the simulation can be used to determine the needed treatment times and temperatures. In the process simulation software MAGMA5, a new fast and efficient algorithm for heat exchange between thermally coupled diffusely radiating interfaces has been implemented and can be used for heat treatment simulation. The accuracy and computational performance of this new radiation model for the heat treatment of ADI is illustrated here for a real industrial suspension part. The steering knuckle is heated in a typical heat treatment box. Surface-to-surface radiation between the parts and with the surrounding furnace results in inhomogeneous temperature distributions. Integrated capabilities to perform virtual experiments and automatic optimization are used to determine optimal process conditions to meet both the quality requirements and the minimum required treatment time during austenitization. ▪

Comparison between Hazen-Williams and Darcy-Weisbach equations to calculate head loss through conveyancing treated wastewater in Kerbala city, Iraq

Reuse of wastewater has been widespread in this era to support the water sustainability process. Therefore, treated wastewater should be conveyed to suitable places and adopted for different uses. This study presents an empirical relationship between the Darcy-Weisbach and Hazen-Williams equations for four types of pipe material (ductile iron, GRP, concrete, and plastic) by using WaterCAD Version 8i. Two hydraulic models were developed to estimate the head loss in pipes by using different diameters: first, using pipe diameters from 800 mm to 1,200 mm for a flow rate of 1.16 m3/s, second, adopting pipe diameter from 1,600 mm to 2,000 mm for a flow rate of 4.63 m3/s. The study results are the head loss values obtained from the Darcy-Weisbach and Hazen-Williams equations, which were used to correlate them using IBM SPSS Statistics. The correlation coefficient between both equations turned out to be 0.991, 0.990, 0.990, and 0.990 for ductile iron, GRP, concrete, and plastic pipe materials. Additionally, the relationship between head loss and pipe diameter is negatively proportioned for both equations. Also, both head loss equation results are the same. The head loss values in the Darcy’s equation were higher for ductile iron and GRP materials, while being lower for concrete and plastic materials for both models. Selecting concrete or plastic pipes to convey treated wastewater is better than other pipe materials. Another conclusion is that the pipe diameter affects the head loss magnitude irrespective of the kind of equation whether Darcy-Weisbach or Hazen-William equation. Finally, this relationship is very useful for designers in converting the head loss values obtained using these equations.

Procena čvrstoće snopa materijala metalnog zupčanika

Expressions for the pulsating or beam strengths of many popular metallic gear materials are derived based on the tensile strength and endurance ratio. The strength values predicted are for a reliability of 99% at load cycles corresponding to that of the endurance strength of the materials. The expressions are based on the consideration of the revised Lewis gear root stress formula by treating the design parameters as random variables associated with the lognormal probability density function and application of the Gerber fatigue failure rule. Pulsating strength predictions are compared with those of AGMA estimates for through-hardened steels and other materials. The variances between model predictions and AGMA values for steel and ductile cast iron materials are reasonably low. Low variances between model and AGMA values for high-strength gray cast iron and cast bronze were also observed. However, high variances between model and AGMA values for low-strength gray cast iron and cast bronze were found. Overall, the model estimates are considered sufficiently accurate for preliminary design applications where initial sizes of gears are generated. The study showed that for many metallic gear materials, the average pulsating strength ratio is 0.36 at 99% reliability. Therefore, the suggestion by Buckingham, that the fatigue strength of a gear tooth is approximately one-third (0.333) of the tensile strength of the material is justified.

Investigation of the machining performance of ferritic ductile cast iron in WEDM using response surface methodology

Wire electrical discharge machining (WEDM) technology is a special electrothermal processing method that can precisely production of parts with variable stiffness with sharp edges or production of complex geometric parts which are difficult to produce by traditional manufacturing methods. It has an important place in production sector in terms of low energy consumption. In this study, the relationship between processing parameters on surface quality on the ferritic ductile cast iron (GGG-40) material in WEDM process with molybdenum wire was investigated by Response Surface Methodology (RSM). The aim of this study is to determine the optimum process parameters for low-cost production of GGG-40 material with sharp-edged and complex geometry parts using the WEDM method. In experimental works, surface roughness, and process time were investigated using table feedrate, pulse on time, and pulse space as cutting parameters. The surfaces obtained as a result of the experiments were evaluated in terms of surface quality with Scanning Electron Microscopy (SEM), and surface roughness device. According to the findings, it has been observed that the surface roughness has increased with increasing table feedrate, and pulse on time, and surface roughness decreased with pulse space increasing. Also, it is understood that pulse on time is the most important factor effecting surface quality. It has been found that the process time depends on only the table federate where they are inversely proportional. As result of RSM analysis, optimum cutting parameters were obtained in terms of lowest surface roughness, lowest process time and best time/performance condition on both parameters for ferritic ductile cast iron in WEDM process.

