Francesco Iacoviello | University of Cassino and Southern Latium (original) (raw)

Papers by Francesco Iacoviello

Engineering Failure Analysis, 2017

Procedia Structural Integrity, 2017

During their operation, modern aircraft engine components are subjected to increasingly demanding... more During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.

Ductile irons offer a wide range of mechanical properties at a lower cost than the older malleabl... more Ductile irons offer a wide range of mechanical properties at a lower cost than the older malleable iron. These properties mainly depend on the shape characteristics of the metal matrix microstructure and on the graphite elements morphology; these geometrical features are currently evaluated by the experts visual inspection. This work provides an automatic procedure for a reliable standard estimation of the material microstructure morphology based on a novel image segmentation technique. The procedure has been successfully tested on specimens of different kinds of ductile irons of a typical production.

I meccanismi di danneggiamento nelle ghise sferoidali sono influenzati dalla matrice della micros... more I meccanismi di danneggiamento nelle ghise sferoidali sono influenzati dalla matrice della microstruttura e dalla presenza degli elementi di grafite. In questo lavoro sono stati investigati i meccanismi di danneggiamento in quattro ghise sferoidali ferrito-perlitiche sottoposte a sollecitazione di trazione mediante analisi delle superfici laterali dei provini al microscopio elettronico a scansione effettuate durante lo svolgimento della prova medesima (prove di trazione in situ). L'analisi di immagine quantitativa dell'evoluzione del danneggiamento ha permesso di quantificare l'evoluzione del processo, evidenziando l'importanza della microstruttura e l'importanza del ruolo svolto dagli elementi di grafite. L'importanza del distacco degli elementi di grafite dalla matrice metallica (debonding), spesso indicato come il principale o l'unico meccanismo di danneggiamento che coinvolge gli elementi di grafite, è confermata solo parzialmente.

Ductile irons offer a wide range of mechanical properties at a lower cost than the older malleabl... more Ductile irons offer a wide range of mechanical properties at a lower cost than the older malleable iron. These properties mainly depend on the shape characteristics of the metal matrix microstructure and on the graphite elements morphology; these geometrical features are currently evaluated by the experts visual inspection. This work provides an automatic procedure for a reliable estimation of standard parameters of the material microstructure morphology based on a novel image segmentation technique. The procedure has been validated versus standard segmentation techniques, and successfully tested on specimens of different kinds of ductile irons of a typical production.

ABSTRACT L&#39;analisi dei micromeccanismi di danneggiamento nelle ghise sferoidali si è ... more ABSTRACT L&#39;analisi dei micromeccanismi di danneggiamento nelle ghise sferoidali si è prevalentemente focalizzata sulle ghise sferoidali a matrice ferritica. In letteratura si è solitamente concentrata l&#39;attenzione sulla nucleazione di vuoti in corrispondenza degli sferoidi di grafite e sulla crescita di questi vuoti fino alla rottura catastrofica. Recentemente è stato verificato sperimentalmente che il ruolo svolto dagli sferoidi di grafite nelle ghise sferoidali a matrice ferritica è più complesso e che non può essere confinato al solo &quot;debonding&quot; dello sferoide dalla matrice ferritica. In questo lavoro vengono analizzati i micromeccanismi di danneggiamento a trazione in una ghisa sferoidale con matrice completamente perlitica mediante prove di trazione effettuate su microprovini ed osservazione al microscopio elettronico a scansione (SEM) della superficie laterale durante lo svolgimento della prova meccanica (prove &quot;in situ&quot;). Durante lo svolgimento della prova si è focalizzata l&#39;attenzione sia sul ruolo svolto dagli sferoidi di grafite che sull&#39;evoluzione del danneggiamento della matrice perlitica.

