Initial Oxidation Stage of SiMo and SiNb-xAl Ductile Cast Irons in Air and CO2-Containing Atmospheres

Çelik, Gülperi; Atapek, Ş. Hakan; Polat, Soner

doi:10.1007/s40962-022-00883-w

Cited by 4 publications

(4 citation statements)

References 63 publications

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“…The experiment was based on the controlled retraction of samples melted in thin ceramic tubes from the hot section into the cold section of a purpose-built special stand, as in the Bridgman–Stockbarger method [ 12 ]. It allowed the achievement of directional crystallization of SiMo5-1-based alloys having from ~1.5 to ~3.5 wt.…”

Section: Discussionmentioning

confidence: 99%

“…Melting was performed in the PEKr-1500 furnace dedicated for directional crystallization experiments produced by PUH ENERGOSYSTEM (Skawina, Poland) ( Figure 3 ). It is a stand designed for experiments with the Bridgman–Stockbarger method [ 12 ]. Melting of the batch was performed in the electromagnetic induction tube furnace.…”

Section: Methodsmentioning

confidence: 99%

“…It has stimulated extensive research in that area, including the examination of parts made of these alloys subjected to tests by work, i.e., installed in car exhaust manifolds [7][8][9]. These and accompanying laboratory testing showed that oxidizing atmospheres, and especially those rich in water vapor or SO 2 , cause fast growth consisting of iron oxides growing outward and iron-silicon spinel growing inward with a layer of SiO 2 at the scale/substrate boundary [7][8][9][10][11][12]. The scale weight gain with time follows a roughly parabolic trend typical for out-of-core diffusion-controlled processes, which could eventually limit corrosioninduced degradation.…”

Section: Introductionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Morgiel,

Kopyciński

2024

Materials

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“…The high-temperature performance of SiMo nodular iron can be improved by alloying with chromium, aluminum, vanadium, or nickel, which is recognized for having ability to enhance the oxidation resistance of steel [16,[31][32][33][34]. Ekström et al [16] studied the effect of 0.5 to 1 wt% Cr and 1 wt% Ni on the high-temperature oxidation of SiMo ductile iron in air and exhaust gases.…”

Section: Introductionmentioning

confidence: 99%

High Temperature Oxidation Behavior of High Al-Si Alloyed Vermicular Graphite Cast Iron for Internal Combustion Engine’s Hot-End Exhaust Components

Yilmaz,

Bayata,

Solak

2024

Metals

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This study investigated the influence of high silicon (4.2 wt%) and varying aluminum (3.5–4.8 wt%) content on the high temperature oxidation behavior and thermophysical properties of SiMoAl vermicular graphite cast iron for hot-end exhaust components. Isothermal oxidation tests at 800 °C and nonisothermal oxidation tests in a dry-air atmosphere were conducted on SiMo nodular iron, along with two SiMoAl vermicular graphite cast iron variants alloyed with 3.5 wt% Al and 4.8 wt% Al. The investigations revealed the formation of a thin duplex layer of oxide scale, consisting of an iron-rich external oxide layer and continuous aluminum oxide at the metal/oxide interface. Although aluminum oxide acted as a protective barrier by impeding the solid-state diffusion of oxygen, severe subsurface oxidation was observed due to the interconnected vermicular graphite covered by aluminum oxides after decarburization. Furthermore, based on nonisothermal oxidation experiments, the effective activation energy of oxidation was found to be significantly increased by the addition of aluminum, even though the oxidation activation energies of SiMoAl samples exhibited small changes in comparison to each other. Additionally, thermophysical analysis demonstrated a substantial decrease in the thermal conductivity and a slight increase in the thermal expansion with the addition of aluminum.

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High temperature oxidation of inoculated high Si/SiMo ductile cast irons in air and combustion atmospheres

Stan,

Chisamera,

Lascu

et al. 2024

China Foundry

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Initial Oxidation Stage of SiMo and SiNb-xAl Ductile Cast Irons in Air and CO2-Containing Atmospheres

Cited by 4 publications

References 63 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

High Temperature Oxidation Behavior of High Al-Si Alloyed Vermicular Graphite Cast Iron for Internal Combustion Engine’s Hot-End Exhaust Components

High temperature oxidation of inoculated high Si/SiMo ductile cast irons in air and combustion atmospheres

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