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18 pages, 8196 KiB

Open AccessArticle

Enhancing Aluminum Alloy Properties Through Low Pressure Forging: A Comprehensive Study on Heat Treatments

by Silvia Cecchel and Giovanna Cornacchia

Metals 2025, 15(7), 797; https://doi.org/10.3390/met15070797 - 15 Jul 2025

Viewed by 199

The weight reduction is a key objective in modern engineering, particularly in the automotive industry, to enhance vehicle performance and reduce the carbon footprint. In this context aluminum alloys are widely used in structural automotive applications, often through forging processes that enhance mechanical [...] Read more.

The weight reduction is a key objective in modern engineering, particularly in the automotive industry, to enhance vehicle performance and reduce the carbon footprint. In this context aluminum alloys are widely used in structural automotive applications, often through forging processes that enhance mechanical properties compared to the results for casting. However, the high cost of forging can limit its economic feasibility. Low pressure forging (LPF) combines the benefits of casting and forging, employing controlled pressure to fill the mold cavity and improve metal purity. This study investigates the effectiveness of the LPF process in optimizing the mechanical properties of AlSi7Mg aluminum alloy by evaluating the influence of three different magnesium content levels. The specimens underwent T6 heat treatment (solubilization treatment followed by artificial aging), with varying aging times and temperatures. Microstructural analysis and tensile tests were conducted to determine the optimal conditions for achieving superior mechanical strength, contributing to the design of lightweight, high-performance components for advanced automotive applications. The most promising properties were achieved with a T6 treatment consisting of solubilization at 540 °C for 6 h followed by aging at 180 °C for 4 h, resulting in mechanical properties of σ_y 280 MPa, σ_m 317 MPa, and A% 3.5%. Full article

(This article belongs to the Special Issue Advances in Lightweight Alloys, 2nd Edition)

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15 pages, 12435 KiB

Open AccessArticle

Additive Manufacturing for Rapid Sand Casting: Mechanical and Microstructural Investigation of Aluminum Alloy Automotive Prototypes

by Silvia Cecchel and Giovanna Cornacchia

Metals 2024, 14(4), 459; https://doi.org/10.3390/met14040459 - 13 Apr 2024

Cited by 3 | Viewed by 2458

Abstract

The automotive industry is undergoing a rapid evolution to meet today’s challenges; therefore, continuous innovation and product development are needed. Validation tests on prototypes play a crucial role in moving new components into industrial production. There is also a pressing need for faster [...] Read more.

The automotive industry is undergoing a rapid evolution to meet today’s challenges; therefore, continuous innovation and product development are needed. Validation tests on prototypes play a crucial role in moving new components into industrial production. There is also a pressing need for faster prototyping processes. In this context, rapid sand casting (RSC), based on additive manufacturing technology, offers a promising solution for a quick production of sand molds. While this technology is already employed in the industry, the need to deepen the general understanding of its impact on the casting properties is still a relevant item. In this study, different geometries of automotive prototypes made of aluminum EN AC 42100-T6 alloy were experimentally analyzed. Microstructural examinations, tensile tests, and fractography and porosity analyses were conducted. The findings demonstrate the considerable potential of RSC, giving, in general, high mechanical properties. A comparative analysis with prototypes produced through traditional sand casting revealed similar results, with RSC exhibiting superior yield strength and stress at brake. However, both technologies revealed a reduced elongation percentage, as expected. Future efforts will focus on standardizing the RSC process to enhance ductility levels. Full article

(This article belongs to the Special Issue Light Alloy and Its Application (2nd Edition))

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27 pages, 13630 KiB

Open AccessArticle

An Insight into the Defects-Driven Plasticity in Ductile Cast Irons

by Giuliano Angella, Marcello Taloni, Marcin Górny, Jacek Tarasiuk, Sebastian Wronski, Roberto Montanari, Matteo Pedranz, Matteo Benedetti, Vigilio Fontanari and Danilo Lusuardi

Materials 2023, 16(10), 3748; https://doi.org/10.3390/ma16103748 - 15 May 2023

Cited by 3 | Viewed by 1261

Abstract

The microstructure and tensile behavior of two heavy section castings that had chemical compositions typical of GJS400 were investigated. Conventional metallography, fractography, and micro-Computer Tomography (μ-CT) were employed, enabling the quantification of the volume fractions of eutectic cells with degenerated Chunky Graphite (CHG), [...] Read more.

