Solidification Behavior, Microstructure, Mechanical Properties, Hot Oxidation and Thermal Fatigue Resistance of High Silicon SiMo Nodular Cast Irons

Li, D.; Perrin, R.; Burger, G.; McFarlan, D.; Black, B.; Logan, Robert; Williams, Robert J.

doi:10.4271/2004-01-0792

Cited by 28 publications

(25 citation statements)

References 4 publications

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“…Effectively, silicon is often seen to accumulate between the iron oxide scale and the matrix in LGI, CGI and SGI [19,[45][46][47]50]. Several investigators have also reported that a higher content of silicon in SGI results in a slower growth of the iron oxide film, which is consistent with the above argument [19,44,53].…”

Section: Effects Of An Elevated Temperaturesupporting

confidence: 75%

“…When cast iron specimens are exposed to elevated temperatures for a long time in ambient air, they grow in size and experience surface oxidation, or scaling [19,[43][44][45][46][47]. The scaling phenomenon is clearly reflected by preforming mass evolution measurements, where significant mass changes are observed after a long period of time at high temperatures due to the additional mass acquired through surface oxide formation [19,46,47].…”

Section: Effects Of An Elevated Temperaturementioning

confidence: 99%

“…However, the significant content of silicon in cast iron grades has frequently been argued to play an important role in the formation of the surface scale. In particular, it is believed to contribute to an improved oxidation resistance [19,44,45,50]. The scaling of the Fe-Si system, which arguably should be similar to the matrix in cast iron, was reviewed by Birk et al [51] by reference to the work of Adachi and Meier [52].…”

Section: Effects Of An Elevated Temperaturementioning

confidence: 99%

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Fatigue of Heavy-Vehicle Engine Materials: Damage Mechanisms, Laboratory Experiments and Life Estimation

Norman¹

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Due to increasing demands on sustainability exerted by end-costumers and policy makers, heavy-vehicle manufacturers are urged to increase the engine efficiency in order to reduce the exhaust gas emission. However, increasing the efficiency is also associated with an elevated fatigue rate of the materials constituting the engine parts, which consequently reduces the engine service life. The aim of the present thesis is therefore to confront the expected increase by studying the fatigue behaviour and damage mechanisms of the materials typically employed in heavy-vehicle diesel engines. With this knowledge, this work seeks to guide the development of new heavy-vehicle engine materials, as well as to develop improved life estimation methods designated to assist the mechanical design of durable heavy-vehicle engines.In essence, a large set of thermo-mechanical fatigue (TMF) and combined thermo-mechanical and high-cycle fatigue (TMF-HCF) tests is conducted at engine load conditions on laboratory specimens of lamellar, compacted and spheroidal graphite iron. In this way, the fatigue performance and associated damage mechanisms are investigated. In particular, a new fatigue property is identified, the TMF-HCF threshold, which quantifies how resistant a material is to superimposed high-cycle fatigue.The damage mechanism at low temperatures ( 500 o C) is confirmed to consist of the initiation, propagation and coalescence of numerous microcracks. Based on this, a successful fatigue life estimation model is formulated, allowing accurate estimations of TMF and TMF-HCF tests on smooth specimens, and TMF tests on notched specimens. In the latter case, the microcrack growth behaviour in non-uniform cyclic stress fields and its implications for life estimation are clarified. At elevated temperatures ( 500 o C), surface oxidation is shown to govern the fatigue performance of cast iron grades intended for exhaust manifolds. It is observed that oxide intrusions are induced, from which surface fatigue cracks are initiated. Consequently, an optimal material at these conditions should have a low oxide growth rate and few casting defects at the surface, as these factors are found to stimulate the growth of intrusion.iii Populärvetenskaplig sammanfattningMen anledning av ökande krav på hållbarhet från slutkunder och beslutsfattare pressas tillverkare av tunga lastbilar att öka drivlinans verkningsgrad och minska utsläppen av luftföroreningar. För dieselmotorn som är den vanligaste motortypen i tunga lastbilar förväntas i dagsläget det största bidraget till att möta kraven vara att öka motorns verkningsgrad. Högre verkningsgrad innebär lägre bränsleförbrukning, vilket i sin tur står i direkt proportion till mängden utsläppt koldioxid. Denna eftertraktade förbättring åstadkoms generellt genom att öka kompressionsförhållandet, vilket medför en ökning i det maximala förbränningstrycket och temperaturen i förbränningskam-maren. Till följd av detta uppkommer även ett ökat slitage av motorkomponenterna, i tekniska sammahang kallat utma...