ABSTRACT La zincatura a caldo discontinua è una delle metodologie più diffuse per l’applicazione ... more ABSTRACT La zincatura a caldo discontinua è una delle metodologie più diffuse per l’applicazione di un rivestimento in grado di proteggere l’acciaio dalla corrosione generalizzata. L’efficacia di tale protezione è tuttavia influenzata dal livello di danneggiamento conseguente deformazioni plastiche di elevata entità sia di tipo statico che di tipo ciclico. Lo scopo di questo lavoro è quello di analizzare le proprietà meccaniche di laminati in acciaio zincato a caldo mediante prove di flessione cicliche eseguite con una procedura non standardizzata. Sono state analizzate due differenti tipologie di rivestimento: una prima, ottenuta con procedimento classico, ed una seconda ottenuta con un bagno di lega Zinco-Alluminio al 5% wt. Per ognuna di esse è stata ottenuta la risposta meccanica in termini di “deformazione angolare – coppia applicata” e lo stato di danneggiamento è stato analizzato mediante osservazione al microscopio ottico delle sezioni longitudinali, definendo come parametro di danno la densità di cricca, espressa in numero di cricche per unità di lunghezza di arco deformato. I risultati hanno permesso di determinare l’attitudine dei due rivestimenti alle lavorazioni plastiche a freddo ed il loro utilizzo in applicazioni soggette a carichi dinamici.

Ductile cast irons (DCIs) combine the good castability of gray irons and the toughness of steels.... more Ductile cast irons (DCIs) combine the good castability of gray irons and the toughness of steels. This is due to their peculiar graphite elements shape, obtained by means of a chemical composition control and not by means of extended annealing treatment of white irons as in malleable irons. DCIs are widely used in a number of applications, e.g. wheels, gears, crankshafts in cars and trucks etc.; ferritic DCIs are characterized by good ductility, with tensile strength values that are equivalent to a low carbon steel. In this work, damaging micromechanisms in a ferritic DCI have been investigated by means of insitu scanning electron microscope observations. Specimens were ground and polished and pulled intermittently with a tensile holder and observed in situ using a scanning electron microscope (SEM), considering 21 graphite nodules. During tests, specimen deformation and applied load were measured by means of a Linear Variable Differential Transformer (LVDT) and two miniature load cell (10 kN each), respectively. On the basis of the experimental results, the following conclusions can be summarized: voids growth due to graphite spheroids-ferritic matrix debonding seems to have a reduced importance; cracks initiation and propagation inside graphite spheroids seems to be a more important damaging micromechanism. Other graphite nodules damaging micromechanisms have been observed, like an "onion-like" one.

ABSTRACT Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on stee... more ABSTRACT Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on steels, in order to provide sacrificial protection against corrosion over all the steel surface. The efficiency of the protection is affected by the coating mechanical response to loading: cracking and coatings delamination during forming and/or during service could decrease the corrosion resistance and could allow the contact between the environment and the substrate (the steel). In this work, fatigue damaging mechanisms of hot dip zinc coated steel plates were investigated by means of a non-standard fatigue bending test performed considering high strain levels. Fatigue damaging micromechanisms were investigated by means of LOM (light optical microscope) analysis of metallurgically prepared longitudinal section of tested specimens, considering different applied cycle numbers (from 1 up to 1000).

Ductile cast irons are characterized by an interesting mechanical properties combination (high du... more Ductile cast irons are characterized by an interesting mechanical properties combination (high ductility, high tensile strength, good wear resistance). Graphite nodules morphological peculiarities and matrix microstructure (both chemical composition and heat treatment controlled) strongly affect the mechanical behaviour and the damaging micromechanisms, also considering very simple loading conditions (e.g. tensile test conditions). Focusing ferritic ductile irons, matrix-graphite nodule debonding is often identified as the main damaging micromechanism, and numerous studies provided analytical laws to describe growth of a single void, depending on the void geometries and matrix behaviour. In this work, ferritic DCI damaging micromechanisms were investigated, under uniaxial tensile tests, considering the triaxiality influence. SOMMARIO. Le ghise sferoidali sono caratterizzate da un'interessante combinazione delle proprietà meccaniche, (elevata duttilità, elevata resistenza meccanica, buona resistenza all'usura). Le peculiarità morfologiche degli elementi di grafite e la microstruttura della grafite (dipendente sia dalla composizione chimica che dal trattamento termico) influenzano notevolmente il loro comportamento meccanico ed i micromeccanismi di danneggiamento. Considerando le ghise sferoidali a matrice ferritica, il principale meccanismo di danneggiamento è stato spesso identificato con il distacco degli sferoidi dalla matrice: numerosi studi hanno proposto quindi delle relazioni analitiche finalizzate alla descrizione della crescita del singolo vuoto generato dal distacco matrice-sferoide, considerando la geometria del vuoto ed il comportamento della matrice. In questo lavoro è stata analizzata l'evoluzione dei meccanismi di danneggiamento di una ghisa sferoidale ferritica sottoposta ad una prova di trazione, considerando l'influenza della triassialità.

