This research assesses the industrial viability of black slag from electric arc furnace (EAF) as an eco-friendlier alternative to carbon black (CB) in nitrile butadiene rubber (NBR) formulations for technical components. Three compounds, at equal filler volume fraction, were prepared: a conventional CB-filled NBR, a fully slag-filled version, and a partial substitution (50 % slag and 50 % carbon black). Rheometric analysis showed that replacing CB with slag does not affect vulcanization kinetics, temperature dependence or activation energy; only the maximum torque (MH) and thus cured-rubber mechanical properties varied. Adding slag slightly lowers material viscosity (reduced minimum torque, ML). Injection molding of O-rings encountered filling problems: coarse slag particles (<= 100 mu m) blocked narrow mold gates (approximate to 50 mu m). By contrast, compression molding of flat plates encountered no processing issues. Mechanical tests revealed that tensile and tear strengths progressively decrease as slag content rises, driven by the slag angular shape and particle size. Tribological trials indicated that while friction coefficients drop with more slag, wear rates increase. ATR-FTIR spectra confirmed that slag does not alter the NBR's molecular structure, and thermal conductivity and glass transition temperature (approximate to-25.5 degrees C) remain unchanged. Notably, slag inclusion enhances thermal degradation resistance. Overall, the 50 % slag formulation strikes the best balance between environmental impact and performance, offering substantial eco-benefits with moderate loss of mechanical strength. Future work should target improved slag size and shape and/or alternative moulding techniques, such as injection-compression, to fully leverage EAF slag's potential as a sustainable, drop-in filler in high-performance elastomers.

This study investigates the effects of partial recrystallization and corrosion on the fatigue behavior of EN AW6082 T6 aluminum alloy, widely used in automotive structural components. The research explores how partial recrystallization, often occurring during processing, influences fatigue properties when combined with corrosion. Fatigue tests were conducted on recrystallized and non-recrystallized samples, both in corroded and non-corroded conditions, with corrosion simulated using the standardized PV 1113 test. Metallurgical analysis revealed grain dissolution pit-associated intergranular corrosion. Fatigue life curves were generated, and fatigue strength at 2E6 cycles was determined. Results showed that recrystallization had complex effects on fatigue performance, with recrystallized specimens exhibited a steeper fatigue life curve, characterized by reduced life at lower stresses and extended life at higher stresses. Corrosion accelerated fatigue degradation across all conditions, with the most severe impact at lower stresses. However, recrystallization under corrosive conditions mitigated corrosion's impact on long-term fatigue performance by allowing for more gradual degradation at high cycle counts. This study highlights the importance of understanding the interaction between recrystallization, corrosion, and fatigue to optimize material performance in automotive applications.

Electric arc furnace (EAF) slag, a by-product of steelmaking commonly utilized as artificial aggregate, still faces significant landfilling despite extensive reuse. This study explores sustainable alternatives to minimize landfilling by investigating the environmental benefits of incorporating EAF slag as filler in epoxy mortar, as a substitute for a natural material such as river sand. Experimental results demonstrate that slag-filled mortar exhibits comparable or superior mechanical performance to sand-filled mortar, making it a technically feasible substitute. Moreover, the heavy metals leaching of slag, which is one of the major concerns about the reuse of this material, is reduced thanks to the incorporation into the polymeric matrix, ensuring a safe reuse. To quantify these sustainability benefits, a comparative life cycle assessment is conducted for two scenarios involving the production of a functional unit of 1 m 2 of epoxy mortar, typically applied in epoxy screeds, using sand or slag at equal volume fraction. Scenario 1 encompasses slag landfilling and sand extraction, while scenario 2 involves slag reuse as a filler, avoiding landfilling and sand extraction. Life cycle impact assessment using the Environmental Footprint 3.0 method reveals across-the-board reductions. The majority of analyzed impact categories experience a reduction of over 90% attributed to the avoidance of slag disposal and landfill inertization. Overall, reusing slag as an epoxy filler presents significant sustainability benefits compared to disposal, promoting the adoption of this industrial symbiosis application.

Selective laser melted (SLM) CoCrMo alloy holds promise in various biomedical and industrial applications, requiring exceptional tribological properties to withstand contact interactions and wear. Despite this, research on SLM-CoCrMo tribology remains relatively unexplored. This study presents a comprehensive comparative analysis, evaluating the impact of heat treatments, specifically at 800 degrees C/2 h, 1150 degrees C/2 h, and hot isostatic pressing (HIP), under varying load levels (2 N, 5 N, and 7 N) and sliding conditions (single way or reciprocating). The results demonstrate that different combinations of load, sliding condition, and heat treatment induce diverse wear mechanisms, significantly influencing the alloy's tribological performance. Specifically, the as-built (AB) condition showed the highest wear rates at 2 N, whereas HIP-treated samples exhibited a significant reduction in wear rate compared to AB specimens at 7 N, under both reciprocating and single-way sliding conditions. Among the investigated conditions, HIP treatment emerged as the optimal compromise between wear resistance and mechanical properties. The findings provide valuable insights for optimizing the tribological behavior of the SLM-CoCrMo alloy, especially in load-bearing biomedical applications such as joint implants and prosthetics components.

