Microstructural study of the mechanical response of compacted graphite iron: An experimental and numerical approach

Pina, Juan Carlos; Shafqat, Salman; Kouznetsova, V Varvara; Geers, M.G.D.

doi:10.1016/j.msea.2016.02.017

Cited by 26 publications

(24 citation statements)

References 26 publications

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“…Although CGI has been discovered for more than forty years and despite a few papers have been published [23,24,25,26], its properties are not well known yet.…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth in compacted and spheroidal graphite cast irons

Hosdez

Limodin

Najjar

et al. 2020

International Journal of Fatigue

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The present paper focuses on the fatigue life of a Compacted Graphite cast Iron (CGI) as compared to a Spheroidal Graphite cast Iron (SGI). Fatigue crack growth laws have been determined with digital image correlation. Main difference between the materials is that cracks propagate faster in the CGI than in the SGI. X-ray tomography was also used in order to assess graphite morphologies and crack shapes. A complex morphology was observed for the vermicular graphite with rounded edges that limit notch effects. The crack spreads easily in CGI via a quasi cleavage mechanism and by propagating through graphite mainly by breaking the vermicules.

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“…Although CGI has been discovered for more than forty years and despite a few papers have been published [23,24,25,26], its properties are not well known yet.…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth in compacted and spheroidal graphite cast irons

Hosdez

Limodin

Najjar

et al. 2020

International Journal of Fatigue

View full text Add to dashboard Cite

show abstract

“…3,4) An acceptable CGI should contain less than 20% spheroidal graphite and more than 80% compacted form graphite, without any flake graphite which can cause local weaknesses and lead to failure. 5) As we all know, the technological window of CGI production is very narrow, and the fading effects should be considered. Therefore, the initial starting status of the molten iron should be held far away from the flake graphite region.…”

Section: Introductionmentioning

confidence: 99%

“…7,8) Nowadays, several casting methods of CGI have been developed, trying to find a precise control method for the final microstructure. 5,6) Thermal analysis is the reflection of a solidification history of its related sample in which each phase transformation causes a thermal event on its cooling curve. 9) The characteristic temperatures on the cooling curve are called "metallurgical fingerprint" of molten iron metallurgical state.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Vermicularity of Compacted Graphite Iron Based on Multiple Characteristic Points of Thermal Analysis

et al. 2021

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The vermiculation effects of compacted graphite cast iron are seriously affected by the metallurgical and technological factors. The change of characteristic points on the cooling curve is attributed to the interaction of these factors, so it is difficult to establish the evaluation relationship between the vermicularity and the characteristic points of thermal analysis curve. Based on the idea of statistics, a method was studied to evaluate the vermicularity of molten iron by comparing with an established characteristic points representation model of hypothetical ideal metallurgical quality state under the production condition. The results showed that the method can meet the requirements of evaluating the vermicularity of molten iron by multiple characteristic points on the cooling curve. As the matching process among cooling curves was omitted, the calculation and evaluation efficiency can be improved. In addition, it is expected to achieve on-line classification and regulation of vermiculation effect in front of furnace by expanding the sample capacity for establishing the characterization model.

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“…An alternative approach to the unit-cell approach is to model a twodimensional representation of the microstructure obtained either conceptually or through optical or scanning electron microscopy [32,34,97,[123][124][125][126]. The advantage is the possibility of directly comparing the model with experimental observations, such as strain measurements using digital image correlation (DIC) [34,97,126].…”

Section: Constitutive Modellingmentioning

confidence: 99%

“…The advantage is the possibility of directly comparing the model with experimental observations, such as strain measurements using digital image correlation (DIC) [34,97,126]. On the other hand, the models are often insufficient due to the negligence of the underlying bulk material.…”

Section: Constitutive Modellingmentioning

confidence: 99%

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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Microstructural study of the mechanical response of compacted graphite iron: An experimental and numerical approach

Cited by 26 publications

References 26 publications

Fatigue crack growth in compacted and spheroidal graphite cast irons

Fatigue crack growth in compacted and spheroidal graphite cast irons

Evaluation of Vermicularity of Compacted Graphite Iron Based on Multiple Characteristic Points of Thermal Analysis

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

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