Ductile Iron Research Articles

Fatigue Analysis of Prosthetic Osseointegration with a Novel Protection System

Recent advancements in osseointegration technology offer a promising alternative to traditional prosthetic limbs, leading to improved comfort and functionality for amputees. However, the primary concern lies in the risk of catastrophic failure and falling due to fractures within the osseointegration system. To address this challenge, a protective system has been designed. The new design includes an internally rod part with a notch at the bottom to ensure failure at that point, made of ductile cast iron. A cover made of Ti6Al4V alloy is placed to ensure fracture isolation within the protection nail during sudden loading, preventing unexpected falls. After conducting tensile tests for the mentioned alloys and materials, and then relying on the ground reaction force in the numerical analysis using SolidWorks software, Finite Element Analysis (FEA) simulations confirmed the effectiveness of this design, with the expected fracture point occurring in the protection nail after exceeding 54973 walking cycles, surpassing the expected maintenance lifespan of the prosthetic limb. This design represents a significant step forward in enhancing the safety and reliability of integrated prosthetic limbs, ultimately leading to improved mobility and peace of mind for amputees.Recent advancements in osseointegration technology offer a promising alternative to traditional prosthetic limbs, leading to improved comfort and functionality for amputees. However, the primary concern lies in the risk of catastrophic failure and falling due to fractures within the osseointegration system. To address this challenge, a protective system has been designed. The new design includes an internally rod part with a notch at the bottom to ensure failure at that point, made of ductile cast iron. A cover made of Ti6Al4V alloy is placed to ensure fracture isolation within the protection nail during sudden loading, preventing unexpected falls. After conducting tensile tests for the mentioned alloys and materials, and then relying on the ground reaction force in the numerical analysis using SolidWorks software, Finite Element Analysis (FEA) simulations confirmed the effectiveness of this design, with the expected fracture point occurring in the protection nail after exceeding 54973 walking cycles, surpassing the expected maintenance lifespan of the prosthetic limb. This design represents a significant step forward in enhancing the safety and reliability of integrated prosthetic limbs, ultimately leading to improved mobility and peace of mind for amputees.

Effect of Cu Addition Above the Solubility Limit on Microstructure Formation and Cu Segregation in 800 MPa Grade Ductile Cast Iron During Solidification

In this study, the effect of 3 mass%Cu additions on microstructure formation and Cu segregation in 800 MPa grade ductile cast iron during solidification was investigated. The calculated phase diagram showed that after the addition of 3 mass%Cu, the Cu phase with a negligible amount appeared below 1000°C, and most Cu was included in the matrix. Based on optical microstructure, after the addition of 3 mass%Cu, the size of graphite nodules became finer, and the microstructure rarely had an area with α-ferrite. Image analysis showed that the fraction of pearlite increased significantly, indicating that Cu greatly promoted the formation of pearlite. Compositional analysis by scanning electron microscopy indicated that the pearlitic area also contained approximately 3 mass%Cu, which corresponds to those of primary and secondary austenite calculated. A small and bright phase particle containing a large amount of Cu was observed at the interface of graphite and matrix.

Multi Response Modelling and Optimisation of Copper Content and Heat Treatment Parameters of ADI Alloys by Combined Regression Grey-Fuzzy Approach

This paper deals with the austempering of ductile iron (ADI) and clarifies the influential austempering parameters during the production of ADI. During the austempering process, the heat treatment parameters can be varied, thus influencing the final microstructure and, of course, the mechanical properties of ADI. To appropriately conduct experiments and obtain good results, an experimental plan was developed using the Design Expert 13 software. Along with the heat treatment parameters, the influence of the copper content on the ADI toughness, tensile strength, and elongation was determined. The obtained results from this experiment were used to develop unique mathematical models which describe the influences of heat treatment and copper content on the observed mechanical properties of ADI samples. These mathematical models can be applied to predict the analysed mechanical properties of ADI in the dependence of heat treatment parameters and copper content in base ductile iron. For the multi response optimisation of toughness, tensile strength, and elongation, a hybrid grey-fuzzy technique was presented as a significant contribution to the enhancement of the analysed mechanical properties. Consequently, the copper content and heat treatment parameter levels that resulted in the maximal mechanical properties’ functions were defined.

