The current study investigates the microscale mechanical properties of the constituent phases and their influence on the macroscale properties of multi-phase steels with different microstructural constituents. Two steels, a Transformation Induced Plasticity (TRIP) and an enhanced ductility Dual Phase (DH) steel were produced in a continuous annealing line (CAL). Optical microscopy and EBSD results were utilized for segmentation of microstructural phase constituents. Macroscale mechanical properties were obtained using tensile testing and microscale properties with nanoindentation mapping. The hardness of each constituent is extracted from the hardness maps using a clustering algorithm. TRIP steel shows a homogeneous distribution of retained austenite in ferrite matrix and a small amount of bainite/martensite which is non-banded. In contrast, DH steel shows heterogeneous microstructures where martensite/bainite/retained austenite is found to be banded in the ferrite matrix. Both steels exhibit notable variations in hardness across their constituent phases, which are associated with the resulting microstructural characteristics. Nanoindentation results show that overall hardness/strength in TRIP steel is contributed from ferrite (66 %), retained austenite (33 %) and martensite/bainite (1 %). Whereas in DH steel, it is contributed from ferrite (55 %), mixture of RA, martensite/bainite (∼40 %) and martensite (∼5 %). The macroscopic behavior of TRIP and DH steels was explained and discussed using the rule of mixtures in conjunction with the microscopic properties of individual phases.

Urban stormwater is sometimes a risk, sometimes a resource. To address both aspects, the Three Points Approach (3PA) is advocated. This research applied the 3PA to map stormwater approaches in two Chinese and four European cities. While all cities have targets for the Technical Design Domain, none have targets for all domains; and thereby lack interventions to maximize benefits of frequent small events in the Day-to-Day Domain or minimize flood risks of rare large events in the Extreme Domain. Using open global precipitation data cities’ stormwater targets were expressed as more comparable rain depths, demonstrating that event depths within the Day-to-Day Domain in Chinese cities, cover much of the same range as those within the Technical Design Domain in the European cities. Expressing targets as depths in the context of the 3PA framework may facilitate transdisciplinary and transnational knowledge sharing, paving the way for management strategies covering all three domains.

A carbide-free bainitic microstructure is suitable for achieving a combination of ultra high strength and high ductility. In this work, a steel containing nominally 0.34C-2Mn-1.5Si-1Cr (wt.%) was produced via industrial hot rolling and laboratory heat treatments. The austenitization (900°C, 30 min.) and austempering (300-400°C, 3 h) treatments were done in salt bath furnaces. The austempering treatments were designed to approximately simulate the coiling step, following hot rolling and run-out-table cooling, when the bainitic transformation would take place and certain amount of austenite would be stabilized due to suppression of carbide precipitation. The microstructures and various mechanical properties (tensile properties, bendability, flangeability, and room and subzero temperature impact toughness) relevant for applications were characterized. It was found that the mechanical properties were highly dependent on the stability of the retained austenite, presence of martensite in the microstructure and the size of the microstructural constituents. The highest amount of retained austenite (∼ 27 wt.%) was obtained in the sample austempered at 375°C but due to lower austenite stability and coarser overall microstructure, the sample exhibited lower tensile ductility, bendability, flangeability and impact toughness. The sample austempered at 400°C also showed poor properties due to the presence of initial martensite and coarse microstructure. The best combination of mechanical properties was achieved for the samples austempered at 325-350°C with a lower amount of retained austenite but with the highest mechanical stability.

This paper deals with the shunt compensation design of long 380kV-50Hz XLPE cables by simulating a double-circuit partially cabled connection with the transmission length of 80km in the Dutch transmission system. The proposed procedure for shunt compensation sizing is fully elaborated in this paper. Four sizing criteria are used to find the minimum required size of compensation. All simulations are performed for different cable lengths. Moreover, different compensation arrangements including line-end and distributed arrangements are compared in terms of minimum required compensation size. Finally, the influence of mixed-line configuration, i.e. the number and the location of cable sections, on the minimum required compensation size is investigated by simulating five mixed-line configurations. All simulations are performed for two load-flow scenarios representing two extreme situations in the future planning of the Dutch transmission grid.