In recent decades, one can observe a great increase in the replacement of traditional materials with polymer composites in high-strength and lightweight applications. High fuel consumption by automobile and aerospace vehicles built from legacy alloys has been a great challenge to material engineers. This has called for researches into lighter material development of the same or even superior mechanical properties to the existing materials in this area of applications. In the present study, epoxy based simple and hybrid composites were prepared with the incorporation of industrial waste as fillers at different weight percentages. Effect of filler type, combination and its concentration on mechanical properties such as tensile, impact and flexural strength were investigated. SEM analysis was carried out for fractured surfaces of composites, wherein minor voids, crack initiations and filler pullouts were seen indicating the necessity of coupling agent addition for still better performance. Among hybrid composites, epoxy/fly ash/red mud/aluminium powder (91/6/1.5/1.5 wt%) has showed the highest ultimate tensile modulus, flexural strength and hardness value compared to other composites under study.
{"title":"Mechanical and Fractured surface characterization of epoxy/red mud/fly ash/ aluminium powder filled hybrid composites for automotive applications","authors":"K. Anil, A. Hemavathi, A. Adeebpasha","doi":"10.3221/igf-esis.64.06","DOIUrl":"https://doi.org/10.3221/igf-esis.64.06","url":null,"abstract":"In recent decades, one can observe a great increase in the replacement of traditional materials with polymer composites in high-strength and lightweight applications. High fuel consumption by automobile and aerospace vehicles built from legacy alloys has been a great challenge to material engineers. This has called for researches into lighter material development of the same or even superior mechanical properties to the existing materials in this area of applications. In the present study, epoxy based simple and hybrid composites were prepared with the incorporation of industrial waste as fillers at different weight percentages. Effect of filler type, combination and its concentration on mechanical properties such as tensile, impact and flexural strength were investigated. SEM analysis was carried out for fractured surfaces of composites, wherein minor voids, crack initiations and filler pullouts were seen indicating the necessity of coupling agent addition for still better performance. Among hybrid composites, epoxy/fly ash/red mud/aluminium powder (91/6/1.5/1.5 wt%) has showed the highest ultimate tensile modulus, flexural strength and hardness value compared to other composites under study.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48087231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present article aims to summarize the research study that was conducted the efficiency of methods and techniques designed for the detection and localization of faults in civil engineering structures, particularly in bridge structures. The diagnosis of a real reinforced concrete bridge by a visual inspection is presented. Then, three numerical damage detection and localization methods, namely the eigenfrequency change method, the eigenstrain change method (Coordinate Modal Assurance Criterion – CO-MAC), and the strain energy change method, are explicitly presented. Furthermore, the modeling of the bridge, before and after damage, using the Ansys software was carried out in order to identify all possible bridge defects. Afterward, the numerical results are graphically represented using the above mentioned methods. This made it possible to confirm the initial diagnosis and hence assess the damages observed on site and also in other zones.
{"title":"Damage identification in RC bridges by confronting two approaches: visual inspection and numerical analysis","authors":"Mohammed Ayad, N. Boumechra, K. Hamdaoui","doi":"10.3221/igf-esis.64.05","DOIUrl":"https://doi.org/10.3221/igf-esis.64.05","url":null,"abstract":"The present article aims to summarize the research study that was conducted the efficiency of methods and techniques designed for the detection and localization of faults in civil engineering structures, particularly in bridge structures. The diagnosis of a real reinforced concrete bridge by a visual inspection is presented. Then, three numerical damage detection and localization methods, namely the eigenfrequency change method, the eigenstrain change method (Coordinate Modal Assurance Criterion – CO-MAC), and the strain energy change method, are explicitly presented. Furthermore, the modeling of the bridge, before and after damage, using the Ansys software was carried out in order to identify all possible bridge defects. Afterward, the numerical results are graphically represented using the above mentioned methods. This made it possible to confirm the initial diagnosis and hence assess the damages observed on site and also in other zones.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46201715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The article conducts a study on the iron tailings sand concrete's fracture behaviour based on the double-K criterion. Five sets of standard three-point bending beam specimens of concrete with 0%, 25%, 50%, 75% and 100% iron tailings sand replacement river sand respectively were fracture tested, and the P-CMOD and P- ε curves of each set of specimens were measured to determine the pertinent fracture parameters. The specimens were also microscopically tested using scanning electron microscopy and mercury intrusion porosimetry. The results demonstrate that the fracture processes and damage patterns of iron tailings sand concrete and river sand concrete are comparable; the addition of iron tailings sand improves initial cracking load and initial cracking toughness more significantly than unstable cracking load and unstable cracking toughness; the ductility of iron tailings sand concrete is marginally inferior; and the results of microscopic tests demonstrate that the addition of iron tailings sand can improve the morphology and pore structure of the interface transition zone. Therefore, from the assessment of fracture mechanics, iron tailings sand can totally replace river sand in equivalent quantities for concrete preparation, which will provide great potential for the secondary use of iron tailings sand.