Effects of Manganese and Heat Treatment on Mechanical Properties in Spheroidal Graphite Cast Iron

Effects of Manganese and Heat Treatment on Mechanical Properties in Spheroidal Graphite Cast Iron

Cement-mortar lining failure and metal release caused by electrochemical corrosion of ductile iron pipes in drinking water distribution systems

The electrochemical corrosion of ductile pipes (DPs) in drinking water distribution systems (DWDS) has a crucial impact on cement-mortar lining (CML) failure and metal release, potentially leading to drinking water quality deterioration and posing a risk to public health. An in-situ scanning vibrating electrode technique (SVET) with micron-scale resolution, microscopic scale detection and water quality analysis were used to investigate the corrosion behavior and metal release from DPs throughout the whole CML failure process. Metal pollutants release occurred at three different stages of CML failure process, and there are potential risks of water quality deterioration exceeding the maximum allowable levels set by national standards in the partial failure stage and lining peeling stage. Furthermore, the effects of water chemistry (Cl−, SO42−, NO3−, and Ca2+) on corrosion scale growth and iron release activity, were investigated during the CML partial failure stage. Results showed that the CML failure process in DPs was accelerated by the autocatalysis of localized corrosion. Cl− was found to damage the uncorroded metal surface, while SO42− mainly dissolved the corrosion scale surface, increasing iron release. Both the oxidation of NO3− and selective sedimentation of Ca2+ were found to enhance the stability of corrosion scales and inhibit iron release.

Microstructures, Compressive Residual Stress, Friction Behavior, and Wear Mechanism of Intensive Quenched Ductile Iron

Microstructures, Compressive Residual Stress, Friction Behavior, and Wear Mechanism of Intensive Quenched Ductile Iron

The pressure treatment effect on the high‑strength austempered ductile iron structure

This paper presents the results of a study on the effect of pressure treatment (direct hot extrusion) on the structure of graphite inclusions and the metallic matrix of high‑strength austempered ductile iron. Comparative analysis of the cooling processes of the cast high‑strength ductile iron billet without deformation and after deformation was carried out using simulation modeling methods. The results of the study on the effect of hot deformation (up to 950–970 ℃) on the fracture structure and mechanical properties of austempered high‑strength ductile iron billets are presented.

Sprecific of distribution of chemical elements in graphite inclusions in as‑cast and deformed ductile cast iron

Sprecific of distribution of chemical elements in graphite inclusions in as‑cast and deformed ductile cast iron

Correction to: Tool life experiment of coated cermet during nodular cast iron turning

Correction to: Tool life experiment of coated cermet during nodular cast iron turning

Constraint effects on fracture toughness of ductile cast iron in the ductile regime

To assess the effect of constraint loss on fracture toughness of ductile cast iron (DCI), GJS-400–15, in the ductile regime at 0 °C, the fracture toughness was characterised with two different types of fracture toughness specimens, compact tension (C(T)) and single edge tension (SE(T)) specimens. The constraint state in the specimens was quantified using finite element analysis. Overall, the constraint dependence of fracture toughness for DCI is comparable to typical ferritic structural steels. For the obtained J-R curves, the fracture toughness increases as the crack grows, and the crack growth is stable on macroscopic scale up to J = 290 kJ/m2. Independent of the constraint state in the stable crack growth regime, the global failure mechanism is ductile fracture, including occasional local brittle areas.

Genetic algorithm (GA)–backpropagation (BP) network approach for hardness prediction of austempered ductile iron (ADI)

Hardness serves as a crucial indicator for assessing the success of quenching treatment in the steel and iron industry, impacting the processability and wear properties of materials. In the present study, a dataset comprising 125 hardness values of the QT500-7 sample subjected to various austempering heat treatment parameters was utilised to train a neural network model for predicting the hardness of austempered ductile iron (ADI). The established model based on a genetic algorithm and error backpropagation algorithm demonstrates high accuracy in predicting the hardness of ADI if given heat treatment parameters. The mean square error of the model was about 1.019, indicating the reliability and precision of the model in predicting the hardness of ADI based on the specified heat treatment parameters.

