The present work is concerned with the determination of boron activation energy in the C35 steel and an estimation of the mass gain generated by the boriding treatment. The boride layers are produced by the pack-boriding method on the C35 steel in the temperature range of 800−1000 °C for a treatment time ranging from 0.5 to 8 h. The presence of both FeB and Fe2B phases was confirmed by the X-ray diffraction technique and by a microscopic examination of the cross-sections of borided samples. The boron activation energy was evaluated as 153.1 kJ mol-1 in the temperature range of 800−1000 °C. This value of energy is in agreement with the literature data. The mass gain was measured by weighing the samples before and after the boriding treatment by the weighing technique. The evolution of mass gain as a function of temperature and time can be described by a parabolic law. Finally, an iso-thickness diagram was established to be used as a tool to optimize the boride layers thicknesses according to the industrial application.

Lightweight steel-framed (LSF) structural elements in building construction provide a way of increasing building sustainability. These structural elements present great potential for recycling and reuse, allowing the conservation of natural resources and the environment. When compared with other materials, these construction components also provide other advantages: reduced weight with simultaneous high mechanical strength; easier prefabrication, allowing modular elements and higher quality control; shorter periods for assembling the building on-site; no dimensional variations caused by moisture; and low cost. The high thermal conductivity of steel could be a drawback, leading to thermal bridges if not well designed and executed. In the case of LSF components (e.g. walls and slabs) it is necessary to take special care with the elements’ design optimisation, with it being essential to use continuous thermal insulation. The building envelope thermal performance is crucial to provide good thermal behaviour and energy efficiency, allowing a reduction of operational energy. In this paper, the LSF construction system is analysed in order to show its main advantages and drawbacks. The assessment of embodied and operational energy is essential to perform a life cycle analysis. The reduction of both energies’ consumption is crucial to increase the sustainability label. Special focus will be given to the mitigation strategies of operational energy in LSF construction.

Maximization of non-coking coal in coal blend is eloquent interest among researchers in coke making throughout the world. To maximize the non-coking coals in coal blend with the scarce and expensive coking coals is an essential practice in the iron and steel industry. The fundamental aspect of the coal blending theory of low value coals to produce good quality of metallurgical coke in non-recovery coke making process was investigated in this study by using the composite coking potential technique. The implementation of the technique has yielded use of up to 25% pulverized coal injection, 20% raw petroleum coke as a component of coal blend. Results show that the coal blend having composite coking potential value of \hbox{$\geqslant $}⩾4.8 is desired to achieve the targeted coke strength after reaction of \hbox{$\geqslant $}⩾65.

From a ferrite/martensite cold-rolled microstructure, the interaction between ferrite recrystallization and austenite formation is investigated. It is observed that a slow heating rate promotes the ferrite recrystallization and a homogeneous microstructure, whereas a fast heating rate delays the recrystallization and leads to heterogeneously distributed austenite islands.

Certification initiatives are product-focused, rely on standards and use sustainability metrics to inform end-users on the provenance of commodities. In the metals sector, the phenomenon of formal certification programs has recently gained traction. Four initiatives are reviewed to illustrate the status and prospects of metal certification. The prime case is the Conflict Free Smelter Program operated by the global electronics industry. This scheme has developed and applied standards on mineral chain-of-custody, including use of third-parties to audit smelters and refineries all over the world. Additional programs discussed are the Green Lead Project, Fair Trade and Fair Mined gold, and the Responsible Jewellery Council. Collectively these initiatives address a variety of sustainability criteria, including social, economic and environmental dimensions, but focus only on precious and specialty metals (Au, platinum group, Pb, Sn, Ta and W). Metals certifications programs are building capacity and infrastructure compared to mature programs in agriculture and other commodity sectors. Opportunities and issues for growth of metals certification are considered.

The beneficial effect of B on the hot ductility of 20CrMnTi steel with 0.05% Sn was investigated. The results show that there is a trough in the hot ductility-temperature curve. With the increase in the B content, the trough shifts to a lower temperature and becomes shallow, and the hot brittle range becomes narrow. In addition, B greatly enhancing the hot ductility was due mainly to its suppressing the Sn segregation, retarding the austenite/ferrite deformation, accelerating the onset of dynamic recrystallization (DRX) and promoting the intragranular nucleation of ferrite. Moreover, in the present case, adding 92 ppm B can nucleation of ferrite. Moreover, in the present case, adding 92 ppm B can obtain the best effect in improving the hot ductility of 20CrMnTi steel with 0.05% Sn.