{"title":"Fracture behaviour of concrete with different replacement rates of iron tailings sand based on double-K criterion","authors":"Yao Zhang, W. Ma, H. Kang, Qiang Li","doi":"10.3221/igf-esis.64.11","DOIUrl":"https://doi.org/10.3221/igf-esis.64.11","url":null,"abstract":"The article conducts a study on the iron tailings sand concrete's fracture behaviour based on the double-K criterion. Five sets of standard three-point bending beam specimens of concrete with 0%, 25%, 50%, 75% and 100% iron tailings sand replacement river sand respectively were fracture tested, and the P-CMOD and P- ε curves of each set of specimens were measured to determine the pertinent fracture parameters. The specimens were also microscopically tested using scanning electron microscopy and mercury intrusion porosimetry. The results demonstrate that the fracture processes and damage patterns of iron tailings sand concrete and river sand concrete are comparable; the addition of iron tailings sand improves initial cracking load and initial cracking toughness more significantly than unstable cracking load and unstable cracking toughness; the ductility of iron tailings sand concrete is marginally inferior; and the results of microscopic tests demonstrate that the addition of iron tailings sand can improve the morphology and pore structure of the interface transition zone. Therefore, from the assessment of fracture mechanics, iron tailings sand can totally replace river sand in equivalent quantities for concrete preparation, which will provide great potential for the secondary use of iron tailings sand.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43794826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Damage in RC structures causes the degradation of stiffness and frequency parameters. In this study, the relationship between the two coefficients and damage severities is numerically investigated considering a three-dimensional (3D) reinforced concrete (RC) frame in which the concrete damage plasticity model (CDPM) and the elastoplastic model are selected to define concrete and reinforcement materials, respectively. Crack propagation of the frame is obtained utilizing a nonlinear static pushover analysis (NSPA). After the pushing procedure, according to the base shear force versus top displacement curve, the bending stiffness of the RC structure is determined rapidly. Thereafter, the degradation of the first frequency is obtained based directly on the nonlinear curve of stiffness. As a result, it is observed that the degradation of the first frequency of the RC frame is proportional to the severity of damage but not linearly. More significant damage, a more profound decrease in the modal characteristic. Particularly, the fundamental frequency of the RC frame reduces gradually until the base shear force reaches 70% of the ultimate value at which the parameter is about 60% of the counterpart at the intact stage. After that, the reduction gets more significant when the bending capacity approaches the ultimate value.
{"title":"Degradation of the first frequency of an RC frame with damage levels","authors":"Q. Nguyen, R. Livaoğlu","doi":"10.3221/igf-esis.64.01","DOIUrl":"https://doi.org/10.3221/igf-esis.64.01","url":null,"abstract":"Damage in RC structures causes the degradation of stiffness and frequency parameters. In this study, the relationship between the two coefficients and damage severities is numerically investigated considering a three-dimensional (3D) reinforced concrete (RC) frame in which the concrete damage plasticity model (CDPM) and the elastoplastic model are selected to define concrete and reinforcement materials, respectively. Crack propagation of the frame is obtained utilizing a nonlinear static pushover analysis (NSPA). After the pushing procedure, according to the base shear force versus top displacement curve, the bending stiffness of the RC structure is determined rapidly. Thereafter, the degradation of the first frequency is obtained based directly on the nonlinear curve of stiffness. As a result, it is observed that the degradation of the first frequency of the RC frame is proportional to the severity of damage but not linearly. More significant damage, a more profound decrease in the modal characteristic. Particularly, the fundamental frequency of the RC frame reduces gradually until the base shear force reaches 70% of the ultimate value at which the parameter is about 60% of the counterpart at the intact stage. After that, the reduction gets more significant when the bending capacity approaches the ultimate value.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48125381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Parsa Ghannadi, S. S. Kourehli, Seyedali Mirjalili
In recent years, many innovative optimization algorithms have been developed. These algorithms have been employed to solve structural damage detection problems as an inverse solution. However, traditional optimization methods such as particle swarm optimization, simulated annealing (SA), and genetic algorithm are constantly employed to detect damages in the structures. This paper reviews the application of SA in different disciplines of structural health monitoring, such as damage detection, finite element model updating, optimal sensor placement, and system identification. The methodologies, objectives, and results of publications conducted between 1995 and 2021 are analyzed. This paper also provides an in-depth discussion of different open questions and research directions in this area.