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 σy 280 MPa, σm 317 MPa, and A% 3.5%.

This research explores the valorization of ladle furnace (LF) slag as a functional filler in recycled nitrile butadiene rubber (NBR) industrial scrap, addressing waste management challenges in both the steelmaking and rubber industries. A comprehensive characterization of the LF slag was conducted, including its leaching behavior, chemical composition and mineralogy. Notably, the slag exhibited self-pulverizing properties, with 60 % of particles measuring below 90 mu m. XRD and SEM analyses revealed the presence of gamma-dicalcium silicate, beta-dicalcium silicate (larnite), gehlenite, and MgAl2O4 spinel, with their distribution varying according to particle size. Comparative evaluations were performed on virgin NBR, recycled NBR, and recycled NBR reinforced with 10 % v/v LF slag in two distinct particle size ranges (0-50 mu m and 50-100 mu m). The key properties evaluated included crosslink density, hardness, tensile strength, and dynamic mechanical behavior. The incorporation of LF slag promoted devulcanization during calendering, increased hardness and elastic modulus, and enhanced dynamic mechanical performance. Furthermore, leaching tests demonstrated that the NBR matrix significantly reduced the release of hazardous elements from LF slag, bringing leachate concentrations well below regulatory thresholds. These findings highlight the potential to develop sustainable rubber composites entirely from recycled materials, exemplifying the principles of the circular economy.

This study investigates additive-free cold calendering of ELT-derived rubber powders across three particle size fractions (<0.5 mm, 0.5–0.71 mm, and 0.71–0.90 mm) using a two-roll mill without external heating or virgin polymers, aiming to obtain a cohesive material. Results demonstrate particle size effects on material properties. The finest fraction exhibited the highest crosslink density (5.30 × 10−4 mol·cm−3), approximately 18% greater than coarser fractions, correlating with superior hardness (≈65 ShA) and elastic modulus (≈7.5 MPa). Tensile properties ranged from 1.6–1.8 MPa stress and 60–75% elongation at break, positioning calendered sheets between low-temperature compression-molded GTR and high-pressure sintered materials reported in the literature. The cold calendering process achieves competitive mechanical performance with reduced energy consumption, simplified processing, and complete retention of recycled content. These findings support the development of regulation-compliant ELT recycling technologies, with potential applications in nonstructural construction panels, vibration-damping components, and protective barriers, advancing circular economy objectives while addressing emerging microplastic concerns.

This study investigates the valorization of two industrial waste streams - nitrile butadiene rubber (NBR) scraps and electric arc furnace (EAF) slag - in the development of recycled NBR compounds filled with EAF slag as filler. A new recycling method for NBR scraps is employed via calendering at room temperature without the need for curatives, chemical agents, or pre-grinding. The resulting recycled NBR is then used as a matrix for EAF slag particles to produce sustainable rubber compounds that are entirely recycled. Characterization reveals that incorporating EAF slag enhances the devulcanization process of recycled NBR during recycling. The filler grain size affects composite properties like hardness, crosslink density, and tensile modulus, with finer slag particles (<50 mu m) exhibiting improved reinforcement due to increased interaction surface with the rubber matrix. Dynamic mechanical analysis indicates that recycled NBR filled with EAF slag exhibits a more significant Payne effect compared to unfilled recycled NBR, due to filler-matrix interactions. Interestingly, EAF slag facilitates the rapid fractional recovery of the low-strain storage modulus after experiencing high-amplitude strain, ascribed to the formation of a rigid rubber layer around the slag particles. Overall, the findings highlight the potential to valorize these two waste materials effectively by producing functional recycled NBR/EAF slag composites with desirable properties through a simple, industrially viable recycling method without capital-intensive equipment. This represents both environmental and economic benefits through waste valorization and industrial symbiosis.

To date, discarded tires are reused in many applications, however, because of the enormous quantity decommissioned annually, it is essential to continue researching new recycling methods as well as applications to reduce waste and preserve new resources. In the present study, a simple recycling technology of end-of-life tire (ELT) powder is proposed, and the influence of steel slag as filler is assessed. Europe produces about 7 Mt of steel slag annually, and although most of it is reused as an artificial aggregate, about 15% is still landfilled. Also in the case of steel slag, the study of new applications is mandatory so that the combination of these two waste materials, in a 100% recycled composite fits across different industrial sectors facing the same environmental issue. It was found that the leaching of the slag incorporated in the rubber matrix is reduced and that the ELT powder recycled by this technology gives rise to a well-cohesive material. A good rubber -filler interaction was found by swelling test and differential scanning calorimetry (DSC) analysis. The slag reduces the friction coefficient and increases the thermal conductivity. The experimental results showed how some properties of recycled ELT can be improved by adding the steel slag.

