JOM最新文献

Metal additive manufacturing is a manufacturing technology that is being investigated for critical industrial applications in industries such as aerospace, nuclear, and medical. A degree of uncertainty remains around these technologies largely due to process and material repeatability, production controls, and a lack of application-specific material data. This research aimed to investigate the effects of extensively reused (175 reuse cycles) Ti-6Al-4V ELI powder feedstock and build orientation on the produced material. Material chemistry, metallography, pin-type bearing strength, and tensile properties were characterized at different build locations and principal orientations. The literature on pin-type bearing strength for both traditionally and additively manufactured material is lacking. Such information is of value for the design of bolted structural joints and fixtures. The results suggest that although extensively reused powder feedstock does experience drift in material properties due to the reuse process, it can still fulfil feedstock material specification requirements. Furthermore, this powder is capable of producing material that meets produced material specification requirements, exhibits minimal orthotropy in mechanical properties, and has ultimate bearing strength that exceeds Ti-6Al-4V grade 5 wrought material allowables. This research provides valuable information for designing structural joints and contributes to the further industrialization of laser powder bed fusion for critical applications.

Several classes of materials are being proposed for use in fusion reactors including oxide dispersion strengthened (ODS) and reduced activation ferritic-martensitic (RAF/M) steels to withstand the severe and harsh conditions. In this work, the mechanical properties of a Fe-16Cr-4Al-2W-0.3Ti-0.3Y₂O₃ (K3) (ODS) ferritic steel and a Fe-8.9Cr-1.1W-0.47Mn-0.2V-0.14Ta-0.11C (Eurofer 97) (RAF/M) steel) after triple ion beam irradiation were locally evaluated utilizing in-situ micro-pillar compression tests, and continuous stiffness/quasi-static nanoindentation. No change in mechanical properties was observed in the K3 ODS steel. However, the Eurofer 97 RAF/M steel exhibited radiation-induced effects via increases in yield strength. Micro-pillar techniques were expanded to neutron-irradiated materials via an in-situ testing technique employing lift-out methods on Fe-14Cr-0.9Ti-0.3Mo-0.25Y₂O₃ (MA957) ODS ferritic steel. Both the non-irradiated and irradiated compressive yield stresses of the MA 957 micro-pillars were in good agreement with bulk yield stress values reported in the literature, suggesting that the lift-out micro-pillar compression testing technique is a promising method. The demonstration of these techniques on ion beam and neutron irradiated ODS steels and ion beam RAF/M steels gives information to inform models of the material degradation during use in a fusion device.

Suitable foaming slag is beneficial for improving electricity utilization efficiency and reducing the electricity consumption of electric arc furnaces. One key factor determining the foaming performance of slag is the presence of certain solid particles. Additionally, the MgO content in the slag must reach saturation to minimize the consumption of refractory materials. In this study, based on the CaO-SiO₂-MgO-FeO slag system and calculations using FactSage 8.3 software, the saturation of MgO and its influence on the foaming properties of slag were investigated. An isothermal saturation diagram and a ternary isothermal cross-section diagram were constructed to compare the foaming properties of slag under different conditions. The relationship between electricity consumption and the foaming properties was verified by industrial test. The results showed that MgO saturation decreases with increasing slag basicity and increases with rising temperature. The effect of FeO content on MgO saturation was more significant at low basicity (B₂ ≤ 1.6) than at high basicity (B₂ > 1.6). Compared to slag outside the optimal foaming range, the average electricity consumption of slag with saturated MgO within the optimal foaming interval was reduced from 350.57 kWh/ton to 333.12 kWh/ton.