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Section: Effects Of An Elevated Temperaturesupporting

confidence: 75%

Section: Effects Of An Elevated Temperaturementioning

confidence: 99%

Section: Effects Of An Elevated Temperaturementioning

confidence: 99%

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Fatigue of Heavy-Vehicle Engine Materials: Damage Mechanisms, Laboratory Experiments and Life Estimation

Norman¹

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“…Over the past few decades, SiMo ductile irons have been finding increasing applications for high temperature automotive components such as exhaust manifolds and turbocharger housings [1][2][3]. The oxidation resistance, high temperature strength and dimensional stability are required to cope with the increasingly higher temperature internal combustion exhaust gases (may reach up to 880°C) associated with improving the Internal Combustion Engine (ICE) efficiency [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Casting experiments and solidification modeling have shown, that the shrinkage tendency of high Si-Mo containing 4-6% Mo can be controlled in the same level as that of regular SiMo, using suitable C.E (4.35-4.85), depending upon the critical thickness of the casting [3].…”

Section: Introductionmentioning

confidence: 99%

Influence of Cooling Rate on Nature and Morphology of Intercellular Precipitates in Si-Mo Ductile Irons

Youssef

Nofal

Hussein

2018

MSF

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Abstract. This work is designed to better understand the influence of cooling rate on the nature and morphology of intercellular precipitates in Silicon-Molybdenum ferritic ductile iron (SiMo). Plates of 3, 6, 9 mm thickness were cast in greensand and investment casting molds to give a wide spectrum of cooling rates. It was found that at higher cooling rates, the intercellular regions have a lamellar structure typical of pearlite. With decreasing cooling rates, the precipitate contains complex (Fe-Mo-Si) carbides of fine spheroidal or rod-like structure surrounding the eutectic carbides.Intensive Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) and Optical Microscopy (OM) investigations showed that the eutectic carbides are mainly (Fe, Mo, Si) C containing up to 48% Mo, whereas the fine precipitates contain lower Mo-contents. Both carbide types did not show to have a strict stoichometric composition. The solidification and solid-state transformation path was determined using both phase diagram calculated from Thermo-Calc software as well as Differential Scanning Calorimetry (DSC).

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High Temperature Corrosion of Cast Alloys in Exhaust Environments I-Ductile Cast Irons

Tholence

Norell

2007

Oxid Met

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The oxidation behavior of two ductile cast irons was investigated in synthetic diesel and gasoline exhaust gases. The alloys were a SiMo (Fe3.86S-i0.6Mo3C) and a Ni-Resist (Fe32Ni5.3Si2.1C). Polished sections were exposed at temperatures between 650 and 1,050°C, mostly for 50 h. The oxidation product was characterized by means of SEM/EDX, AES, XPS and XRD. Iron oxides nodules formed above a continuous layer of Fe-Si-oxide for SiMo. The alloy failed in forming a continuous silica layer at low temperatures. At 850°C and above silica was formed, but austenite formation enhanced the decarburization. Escaping CO/ CO 2 increased the oxide porosity, and consequently the oxidation rate. The oxidation resistance of Ni-Resist was dependent on Cr assisting the formation of SiO 2 . However, this effect was restrained to cell boundaries in particular when water enhanced the Cr evaporation or the diffusion was slow at low temperatures. Then, the rapid oxidation left metallic Ni particles in the inner oxide.

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Solidification Behavior, Microstructure, Mechanical Properties, Hot Oxidation and Thermal Fatigue Resistance of High Silicon SiMo Nodular Cast Irons

Cited by 28 publications

References 4 publications

Fatigue of Heavy-Vehicle Engine Materials: Damage Mechanisms, Laboratory Experiments and Life Estimation

Fatigue of Heavy-Vehicle Engine Materials: Damage Mechanisms, Laboratory Experiments and Life Estimation

Influence of Cooling Rate on Nature and Morphology of Intercellular Precipitates in Si-Mo Ductile Irons

High Temperature Corrosion of Cast Alloys in Exhaust Environments I-Ductile Cast Irons

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