A fragment from a medieval sword blade was investigated by metallography, Vickers microhardness tests and slag inclusions analysis are to extract technological information about its manufacturing process. Optical microscopy observations and microhardness measurements indicated that the sword blade was forged via hammer welding, combining different steel bars for an optimal balance of hardness and toughness. A steeling technique involved wrapping a steel bar around a composite billet, crafted by enclosing a hypoeutectoid steel bar around a near-eutectoid steel core. Moreover, it was found that the hardness of the cutting edges was increased with a quenching heat treatment. After quenching, the blade exhibited martensitic microstructure with Vickers microhardness ranging from 500 to 640 HV0.3. The compositional data of a large set of nonmetallic inclusions were collected by scanning electron microscopy coupled with X-ray dispersive spectroscopy. Slag inclusion analysis and multivariate statistics confirmed the blade's composite nature and revealed distinct smelting and forging-related SI groups. Liquidus temperatures indicated smelting temperatures of at least 1156°C for the external section and 1031°C for the internal. The forging temperature was estimated at a minimum of 1143°C. These findings provide insight into the blade’s metallurgical history.

A metallurgical study was performed on a 16th–17th century “rapier” sword manufactured in Caino (northern Italy). Metallographic investigations and Vickers microhardness measurements indicate that the rapier was forged by assembling via hammer-welding different hypoeutectoid and near eutectoid steel bars. The rapier blade was heat treated by slack-quenching to increase its hardness, especially near the blade tip, improving the thrusting performance. The chemical composition of slag inclusions was analyzed by scanning electron microscopy coupled with X-ray dispersive spectroscopy. Compositional data of slag inclusions were analyzed by a multivariate statistical strategy aimed to distinguish and classify slag inclusions on the basis of their origin. It was estimated that the temperature reached during the finery and forging processes was at least 1270 °C and 1160 °C, respectively.

This study investigates the use of electric arc furnace (EAF) slag, as a substitute for conventional filler, such as calcium carbonate, in nitrile-butadiene rubber (NBR) composites in different volume fraction. The results demonstrate that slag exhibits morphological traits comparable to calcium carbonate when used as a filler, moreover their processability and mechanical properties are similar. Specifically, at 20% v/v, slag-flled NBR exhibits slightly longer scorch times but unchanged vulcanization times. Both fillers at 20% v/v show comparable hardness, compression strength, and elastic modulus. Tensile properties are also comparable, except for the strain at break, where slag-filled NBR shows a 40% higher tensile strain at break. The environmental impact of this innovative slag application has been evaluated through a comparative life cycle assessment. All assessed impact categories demonstrate a reduction of at least 89%. The study suggests that the use of EAF slag has the potential to promote sustainable waste management.

This study investigates the impact of post-processing techniques on the fatigue behaviour of specimens in Ti6Al4V made by laser powder bed fusion (LPBF) for relevant applications, such as motorsport. Despite the LPBF advantages in terms of complex design and weight reduction, challenges such as reduced fatigue performance persist. Therefore, the application of post-processing treatments can play a critical role. In addition to traditional sandblasting (SB), three post-processing conditions were investigated to enhance mechanical properties under quasi-static and fatigue loading conditions: heat treatment (HT) and the innovative High Pressure Heat Treatment (HPHT) along with dry electropolishing (EP) treatment. The results indicate that both the HT and HPHT treatments produced a macrostructure with equiaxial grains composed of fine alpha + beta lamellae. Mechanical analyses demonstrated that the HPHT-SB-EP condition exhibits properties comparable to those of forged Ti6Al4V used in the automotive field, with a good balance between strength and ductility. The EP treatment effectively reduced surface roughness and inherent surface irregularities caused by the LPBF process. The best fatigue results were achieved with the HPHT-SB-EP condition, despite data scattering. An increase in fatigue resistance was observed by using SB at a higher pressure.

An archaeometallurgical study of a Renaissance breach pike was performed to elucidate its manufacturing process. Optical microscopy observations and microhardness measurements indicated that the breach pike was forged starting from a heterogeneous steel lump. The microstructural features were compatible with post-forging air cooling. The chemistry of a large set of nonmetallic inclusions was investigated by scanning electron microscopy coupled with X-ray dispersive spectroscopy. Compositional data were analyzed by multivariate statistics to distinguish smelting-related slag inclusions. A logistic regression model indicated that the steel was probably produced by the direct method. The liquidus temperatures of the slag inclusions indicated maximum smelting temperatures in the range of 1200 °C to 1300 °C. A thermodynamic-based model was adopted to estimate the average smelting conditions in terms of temperature and oxygen chemical potential and investigate the disequilibrium of slag inclusion–metal systems. For low-disequilibrium systems, the computed temperature values range between 1095 °C and 1118 °C, while the oxygen chemical potentials (μO2) span from −442 to −374 kJ/mol.

