Fulvio Siciliano | Instituto Federal de Educação, Ciência e Tecnologia do Maranhão (IFMA) (original) (raw)

Papers by Fulvio Siciliano

Metals

Thermo-mechanically controlled rolling is a technique used to produce steel strips and plates. On... more Thermo-mechanically controlled rolling is a technique used to produce steel strips and plates. One of the steels widely used in the production of heavy plates for application in oil and gas pipelines is API X80. The hot rolling process of this family of steels consists of applying deformation passes at high temperatures, mainly above Ae3, inside the austenite phase field. It has been shown that during deformation, the phenomenon of dynamic transformation (DT) of austenite into ferrite leads to lower hot deformation resistance within the stable austenite region. In this investigation, hot torsion simulations of an industrial rolling process under continuous cooling conditions were used to monitor the formation of ferrite by DT. Stress–strain flow curves and equivalent mean flow stresses followed by sample characterization via optical and electron microscopy showed the inevitable formation of ferrite above the Ae3. The employed 10-pass deformation schedule was divided into 5 roughing ...

AISTech2020 Proceedings of the Iron and Steel Technology Conference

The use of thermomechanical control processing during hot rolling has played a significant role i... more The use of thermomechanical control processing during hot rolling has played a significant role in improving the mechanical properties of steels in the past several decades. Accurate control of various metallurgical phenomena such as recrystallization, phase transformation and strain-induced precipitation has been the main target of steel industries around the world to push the properties of steels to their limit. Therefore, numerous physical and numerical simulations of hot rolling were developed to predict the microstructure and properties of steels during thermomechanical processing, which allows for quick optimization of manufacturing parameters. One of the most common techniques to physically simulate the actual hot rolling process in a laboratory scale is through hot torsion testing. In the present work, various grades of steels subjected to torsion simulation of hot strip and plate rolling were analyzed to determine the effect of deformation on the initiation of various metallurgical phenomena. The results show that high-temperature deformation can induce unusual metallurgical phenomena, such as dynamic phase transformation, which affects the final microstructure and mechanical properties of steels. These new findings can be employed to accurately control the volume fraction of phases in steels during cooling on the runout table after hot rolling. C. Aranas (left) Assistant Professor, Department of Mechanical Engineering, University of New Brunswick, Fredericton, N.B., Canada (clod.aranas@unb.ca)

Materials Research-ibero-american Journal of Materials, Sep 1, 2005

The evolution in the understanding of the recrystallization phenomena is summarized in this paper... more The evolution in the understanding of the recrystallization phenomena is summarized in this paper. Initially the main developments concerning recrystallization are presented from a historical perspective. Definitions and concepts involving recrystallization are presented regarding it as a solid-state reaction that occurs by nucleation and growth. The recrystallization nucleation mechanisms are subsequently discussed. Finally, the growth step is highlighted, emphasizing boundary and sub-boundary mobilities and the forces acting on the high angle grain boundaries that sweep the microstructure during recrystallization.

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Aug 1, 2002

The present work is an analysis of the influence of the rate of recovery on the Avrami–Johnson–Me... more The present work is an analysis of the influence of the rate of recovery on the Avrami–Johnson–Mehl–Kolmogorov equation which is meant to describe the kinetics of recrystallization. First, an equation for the recovery kinetics is given. This is entering the ...

Materials Science Forum, 2005

Mill logs obtained from the Hylsa CSPTM (thin slab casting/direct rolling – TSC/DR) mill were exa... more Mill logs obtained from the Hylsa CSPTM (thin slab casting/direct rolling – TSC/DR) mill were examined so that the mean flow stresses at each pass were calculated using the Sims equation modified to take into account the forward slip ratio, the redundant strain and the work roll flattening. The mean flow stresses were then compared to predicted values obtained from a model. The microstructures during the CSP process were predicted by a mathematical model which was initially derived for conventional slab/roughing mill/hot strip mill (HSM) processing route. The adapted model takes into account the deformation of the as-cast structure in the finishing CSP mill, by using particular microstructural equations to calculate the softening kinetics and grain sizes. The main metallurgical features such as the occurrence of Nb(C,N) precipitation, the softening mechanism which takes place (static or metadynamic recrystallization) as well as the strain accumulation between passes were calculated....

