This study evaluates the application of metal additive manufacturing—specifically the laser powder bed fusion (LPBF) process—for producing aluminium die-casting mould components, comparing 300-grade maraging steel inserts with conventional H13 tool steel. Efficient thermal management and mould durability are critical in aluminium injection moulding. Still, traditional machining limits the design of cooling channels, resulting in hot spots, accelerated wear, and a reduced service life. LPBF allows the fabrication of complex geometries, enabling conformal cooling channels to enhance thermal control. Component samples were manufactured using maraging steel via LPBF, machined to final dimensions, and subjected to duplex surface treatment (plasma nitriding + CrAlN PVD coating). Thermal performance, dimensional stability, mechanical properties, and wear resistance were experimentally assessed under conditions simulating industrial production. The results demonstrate that LPBF components with optimised cooling channels and surface engineering achieve higher thermal efficiency, an extended service life (up to 2.6×), improved hardness profiles (545 HV0.05 core, 1230 HV0.05 on nitrided surface and 2850 HV0.05 after PVD film deposition), and reduced maintenance frequencies compared to H13 inserts. The study confirms that additive manufacturing, combined with tailored surface treatments and optimised cooling design, overcomes the geometric and thermal limitations of conventional manufacturing, offering a reliable and productive solution for aluminium die-casting moulds.

Metal Injection Molding (MIM) is an established, high-precision manufacturing route for small, geometrically complex metallic components, integrating polymer injection molding with powder metallurgy. State-of-the-art feedstock systems, such as Catamold (polyacetal-based), enable catalytic debinding performed in furnaces operating under ultra-high-purity nitric acid atmospheres (>99.999%). The subsequent thermal stages pre-sintering and sintering are carried out in continuous controlled-atmosphere furnaces or vacuum systems, typically employing inert (N₂) or reducing (H₂) atmospheres to meet the specific thermodynamic requirements of each alloy. However, incomplete decomposition or secondary volatilization of binder residues can lead to progressive hydrocarbon accumulation within the sinering chamber. These contaminants promote undesirable carburizing atmospheres, which, under austenitizing or intercritical conditions, increase carbon diffusion and generate uncontrolled surface carbon gradients. Such effects alter the microstructural evolution, hardness, wear behavior, and mechanical integrity of MIM steels. Conversely, inadequate dew point control may shift the atmosphere toward oxidizing regimes, resulting in surface decarburization and oxide formation effects that are particularly detrimental in stainless steels, tool steels, and martensitic alloys, where surface chemistry is critical for performance. This review synthesizes current knowledge on atmosphere-induced surface deviations in MIM steels, examining the underlying thermodynamic and kinetic mechanisms governing carbon transport, oxidation, and phase evolution. Strategies for atmosphere monitoring, contamination mitigation, and corrective thermal or thermochemical treatments are evaluated. Recommendations are provided to optimize surface substrate interactions and maximize the functional performance and reliability of MIM-processed steel components in demanding engineering applications.

Powder metallurgy enables the production of composite materials, which are of great interest to different branches of the automotive, aerospace, and medical industries. This work investigated the sintering of an Al-xCu and Al-xCu-0.1Sn alloy, with copper concentration between 3.5 and 4.5% and tin added in the range of 0.1%. Compressibility curves were drawn, and the samples were sintered in a high-purity nitrogen-controlled atmosphere furnace. The composites were subjected to subsequent solubilization heat treatment, with cooling in low concentration polymer solutions and artificial aging (T6). The samples were studied using optical, scanning electron, Vickers microhardness, and X-ray diffraction techniques. The results indicated the effectiveness of cooling the samples after solubilization in polymer solutions, the influence of the addition of tin on the aging time, and the mechanical properties of the alloys as a function of the T6 cycles applied.

The characterization of mechanical properties in heat-treated carbon steels, which is crucial for quality control, traditionally relies on destructive testing. This study evaluated the reliability of the non-destructive ultrasonic technique as a metrological alternative for AISI 1045 steel. Samples subjected to six heat treatment conditions (Annealing, Normalizing, Quenching, and Tempering) were characterized by hardness, metallography, and ultrasound. Through linear regression analyses, the multiparametric model combining sound velocity, attenuation, and FWHM demonstrated exceptional metrological precision, resulting in a coefficient of determination of (R² = 96.687%). The metrological robustness of the model was validated by quantifying the Expanded Uncertainty (U), following the GUM (Guide to the Expression of Uncertainty in Measurement). It is concluded that the multiparametric ultrasonic methodology is an accurate, robust, and non-destructive alternative for the quantitative determination of Vickers Hardness in AISI 1045 steels, contributing to the optimization of industrial processes and metrological rigor.

The effect of adding 1 wt.% graphene oxide (GO) to a low-carbon steel feedstock processed by metal injection molding (MIM) was investigated in terms of its thermal behavior, chemical composition after sintering, microstructure, and response to carbonitriding followed by quenching and tempering. Differential scanning calorimetry (DSC) revealed a shift in the melting peak of the polymeric binder system from 158 to 161 °C and a decrease in its apparent melting enthalpy from 112 to 98 J/g, indicating changes in the thermal behavior of the feedstock rather than melting or phase transformation of the steel matrix. Thermogravimetric analysis showed a shift in the onset of mass loss from approximately 325 to 310 °C, with additional decomposition events occurring between approximately 420 and 450 °C. After sintering, the carbon content increased from 0.118 to 0.219 wt.%, accompanied by higher Cr, Ni, and Cu contents. The GO-containing material also exhibited a finer ferritic grain structure and a higher pearlite fraction, together with indications of increased residual porosity and local microstructural heterogeneity. Following carbonitriding, quenching, and tempering, surface microhardness was substantially higher than core microhardness, and the 5% polymer solution produced the highest cooling intensity and surface microhardness among the evaluated quenching media. Overall, the results indicate that GO addition modified the thermal behavior of the polymeric binder system and was associated with changes in the chemical composition, microstructure, and response of sintered MIM low-carbon steel to carbonitriding and subsequent heat treatment.