Electron Beam Melting (EBM) is a powder-bed additive manufacturing technology enabling the production of complex metallic parts with generally good mechanical properties. However, the performance of powder-bed based additively manufactured materials is governed by multiple factors that are difficult to control. Alloys that solidify in cubic crystal structures are usually affected by strong anisotropy due to the formation of columnar grains of preferred orientation. Moreover, processing induced defects and porosity detrimentally influence static and cyclic mechanical properties. The current study presents results on processing of a metastable austenitic CrMnNi steel by EBM. Due to multiple phase transformations induced by intrinsic heat-treatment in the layer-wise EBM process the material develops a fine-grained microstructure almost without a preferred crystallographic grain orientation. The deformation-induced phase transformation yields high damage tolerance and, thus, excellent mechanical properties less sensitive to process-induced inhomogeneities. Various scan strategies were applied to evaluate the width of an appropriate process window in terms of microstructure evolution, porosity and change of chemical composition.

Fabrication of biomimetic materials and scaffolds is usually a micro- or even nanoscale process; however, most testing and all manufacturing require larger-scale synthesis of nanoscale features. Here, we propose the utilization of naturally prefabricated three-dimensional (3D) spongin scaffolds that preserve molecular detail across centimeter-scale samples. The fine-scale structure of this collagenous resource is stable at temperatures of up to 1200°C and can produce up to 4 × 10–cm–large 3D microfibrous and nanoporous turbostratic graphite. Our findings highlight the fact that this turbostratic graphite is exceptional at preserving the nanostructural features typical for triple-helix collagen. The resulting carbon sponge resembles the shape and unique microarchitecture of the original spongin scaffold. Copper electroplating of the obtained composite leads to a hybrid material with excellent catalytic performance with respect to the reduction of p-nitrophenol in both freshwater and marine environments.

Electron beam melting (EBM) is an established powder bed-based additive manufacturing process for the fabrication of complex-shaped metallic components. For metastable austenitic Cr-Mn-Ni TRIP steel, the formation of a homogeneous fine-grained microstructure and outstanding damage tolerance have been reported. However, depending on the process parameters, a certain fraction of Mn evaporates. This can have a significant impact on deformation mechanisms as well as kinetics, as was previously shown for as-cast material. Production of chemically graded and, thus, mechanically tailored parts can allow for further advances in terms of freedom of design. The current study presents results on the characterization of the deformation and strain-hardening behavior of chemically tailored Cr-Mn-Ni TRIP steel processed by EBM. Specimens were manufactured with distinct scan strategies, resulting in varying Mn contents, and subsequently tensile tested. Microstructure evolution has been thoroughly examined. Starting from one initial powder, an appropriate scan strategy can be applied to purposefully evaporate Mn and, therefore, adjust strain hardening as well as martensite formation kinetics and ultimate tensile strength.

As a first step towards optimisation of ladle treatment work, mathematical modelling of heat transfer in the ladle has been undertaken. A numerical model considering heat transfer is developed which can be used for prediction of the ladle lining temperature fields during steel casting sequences depending on wear rates and used lining materials. The model is based on Fourier differential equations. In the cases of dolomite brick, the calculational results are compared with temperature measurements from earlier publications for the periods of charged ladle, teeming, empty state and preheating whereby a good agreement is found.

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The melting of steel scrap in high temperature liquid iron melt is investigated by conducting cold model experiments of the melting of ice sample of different geometries and sizes in an argonstirred vessel containing water. The melting process of ice samples is observed using a highspeed camera. Design of experiments is based on similarity criteria. The relationships between non-dimensional groups related to heat transfer (Nu, Re, Pr, and Gr) are derived for different experimental conditions. The results are compared with those reported in the literature. The heat transfer coefficient is estimated as a function of mixing power and is found to be in good agreement with the calculated values obtained by using reported relationships in literature.

A novel Quenching‐Deformation‐Partitioning (QDP) processing is applied to the Fe–19Cr–4Ni–3Mn–0.5Si–0.14N–0.16C (wt%) TRIP/TWIP steel with a microstructure consisting of austenite and 4 vol% δ‐ferrite in the solution annealed (SA) condition. The QDP processing involves pre‐straining at −40 °C followed by partitioning at 450 °C for 3 min. The volume fraction of strain‐induced α′‐martensite after an engineering pre‐strain of 25% at −40 °C is about 56 vol%. In spite of the formation of precipitates inside the α′‐martensite during partitioning, the austenite is enriched with the interstitial elements C and N. After QDP processing, the steel exhibits outstanding mechanical properties, for example, a yield strength of 1330 MPa, an ultimate tensile strength of 1490 MPa, and a total elongation of 16% at room temperature (RT). The yield strength and the ultimate tensile strength increase by 290% and 70%, respectively, with respect to the SA condition. The reduction of the tensile test temperature from 100 °C to −40 °C results in a concurrent enhancement of strength and ductility. The enhancement of tensile ductility at lower temperatures is explained by the enhanced glide planarity originating from the facilitated dissociation of perfect dislocations into Shockley partials.

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