The microstructure and tensile behavior of two heavy section castings that had chemical compositions typical of GJS400 were investigated. Conventional metallography, fractography, and micro-Computer Tomography (μ-CT) were employed, enabling the quantification of the volume fractions of eutectic cells with degenerated Chunky Graphite (CHG), which was identified as the major defect in the castings. The Voce equation approach was exploited to evaluate the tensile behaviors of the defective castings for integrity assessment. The results demonstrated that the Defects-Driven Plasticity (DDP) phenomenon, which refers to an unexpected regular plastic behavior related to defects and metallurgical discontinuities, was consistent with the observed tensile behavior. This resulted in a linearity of Voce parameters in the Matrix Assessment Diagram (MAD), which contradicts the physical meaning of the Voce equation. The findings suggest that the defects, such as CHG, contribute to the linear distribution of Voce parameters in the MAD. Furthermore, it is reported that the linearity in the MAD of Voce parameters for a defective casting is equivalent to the existence of a pivotal point in the differential data of the tensile strain hardening data. This pivotal point was exploited to propose a new material quality index assessing the integrity of castings. Full article

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11 pages, 3810 KiB

Open AccessArticle

Personalization of Hearing Aid Fitting Based on Adaptive Dynamic Range Optimization

by Aoxin Ni, Sara Akbarzadeh, Edward Lobarinas and Nasser Kehtarnavaz

Sensors 2022, 22(16), 6033; https://doi.org/10.3390/s22166033 - 12 Aug 2022

Cited by 6 | Viewed by 3086

Abstract

Adaptive dynamic range optimization (ADRO) is a hearing aid fitting rationale which involves adjusting the gains in a number of frequency bands by using a series of rules. The rules reflect the comparison of the estimated percentile occurrences of the sound levels with [...] Read more.

Adaptive dynamic range optimization (ADRO) is a hearing aid fitting rationale which involves adjusting the gains in a number of frequency bands by using a series of rules. The rules reflect the comparison of the estimated percentile occurrences of the sound levels with the audibility and comfort hearing levels of a person suffering from hearing loss. In the study reported in this paper, a previously developed machine learning method was utilized to personalize the ADRO fitting in order to provide an improved hearing experience as compared to the standard ADRO hearing aid fitting. The personalization was carried out based on the user preference model within the framework of maximum likelihood inverse reinforcement learning. The testing of ten subjects with hearing loss was conducted, which indicated that the personalized ADRO was preferred over the standard ADRO on average by about 10 times. Furthermore, a word recognition experiment was conducted, which showed that the personalized ADRO had no adverse impact on speech understanding as compared to the standard ADRO. Full article

(This article belongs to the Special Issue Wearable and Unobtrusive Technologies for Healthcare Monitoring)

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14 pages, 1207 KiB

Open AccessFeature PaperArticle

Radiobiological Outcomes, Microdosimetric Evaluations and Monte Carlo Predictions in Eye Proton Therapy

by Giada Petringa, Marco Calvaruso, Valeria Conte, Pavel Bláha, Valentina Bravatà, Francesco Paolo Cammarata, Giacomo Cuttone, Giusi Irma Forte, Otilija Keta, Lorenzo Manti, Luigi Minafra, Vladana Petković, Ivan Petrović, Selene Richiusa, Aleksandra Ristić Fira, Giorgio Russo and Giuseppe Antonio Pablo Cirrone

Appl. Sci. 2021, 11(19), 8822; https://doi.org/10.3390/app11198822 - 23 Sep 2021

Cited by 4 | Viewed by 2917

Abstract

CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) was the first Italian protontherapy facility dedicated to the treatment of ocular neoplastic pathologies. It is in operation at the LNS Laboratories of the Italian Institute for Nuclear Physics (INFN-LNS) and to date, 500 patients [...] Read more.

CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) was the first Italian protontherapy facility dedicated to the treatment of ocular neoplastic pathologies. It is in operation at the LNS Laboratories of the Italian Institute for Nuclear Physics (INFN-LNS) and to date, 500 patients have been successfully treated. Even though proton therapy has demonstrated success in clinical settings, there is still a need for more accurate models because they are crucial for the estimation of clinically relevant RBE values. Since RBE can vary depending on several physical and biological parameters, there is a clear need for more experimental data to generate predictions. Establishing a database of cell survival experiments is therefore useful to accurately predict the effects of irradiations on both cancerous and normal tissue. The main aim of this work was to compare RBE values obtained from in-vitro experimental data with predictions made by the LEM II (Local Effect Model), Monte Carlo approaches, and semi-empirical models based on LET experimental measurements. For this purpose, the 92.1 uveal melanoma and ARPE-19 cells derived from normal retinal pigmented epithelium were selected and irradiated in the middle of clinical SOBP of the CATANA proton therapy facility. The remarkable results show the potentiality of using microdosimetric spectrum, Monte Carlo simulations and LEM model to predict not only the RBE but also the survival curves. Full article

(This article belongs to the Special Issue Applications of Medical Physics)

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9 pages, 1259 KiB

Open AccessArticle

The Role of Autosensitivity Control (ASC) in Cochlear Implant Recipients

by Federica Di Berardino, Diego Zanetti, Daniela Soi, Lara Dalla Costa and Sandro Burdo

Audiol. Res. 2021, 11(1), 22-30; https://doi.org/10.3390/audiolres11010003 - 21 Jan 2021

Viewed by 3435

Abstract

The purpose of the study was to examine the subjective and objective potential advantage for speech understanding in noise achieved by cochlear implant (CI) recipients when using the autosensitivity control (ASC) input signal processing in combination with the adaptive dynamic range optimization (ADRO). [...] Read more.