Scripta Materialia, 2020

Dynamic transformation (DT) of austenite to ferrite can take place in the single austenite phase ... more Dynamic transformation (DT) of austenite to ferrite can take place in the single austenite phase field during thermomechanical processing as shown in the literature. However, despite significant progress on this topic, limited real-time evidence of DT has been published. To address this concern, an in-situ X-ray diffraction measurement was carried out on a pipeline steel before, during and after hot compression. The appearance of ferrite peaks is evident during deformation and these peaks disappear after 9 s of isothermal holding. This work provides an in-situ evidence of both forward and backward dynamic transformation complemented with energy calculations to validate the observations.

Simulation of hot rolling schedules performed in a laboratory scale provides important metallurgi... more Simulation of hot rolling schedules performed in a laboratory scale provides important metallurgical information about the full-scale process. The evaluation of hot deformation resistance during hot rolling is crucial for stable mill operation. In this work, simulation of hot rolling of steels has been performed by means of hot torsion and planestrain compression tests performed on a Gleeble simulation system. Tested schedules match the same conditions used to produce steel coils in industrial scale. The results show excellent correlations between full-scale industrial rolling and small-scale simulation by both torsion and plane-strain compression tests, matching the results of meanflow-stress. Additionally, all mean-flow-stress data produced by mechanical testing and industrial rolling were normalized and plotted together in the same graph, showing that all points follow the same trend with an excellent linear correlation factor. The results also validate the use of different defor...

Tecnologia em Metalurgia Materiais e Mineração, 2020

When austenite is deformed above the Ae 3 temperature, partial amount of it transforms dynamicall... more When austenite is deformed above the Ae 3 temperature, partial amount of it transforms dynamically into ferrite by a displacive mechanism. After unloading, it retransforms back into the stable austenite by a diffusional process. This phenomenon influences the rolling load, which either decreases under isothermal rolling condition or does not progressively increase with decreasing temperature during cooling. In this work, plate rolling simulations employing isothermal and continuous cooling conditions were carried out on a 0.09 wt.% Nb X-70 steel. Pass strains in the range of 0.2-04, interpass times between 10-30 s and strain rate of 1s-1 were employed. The results showed that the critical strains for the initiation of dynamic transformation fell around 0.06 while the critical strain for dynamic recrystallization was 0.12. Under cooling conditions, the ferrite formation is favored as the temperature approaches the Ae 3 line. Such ferrite forms when the driving force for dynamic transformation is higher than the total free energy barrier. Increasing the holding time after rolling increases the amount of austenite available for microstructure control on subsequent stages. The dynamic transformation (DT) mechanism can be used to design improved rolling schedules.

Metalurgia Materiais, 2004

Journal of Materials Research and Technology, 2020

of Nb in the alloy affects both the forward and backward transformation. The present investigatio... more of Nb in the alloy affects both the forward and backward transformation. The present investigation can be used to estimate the amount of formed and retransformed ferrite during Steckel mill operations in order to have a better metallurgical understanding of the process. This may result in better dimensional and quality control during the manufacturing of X70 pipeline steels.

The Minerals, Metals & Materials Series, 2017

A seven-pass rolling schedule was simulated on the McGill hot torsion machine. The first and last... more A seven-pass rolling schedule was simulated on the McGill hot torsion machine. The first and last pass temperatures were 950 and 860°C with 15° of cooling between passes. All of the rolling was carried out above the Ae3 temperature of 845°C that applies to this composition. Interpass times of 10 and 30 s were employed, which corresponded to cooling rates of 1.5 and 0.5°C/s, respectively. Samples were quenched before and after the first, third, fifth, and seventh passes in order to determine the amount of dynamic ferrite produced in a given pass. The data also allowed for estimation of the amounts of ferrite that retransformed to austenite during the holding period. The volume fractions of ferrite and martensite (prior austenite) were determined by optical metallography. The amounts of dynamic ferrite formed increased with pass number, averaging about 13 and 10% per pass for the 10-and 30-s schedules, respectively. The amounts of retransformed ferrite also increased with pass number, averaging about 7% for both interpass times. The effect of employing longer holding intervals above the Ae3 after finish rolling to permit more retransformation is also discussed.

