Materials

This review highlights conventional forging steels and advanced medium-Mn steels containing retained austenite (RA), emphasizing their potential for industrial forging applications. Modern steels intended for forgings are required to combine strength, ductility, toughness and fatigue resistance with good hardenability and machinability at minimal cost. Medium-Mn multiphase steels fulfill these requirements by the strain-induced martensitic transformation (SIMT) of fine, lath-type RA, which can create a strength–ductility balance. Ferritic–austenitic steels provide high ductility with moderate strength, martensitic–austenitic steels show very high strength at the expense of ductility, and bainitic–austenitic steels achieve intermediate properties. Impact toughness and fatigue resistance are strongly influenced by the morphology of RA. The lath-type RA enhances energy absorption and delays crack initiation, while blocky RA may promote intergranular fracture. Low carbon (0.2–0.3 wt.%) combined with elevated manganese (3–7 wt.%) contents provides superior hardenability and machinability, enabling cost-effective air-hardening of components with various cross-sections. Advanced medium-Mn steels provide a superior mechanical performance and economically attractive solution for modern forgings, exceeding the limitations of conventional steel grades.

The growing demand for palladium (Pd) necessitates the development of sustainable and efficient recovery methods. This work presents a green, one-step synthesis of activated carbon (AC) from winemaking waste (grape seeds) via direct pyrolysis, eliminating the need for separate, energy-intensive activation. Remarkably, the AC synthesized at the lowest temperature of 400 °C exhibited the highest Pd(II) adsorption capacity (16.20 mg/g at 50 °C), performing comparably to many literature-reported ACs that underwent complex activation processes. Characterization revealed that this optimal material possessed a favorable point of zero charge (PZC 7.78) and the lowest ash content (4.66%). Higher pyrolysis temperatures (400–800 °C) progressively increased surface basicity (PZC up to 11.00) and carboxylic group content (reaching 0.565 mmol/g at 800 °C). A comprehensive life cycle assessment (LCA) demonstrated the significant environmental advantage of this method, showing a 74% lower total environmental impact and a 92% reduction in acidification potential compared to commercial coal-based AC. These results prove that highly effective Pd(II) recovery can be achieved through a simplified, direct pyrolysis process, offering a sustainable and practical approach for precious metal recycling from waste biomass.

This study investigates the influence of silane coupling agents and multi-walled carbon nanotubes (MWCNTs) on the mechanical, durability, and thermal performance of CFRP rebars manufactured using a pilot-scale pultrusion process. The incorporation of additives extended epoxy working time without causing adverse viscosity effects during processing. Silane-modified CFRP rebars exhibited the highest mechanical performance, achieving a tensile strength of approximately 2649 MPa, an elastic modulus of 156 GPa, and improved bond strength with concrete, which is attributed to enhanced fiber–matrix interfacial adhesion. MWCNT-modified rebars showed slightly lower tensile strength but demonstrated superior thermal resistance, retaining the highest proportion of mechanical properties after exposure to 250 °C due to matrix reinforcement and crack-bridging effects. No significant degradation was observed under simulated marine exposure, while gradual reductions (up to ~7%) occurred in alkaline environments, with silane-modified rebars showing the greatest durability. These findings provide mechanistic insights and practical guidelines for optimizing epoxy formulations to enhance the structural and long-term performance of CFRP rebars.