Microstructure and Mechanical Properties of YAG Laser Welded Spheroidal Graphite Cast Iron

Microstructure and Mechanical Properties of YAG Laser Welded Spheroidal Graphite Cast Iron

ACO EUROBAR EN-GJS-400-18C-LT (5.3123)

Abstract ACO Eurobar EN-GJS-400-18C-LT is a ferritic spheroidal graphite cast iron that is produced by the continuous casting process. It has a minimum tensile strength of 400 MPa (58 ksi) and a minimum elongation of 18%. It has a tensile strength exceeding that of the highest-tensile-strength grade of gray cast iron, together with much higher elongation and impact resistance. It is specifically designed to provide good impact properties at low temperature. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as casting, heat treating, and machining. Filing Code: CI-109. Producer or source: ACO Eurobar GmbH.

Experimental Simulation of Directional Crystallization of SiMo Cast Iron Alloyed with Al and Cr.

SiMo ductile cast iron combines ease of part fabrication with good mechanical properties, including a usable plasticity range. Its poor corrosion resistance inherited from grey cast iron could be alleviated through alloying with Al or Cr additions capable of forming a dense oxide scale protecting the substrate. However, the presence of Al and Cr in cast iron tends to make the material brittle, and their optimum alloying additions need to be studied further. The present work was aimed at investigating the effect of crystallization rates on microstructure changes during directional crystallization of SiMo-type alloys with up to 3.5% Al and 2.4% Cr. The experiment was performed using the Bridgman-Stockbarger method. The tubular crucible was transferred from the hot section to cold section at rates ranging from 5 mm/h to 30 mm/h with a 4/5 crucible length and then quenched. The introduced Al promoted graphitization up to a point, wherein, at the highest applied addition, the graphite precipitation preceded crystallization of the rest of the melt. A rising level of Cr in these alloys from 1% to 2.4% resulted in the formation of low and high contents of pearlite, respectively. The higher crystallization rates proved effective in increasing the ferrite content at the expense of pearlite. In the investigated cast iron samples with smaller applied alloying additions, Widmanstätten ferrite or ausferrite, i.e., fine acircular phase, were often found. The switch from directional crystallization to quenching caused a transition from a liquid to solid state, which started with nucleation of islands of fine austenite dendrites with chunky graphite eutectic separating them. As these islands expanded, they pushed alloying additions to their sides, promoting carbide or pearlite formation in these places and forming a super-cell-like structure. The performed experiments helped gather information concerning the sensitivity of the microstructure of SiMo cast iron modified with Al and Cr to crystallization rates prevailing in heavy cast structures.

Influence of austempering temperatures on microstructure and wear performance of solution strengthened ferritic ductile cast irons

Influence of austempering temperatures on microstructure and wear performance of solution strengthened ferritic ductile cast irons

Graphite-assisted structural design of hierarchically porous SiC(rGO) PDCs with excellent capacity in thermal protection/insulation and load bearing for hypersonic vehicles

High flight speed of hypersonic vehicles will push thermal insulation composites to achieve balanced enhancement of high porosity with increasing load-bearing capability. Herein, hierarchically porous SiC(rGO) polymer-derived ceramics (PDCs) with lightweight, heat-insulating, anti-ablative and tough engineered merits, are designed from polycarbosilane-vinyltriethoxysilane-graphene oxide precursors by re-pyrolysis/graphite-assisted decarburization. Graphite pore-forming agents tightly coupled with SiOxCy/Cfree(rGO) by C-dangling bonds, can inhibit SiOxCy decomposition, increase ceramic network disorder and expedite concurrent removal of Cfree. SiO2 generated from Si-dangling oxidation bonding, efficiently densifies framework to retain mechanical performances, and meanwhile creates more interfaces to enhance phonon scattering. Such structure similar to nodular cast iron confers low thermal conductivity (0.11 W·m-1·K-1), particularly, fully preserves good compressive strength (5.4 MPa) for SiC(rGO)40%. Under both cyclic butane flame ablation (∼1300 °C) and long-term oxidation for 7200 s, self-healing effect of SiO2 imbues products with good structural integrity, shedding light on the opportunity to apply any thermal protection system.