Journal of Materials Research and Technology, 2021

Frontiers in Materials, 2021

In this work, the presence of dynamically formed ferrite above the Ae3 temperature during the phy... more In this work, the presence of dynamically formed ferrite above the Ae3 temperature during the physical simulation of hot rolling was presented. This unusual metallurgical process is known as dynamic transformation (DT). The metastable ferrite phase undergoes a reverse transformation when the temperature is held above the Ae3 by means of a diffusion process. These phenomena affect the rolling load during high-temperature plate rolling. Therefore, a linepipe X70 steel was studied under plate rolling with two-pass roughing and seven-pass finishing strains of 0.4 and 0.2, respectively, applied at strain rate of 1 s−1 and interpasses of 10, 20, and 30 s. The samples were cooling down during deformation, which mimics the actual industrial hot rolling. It was observed that the alloy softens as the hot rolling progresses, as depicted by flow curves and mean flow stress plots, which are linked to the combined effects of dynamic transformation and recrystallization. The former initially occur...

Journal of Materials Research and Technology, 2020

The educated have figured prominently in protests and elections in several MENA countries. The do... more The educated have figured prominently in protests and elections in several MENA countries. The dominant explanation for this pattern centers on grievances and unfulfilled aspirations due to low education returns in the MENA. However, the pattern may simply reflect the unequal participation observed in many democracies where education provides skills and resources that facilitate political participation. This article compares the roles of skills and grievances in explaining the relationship between education and youth political participation during and after the Arab Spring. We use youth surveys with detailed data on education and political participation from Egypt and Tunisia. We control for parental education and family background to partially account for the potential of background to drive the education and participation relationship. Overall, our results are consistent with the skill channel and lend little support to the grievance channel. Our findings raise concerns about the exclusion of uneducated youth from both unconventional and conventional political participation in MENA politics.

MRS Advances, 2019

ABSTRACTPartial amount of austenite can be dynamically transformed into ferrite above the Ae3 tem... more ABSTRACTPartial amount of austenite can be dynamically transformed into ferrite above the Ae3 temperature when it is being deformed. This happens by a displacive mechanism. On removal of the load, it retransforms back into the stable austenite by diffusional processes. Plate rolling simulation under continuous cooling conditions was carried out on a high Nb X70 steel. Pass strains of 0.2 together with interpass times of 10, 20 and 30 s were employed. The initial and final temperatures for the finishing simulation were 920 and 830 °C, respectively. The mean flow stresses (MFS`s) behaviour indicates that dynamic transformation (DT) and recrystallization (DRX) were taking place during straining. It is shown that ferrite is formed during the roughing passes and increases its volume fraction throughout the finishing rolling steps. The ferrite formation is favoured by strain accumulation, shorter time between passes and also when the temperature reaches the Ae3 line. The results obtained ...

Metals

Thermo-mechanically controlled rolling is a technique used to produce steel strips and plates. On... more Thermo-mechanically controlled rolling is a technique used to produce steel strips and plates. One of the steels widely used in the production of heavy plates for application in oil and gas pipelines is API X80. The hot rolling process of this family of steels consists of applying deformation passes at high temperatures, mainly above Ae3, inside the austenite phase field. It has been shown that during deformation, the phenomenon of dynamic transformation (DT) of austenite into ferrite leads to lower hot deformation resistance within the stable austenite region. In this investigation, hot torsion simulations of an industrial rolling process under continuous cooling conditions were used to monitor the formation of ferrite by DT. Stress–strain flow curves and equivalent mean flow stresses followed by sample characterization via optical and electron microscopy showed the inevitable formation of ferrite above the Ae3. The employed 10-pass deformation schedule was divided into 5 roughing ...

AISTech2020 Proceedings of the Iron and Steel Technology Conference

The use of thermomechanical control processing during hot rolling has played a significant role i... more The use of thermomechanical control processing during hot rolling has played a significant role in improving the mechanical properties of steels in the past several decades. Accurate control of various metallurgical phenomena such as recrystallization, phase transformation and strain-induced precipitation has been the main target of steel industries around the world to push the properties of steels to their limit. Therefore, numerous physical and numerical simulations of hot rolling were developed to predict the microstructure and properties of steels during thermomechanical processing, which allows for quick optimization of manufacturing parameters. One of the most common techniques to physically simulate the actual hot rolling process in a laboratory scale is through hot torsion testing. In the present work, various grades of steels subjected to torsion simulation of hot strip and plate rolling were analyzed to determine the effect of deformation on the initiation of various metallurgical phenomena. The results show that high-temperature deformation can induce unusual metallurgical phenomena, such as dynamic phase transformation, which affects the final microstructure and mechanical properties of steels. These new findings can be employed to accurately control the volume fraction of phases in steels during cooling on the runout table after hot rolling. C. Aranas (left) Assistant Professor, Department of Mechanical Engineering, University of New Brunswick, Fredericton, N.B., Canada (clod.aranas@unb.ca)

Materials Research-ibero-american Journal of Materials, Sep 1, 2005

The evolution in the understanding of the recrystallization phenomena is summarized in this paper... more The evolution in the understanding of the recrystallization phenomena is summarized in this paper. Initially the main developments concerning recrystallization are presented from a historical perspective. Definitions and concepts involving recrystallization are presented regarding it as a solid-state reaction that occurs by nucleation and growth. The recrystallization nucleation mechanisms are subsequently discussed. Finally, the growth step is highlighted, emphasizing boundary and sub-boundary mobilities and the forces acting on the high angle grain boundaries that sweep the microstructure during recrystallization.

Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Aug 1, 2002

The present work is an analysis of the influence of the rate of recovery on the Avrami–Johnson–Me... more The present work is an analysis of the influence of the rate of recovery on the Avrami–Johnson–Mehl–Kolmogorov equation which is meant to describe the kinetics of recrystallization. First, an equation for the recovery kinetics is given. This is entering the ...

Materials Science Forum, 2005

Mill logs obtained from the Hylsa CSPTM (thin slab casting/direct rolling – TSC/DR) mill were exa... more Mill logs obtained from the Hylsa CSPTM (thin slab casting/direct rolling – TSC/DR) mill were examined so that the mean flow stresses at each pass were calculated using the Sims equation modified to take into account the forward slip ratio, the redundant strain and the work roll flattening. The mean flow stresses were then compared to predicted values obtained from a model. The microstructures during the CSP process were predicted by a mathematical model which was initially derived for conventional slab/roughing mill/hot strip mill (HSM) processing route. The adapted model takes into account the deformation of the as-cast structure in the finishing CSP mill, by using particular microstructural equations to calculate the softening kinetics and grain sizes. The main metallurgical features such as the occurrence of Nb(C,N) precipitation, the softening mechanism which takes place (static or metadynamic recrystallization) as well as the strain accumulation between passes were calculated....

Scripta Materialia, 2020

Dynamic transformation (DT) of austenite to ferrite can take place in the single austenite phase ... more Dynamic transformation (DT) of austenite to ferrite can take place in the single austenite phase field during thermomechanical processing as shown in the literature. However, despite significant progress on this topic, limited real-time evidence of DT has been published. To address this concern, an in-situ X-ray diffraction measurement was carried out on a pipeline steel before, during and after hot compression. The appearance of ferrite peaks is evident during deformation and these peaks disappear after 9 s of isothermal holding. This work provides an in-situ evidence of both forward and backward dynamic transformation complemented with energy calculations to validate the observations.

Simulation of hot rolling schedules performed in a laboratory scale provides important metallurgi... more Simulation of hot rolling schedules performed in a laboratory scale provides important metallurgical information about the full-scale process. The evaluation of hot deformation resistance during hot rolling is crucial for stable mill operation. In this work, simulation of hot rolling of steels has been performed by means of hot torsion and planestrain compression tests performed on a Gleeble simulation system. Tested schedules match the same conditions used to produce steel coils in industrial scale. The results show excellent correlations between full-scale industrial rolling and small-scale simulation by both torsion and plane-strain compression tests, matching the results of meanflow-stress. Additionally, all mean-flow-stress data produced by mechanical testing and industrial rolling were normalized and plotted together in the same graph, showing that all points follow the same trend with an excellent linear correlation factor. The results also validate the use of different defor...

Tecnologia em Metalurgia Materiais e Mineração, 2020

When austenite is deformed above the Ae 3 temperature, partial amount of it transforms dynamicall... more When austenite is deformed above the Ae 3 temperature, partial amount of it transforms dynamically into ferrite by a displacive mechanism. After unloading, it retransforms back into the stable austenite by a diffusional process. This phenomenon influences the rolling load, which either decreases under isothermal rolling condition or does not progressively increase with decreasing temperature during cooling. In this work, plate rolling simulations employing isothermal and continuous cooling conditions were carried out on a 0.09 wt.% Nb X-70 steel. Pass strains in the range of 0.2-04, interpass times between 10-30 s and strain rate of 1s-1 were employed. The results showed that the critical strains for the initiation of dynamic transformation fell around 0.06 while the critical strain for dynamic recrystallization was 0.12. Under cooling conditions, the ferrite formation is favored as the temperature approaches the Ae 3 line. Such ferrite forms when the driving force for dynamic transformation is higher than the total free energy barrier. Increasing the holding time after rolling increases the amount of austenite available for microstructure control on subsequent stages. The dynamic transformation (DT) mechanism can be used to design improved rolling schedules.

