A study of physico-chemical mechanisms responsible for damage of heat treated and as-cast ferritic spheroïdal graphite cast irons

Dierickx, Pierre; Verdu, Catherine; Reynaud, A.; Fougères, R.

doi:10.1016/1359-6462(95)00496-3

Cited by 32 publications

(13 citation statements)

References 3 publications

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“…In comparison with EPMA analyses, SIMS allows getting better detection limit but with a lower spatial resolution (the graphite/matrix interface appears over a couple of microns on the profiles) and it remains a qualitative analysis. This increase in magnesium at the graphite/matrix interface has been already pointed out by Dierickx et al in heat-treated spheroidal graphite cast iron samples [9]. It reinforces the hypothesis of an action of some trace element on graphite growth by an adsorption and/or absorption at the graphite surface during its growth.…”

supporting

confidence: 72%

Effect of Cooling Rate and Aluminium Addition on Graphite Growth during Solidification and Graphitization

Bourdie

Bruneseaux

Parseval

et al. 2018

MSF

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Abstract. Even using high inoculation levels, mottled structures are often obtained when casting Mg-treated cast irons in thin wall parts. For full graphitization of the cast components, this calls for a subsequent heat-treatment which is generally achieved in the austenite field. The aim of this work was investigating the impact of the process and the cooling rate on the graphite structure for two different casting conditions. The influence of the cooling rate on graphite degeneracy due to the presence of impurity was also investigated considering low-level additions of aluminium. Extensive metallographic investigation has been carried out from which it is concluded that the internal graphite structure is the same for the two studied cooling conditions. Accordingly, the growth mechanism of graphite should be the same when it precipitates from liquid, during eutectic reaction or else solid-state graphitization. Finally, microanalyses suggest magnesium and aluminium do not interact in the same way with graphite during its growth.

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supporting

confidence: 72%

Effect of Cooling Rate and Aluminium Addition on Graphite Growth during Solidification and Graphitization

Bourdie

Bruneseaux

Parseval

et al. 2018

MSF

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“…These values are macroscopically consistent in the sense that they allow recovering the global elastic properties of ductile iron according to common micromechanical homogenization procedures [14]. Furthermore, they are also in fairly 3 good agreement with nano-indentation tests [15] [16] performed according to the OliverPharr method [17]. Nevertheless, the validity of such measurements is quite disputable as graphite is highly anisotropic at the nanoscale, meaning that the concept of nanoindentation based Young's modulus loses its significance.…”

Section: Introductionmentioning

confidence: 66%

A micro-mechanical analysis of thermo-elastic properties and local residual stresses in ductile iron based on a new anisotropic model for the graphite nodules

Andriollo¹,

Thorborg²,

Tiedje³

et al. 2016

Modelling Simul. Mater. Sci. Eng.

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In this paper, the thermo-elastic behavior of the graphite nodules contained in ductile iron is derived on the basis of recent transmission electron microscopy investigations of their real internal structure. The proposed model is initially validated by performing a finite element homogenization analysis to verify its consistency with the room-temperature elastic properties of ductile iron measured at the macro scale. Subsequently, it is used to investigate the formation of local residual stresses around the graphite particles by simulating the manufacturing process of a typical ferritic ductile iron grade, and the results are compared with preliminary measurements using synchrotron X-rays. Finally, the obtained accurate description of the stress & strain field at the micro scale is used to shed light on common failure modes reported for the nodules and on some peculiar properties observed in ductile iron at both micro and macro scale.

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“…The values of the Young's modulus for different temperatures used here are given in Table 3 [51] and those of the thermal expansion coefficient in Table 4 [52]. 6 12.6 13.3 14.0 Table 4 Thermal expansion coefficient of pearlitic steel for different temperature ranges [52] T [ • C] 0-100 0-200 0-300 0-400 α [μm/m • C] 11.…”

Section: Matrixmentioning

confidence: 99%

Microstructural model for the time‐dependent thermomechanical analysis of cast irons

et al. 2015

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In this paper, a multiscale modelling approach is followed for the modelling of time and temperature dependent behaviour of compacted graphite cast iron (CGI) material. Cast irons are often used in heavy duty machinery parts subjected to elevated temperatures for prolonged periods of time. This, in combination with its complex heterogeneous microstructure, plays the crucial role in determining the life time of the material. In this work a 2D microstructural model of CGI is developed. The geometry is based on the micrographs of the material. The pearlitic matrix is modelled with the temperature dependent elasto‐visco‐plastic model calibrated on the pearlitic steel experiments. The graphite particles are modelled as anisotropic elastic. The results of the simulations of tensile and stress relaxation tests at different temperatures between 20 °C and 500 °C show that the macroscopic mechanical behaviour of the ma‐terial deteriorates rapidly above 350 °C. At the microstructural scale, the anisotropic graphite particles act as stress concentrators promoting the formation of strain percolation paths, that become more critical at higher temperatures. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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A study of physico-chemical mechanisms responsible for damage of heat treated and as-cast ferritic spheroïdal graphite cast irons

Cited by 32 publications

References 3 publications

Effect of Cooling Rate and Aluminium Addition on Graphite Growth during Solidification and Graphitization

Effect of Cooling Rate and Aluminium Addition on Graphite Growth during Solidification and Graphitization

A micro-mechanical analysis of thermo-elastic properties and local residual stresses in ductile iron based on a new anisotropic model for the graphite nodules

Microstructural model for the time‐dependent thermomechanical analysis of cast irons

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