High-silicon (1.5–2.5 wt%) steels were designed to achieve carbide-free bainitic matrices with retained austenite through industrial hot rolling, with coiling temperatures of 310 °C and 350 °C. The resulting ultrahigh strength steels (1409–1644 MPa) were characterized through tensile testing, Charpy impact toughness, and Kahn tear tests, while microstructural analysis was performed using scanning electron microscopy and X-ray diffraction. Both yield and tensile strengths correlated strongly with bainitic matrix characteristics, including phase fraction, dislocation density, carbon content, and plate thickness. Ductility showed dependence on film-type austenite content and Md temperature, mechanical stability. The steels exhibited exceptional impact toughness meeting industrial requirements, with ductile fracture behaviour observed down to −100 °C, challenging previous findings. Crack resistance values matched or exceeded those of comparable ultrahigh strength steels. The lower coiling temperature (310 °C) produced retained austenite with higher mechanical stability, benefiting tensile properties and crack resistance, while impact toughness remained largely unaffected by austenite stability due to high strain rates.

In this work, we provide with an overview of the main theories, metallurgical and microstructural concepts used for the design of carbide free bainitic steels adapted to industrial hot rolling and coiling practices. The selected alloys were cast and tested at pilot plant scale and the obtained good combinations of properties tend to validate the thorough and careful approach undertaken to predict the microstructures during the alloy design process.

The development of superior mechanical properties in medium-Mn requires the optimization of microstructural parameters such as retained austenite (RA) stability, volume fraction, and morphology. The present work explores the possibility of using a continuous annealing approach instead of conventional batch annealing to perform an intercritical annealing (IA) treatment in a hot-rolled strip of an Al-alloyed 5Mn steel. Dilatometric studies were performed at a temperature of 680 ºC with soaking times ranging from 1 to 300 min to follow the microstructural changes as a function of time. The microstructures thus obtained were thoroughly characterized by means of X-ray diffraction, SEM and TEM, TEM-EDS microanalysis and EBSD phase and orientation maps. It was observed that with increasing soaking times, the volume fraction of retained austenite gradually increases, albeit at the cost of its stability. The comparison of martensite start temperatures (M_s) based on the chemical composition of austenite at 680 ºC with that experimentally obtained at higher process temperature revealed the effect of the grain size on the reduction of RA stability for longer process times. Accordingly, mechanical tests results showed that the yield stress, tensile strength and hardness decrease with an increase in the IA soaking time.

The novel use of double austempering treatments in a multiphase steel to refine and homogenize the final microstructure and thus improve the material strength have been studied in the 3.3Mn-0.17C-1.6Al-0.23Mo-0.22Si alloy. The microstructural features developed after conventional isothermal austempering treatments at 450 °C and 400 °C were compared with those obtained after two-step heat treatments. These treatments consisted of a first isothermal holding at a temperature slightly above the initial M_s, that was interrupted at 25 and 50% of transformation, followed by a second stage treatment at a lower temperature to complete the bainitic transformation. One- and two-step treatments were performed in a high-resolution dilatometer, and the critical transformation temperatures and phase transformation kinetics were determined from the longitudinal changes recorded during these tests. It was shown that blocky-type austenite was almost completely eliminated after the two-step treatments, which in turn positively reduced the amount of fresh martensite from ∼6 to «1%. It was possible to keep the volume fraction of retained austenite above 10%, while reducing both the thickness of the bainitic plates and the film-like retained austenite by 20% and more than 40%, respectively. These microstructural characteristics made it possible to increase the hardness of the alloy by approximately 50 HV and yield strength by 180 MPa.

Integrated risk assessment approaches to support coastal managers' decisions when designing plans are increasingly becoming an urgent need. To enable efficient coastal management, possible present and future scenarios must be included, disaster risk reduction measures integrated, and multiple hazards dealt with. In this work, the Bayesian network-based approach to coastal risk assessment was applied and tested at two Mediterranean sandy coasts (Tordera Delta in Spain and Lido degli Estensi-Spina in Italy). Process-oriented models are used to predict hazards at the receptor scale which are converted into impacts through vulnerability relations. In each site, results from 96 simulations under different scenarios are integrated by using a Bayesian-based decision network to link forcing characteristics with expected impacts through conditional probabilities. Consultations with local stakeholders and experts have shown that the tool is valuable for communicating risks and the effects of risk reduction strategies. The tool can therefore be valuable support for coastal decision-making.

There exists a large uncertainty about the importance of crossshoreface sediment fluxes both in relation to the dynamic evolution of the shoreface profile and the potential role as a sink or souree to the 'active' zone. The increasing availability of more reliable long-term observational data (direct and indirect) and of more detailed shoreface field observations seems to support earlier suggestions that the shoreface may be a potential souree of coarser sediments to the nearshore. Here, this process is investigated by hindcasting and extrapolating long- and short-term observations available for the shoreface along the Ebro Delta. Analysis of the field data indicates that a structural onshore sediment flux is likely. Although a direct proofthat this is also true on longer-term seales is not easy to substantiate, the careful conclusion is drawn that there exists circumstantial evidence that there is a net long-term feeding of coarser sediment towards the nearshore to an amount which is just about enough to compensate for 'Iosses' due to the present sea-level rise rate in the region.