A methodology for assessing short fatigue crack growth in DCI materials affected by intergranular embrittlement at temperatures nearby 400 °C

A crack growth model for assessing the lifetime and short fatigue crack growth of ductile cast iron materials is proposed. The model bases on the assumption that the crack advance per cycle correlates with the cyclic crack tip opening displacement. Intergranular embrittlement at medium temperatures is accounted for as a temperature and strain rate dependent crack accelerating mechanism. The model is calibrated and successfully applied to predict temperature dependent fatigue lifetime and short crack growth of a ductile cast iron material.

Experimental characterization of the short crack growth behavior of a ductile cast iron (DCI GJS-500) affected by intergranular embrittlement at temperatures nearby 400 [formula omitted

In this investigation, the fatigue and crack growth behavior of the ductile cast iron material (DCI) GJS-500 was experimentally characterized by performing isothermal low cycle fatigue (LCF) tests, out-of-phase thermomechanical fatigue (OPTMF) tests as well as low cycle fatigue tests combined with the replica testing method (LCF-R) within the temperature range RT–500 °C. The studied material exhibits an embrittlement at temperatures nearby 400 °C, leading to a significant higher fatigue crack growth rate and a reduced lifetime, when compared with RT and 500 °C. A possible explanation for the observed higher fatigue crack growth rate coupled with a significant lifetime reduction, is intergranular embrittlement.

Non-linear modelling of Ferro casting ductile shear key of L-Shaped concrete blocks with epoxy joint using Midas FEA

As cast iron with 10-15% of graphite, Ferro Casting Ductile (FCD) Iron material has better mechanical properties than the ones from Grey Cast Iron. Moreover, it is also close to Carbon Steel’s properties. Regarding this condition, FCD has the potential to be used as a shear key, specifically, as a joint of precast segmental concrete bridges. The objective of this paper is to study the mechanical behavior of FCD applied as shear key on a wet precast joint using epoxy. To do so, three-dimensional non-linear numerical modeling using Midas FEA was conducted on two L-shaped concrete blocks connected by a couple of FCD shear key representing precast concrete segmental bridge system. Between these two L-shaped blocks of concrete, epoxy adhesive was applied. Both concrete blocks and FCD shear keys with 50% scale of original geometries were used. The constitutive behavior of each material was obtained from previous test results and literatures. Loading applications were performed in two directions, vertical load to represent load from deck bridge and horizontal load to represent prestressing force. Load bearing capacity of FCD shear keys increases along with the increase of horizontal load. Non-linear analysis results show discrepancy comparing to the experimental ones, with a deviation reaches more than 7%.

Proračun jačine pitinga kod materijala od livenog gvožđa i legura bakra

An attempt is made to predict the pitting strength of cast iron and copper alloy materials from their compressive yield or compressive proof strength for a reliability of 99% at 107 load cycles. The compressive yield or compressive proof strength is related to the tensile strength of ductile cast iron and copper alloy materials by a proportionality factor. Two proportionality factors are used for brittle cast iron materials. The pitting strength formulation incorporates a nominal design factor at 99% reliability which is estimated from a probabilistic model based on the lognormal probability density function. Pitting strength estimates from the predictions are compared with those of American Gear Manufacturers Association (AGMA) estimates and data from other sources. The predicted values for gray cast irons had variances in the range of -11.28% to 25%. Ductile cast iron pitting strength estimates deviated from those of AGMA by -30.28% to 1.73% and 16.76% to 36.34% for Austempered ductile irons. The variances obtained for cast bronze were from 11.17% and 14.73%, but the sample size was small. These variances appear to be reasonable due to the many factors that can influence pitting resistance. Since pitting strength data for many grades of cast iron and copper alloys are not available (especially in the public domain), they may be estimated by the expressions developed in this study for initial design sizing. Also, the pitting strength of new cast iron and copper alloy materials could likewise be estimated for initial design sizing. This will eliminate long and costly contact fatigue testing at the initial design phases, which of course is necessary for design validation.

Research and Analysis of the Effect of Heat Treatment on Damping Properties of Ductile Iron

Abstract With the continuous development of metal manufacturing technology, high-strength and high-hardness ductile iron materials have excellent comprehensive performance. Many performance indexes are comparable to those of alloy steels, and they have excellent casting properties. Many large-scale parts produced by cast steel are slowly being replaced by this material. Ductile iron is obtained by a spheroidizing treatment and inoculation to obtain spheroidal graphite. The mechanical properties of cast iron have been effectively improved, especially plasticity and toughness, and the strength obtained is higher than that of carbon steel. Ductile iron has the properties of iron and the properties of steel. It is a new type of engineering material with high plasticity, strength, corrosion resistance, and wear-resistance. Because of its excellent performance, it has been successfully used to cast parts with high-stress conditions, high strength, toughness and wear resistance. Due to the small splitting effect of ductile iron on the metal matrix, the stress concentration is effectively eliminated. Therefore, the matrix structure of ductile cast iron is changed by heat treatment, thereby improving its mechanical properties and the damping performance of the material itself. Through a heat treatment process experiment of ductile iron, the related process and technical measures of damping performance in the heat treatment production process are obtained.