{"title":"A review of the application of the simulated annealing algorithm in structural health monitoring (1995-2021)","authors":"Parsa Ghannadi, S. S. Kourehli, Seyedali Mirjalili","doi":"10.3221/igf-esis.64.04","DOIUrl":"https://doi.org/10.3221/igf-esis.64.04","url":null,"abstract":"In recent years, many innovative optimization algorithms have been developed. These algorithms have been employed to solve structural damage detection problems as an inverse solution. However, traditional optimization methods such as particle swarm optimization, simulated annealing (SA), and genetic algorithm are constantly employed to detect damages in the structures. This paper reviews the application of SA in different disciplines of structural health monitoring, such as damage detection, finite element model updating, optimal sensor placement, and system identification. The methodologies, objectives, and results of publications conducted between 1995 and 2021 are analyzed. This paper also provides an in-depth discussion of different open questions and research directions in this area.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46631367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research studies and assesses the possibility of employing UHPFRC in exterior beam-column joints (BCJs). Eight specimens with various concrete material characteristics and steel reinforcing details are cast and examined under repeated loads. Normal concrete with seismic reinforcing details is used as a control specimen. For certain specimens, UHPC, UHPFRC with 1% steel fiber, and UHPFRC with 2% steel fiber are poured into all BCJs, and others are poured into the critical zone only. The consequences of removing stirrups from the joint were studied. All specimens' crack patterns, hysteresis and envelope curves, ductility factor, stiffness degradation, and energy dissipation are assessed and corresponded to the control sample. The results demonstrate that UHPFRC strengthened the joint, prevented crack development and extension and the shear failure in the joint, and formed the plastic hinge in the beams. UHPFRC outperforms normal concrete with seismic reinforcing details and UHPC without steel fiber in bearing capacity, ductility, stiffness, and energy dissipation. UHPFRC with 1% steel fiber enhanced joint behavior, while UHPFRC with 2% steel fiber was better. Casting the whole sample with UHPFRC achieved very little improvement. The presence of stirrups in the UHPFRC beam-column joint has little effect on its properties. It is more economical to casting UHPFRC in the joint zone only and reduce or eliminate these stirrups in the case of UHPFRC
{"title":"The impact of utilizing UHPFRC in beam-column joints with different patterns of transverse reinforcement","authors":"A. Abdo, H. Mohamed, Talaat Ryad, S. M. Ahmed","doi":"10.3221/igf-esis.64.02","DOIUrl":"https://doi.org/10.3221/igf-esis.64.02","url":null,"abstract":"This research studies and assesses the possibility of employing UHPFRC in exterior beam-column joints (BCJs). Eight specimens with various concrete material characteristics and steel reinforcing details are cast and examined under repeated loads. Normal concrete with seismic reinforcing details is used as a control specimen. For certain specimens, UHPC, UHPFRC with 1% steel fiber, and UHPFRC with 2% steel fiber are poured into all BCJs, and others are poured into the critical zone only. The consequences of removing stirrups from the joint were studied. All specimens' crack patterns, hysteresis and envelope curves, ductility factor, stiffness degradation, and energy dissipation are assessed and corresponded to the control sample. The results demonstrate that UHPFRC strengthened the joint, prevented crack development and extension and the shear failure in the joint, and formed the plastic hinge in the beams. UHPFRC outperforms normal concrete with seismic reinforcing details and UHPC without steel fiber in bearing capacity, ductility, stiffness, and energy dissipation. UHPFRC with 1% steel fiber enhanced joint behavior, while UHPFRC with 2% steel fiber was better. Casting the whole sample with UHPFRC achieved very little improvement. The presence of stirrups in the UHPFRC beam-column joint has little effect on its properties. It is more economical to casting UHPFRC in the joint zone only and reduce or eliminate these stirrups in the case of UHPFRC","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43696303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents the results of a comparative experimental study on the influence of date palm fibers to replace polypropylene fibers used as reinforcement in self-compacting concrete (SCC). Indeed, the use of polypropylene fibers makes it possible to reduce the plastic shrinkage of concrete. Date palm fibers have mechanical characteristics (tensile strength and elasticity modulus) largely sufficient to replace polypropylene fibers. The use of natural fibers has several advantages, they are natural, renewable, have no affect the environment and require little energy for their transformation, unlike synthetic fibers. In this comparative study, polypropylene fiber is used as control material and date palm fiber as study material. The results obtained show that the two types of fibers decrease the fluidity and the compressive strength but increase the flexural strength and decrease the shrinkage. Date palm fibers delay the appearance of cracks more than polypropylene fibers. Date palm fibers guarantee the best results of SCCs in fresh and hardened state