Ductile cast irons (DCI) mechanical properties are strongly influenced both by the matrix and by ... more Ductile cast irons (DCI) mechanical properties are strongly influenced both by the matrix and by the graphite elements morphological peculiarities. These elements cannot be merely considered as "microvoids embedded in a metal matrix", but their presence implies a modification of the damaging micromechanisms, depending on the metal matrix microstructure. In this work, a ferritic DCI has been considered. Tensile tests have been performed on notched tensile specimen: quantitative image analysis approach has been applied in order to analyze the possibility to consider the graphite nodules as indicators of the damaging level evolution. SOMMARIO. Le proprietà meccaniche delle ghise sferoidali (DCI) sono fortemente influenzate sia dalle caratteristiche della matrice che dalle peculiarità morfologiche degli elementi di grafite. Questi elementi non possono essere solo considerati come "microvuoti immersi in una matrice metallica", ma la loro presenza implica una modifica dei micromeccanismi di danneggiamento, in funzione della microstruttura della matrice metallica. In questo lavoro è stata considerata una ghisa sferoidale a matrice metallica. Sono state effettuate delle prove di trazione utilizzando dei provini intagliati e, mediante l'analisi di immagine quantitativa, è stata analizzata la possibilità di considerare i noduli di grafite come degli indicatori dell'evoluzione del danneggiamento.

In the last years, the role played by graphite nodules was deeply investigated by means of tensil... more In the last years, the role played by graphite nodules was deeply investigated by means of tensile and fatigue tests, performing scanning electron microscope (SEM) observations of specimens lateral surfaces during the tests ("in situ" tests). According to the experimental results, it is evident that graphite nodules damaging micromechanisms can't be merely classified as matrix nodule debonding, but depend on different parameters (e.g., loading conditions and matrix microstructure). In this work, the influence of microstructure and loading conditions on fatigue crack propagation resistance in DCIs is discussed. On the basis of experimental results, the applicability of ASTM E399 standard on the characterization of fatigue crack propagation resistance in ferritic-pearlitic DCIs is critically analyzed, mainly focusing the stress intensity factor amplitude role.

Versatility and higher performances at lower cost if compared to these of steels with analogous p... more Versatility and higher performances at lower cost if compared to these of steels with analogous performances are the main advantages of Ductile Cast Irons (DCIs). In the last years, the research group of Metallurgy of the Università di Cassino e del Lazio Meridionale deeply investigated the damaging micromechanisms in ferritic pearlitic and austempered DCIs by means of tensile and fatigue tests, mainly performing scanning electron microscope (SEM) or Digital Microscope (DM) observations of specimens lateral surfaces during the tests ("in situ" tests). In this work, graphite nodules mechanical behaviour is investigated by means of nano indentation tests and results are compared with the damaging micromechanisms observed in ferritic DCIs. SOMMARIO. Le ghise sferoidali sono caratterizzate da elevate prestazioni e da una notevole versatilità. Tali caratteristiche sono disponibili ad un costo ridotto, comparando le ghise sferoidali con acciai caratterizzate da un analogo comportamento meccanico. Negli ultimi anni, il gruppo di ricerca di Metallurgia dell'Università di Cassino e del Lazio Meridionale ha investigato in maniera approfondita i micromeccanismi di danneggiamento nelle ghise sferoidali mediante prove di trazione e prove di fatica, principalmente effettuando osservazioni delle superfici laterali durante le prove (prove "in situ") sia utilizzando un microscopio elettronico a scansione (SEM) che un microscopio digitale (DM). In questo lavoro, il comportamento meccanico dei noduli di grafite è stato investigato mediante prove di nanodurezza ed i risultati sono stati comparati con i meccanismi di danneggiamento osservati nelle ghise sferoidali ferritiche.