Tribological Performance of Austempered and Tempered Ductile Iron

Austempered ductile iron with its unique ausferritic structure is produced by an isothermal heat treatment process. Austempered ductile iron is a potential material to substitute for traditional steel castings and forgings in current industry due to its excellent mechanical properties. The tempering process is frequently used to enhance the ductility and toughness of a material and reduce residual stress. In this research, the phase transformation of austempered ductile iron was studied by applying various tempering temperatures with constant holding duration. It was found that the ausferritic structure was decomposed into dispersive cementite particles after receiving a tempering temperature of 538 °C or higher. The specific amount of retained austenite was analyzed by X-ray diffraction. The wear resistance of tempered austempered ductile iron was investigated by using a ball-on-disk sliding test configuration. The results were compared with conventional quenched and tempered ductile iron under equivalent hardness. Both austempered ductile iron and tempered austempered ductile iron samples had better wear resistance than quenched and tempered ductile iron. The results presented in this research can be utilized as a reference in the tempering treatment of austempered ductile iron material for future applications.

A New High Strength High Ductile Nodular Iron

Years ago, especially in Sweden, a new family of ductile iron materials was propagated: Solid solution strengthened ferritic ductile iron. Since the 2011 edition, three grades are integrated into the European Standard EN 1563: EN-GJS-450-18, EN-GJS-500-14 and EN-GJS-600-10. The introduction of these materials into the European standard generated a large interest of many engineers, which came to a real hype meanwhile. The reason is clear: While GJS-450-18 is not very different from the standard GJS-400-15, especially the grade EN-GJS-500-14 promises to have big advantages compared to the standard grade EN-GJS-500-7. Same tensile strength, from 320 MPA to 400 MPa raised 0.2%- proof strength and from 7% to 14 % doubled elongation after fracture are very interesting properties of course and the pure ferritic structure promises a better machinability furthermore. With the higher strength grade EN-GJS-600-10 very early sceptic comments raised, because the Silicon content to reach the required strength is such high, that the risk of an embrittlement of the ferrite even at room temperature and on a tensile test bar is high. But up to now, the grade EN-GJS-500-14 has the reputation to be a high strength and very high ductile material. So, a customer of us also substituted a part from steel to EN-GJS-500-14. All calculations showed a very good performance of the parts, but as soon as in serial production field damages occurred in a manner that the parts completely broke without advance warning. The investigation of the damages showed, that the parts are not only statically and cyclically loaded, but also by strikes. Deeper investigations about strike loads confirmed, that EN-GJS-500-14 is not really ductile under these conditions. The reflection to the philosophy we had with our SiboDur-700 concept, namely to combine a moderate solid solution strengthening with a moderate strengthening by pearlite with Copper, brought us to a new high strength high ductile material we call SiboDur-500. Same strength as EN-GJS-500-14, 10 % lower in 0.2%- proof stress, slightly lower in elongation after fracture, but double to more than four times energy consumption at strike loads depending om temperature!

Computational and Experimental Mechanical Modelling of a Composite Grouted Splice Sleeve Connector System.

Owing to its controllable tolerance, simple operation and no need for welding at construction site, the composite system involving grouted cement material, steel material and ductile iron material is widely used as grouted splice sleeve (GSS) connector for connecting precast concrete structures. However, the current design recommendations for such a composite connection system do not accurately account for its material nonlinearity behavior. In the present study, a three-dimensional nonlinear finite element model of a GSS connector is developed by considering the nonlinear material behavior of each component to fully investigate its mechanical performance under axial tension. To validate the proposed computational model and demonstrate the nonlinear response of the GSS connector, the pullout experimental test of two engineering specimens is carried out under monotonic tensile load, and a good agreement between the numerical and experimental test results is observed. Then, the sensitivity analysis of some controlling material properties and geometrical parameters is performed using the validated computational model to further understand the performance of such a composite structure in load carrying capacity and ductility of the connections to meet the rapid engineering applications of precast concrete structures.

Towards a temperature dependent and probabilistic lifetime concept for nodular ductile cast iron materials undergoing isothermal and thermo-mechanical fatigue

In this investigation, the fatigue behaviour of a ductile cast iron with high content of silicon and molybdenum, was experimentally characterized by performing isothermal low cycle fatigue (LCF) tests as well as out-of-phase thermomechanical fatigue (OPTMF) tests within the temperature range RT – 500 °C. The studied material shows an embrittlement at temperatures nearby 400 °C. A possible explanation for the observed lifetime reduction is intergranular embrittlement (IE). A mechanism based lifetime model is proposed for assessing the lifetime. The model is based on the assumption that the crack advance per cycle is correlated with the cyclic crack tip opening displacement (ΔCTOD) attributed to the crack tip blunting caused by accumulation of plastic and creep deformations ahead of the crack tip. Intergranular embrittlement is accounted for by introducing a temperature and strain rate dependent prefactor in the crack growth law, which only acts in a certain temperature range. The model is calibrated for a GJS material and successfully applied to predict the lifetime of this material when undergoing isothermal and non-isothermal mechanical loadings. A probabilistic interpretation of the scatter of the investigated material is presented in conjunction with the random nature of the initial defect size distribution.