{"title":"Effect of date palm and polypropylene fibers on the characteristics of self-compacting concretes: comparative study","authors":"Dounia Derdour, Mourad Behim, M. Benzerara","doi":"10.3221/igf-esis.64.03","DOIUrl":"https://doi.org/10.3221/igf-esis.64.03","url":null,"abstract":"This article presents the results of a comparative experimental study on the influence of date palm fibers to replace polypropylene fibers used as reinforcement in self-compacting concrete (SCC). Indeed, the use of polypropylene fibers makes it possible to reduce the plastic shrinkage of concrete. Date palm fibers have mechanical characteristics (tensile strength and elasticity modulus) largely sufficient to replace polypropylene fibers. The use of natural fibers has several advantages, they are natural, renewable, have no affect the environment and require little energy for their transformation, unlike synthetic fibers. In this comparative study, polypropylene fiber is used as control material and date palm fiber as study material. The results obtained show that the two types of fibers decrease the fluidity and the compressive strength but increase the flexural strength and decrease the shrinkage. Date palm fibers delay the appearance of cracks more than polypropylene fibers. Date palm fibers guarantee the best results of SCCs in fresh and hardened state","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47347899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Movement joints are needed in bridges to accommodate longitudinal expansion and contraction. Enough joint width needs to be available to accommodate not only longitudinal expansion but also expected movements of joints during earthquakes. This may result in excessive joint openings. Devices that can dissipate energy have been suggested to reduce joint displacements. Shape memory alloy (SMA) is one of these energy dissipation devices, which is well known for its ability to return to its natural shape after being deformed. Several cases of bridges and different conditions of seismic events are modeled and tested using developed software programs in MATLAB to show the efficiency of using SMA inside bridge joint openings. These models include the case of two adjacent frames with SMA inside them (2–frames), the case of multi–frames with constant hysteretic SMAs between every two of them (N–frames), the case of multi–frames with constant hysteretic SMAs taking the delay of seismic forces between frames into consideration (delay), and the case of variable masses of bridge frames. Also, parametric studies are performed to show the impacts of all parameters of bridge frames and SMA retrofit devices on seismically joint openings. The results show that the superelastic SMA device plays a huge role in controlling bridge opening and enables limiting the joint width of all models during earthquakes with different values reaching 60% in some cases depending on bridge frame properties, ground motion characteristics, and the hysteretic properties of SMA devices.
{"title":"Efficiency of shape memory alloy seismic restrainers for several conditions of bridge joints","authors":"Mohamed H. El-Feky, A. Eraky, Alaa M. Sharabash","doi":"10.3221/igf-esis.64.07","DOIUrl":"https://doi.org/10.3221/igf-esis.64.07","url":null,"abstract":"Movement joints are needed in bridges to accommodate longitudinal expansion and contraction. Enough joint width needs to be available to accommodate not only longitudinal expansion but also expected movements of joints during earthquakes. This may result in excessive joint openings. Devices that can dissipate energy have been suggested to reduce joint displacements. Shape memory alloy (SMA) is one of these energy dissipation devices, which is well known for its ability to return to its natural shape after being deformed. Several cases of bridges and different conditions of seismic events are modeled and tested using developed software programs in MATLAB to show the efficiency of using SMA inside bridge joint openings. These models include the case of two adjacent frames with SMA inside them (2–frames), the case of multi–frames with constant hysteretic SMAs between every two of them (N–frames), the case of multi–frames with constant hysteretic SMAs taking the delay of seismic forces between frames into consideration (delay), and the case of variable masses of bridge frames. Also, parametric studies are performed to show the impacts of all parameters of bridge frames and SMA retrofit devices on seismically joint openings. The results show that the superelastic SMA device plays a huge role in controlling bridge opening and enables limiting the joint width of all models during earthquakes with different values reaching 60% in some cases depending on bridge frame properties, ground motion characteristics, and the hysteretic properties of SMA devices.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49342539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Girelli, Maverick Giovagnoli, M. Tocci, A. Fortini, M. Gelfi, M. Merlin, A. Pola
In the present study the impact behavior of gravity casting AlSi10Mg alloy was evaluated with an instrumented Charpy pendulum. The effect of hot isostatic pressing, also followed by a T6 treatment, was analyzed in comparison with samples in the as-cast, annealed and T6 conditions. Furthermore, the effect of the innovative high-pressure T6 was investigated. It was found that the hot isostatic pressing is able to ensure densification of the alloy with an increase in both hardness and energy absorbed during impact. The T6 treatment performed at atmospheric pressure after the hot isostatic pressing is able to increase hardness and peak force. At the same time, the innovative high-pressure T6 is able to ensure similar results than those of hot isostatic pressing followed by T6, leading to a significant decrease in the treatment duration and costs and reducing the carbon footprint of the manufacturing process.
