Nickel-based superalloys, such as Rene N5, are commonly used in high-temperature turbine components due to their exceptional mechanical strength and stability. While platinum is recognized for its role in enhancing oxidation resistance and microstructural stability, its impact on mechanical performance has not been thoroughly investigated. This study explores the effects of platinum additions ranging from 0 to 5 wt.% on the microhardness and microstructure of Rene N5 in both as-cast and heat-treated conditions. Thermo-Calc simulations indicated that the additions of platinum influence phase stability and precipitation behavior. Vickers microhardness measurements were conducted under a 0.1 kgf, while light microscopy and scanning electron microscopy (SEM) were utilized for microstructural analysis. In the as-cast state, the highest hardness was recorded for the Pt-free variant (486 HV), with the hardness values of the other compositions ranging from 452 HV to 477 HV. After heat treatment, the hardness generally decreased, resulting in values between 385 HV (for 3% Pt) and 420 HV (for 5% Pt). SEM observations clearly revealed the very distinct presence of intermetallic γ′ precipitates in both dendritic regions and interdendritic spaces.

This work was supported by the National Science Center (Poland) under project “Monocrystalline Ni-based superalloys modified with platinum for the production of critical rotating turbine components of aircraft engines” (2023/51/D/ST11/00945).

Laser Powder Bed Fusion (L-PBF) is a leading metal additive manufacturing process capable of producing complex, high-performance components sustainably. AlSi10Mg is one of the most widely used aluminium alloys in L-PBF due to its low density, high mechanical strength, and thermal stability, making it ideal for the aerospace and automotive industries and other demanding applications. However, its large-scale adoption is limited by the challenge of simultaneously optimizing mechanical performance, surface finish, productivity, and cost-effectiveness.

This study examines the influence of layer thickness, laser power, scan speed, and hatch distance on quality, build rate, and cost. Using gas-atomized AlSi10Mg powder, fifty-four cubic specimens were fabricated and analyzed. Scan speed and layer thickness had the greatest impact on densification, with an optimal volumetric energy density of 35–45 J/mm³ achieving >99% relative density with minimal porosity. Higher scan speeds increased pore size, while higher laser power reduced it. The best surface quality was achieved with thinner layers, lower scan speeds, and higher laser powers, whereas higher build rates generally increased roughness.

Mechanical performance correlated with density and pore size, with optimized 60 µm builds matching or exceeding the strength and ductility of 40 µm builds. The highest-performing sample reached UCS = 420 MPa, YS = 340 MPa, and strain at failure = 0.25. Increasing the build rate from 6.7 to 12.5 mm³/s reduced the build time by 40% for single parts and 70% for 16-part batches. A cost model for a turbine wheel case study identified machine time as the dominant cost driver, with up to 70% cost reduction achievable through higher build rates and full platform utilization without compromising density.

These findings show that careful parameter optimization can deliver high quality, mechanical integrity, productivity, and cost efficiency, enabling L-PBF adoption where performance and economics are equally critical.

Hadfield steel (mangalloy, 1.2% C, 13% Mn) is known for its exceptional wear resistance and ability to work-harden under impact loads, yet conventional heat treatment does not increase its hardness. Dynamic alloying in the super-deep penetration (SDP) mode, a process which involves the introduction of high-velocity streams of powder particles into bulk steel, offers a novel approach for the solid-state modification of its properties. The aim of this study was to determine how SDP processing using SiC-based powder mixtures with different metallic additives affects the microstructure and hardness of Hadfield steel.

Cast Hadfield steel samples were dynamically treated with SiC powders (<100 μm) mixed with nickel (Ni) or tin (Sn). The SDP process was performed at an average particle velocity of approximately 3000 m/s, with a penetration depth of up to 100 mm. The microstructure and element distribution were examined using scanning electron microscopy and elemental mapping, while the hardness was measured using Rockwell (HRB) and Brinell (HB) methods before and after processing, as well as following heat treatment.

SDP processing resulted in a deep incorporation of Ni and Sn into the steel matrix and a significant increase in hardness. Compared to the as-cast state (61–62 HRB; 109–112 HB), the SiC+Ni treatment increased hardness to 78–80 HRB (146–149 HB), and the SiC+Sn treatment to 76–77 HRB (143–145 HB), corresponding to improvements of about 29% and 24.5%, respectively. Post-processing heat treatment had minimal effect, confirming that strengthening occurs primarily during dynamic alloying.

These results show that SDP-based dynamic alloying effectively transforms Hadfield steel into a composite-like material with enhanced mechanical performance. The process enables deep, homogeneous alloying in the solid state without melting or quenching, thereby lowering energy consumption and expanding the technological potential of high-manganese steels for wear-resistant components in mining, construction, and heavy machinery.

