Determination of the relationship between microstructure and constitutive behaviour of nodular cast iron with a unit cell model

Abstract

Unit cell models have been proposed to predict the constitutive law and failure of ductile materials with complex microstructures, such as ferritic nodular cast iron and particulate metal matrix composites (PMMCs). The present contribution aims to extend this modelling approach to the prediction of the constitutive response of nodular cast iron with a mixed ferritic/pearlitic matrix. The finite element method is used within the framework of continuum mechanics to carry out the calculations. The effect of some microstructural features, such as graphite volume fraction and ferrite-pearlite ratio of the matrix, on the mechanical performance is determined. The computational results are compared to results obtained in a previous experimental activity on nodular cast irons.

Micromechanisms of fracture in nodular cast iron: From experimental findings towards modeling strategies – A review

“…As could be expected from the observed early debonding of graphite particles reported in Section 2, the model with void gives a better agreement to experimental results. Collini and Nicoletto [24] investigated cell models with and without unbonded elastic graphite particles. Hardly any difference between the results of both simulations is observed.…”

“…For this purpose the bull's eye structure (Fig. 1b) was resolved in cell model simulations [23,24,65,87,88] as shown in Fig. 11.…”

“…Chuzhoy et al [23] extracted the elastic-plastic properties of ferrite and pearlite individually from heats resembling both constituents. In contrast, Collini and Nicoletto [24,87,88] performed an inverse parameter identification based on some ad-hoc assumptions. With these models, Kobayashi and Toda [65] focused on the initiation of microcracks, whereas Collini and Nicoletto [24] could predict correctly the effect of the ferrite content on the macroscopic yield stress.…”

“…In contrast, Collini and Nicoletto [24,87,88] performed an inverse parameter identification based on some ad-hoc assumptions. With these models, Kobayashi and Toda [65] focused on the initiation of microcracks, whereas Collini and Nicoletto [24] could predict correctly the effect of the ferrite content on the macroscopic yield stress. The predictions of the macroscopic yield curve were improved in [87,88] by considering deviations from the idealized single unit cell model.…”

La modellazione microstrutturale di materiali a struttura eterogenea: princìpi ed applicazioni

“…Diversi lavori sono reperibili in letteratura sull'utilizzo di celle unitarie per lo studio e la previsione del comportamento meccanico della ghisa nodulare, inerenti le proprietà elastiche, la simulazione del danneggiamento, o l'effetto della presenza di tensioni termiche, [31][32][33][34]. In un lavoro del presente autore [35] si è presentato un modello a cella unitaria della ghisa nodulare, mostrato in Fig. 6, che comprendesse anche la fase perlitica nella matrice ferrosa.…”