Comparison of the Erosive Wear Resistance of Ductile Cast Iron Following Laser Surface Melting and Alloying

This article presents research results on the influence of the laser surface melting and alloying processes on the erosive wear resistance of ductile cast iron. For the research, an EN-GJS 350-22 ductile cast iron surface was laser-melted and laser-alloyed with titanium powder in an argon and nitrogen atmosphere. Solid-particle erosion tests were carried out on the laser-melted and -alloyed surface layers and the base material according to the ASTM G76-04 standard with 30° and 90° impingement angles. The erosive wear resistance results were correlated with Vickers hardness and microstructural test results with the use of SEM (scanning electron microscopy), TEM (transmission electron microscopy), EDS (energy dispersive spectroscopy), and XRD (X-ray diffraction). The mechanisms of erosive wear were also analyzed for the laser-treated surface layers and the base material. The research showed that the laser melting and alloying processes with titanium powder had a positive effect on the hardness and erosive wear resistance of the ductile cast iron surface due to microstructure modification. Moreover, despite the lower hardness of the laser-alloyed surface layers, their composite microstructure had a positive impact on the erosive wear resistance in comparison to the laser-melted surface layers.

Unveiling the transformation of 2,4,6-trihalophenols by active species in drinking water pipelines: The role of goethite

The long-term accumulated pipe scale in the water distribution system (WDS) is vital for ensuring the safety of drinking water delivery. This study revealed a novel positive role of pipe scale in triggering interface free radicals for aromatic substances degradation. The goethite (main constituents of pipe scale) converts from the trivalent state to the divalent state by withdraw electrons from aromatic phenolic compounds. Active free radicals such as hydroxyl radical (OH), Cl, and ClO were subsequently formed via a cascade of chain reactions under WDS conditions, among which OH was the dominate active species driving efficient transformation of 2,4,6-trichlorophenol (60.8%) and 2,4,6-tribromophenol (80.5%) and the corresponding toxicity attenuation. The goethite mediated chlorination is a surface reaction following Langmuir–Hinshelwood model. Our works revealed the presence of natural source of OH for disinfection byproducts transformation. Given the ubiquitous existence of iron scales inside ductile iron pipe, the finding renewed the understanding of the impact of WDS on drinking water quality.

Inhomogeneity in mechanical properties of ductile iron pipes: A comprehensive analysis

Ductile iron pipes are widely used in pipe manufacturing for water and sewage transmission and distribution. In pipeline standards such as EN545, the pipe material is assumed isotropic and its mechanical properties are determined by tensile testing of round bars extracted along the longitudinal direction. This study experimentally examined the mechanical properties of centrifugal casting ductile iron pipes, focusing on the effects of sampling orientation, location, preparation, and test methodology. A ring hoop tension test (RHTT) was designed to evaluate circumferential properties. Force analysis of RHTT was performed and theoretical equation was derived to quantify the friction coefficient that existed between the coupon specimen and the loading fixture. A numerical study was conducted to further validate the effectiveness of the proposed theory. The test results indicated that the pipe mechanical property was inhomogeneous across the wall thickness, being inferior in the internal section and superior in the middle and external sections. This inferior layer would develop crack first and lead to subsequent outward propagation. This phenomenon led to a substantial degradation in the overall mechanical performance of the entire specimens, in comparison to the material in the middle portion. The material exhibited better performance in the circumferential direction compared to the longitudinal direction in terms of its mechanical properties, such as tensile strength and ductility. Flattened specimens showed enhanced strength and reduced ductility compared to the base pipe material. Fractographic and metallographic analyses revealed the existence of casting defects of porosity and agglomerated graphite in the internal section, which were the primary cause of material inhomogeneity. The round bars suggested per EN545 tended to overestimate the actual mechanical behaviour of ductile iron pipes, and may not be a true representation of the finished product of pipes. Flattened specimens as per ASTM E8/E8M were not recommended for ductile iron pipe material assessment, as the flattening process altered the stress–strain characteristics significantly.

Tool life experiment of coated cermet during nodular cast iron turning

AbstractIn this study, the application of physical vapor deposition (PVD) coatings on various cermet substrates for the machining of nodular cast iron was investigated, given that cermet materials are traditionally not the primary choice for such applications. Through the evaluation of key parameters including wear on the flank face and surface roughness, and with vibration analysis serving as a supplementary measurement, it was discovered that machining stability is compromised by the inherent brittleness of cermet and the adhesion of material on the rake face. While the application of coatings was found to extend tool life, the cermet-coating combinations did not surpass the performance of other materials such as cemented carbide with multi-layer coatings. Notably, the stability of surface roughness across various stages of tool wear was observed.