Lecture Notes in Computational Vision and Biomechanics, 2014

ABSTRACT Ductile cast irons offer and interesting combination of overall mechanical properties an... more ABSTRACT Ductile cast irons offer and interesting combination of overall mechanical properties and technological peculiarities, allowing to obtain a high castability (peculiar of cast irons) with good tensile strength and toughness values (peculiar of steels). This result is due to their chemical composition that allows to obtain graphite elements in nodular shape directly from the melt. Ductile cast iron mechanical properties are strongly influenced both by the matrix microstructure and by the graphite nodules. The role of these elements cannot be merely ascribed to a simple matrixgraphite “debonding” damaging mechanism, but, according to previously published results, this role is more complex. In this work, customized image processing procedures were optimized to analyze the evolution of the damaging micromechanisms in a fatigue loaded ferritic ductile cast iron, focusing the graphite elements.

Fundamentals, Methods and Applications, 2012

ABSTRACT Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on stee... more ABSTRACT Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on steels, in order to provide sacrificial protection against corrosion over all the steel surface. In the last years new alloying elements on the Zn bath are studied to optimize properties oriented to new market requirements. In this work a new approach is proposed in order to quantify the main morphological properties of an ZnTiFe phase rich in Ti, present only in coatings produced by baths containing Ti. No quantitative studies have been yet carried out on intermetallic phases formation as consequence of Ti addition in the Zn bath. The innovative approach for ZnTi-based coatings has been applied to five different dipping times, thus allowing to evaluate the kinetic of formation.

Fundamentals, Methods and Applications, 2012

ABSTRACT Due to the peculiar graphite elements shape, ductile cast irons (DCIs) are able to combi... more ABSTRACT Due to the peculiar graphite elements shape, ductile cast irons (DCIs) are able to combine the high castability of gray irons with the toughness of steels. This result is obtained by means of a chemical composition control and not by means of an extended, and expensive, annealing treatment of white irons (that is necessary to obtain malleable irons). Focusing ferritic DCIs, different damaging micromechanisms should be investigated considering both ferritic matrix and the role played by graphite nodules: according to the observed micromechanisms, it is evident that graphite nodules role can’t be summarized with a simple “debonding”, usually considered as the only effective in numerical simulations. In this work, damaging micromechanisms in fatigue loaded ferritic DCI specimens were investigated by means of scanning electron microscope (SEM) during the fatigue test (“in situ” tests). Focusing graphite nodules, customized image processing procedures were optimized in order to quantify the evolution of damaging micromechanisms with the loading cycles number.

Lecture Notes in Computational Vision and Biomechanics, 2013

In this paper Synthetic Aperture Radar (SAR) images in X-band were analyzed in order to infer gro... more In this paper Synthetic Aperture Radar (SAR) images in X-band were analyzed in order to infer ground properties from data. The aim was to classify different zones in peri-urban forestries integrating information from different sources. In particular the X band is sensitive to the moisture content of the ground that can be therefore put into relation with the gray level of the image; moreover, the gray level is related to the smoothness and roughness of the ground. An integration of image segmentation and machine learning methods is studied to classify different zones of peri-urban forestries, such as trees canopies, lawns, water pounds, roads, etc., directly from the gray level signal properties. As case study the X-SAR data of a forest near Rome, the Castel Fusano area, are analyzed.

