Aluminium in compacted graphite iron

Gumienny, G.; Kurowska, B.; Klimek, L.

doi:10.1007/s41230-020-9013-x

Cited by 6 publications

(10 citation statements)

References 15 publications

(4 reference statements)

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“…% boosts precipitation of M 6 C carbides at ferrite grain boundaries (simultaneously, Si-stabilizing ferrite has to be added to counteract the development of pearlite) and allows the tensile strength of these alloys to rise from ~400 MPa to ~600 MPa, even as the elongation falls from ~8% to ~4% [ 1 , 2 , 3 ]. These relatively good plastic properties, being unusual for cast iron, are achieved by graphite spheroidization in the ferritic matrix caused by the addition of Mg [ 4 , 5 , 6 ]. As in the case of most metallic materials, their tensile strength lowers with the rise in temperature, i.e., in the case of SiMo51, its R m at RT equals ~610 MPa, but at 800 °C, it falls down to ~53 MPa, limiting its application potential.…”

Section: Introductionmentioning

confidence: 99%

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

Morgiel,

Kopyciński

2024

Materials

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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.

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Section: Introductionmentioning

confidence: 99%

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

Morgiel,

Kopyciński

2024

Materials

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“…An example of a CGI microstructure is shown in Figure 1a,b. Different microstructures of CGI: ferritic-pearlitic (a) [2], ausferritic (b) [3].…”

Section: Introductionmentioning

confidence: 99%

“…Due to the unique Figure 1. Different microstructures of CGI: ferritic-pearlitic (a) [2], ausferritic (b) [3]. The matrix of unalloyed CGI usually consists of ferrite and pearlite (Figure 1a).…”

Section: Introductionmentioning

confidence: 99%

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Data-Driven Model Selection for Compacted Graphite Iron Microstructure Prediction

et al. 2022

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Compacted graphite iron (CGI), having a specific graphite form with a large matrix contact surface, is a unique casting material. This type of cast iron tends to favor direct ferritization and is characterized by a complex of very interesting properties. Intelligent computing tools such as artificial neural networks (ANNs) are used as predictive modeling tools, allowing their users to forecast the microstructure of the tested cast iron at the level of computer simulation. This paper presents the process of the development of a metamodel for the selection of a neural network appropriate for a specific chemical composition. Predefined models for the specific composition have better precision, and the initial selection provides the user with automation of reasoning and prediction. Automation of the prediction is based on the rules obtained from the decision tree, which classifies the type of microstructure. In turn, the type of microstructure was obtained by clustering objects of different chemical composition. The authors propose modeling the prediction of the volume fraction of phases in the CGI microstructure in a three-step procedure. In the first phase, k-means, unsupervised segmentation techniques were used to determine the metamodel (DT), which in the second phase enables the selection of the appropriate ANN submodel (third phase).

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“…% facilitated the cast iron graphitization, but its further increase suppressed the graphite precipitation and promoted the formation of carbides. On the other hand, Gumienny et al [19] concluded that Al with a concentration of up to 2.4 wt.% in compacted graphite iron exhibits graphitizing properties, above this concentration it is a carbideforming element. In the same research, it was also pointed out that with an Al content higher than 8 wt.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evolution as a Function of Increasing Aluminum Content in Novel Lightweight Cast Irons

Obregon

Sánchez

Eguizabal

et al. 2021

Metals

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In the context of the development of new lightweight materials, Al-alloyed cast irons have a great potential for reducing the weight of the different part of the vehicles in the transport industry. The correlation of the amount of Al and its effect in the microstructure of cast irons is not completely well established as it is affected by many factors such as chemical composition, cooling rate, etc. In this work, four novel lightweight cast irons were developed with different amounts of Al (from 0 wt. % to 15 wt. %). The alloys were manufactured by an easily scalable and affordable gravity casting process in an induction furnace, and casted in a resin-bonded sand mold. The microstructural evolution as a function of increasing Al content by different microstructural characterization techniques was studied. The hardness of the cast irons was measured by the Vickers indentation test and correlated with the previously characterized microstructures. In general, the microstructural evolution shows that the perlite content decrease with the increment of wt. % of Al. The opposite occurs with the ferrite content. In the case of graphite, a slight increment occurs with 2 wt. % of Al, but a great decrease occurs until 15 wt. % of Al. The addition of Al promotes the stabilization of ferrite in the studied alloys. The hardness obtained varied from 235 HV and 363 HV in function of the Al content. The addition of Al increases the hardness of the studied cast irons, but not gradually. The alloy with the highest hardness is the alloy containing 7 wt. % Al, which is correlated with the formation of kappa-carbides and finer perlite.

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Aluminium in compacted graphite iron

Cited by 6 publications

References 15 publications

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

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

Data-Driven Model Selection for Compacted Graphite Iron Microstructure Prediction

Microstructural Evolution as a Function of Increasing Aluminum Content in Novel Lightweight Cast Irons

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