The purpose of the study was to examine the subjective and objective potential advantage for speech understanding in noise achieved by cochlear implant (CI) recipients when using the autosensitivity control (ASC) input signal processing in combination with the adaptive dynamic range optimization (ADRO). Eighteen subjects (8 females, 10 males, mean age 17.7 ± 6.7) were enrolled in a prospective open blinded comparative study between the ASC + ADRO condition vs. the ADRO alone; 16 were sequential binaural and 2 were monoaural CI recipients. All patients had been wearing their CI for at least 3 years, had no additional disabilities, had an age-appropriate receptive and expressive language. Word recognition performances in noise (at signal-to-noise ratio +5 dB HL) were significantly better in the ADRO-alone condition than in the ADRO + ASC condition. (p = 0.03) These objective outcomes were in agreement with the subjective reports. No significant difference was found in quiet. Our results, apparently in contrast with other reports in the literature, suggest that the decision of adding the slow-acting automatic reduction in microphone sensitivity provided by ASC should be limited to selected CI recipients. Full article

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20 pages, 7332 KiB

Open AccessArticle

Correlation between Numerical and Experimental Structural Resistance of a Safety Relevant Aluminum Automotive Component

by Silvia Cecchel, Davide Ferrario, Francesco Mega and Giovanna Cornacchia

Metals 2019, 9(9), 949; https://doi.org/10.3390/met9090949 - 29 Aug 2019

Cited by 2 | Viewed by 4124

Abstract

Accurate implementation of weight reduction for the development of innovative safety-relevant components, such as suspension assemblies, requires a careful evaluation of the structural resistance. The validation of these critical parts usually employs Finite Element Analysis (FEA) during the design phase and laboratory tests [...] Read more.

Accurate implementation of weight reduction for the development of innovative safety-relevant components, such as suspension assemblies, requires a careful evaluation of the structural resistance. The validation of these critical parts usually employs Finite Element Analysis (FEA) during the design phase and laboratory tests on prototypes during later stages. However, the results of these established methods have rarely been numerically compared. The present paper introduces a method for comparing FEA and testing, based on the elaboration of micro-strains acquired with strain gauges positioned in specific regions. The model was applied to the real case study of an innovative lightweight cross beam. FEA simulations and bench tests under different conditions that were representative of the operating environments were carried out. Two different relevant configurations of fatigue bench tests were considered. Then, the data obtained from testing were numerically elaborated in order to compare them with the analytical results. Real data from in-field measurements were used. The cross beam endured at the elevate mission loads reproduced at the bench test. The FEA and testing results were aligned. The correlation method was proven to be reliable, since it made it possible not only to numerically evaluate the testing output, but also to validate the calculation tools, and it could be extended to similar applications in future. Full article

(This article belongs to the Special Issue Selected Papers from LightMat 2019)

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19 pages, 5750 KiB

Open AccessArticle

Fatigue and Fracture Resistance of Heavy-Section Ferritic Ductile Cast Iron

by Matteo Benedetti, Elisa Torresani, Vigilio Fontanari and Danilo Lusuardi

Metals 2017, 7(3), 88; https://doi.org/10.3390/met7030088 - 10 Mar 2017

Cited by 21 | Viewed by 11827

Abstract

In this paper, we explore the effect of a long solidification time (12 h) on the mechanical properties of an EN-GJS-400-type ferritic ductile cast iron (DCI). For this purpose, static tensile, rotating bending fatigue, fatigue crack growth and fracture toughness tests are carried [...] Read more.

In this paper, we explore the effect of a long solidification time (12 h) on the mechanical properties of an EN-GJS-400-type ferritic ductile cast iron (DCI). For this purpose, static tensile, rotating bending fatigue, fatigue crack growth and fracture toughness tests are carried out on specimens extracted from the same casting. The obtained results are compared with those of similar materials published in the technical literature. Moreover, the discussion is complemented with metallurgical and fractographic analyses. It has been found that the long solidification time, representative of conditions arising in heavy-section castings, leads to an overgrowth of the graphite nodules and a partial degeneration into chunky graphite. With respect to minimum values prescribed for thick-walled (t > 60 mm) EN-GJS-400-15, the reduction in tensile strength and total elongation is equal to 20% and 75%, respectively. The rotating bending fatigue limit is reduced by 30% with respect to the standard EN-1563, reporting the results of fatigue tests employing laboratory samples extracted from thin-walled castings. Conversely, the resistance to fatigue crack growth is even superior and the fracture toughness comparable to that of conventional DCI. Full article

(This article belongs to the Special Issue Fatigue Damage)

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