Frattura ed Integrità Strutturale, 2014

In the last decades, damaging micromechanisms in ductile cast irons (DCIs) have been widely inves... more In the last decades, damaging micromechanisms in ductile cast irons (DCIs) have been widely investigated, considering both the matrix microstructure and the loading conditions influence. Considering the graphite nodules, they were initially considered as voids embedded and growing in a ductile metal matrix (especially considering ferritic ductile cast irons). Recent experimental results allowed to identify a more complex role played by the graphite nodules, depending on the matrix microstructure. In this work, damaging micromechanisms in a pearlitic DCI were investigated by means of tensile tests performed on notched specimen, mainly focusing the role played by graphite elements and considering the stress triaxiality influence.

Engineering Failure Analysis, 2017

Procedia Structural Integrity, 2017

Ductile irons offer a wide range of mechanical properties at a lower cost than the older malleabl... more Ductile irons offer a wide range of mechanical properties at a lower cost than the older malleable iron. These properties mainly depend on the shape characteristics of the metal matrix microstructure and on the graphite elements morphology; these geometrical features are currently evaluated by the experts visual inspection. This work provides an automatic procedure for a reliable estimation of standard parameters of the material microstructure morphology based on a novel image segmentation technique. The procedure has been validated versus standard segmentation techniques, and successfully tested on specimens of different kinds of ductile irons of a typical production.

Lecture Notes in Computational Vision and Biomechanics, 2014

Fundamentals, Methods and Applications, 2012

ABSTRACT Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on stee... more ABSTRACT Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on steels, in order to provide sacrificial protection against corrosion over all the steel surface. In the last years new alloying elements on the Zn bath are studied to optimize properties oriented to new market requirements. In this work a new approach is proposed in order to quantify the main morphological properties of an ZnTiFe phase rich in Ti, present only in coatings produced by baths containing Ti. No quantitative studies have been yet carried out on intermetallic phases formation as consequence of Ti addition in the Zn bath. The innovative approach for ZnTi-based coatings has been applied to five different dipping times, thus allowing to evaluate the kinetic of formation.

Fundamentals, Methods and Applications, 2012

Lecture Notes in Computational Vision and Biomechanics, 2013

Frattura ed Integrità Strutturale, 2014

Atti del Convegno IGF9 , Jun 1993

Innovation Stainless Steel 1993 International Conference, Oct 1993

3rd international metallurgical symposium, May 1994

Idrogeno e metalli, May 1994

Fourth International Conference on Duplex Stainless Steels, Nov 1994

Third World Congress on Computational Mechanics, 1994

The fifth International Symposium on equipment for Structural Analysis, Mechanical testing and Technology Transfer, Sep 1994

Corrosion sous contrainte, Fatigue-Corrosion, Jun 1995

Nové materiàlya technologie, Sep 1995

Hydrogen and surface technology

Duplex stainless steels are largely used for under-sea application and in chemical, petrochemical... more Duplex stainless steels are largely used for under-sea application and in chemical, petrochemical and nuclear plants. These materials are characterised by very good mechanical properties and corrosion resistance (i.e. pitting) and a very advantageous quality/price ratio. The establishing of microgalvanic cells between noble and less noble steels, welding process or localised corrosion, are responsible of hydrogen cathodic charging. Duplex stainless steel structure is sensitive to the presence of hydrogen and hydrogen embrittlement can affect the performance of these steels.