Metalurgia Materiais, 2004

Journal of Materials Research and Technology, 2020

of Nb in the alloy affects both the forward and backward transformation. The present investigatio... more of Nb in the alloy affects both the forward and backward transformation. The present investigation can be used to estimate the amount of formed and retransformed ferrite during Steckel mill operations in order to have a better metallurgical understanding of the process. This may result in better dimensional and quality control during the manufacturing of X70 pipeline steels.

The Minerals, Metals & Materials Series, 2017

A seven-pass rolling schedule was simulated on the McGill hot torsion machine. The first and last... more A seven-pass rolling schedule was simulated on the McGill hot torsion machine. The first and last pass temperatures were 950 and 860°C with 15° of cooling between passes. All of the rolling was carried out above the Ae3 temperature of 845°C that applies to this composition. Interpass times of 10 and 30 s were employed, which corresponded to cooling rates of 1.5 and 0.5°C/s, respectively. Samples were quenched before and after the first, third, fifth, and seventh passes in order to determine the amount of dynamic ferrite produced in a given pass. The data also allowed for estimation of the amounts of ferrite that retransformed to austenite during the holding period. The volume fractions of ferrite and martensite (prior austenite) were determined by optical metallography. The amounts of dynamic ferrite formed increased with pass number, averaging about 13 and 10% per pass for the 10-and 30-s schedules, respectively. The amounts of retransformed ferrite also increased with pass number, averaging about 7% for both interpass times. The effect of employing longer holding intervals above the Ae3 after finish rolling to permit more retransformation is also discussed.

Journal of Materials Research and Technology, 2021

Frontiers in Materials, 2021

In this work, the presence of dynamically formed ferrite above the Ae3 temperature during the phy... more In this work, the presence of dynamically formed ferrite above the Ae3 temperature during the physical simulation of hot rolling was presented. This unusual metallurgical process is known as dynamic transformation (DT). The metastable ferrite phase undergoes a reverse transformation when the temperature is held above the Ae3 by means of a diffusion process. These phenomena affect the rolling load during high-temperature plate rolling. Therefore, a linepipe X70 steel was studied under plate rolling with two-pass roughing and seven-pass finishing strains of 0.4 and 0.2, respectively, applied at strain rate of 1 s−1 and interpasses of 10, 20, and 30 s. The samples were cooling down during deformation, which mimics the actual industrial hot rolling. It was observed that the alloy softens as the hot rolling progresses, as depicted by flow curves and mean flow stress plots, which are linked to the combined effects of dynamic transformation and recrystallization. The former initially occur...

Journal of Materials Research and Technology, 2020

The educated have figured prominently in protests and elections in several MENA countries. The do... more The educated have figured prominently in protests and elections in several MENA countries. The dominant explanation for this pattern centers on grievances and unfulfilled aspirations due to low education returns in the MENA. However, the pattern may simply reflect the unequal participation observed in many democracies where education provides skills and resources that facilitate political participation. This article compares the roles of skills and grievances in explaining the relationship between education and youth political participation during and after the Arab Spring. We use youth surveys with detailed data on education and political participation from Egypt and Tunisia. We control for parental education and family background to partially account for the potential of background to drive the education and participation relationship. Overall, our results are consistent with the skill channel and lend little support to the grievance channel. Our findings raise concerns about the exclusion of uneducated youth from both unconventional and conventional political participation in MENA politics.

MRS Advances, 2019

ABSTRACTPartial amount of austenite can be dynamically transformed into ferrite above the Ae3 tem... more ABSTRACTPartial amount of austenite can be dynamically transformed into ferrite above the Ae3 temperature when it is being deformed. This happens by a displacive mechanism. On removal of the load, it retransforms back into the stable austenite by diffusional processes. Plate rolling simulation under continuous cooling conditions was carried out on a high Nb X70 steel. Pass strains of 0.2 together with interpass times of 10, 20 and 30 s were employed. The initial and final temperatures for the finishing simulation were 920 and 830 °C, respectively. The mean flow stresses (MFS`s) behaviour indicates that dynamic transformation (DT) and recrystallization (DRX) were taking place during straining. It is shown that ferrite is formed during the roughing passes and increases its volume fraction throughout the finishing rolling steps. The ferrite formation is favoured by strain accumulation, shorter time between passes and also when the temperature reaches the Ae3 line. The results obtained ...