{"title":"Impact behavior of gravity cast AlSi10Mg alloy: Effect of hot isostatic pressing and innovative high pressure T6 heat treatment","authors":"L. Girelli, Maverick Giovagnoli, M. Tocci, A. Fortini, M. Gelfi, M. Merlin, A. Pola","doi":"10.3221/igf-esis.64.13","DOIUrl":"https://doi.org/10.3221/igf-esis.64.13","url":null,"abstract":"In the present study the impact behavior of gravity casting AlSi10Mg alloy was evaluated with an instrumented Charpy pendulum. The effect of hot isostatic pressing, also followed by a T6 treatment, was analyzed in comparison with samples in the as-cast, annealed and T6 conditions. Furthermore, the effect of the innovative high-pressure T6 was investigated. It was found that the hot isostatic pressing is able to ensure densification of the alloy with an increase in both hardness and energy absorbed during impact. The T6 treatment performed at atmospheric pressure after the hot isostatic pressing is able to increase hardness and peak force. At the same time, the innovative high-pressure T6 is able to ensure similar results than those of hot isostatic pressing followed by T6, leading to a significant decrease in the treatment duration and costs and reducing the carbon footprint of the manufacturing process.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49364311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Boniardi, A. Casaroli, Laura Sirangelo, Sergio Monella, Michele Mazzola
The automotive industry is continuously looking for an innovative mix of new steels and manufacturing techniques in order to improve process chain efficiency and cost reduction. To this aim, boron steels are becoming increasingly popular thanks to their high hardenability and machinability. Due to their reduced finishing steps, boron steels are commonly processed using fine blanking technologies. The success of fine blanking on boron steel components is due to heat treatments which must be carefully designed to avoid precipitation of boron-rich compounds that would lower steel hardenability. At high temperature, boron is very reactive with oxygen and nitrogen. The main focus of this paper is to show some drawbacks that can occur during heat treatments of automotive components. An experimental campaign was performed on two different boron steels, namely EN 34MnB5 and EN 22MnB5. The steel samples were previously spheroidized annealed in a neutral environment (hydrogen/nitrogen atmosphere), and then fine blanked to obtain specific automotive components which were subsequently quenched and tempered. Experimental tests revealed precipitation of nanometric compounds, causing strong grain refinement and localized decrease of steel hardenability. Hardenability problems were brought back to nitrogen pick-up during initial spheroidize annealing treatments.
{"title":"Failure Analysis of Boron Steel Components for Automotive Applications","authors":"M. Boniardi, A. Casaroli, Laura Sirangelo, Sergio Monella, Michele Mazzola","doi":"10.3221/igf-esis.64.09","DOIUrl":"https://doi.org/10.3221/igf-esis.64.09","url":null,"abstract":"The automotive industry is continuously looking for an innovative mix of new steels and manufacturing techniques in order to improve process chain efficiency and cost reduction. To this aim, boron steels are becoming increasingly popular thanks to their high hardenability and machinability. Due to their reduced finishing steps, boron steels are commonly processed using fine blanking technologies. The success of fine blanking on boron steel components is due to heat treatments which must be carefully designed to avoid precipitation of boron-rich compounds that would lower steel hardenability. At high temperature, boron is very reactive with oxygen and nitrogen. The main focus of this paper is to show some drawbacks that can occur during heat treatments of automotive components. An experimental campaign was performed on two different boron steels, namely EN 34MnB5 and EN 22MnB5. The steel samples were previously spheroidized annealed in a neutral environment (hydrogen/nitrogen atmosphere), and then fine blanked to obtain specific automotive components which were subsequently quenched and tempered. Experimental tests revealed precipitation of nanometric compounds, causing strong grain refinement and localized decrease of steel hardenability. Hardenability problems were brought back to nitrogen pick-up during initial spheroidize annealing treatments.","PeriodicalId":38546,"journal":{"name":"Frattura ed Integrita Strutturale","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44889618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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