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.

Structural automotive components are extensively made of aluminum alloy forgings, due to the elevate strength and low weight required. These products are frequently subjected to recrystallization. Recrystallization, often limited to surface or forging portions, is expected to reduce its tensile strength and corrosion resistance, but the literature is scarce on this subject. For a more comprehensive understanding, the present research studied the corrosion behavior of samples collected from EN AW 6082-T6 forged components, designed to expose both recrystallized and not recrystallized surfaces to the corrosive environment. Several standardized corrosion tests (i.e., PV 1113, ISO 11846, and VW 96380) were applied to assess the most representative with respect to real field exposure. Tensile tests were performed in four different conditions, recrystallized and not recrystallized specimens in an as-forged state or after corrosion. The recrystallization led to a reduction in tensile properties, but this gap was compensated by a higher corrosion resistance than the not recrystallized samples. Consequently, the mechanical properties became comparable after the corrosion test. The main purpose of the paper is to study the effect of recrystallization phenomenon, typically encountered in aluminum alloy forgings, on tensile and corrosion resistance. The results highlight the fact that recrystallization reduced the tensile properties, but the corrosion resistance is higher than that of not recrystallized samples. Consequently, the mechanical properties are comparable after the corrosion test. image

Additive manufacturing (AM) could be used to reduce the production times of prototypes; however, further research is required to address metals structural parts. To obtain the correct properties, some relevant factors to be considered are the build volume, shape factor, and the need for specific heat treatments. This study aims to evaluate the reliability of AM prototypes applied at a new powertrain system developed to reduce vehicle emissions. Firstly, it was investigated the mechanical behavior, microstructure, and the effect of sample size and heat treatments on both specimens and prototypes made of AM 17-4PH steel. Finite Element Analysis (FEA) was performed to evaluate the structural resistance. Finally, the prototypes were produced, analyzed, and tested on a functional engine test bench to evaluate their reliability. The mechanical properties decreased with an increase in the sample volume. After heat treatment, the yield strength increased, due to the transformation of δ-ferrite in martensite and the reduction of retained austenite. The engine test bench was successfully completed. The conclusions set the basis for similar future applications of time-effective prototypes that can be dimensioned owing to appositely developed postprocesses that guarantee the required resistance.

Carbon black (CB) is the most widely used reinforcing filler for rubber. Nowadays there are several concerns regarding this traditional petroleum-based filler: on one side its environmental footprint is enormous and its production process is no more sustainable and on the other side its price increases annually. For these reasons, sustainable alternative fillers are being studied. In the present research the main waste of the steel industry, namely the steel slag from electric arc furnace (EAF), is investigated as non-conventional filler for a nitrile butadiene rubber matrix (NBR). The slag has been characterized to ensure its safe reuse as filler according to the heavy metals leaching. The slag filled compounds have been characterized and compared to CB filled compounds, in terms of processability by rheometric parameters, mechanical properties, Payne effect, and physicochemical properties to investigate the filler-matrix interaction. From the obtained results, it was shown that EAF slag-filled NBRs are comparable to CB filled NBRs in terms of crosslink kinetics and, when compared at the same hardness level, are comparable in terms of viscosity, stiffness, and elongation at break, while when compared at the same filler volume fraction are similar in terms of compression set and stress relaxation.

An archaeometallurgical characterization of a VI to VII century Lombard steel bar from Ponte di Val Gabbia I site (northern Italy) was performed to reconstruct its manufacturing process and extract processing thermochemical parameters ( i.e. , temperature and oxygen chemical potential) from the slag inclusion-metal systems. Metallographic observations by optical microscopy and Vickers microhardness measurements indicated that the steel bar was forged from a heterogeneous steel lump, most probably an iron bloom, which was cooled in the air after the forging process. The chemical composition of non-metallic inclusions was determined by scanning electron microscopy coupled with X-ray dispersive spectroscopy. A multivariate statistical analysis of the smelting-derived non-metallic inclusions chemistry allowed to conclude that the steel bar was obtained by the direct or bloomery method. Under the hypothesis of local near-equilibrium conditions for the slag inclusion-metal systems, a thermodynamic-based strategy was adopted to estimate the firing conditions in the bloomery furnace in terms of both temperature and oxygen chemical potential of the reducing gas atmosphere. In particular, the computed temperatures are in the range of 1003 °C to 1171 °C, whereas the values of oxygen chemical potential vary between − 447.47 and − 385.79 kJ/mol.