Electrical Discharge Machining (EDM) is extensively utilized for machining hard and thermally resistant materials like OHNS (Oil-Hardened Non-Shrinking) die steel. The performance of EDM is influenced not only by process parameters but also by the metallurgical properties of the workpiece, which can be altered through heat treatment and subsequent cooling. This research investigates the impact of different cooling methods—air cooling, water quenching, and oil quenching—after uniform austenitizing heat treatment on the performance characteristics of EDM, including material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR). The heated workpieces were cooled using the three aforementioned media to induce varied microstructural and hardness properties. EDM experiments were subsequently carried out using constant parameters to isolate the effect of heat treatment under different machining conditions, like rough, semi-finish, and finish. The results revealed significant variations in EDM performance across the differently cooled specimens. The experimental results indicate that heat treatment significantly influences EDM performance; hardened workpieces exhibited higher MRR but also increased tool wear and surface roughness as compared to non-treated workpieces. The air cooling, water quenching, and oil quenching of the workpieces could increase MRR by 18-82%, 7-70%, 8-75%, TWR by 7-43%, 26-98%, 20-56% and SR by 42-111%, 36-166%, 100-208%, respectively, as compared to a non-treated workpiece. These findings emphasize the critical role of pre-machining heat treatment and cooling strategy in optimizing EDM efficiency and surface quality for precision tooling applications.

Solid Expandable Tubular (SET) technology is a proven method in oil and gas drilling, enabling water shutoff, zonal isolation, and life extension of wells through in situ plastic expansion of steel casing. The expansion mandrel, a precision-engineered conical tool, performs this cold expansion under demanding downhole conditions. D6 steel (a high-carbon, high-chromium cold-work tool steel) was selected for its manufacture. This tool steel has exceptional wear and abrasion resistance, high compressive strength, dimensional stability, and heat-treatment versatility. These properties make it well suited for repeated contact, resistance to plastic deformation, and consistent expansion performance.

This study investigates the influence of heat treatment on D6 steel to determine an optimum sequence for SET mandrel applications. The process includes annealing, austenitizing, air and oil quenching, and single and double tempering at six temperatures (100-600°C). Mechanical testing (following ASTM standards) included Rockwell hardness, Charpy V-notch impact toughness, and tensile properties, supported by microstructural and fractographic analyses. Single tempering produced variable properties and reduced strengths, while double tempering with air cooling (DTA) or oil quenching (DTO) yielded superior results. DTO at 400°C achieved maximum hardness (57 HRC), whereas DTA at 400°C offered slightly lower hardness (52 HRC) but higher yield and tensile strengths with improved ductility. Considering overall performance, DTA at 400 °C is recommended for optimum combination of hardness, toughness, and ductility, enhancing mandrel life and tubular expansion accuracy. The findings provide practical heat treatment guidelines for D6 steel in SET applications, improving durability, dimensional precision, and operational efficiency in harsh oilfield environments.

Cement manufacturing traditionally relies on the decarbonation of raw materials, mainly calcium carbonate (CaCO₃), obtained from limestone and other calcareous rocks. In conventional processes, this reaction occurs through calcination in high-temperature kilns, releasing large amounts of CO₂, representing nearly 8% of global emissions from the construction sector. In line with the United Nations Sustainable Development Goals, which target net-zero greenhouse gas emissions by 2050, the cement industry is exploring alternative, cleaner production methods for clinker. This study evaluates the potential of replacing the thermal decomposition of materials that provide CaCO₃ with an electrochemical decarbonation process carried out in an H-type electrochemical cell equipped with an ion-exchange membrane. Direct current from a regulated power supply drives the reaction, producing Ca(OH)₂ as a solid precipitate, while generating pure streams of H₂, O₂, and CO₂. The gases can be collected using sealed gas sampling systems for subsequent utilization in clean energy applications or industrial processes. This substitution not only reduces the carbon footprint of the cement industry by enabling CO₂ capture at the point of generation but also yields a reactive Ca(OH)₂ suitable for clinker production. The process is currently at the laboratory scale, with ongoing analysis focusing on reaction efficiency, gas yield, and the economic feasibility of producing one ton of cement using this method, thereby delivering valuable insights into its potential large-scale implementation.

Understanding the phase transformation kinetics from delta-ferrite (δ) to austenite (γ) is essential for optimizing post-weld heat treatment (PWHT) protocols in 9Cr steel welds, which are extensively used in high-temperature pressure components such as steam headers, piping, and turbine casings. The stability and dissolution behavior of δ-ferrite directly influence the final microstructure, mechanical properties, and long-term service performance of these steels. In this study, dilatometry was employed to investigate the δ→γ transformation under precisely controlled heating conditions. δ-ferrite–containing Grade P91 steel specimens, produced via weld metal solidification, were subjected to a range of heating rates representative of industrial PWHT practices. Dimensional changes were continuously monitored to capture transformation events with high temporal resolution. The onset and completion temperatures of the δ→γ transformation were determined for each heating rate, and transformation kinetics were quantitatively analyzed. Results show that both heating rate and prior microstructure exert a pronounced influence on transformation behavior. Higher heating rates shift the transformation to higher temperatures and, in some cases, result in incomplete δ-ferrite dissolution, potentially leading to microstructural inhomogeneity. These findings provide critical insights into the transformation mechanisms in Grade 91 steels and highlight the importance of carefully controlling PWHT parameters to achieve a fully homogenized and stable tempered martensitic microstructure, thereby improving mechanical performance and service reliability in welded components.