Convegno IGF12 , Jun 1996

Localized Damage III Computer-Aided Assessment and Control, 1994

Hydrogen effects on material behaviour, 1994

Treccani - XXI Secolo, 2010

Acta Fracturae, Jul 1, 2013

Pseudo-elastic (PE) materials are an important class of metallic alloy which exhibit unique featu... more Pseudo-elastic (PE) materials are an important class of metallic alloy which exhibit unique features
with respect to common engineering metals. Because of these unique properties, PEs are able to recover their
original shape after high values of mechanical deformations, by removing the mechanical load (PE). From the
microstructural point of view shape memory and pseudo-elastic effects are due to a reversible solid state
microstructural diffusionless transitions from austenite to martensite, which can be activated by mechanical
and/or thermal loads. Copper-based shape memory alloys are preferred for their good memory properties and
low cost of production.
This paper describes the main crack initiation and its propagation in an tensile test in order to evaluate crack
path and its behaviour at low and at high values of deformation. Both grain boundary chemical properties and
X-ray diffraction will be discussed in order to correlate structural transition involved in an Cu-Zn-Al alloy
characterized by a PE behaviour.

Acta Fracturae, Jul 1, 2013

Versatility and higher performances at lower cost if compared to these of steels with analogous ... more Versatility and higher performances at lower cost if compared to these of steels with analogous
performances are the main advantages of Ductile Cast Irons (DCIs).
In the last years, the research group of Metallurgy of the Università di Cassino e del Lazio Meridionale deeply
investigated the damaging micromechanisms in ferritic pearlitic and austempered DCIs by means of tensile
and fatigue tests, mainly performing scanning electron microscope (SEM) or Digital Microscope (DM)
observations of specimens lateral surfaces during the tests (“in situ” tests).
In this work, graphite nodules mechanical behaviour is investigated by means of nano indentation tests and
results are compared with the damaging micromechanisms observed in ferritic DCIs.

Acta Fracturae, Jul 1, 2013

"Some Cu-Zn-Al alloy is able to exhibit an important feature: the Pseudo-Elastic behavior, commo... more "Some Cu-Zn-Al alloy is able to exhibit an important feature: the Pseudo-Elastic behavior,
commonly defined as PE alloy. The PE effect is the result of a non-diffusion microstructure changing
characterized by a good reversibility at environmental temperature. Furthermore, the copper-based shape
memory alloys are preferred for their good memory properties and low cost of production.
In this work, fatigue crack propagation and microstructural fracture micromechanisms are analyzed in order to
identify microstructure influence on fatigue behavior of Cu-Zn-Al PE alloy."

Acta Fracturae, Jul 1, 2013

The purpose of this paper is to study the phase transformation induced by the cold rolling of a C... more The purpose of this paper is to study the phase transformation induced by the cold rolling of a Cu-
Zn-Al alloy fabricated in our laboratories. Flat specimens were made from the alloy. They were subsequently
heat treated at 850°C/20 min, quenched in water at 100°C, treated at 320°C/30 min, quenched in water at
100°C, cooled in air up to room temperature.
To correlate the microstructure variations with the entity of the imposed deformation, the samples were cold
rolled selectively (each 2.5%) up to 15% of deformation. On each cold rolled sample, the microstructures were
investigated by LOM and XRD. The deformation has contributed to β3 (L21) ordering of the structure and to
occur the martensitic transformation. The martensite obtained is the M18R type.
This result shows that the parameter which most influences the type of obtainable martensite is determined by
the order of the parent phase. During testing it was found that the martensite enucleates in appreciable
quantities even at a level of deformation of 2.5% of the specimen. An increase of the martensite up to a
deformation of 15% was observed. It has not been possible to continue beyond this level of deformation, due
to the presence of transgranular cracks.

Acta Fracturae, Jul 1, 2013

Generally speaking the rockfall protection net wires are Zinc or Zn-Al coated. This provides to t... more Generally speaking the rockfall protection net wires are Zinc or Zn-Al coated. This provides to the
net a durable protection against corrosion. Due to their function, the rockfall protection nets can be damaged
over time, and must be replaced. The aim of this work is to investigate the damage that the wire undergoes
when subjected to “U” bending, in order to obtain a significant stress. Furthermore it has been analyzed the
behavior of a Zn-high Al coating in comparison with the coatings normally used.

