Additive manufacturing (AM) of high-strength steels, such as 18Ni300 maraging steel, has attracted considerable attention in aerospace and tooling applications due to its excellent mechanical properties and design flexibility. However, the durability of AM components is significantly affected by both cyclic loading and environmental factors, particularly corrosion. This study investigates the combined effect of heat treatment and corrosive ageing on fatigue performance and hardness of additively manufactured 18Ni300 specimens. Corrosion tests were carried out in an ageing chamber according to ISO 9227 using the acetic acid salt spray (AASS) method for 7 days, at a temperature of 35 ± 2° C. Half of the specimens were exposed to these conditions, while the remaining samples served as a reference group. Hardness measurements (Vickers method) were performed to evaluate the influence of heat treatment and corrosion on surface properties. All specimens were subjected to cyclic loading to determine fatigue behaviour. Fractographic analysis was carried out to identify crack initiation and propagation mechanisms. The results demonstrate the influence of the corrosive environment on fatigue life and hardness, providing information on the degradation mechanisms and contributing to the optimization of post-processing strategies for AM maraging steels under demanding service conditions.
Chronic wounds impose a considerable clinical and economic burden, and their effective management requires objective, repeatable monitoring over time. Smartphone-based photogrammetry may enable acquisition of 3D metrics without the need for expensive dedicated scanners. This scoping review aimed to identify and organize digital methodologies applicable to wound measurement and monitoring, with particular emphasis on smartphone photogrammetry as a practical approach for routine care. A scoping review was conducted to identify digital wound measurement methodologies. The included approaches were organized according to the main pipeline stages: acquisition, reconstruction, and analysis. Reported metrics, including area, depth, volume, and tissue-assessment elements, were catalogued, and validation approaches, comparison methods, and implementation factors were summarized. In addition, a practical photogrammetry workflow with basic quality control (QC) gates is presented as pragmatic guidance informed by the reviewed literature for use during routine dressing changes. A review of the literature reveals that trend analysis, such as the percentage reduction over time appears to have high clinical relevance. Furthermore, the literature indicates that consistency and repeatability of measurement appear to be more important than single-measurement accuracy. Two-dimensional measurements can underestimate wound size on anatomically curved surfaces. In contrast, three-dimensional metrics, such as depth and volume, along with depth maps, may provide a more informative description of deep wounds. In deeper wounds, reductions in depth or volume (Z-axis changes) may precede visible reductions in the two-dimensional outline. The quality of the results appears to be strongly influenced by the acquisition conditions, such as angle, lighting, stability, and marker. The comparability of volumes is limited by the lack of clear definitions of the reference surface and inconsistent reporting of agreement and error metrics. Smartphone photogrammetry is an attractive implementation solution for clinics and telemedicine; however, its efficacy is contingent upon the standardization of acquisition, the integration of simple QC gates, and the establishment of transparent definitions of 3D metrics and compliance reporting. These measures may enhance comparability, facilitating reliable assessments between visits and centers.
Fatigue assessment of additively manufactured (AM) metals is typically based on limited datasets. The small sample sizes increase the risk of misinterpreting the effects of process parameters, geometry, or heat treatment on fatigue life, particularly when scatter shows dependence on stress. This stress-dependent scatter, heteroscedasticity, originates from the interaction of surface roughness, defect morphology, and subsurface porosity, yet it is rarely considered in fatigue design methodologies. In this study, unmachined, aged AM 18Ni300 mar-aging steel specimens with diameters of 3 mm (83 tests) and 4 mm (58 tests) were tested under fully reversed cyclic loading. While both groups showed similar mean fatigue lives, the smaller-diameter specimens exhibited pronounced heteroscedasticity at low stress amplitudes due to competing surface and subsurface crack initiation mechanisms. Bayes factor analysis revealed stress-and size-dependent variance changes, while a stratified bootstrap approach quantified how limited sample sizes affect SN-curve stability. The resulting empirical distributions of regression errors and failure probabilities demonstrated that datasets two to three times larger than ISO 12107 recommendations are required to maintain conservative design reliability. Microcomputed tomography and areal profilometry revealed higher contouring porosity in the smaller-diameter specimens, similar maximum defect sizes, and marginally lower roughness, a combination consistent with the observed heteroscedasticity at low stress amplitudes and the shift toward subsurface-driven failure.
In the Direct Metal Laser Sintering (DMLS) process, up to 96 % of the powder is left unused in the build chamber, while just a tiny percentage of the entire powder is fused to make the component. Due to the high cost and energy demands of powder production and atomization, the ability to collect, recondition, and reuse unfused powder in subsequent builds is essential for improving the environmental and economic sustainability of DMLS operations. Although powder reuse reduces production costs and material waste, ongoing research is still needed to determine how many reuse cycles can be performed without compromising component quality. Therefore, this research explores key process parameters such as built-up thickness of 30, 45, and 60 mu m and exposure duration of 90, 130, and 170 mu m that influence powder reutilization, aiming to determine the optimal reusability for maintaining powder quality and enhancing the performance of DMLS-manufactured parts. Moreover, this research also highlights how the reutilized AlSi10Mg powders influenced the micro-voids, tensile strength and reduced modulus of DMLS parts. To understand the linearity of the received responses, two ensemble models (Bagging and Random Forest) were compared. The confirmation by the ensemble models leads to finding the optimal variable for printing. The experimental validation confirms 5 times reutilization of AlSi10Mg power has enhanced the tensile strength by 55.4 % and reduced modulus by 68.26 %. The influence of clustered particles on the fracture nucleation was also examined based on the reduced modulus mapping and fractography analysis.