Metal additive manufacturing, particularly Laser Powder Bed Fusion (L-PBF), enables the fabrication of geometrically complex components such as those made from Ti-6Al-2Sn-4Zr-2Mo (Ti-6242). However, the as-built surface condition often exhibits high roughness and partially fused particles, which can negatively impact part life and wear resistance. This study focused on optimizing L-PBF process parameters to maximize relative density and minimize defects, followed by a comprehensive evaluation of mechanical, thermal, and chemical base surface post-treatment techniques: grinding, tumble finishing, laser polishing, and chemical polishing. Process optimization identified a parameter set—200 W laser power, 1000 mm/s laser scan speed— that achieved the highest density (~99%) and relatively low surface roughness, selected as the baseline for surface treatment trials. All post-processing methods significantly reduced surface roughness, with grinding achieving the greatest reduction, followed by tumble finishing, laser polishing, and chemical polishing. SEM analysis and roughness profiling revealed distinct mechanisms of surface modification, including plastic deformation, abrasive smoothing, and localized melting. Nanoindentation tests indicated that laser polishing slightly reduced near-surface hardness due to thermal relaxation, while tumble finishing caused localized strain hardening. These results highlight the importance of combining optimized build parameters with tailored surface finishing strategies to enhance the performance of Ti-6242 AM components, particularly for applications demanding high surface integrity and mechanical reliability.

The pursuit of sustainable materials for additive manufacturing has drawn significant attention from both industry and academia. This study focuses on the development and optimization of jute–polylactic acid (PLA) composite filaments as a biodegradable alternative to petroleum-based thermoplastics for 3D printing. Key challenges, including filament thickness, uniformity, brittleness, and printability, were addressed by optimizing the material composition. The Taguchi design of experiment was employed with three factors and three levels. Filaments were produced using PLA blended with 5 wt%, 7.5 wt%, and 10 wt% jute fiber via a single-screw extruder under three different outlet temperatures (150℃, 155℃, and 160℃). An automated winding system, incorporating microprocessor control, tension regulation, and a diameter measuring sensor, was designed to enhance filament uniformity. The printability of the jute filament is checked based on the product surface morphology by changing the nozzle size of the 3D printer. After optimizing the nozzle size, the filaments were mechanically and thermally characterized. Mechanical characterization, including tensile (ASTM D638) and flexural (ASTM D790) strength tests, demonstrated improved strength properties with increasing jute reinforcement percentage, particularly at 10 wt.%. However, at 10 wt.% jute, increased brittleness and extrusion discontinuity were observed. At higher temperatures, this discontinuity was minimized. Thermogravimetric Analysis (ASTM D3850), water uptake (ASTM 570), and microscopic imaging further supported these results, revealing enhanced thermal stability but increased moisture absorption with higher jute content in the filament.

There is increasing interest in thermoplastic polymer matrix composites due to their potential for simplified recycling and integration into circular economy strategies. A straightforward method for their production is film stacking, where a laminate is pre-assembled as alternating layers of thermoplastic films and fiber reinforcements, then consolidated by compression molding in a hot-plate press. This method requires the matrix to be available in film form.

In this work, a glass fiber reinforced polyamide 6 laminate was produced via film stacking. The composite’s quality depends strongly on processing parameters that control polymer melt infiltration prior to matrix solidification.

Laminate composition was assessed by the calcination method. Mechanical and physical properties—tensile, flexural, and density—were measured and compared to predictions from micromechanics and classical laminate theory. Charpy impact strength was also evaluated using notched and unnotched edgewise specimens, as well as unnotched flatwise specimens.

A composite with approximately 45 wt% glass fiber content, in line with predictions, was obtained. The tensile modulus (~12 GPa) matched theoretical estimates, while the flexural modulus (~9 GPa) was slightly lower, suggesting incomplete fiber tow wet-out. This indicates potential for optimization of processing conditions.

Impact testing yielded Charpy values of 55 kJ/m² (notched) and 75 kJ/m² (unnotched) in edgewise configuration, demonstrating significant notch sensitivity. Flatwise results were inconclusive due to specimen flexibility.

The obtained results provide a property baseline for this composite system and support future improvements to compression molding parameters in film stacking.