Acta Fracturae, Jul 1, 2013

Ductile cast irons are characterized by an interesting mechanical properties combination (high d... more Ductile cast irons are characterized by an interesting mechanical properties combination (high
ductility, high tensile strength, good wear resistance). Graphite nodules morphological peculiarities and matrix
microstructure (both chemical composition and heat treatment controlled) strongly affect the mechanical
behaviour and the damaging micromechanisms, also considering very simple loading conditions (e.g. tensile test
conditions). Focusing ferritic ductile irons, matrix - graphite nodule debonding is often identified as the main
damaging micromechanism, and numerous studies provided analytical laws to describe growth of a single void,
depending on the void geometries and matrix behaviour. In this work, ferritic DCI damaging micromechanisms
were investigated, under uniaxial tensile tests, considering the triaxiality influence.

CompImage 2012, Sep 5, 2012

Due to the peculiar graphite elements shape, ductile cast irons (DCIs) are able to combine the h... more Due to the peculiar graphite elements shape, ductile cast irons (DCIs) are able to combine the
high castability of gray irons with the toughness of steels. This result is obtained by means of a chemical composition
control and not by means of an extended, and expensive, annealing treatment of white irons (that is
necessary to obtain malleable irons). Focusing ferritic DCIs, different damaging micromechanisms should be
investigated considering both ferritic matrix and the role played by graphite nodules: according to the observed
micromechanisms, it is evident that graphite nodules role can’t be summarized with a simple
“debonding”, usually considered as the only effective in numerical simulations. In this work, damaging
micromechanisms in fatigue loaded ferritic DCI specimens were investigated by means of scanning electron
microscope (SEM) during the fatigue test (“in situ” tests). Focusing graphite nodules, customized image processing
procedures were optimized in order to quantify the evolution of damaging micromechanisms with the
loading cycles number.

CompImage 2012, Sep 5, 2012

Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on steels, in o... more Hot-dip galvanizing is one of the most used methods to apply zinc-based coatings on steels, in
order to provide sacrificial protection against corrosion over all the steel surface. In the last years new alloying
elements on the Zn bath are studied to optimize properties oriented to new market requirements. In this
work a new approach is proposed in order to quantify the main morphological properties of an ZnTiFe phase
rich in Ti, present only in coatings produced by baths containing Ti. No quantitative studies have been yet
carried out on intermetallic phases formation as consequence of Ti addition in the Zn bath. The innovative
approach for ZnTi-based coatings has been applied to five different dipping times, thus allowing to evaluate
the kinetic of formation.

CompImage 2012, Sep 5, 2012

Tenacità e resistenza a fatica delle leghe metalliche, 2011

Una lancia che si rompe, una colonna fratturata, un serbatorio in pressione che esplode, un alber... more Una lancia che si rompe, una colonna fratturata, un serbatorio in pressione che esplode, un albero motore che si frattura, manufatti caratterizzati da un comportamento soddisfacente a temperatura ambiente che improvvisamente collassano in una fredda notte d’inverno. Tutti eventi catastrofici che, fino all’inizio del secolo scorso, venivano collegati unicamente al superamento di valori critici della sollecitazione unitaria applicata. L’approfondimento dei meccanismi di danneggiamento ha consentito di chiarire il ruolo svolto dalle difettosità del materiale, qualunque sia la loro origine, ovvero presenti già al momento della produzione (ad
esempio ottenute durante la solidificazione) o legate ai processi di lavorazione, oppure ancora, generate durante l’esercizio stesso del manufatto. Lo sviluppo dei difetti diventa quindi parte
integrante della vita stessa del manufatto e quest non visti esclusivamente come punti di intrinseca debolezza del materiale ma anche, e forse soprattutto, come concentratori e modificatori dello stato di sforzo.

PhD Thesis, 1997

Les aciers inoxydables austéno-ferritiques sont largement utilisées dans l'industrie pétrolière, ... more Les aciers inoxydables austéno-ferritiques sont largement utilisées dans l'industrie pétrolière, pour la production et le transport de pétrole brut ou de gaz, dans l'industrie chimique, dans l'industrie nucléaire....