Hot tearing defects appear during the last steps of casting solidification of dendrites. The crystalline structure traps a small amount of liquid metal, which is depressed, and cavities are spontaneously initiated. Molecular dynamics (MD) simulations of pure iron are able to predict, on one hand, the high temperature elastic modulus of crystals, and on the other hand, the cavitation event in liquid metal and near the solid-liquid growth front. High values of elastic tensor components are predicted close to the melting temperature. We conclude that a weakening of the mechanical properties of the crystal is not the reason for failure initiation. The crystals are thinned by partial melting as the effect of negative pressure increases. The cavitation is spontaneously initiated under a very high negative pressure. The cavity expands very quickly and applies a pressure wave to the thinned crystals. We propose that this crystal thinning/pressure wave coupling is able to initiate cracks inside the crystal.

Recently, the issue of sustainable resource management has been increasingly recognized. Economic growth of human activity is associated with a rapid rise in the use of resources in our economy, and society has a potential environmental impact. The UNEP International Resource Panel (IRP) pointed out the importance of decoupling resource use and negative environmental impacts from economic activity (UNEP IRP 2011). In order to optimize the material cycles and increase resource efficiency, material flow analysis (MFA) is a powerful tool to understand the resource consumption and material cycle in the national economy. In this study, we present the results of global material flow analysis of nickel, which is one of the important resources for reducing energy use and CO2 emission in our society, and discuss the importance and possibility of controlling its resource logistics. This study also introduces the challenge of identifying the land-use changes in nickel mining sites by a remote-sensing technique, and knowledge to increase the resource efficiency in metal recycling based on the metallurgical thermodynamic approach. The results indicated the importance of recovery of nickel in recycling policies for end-of-life (EoL) vehicles and constructions. Improvement in EoL sorting technologies and implementation of designs for recycling/disassembly at the manufacturing phase are needed. Possible solutions include development of sorting processes for steel scrap and introduction of easier methods for identifying the composition of secondary resources. Recovery of steel scrap with a high alloy content will reduce primary inputs of alloying elements and contribute to more efficient resource use.

The accuracy of the parameters is of great importance in the calculation and simulation of the COREX process. Therefore, it is necessary to measure some parameters, especially the heat loss and its distribution, which have not been reported before. Based on the characteristics of the two sets of the Baosteel COREX-3000 process, a method and standard are established for the heat loss and its distribution. Then the heat loss and distribution are calculated based on the measured parameters. The results show that the total heat loss of the two COREX processes is 495.4 MJ/tHM and 413.7 MJ/tHM. The heat loss caused by cooling water accounts for more than 93% of the total heat loss while the heat loss of furnace shells is less than 7%. The main heat loss caused by cooling water takes place at the tap hole zone, which is also the part of the COREX system with the most heat loss Its heat loss is about 30% of the heat loss caused by cooling water and 28% of the total heat loss of the COREX system. The main heat loss of furnace shells takes place at the dome of the melter-gasifier and the reducing gas entrance position of the shaft furnace, where the heat loss accounts for nearly 90% of the heat loss of furnace shells. It is also found that the energy utilization efficiency of the 1# COREX system is much lower than that of the 2# COREX system after comparison.

The growth velocity during solidification of an undercooled melt of a Co-Cu alloy processed by electromagnetic levitation was measured using a high speed video camera. Applying a model of local non-equilibrium solidification, theoretical predictions of dendrite growth velocity and dendritic growth radii are compared with high-accuracy measurements of the growth kinetics. As the undercooling ΔT reaches a critical value consistent with the dendrite growth velocity being equal to the atomic diffusion speed VD in bulk liquid, ΔT = ΔT(VD), the velocity-undercooling relationship exhibits a break-point. A distinct change in the dendritic growth mechanism exists with the onset of complete solute trapping and chemically partitionless solidification of the core of the main stems of the dendrites occurs. A complete transition to the thermally controlled growth of dendrites occurs at ΔT = ΔT(VD) that leads to essential changes in the microstructure of dendritic patterns The phenomenon of dendritic fragmentation in Co-Cu melts, solidifying at ΔT < ΔT(VD), is discussed.

The nature of the intermetallic layer which forms on the steel surface during immersion in typical galvanizing baths for galvannealed (GA) sheets production has been investigated on two commercial Titanium-stabilized Interstitial-Free (Ti-IF) steel substrates galvanized in baths with different Al contents. Results from this study show that in both cases the inhibition layer is biphasic and composed of a very thin Al-rich phase layer, identified as Fe2Al5Znx, and a thicker Zn-rich phase layer on top of it, identified as δ. Experimental results also show that the Fe2Al5Znx phase layer becomes discontinuous when decreasing the bath Al content. Discussions about the mechanisms of formation and the final microstructure of this inhibiting layer are also tackled in this paper by means of the Al-Fe-Zn ternary phase diagram at 460 °C and assumptions to justify any deviation from thermodynamic equilibrium are as well proposed.

The influence of TiO2 addition to LF refining slag on Ti-stabilized stainless steel was evaluated using a vacuum induction furnace at 1873 K. The effect of CaO-SiO2-MgO-Al2O3 basic slags with different TiO2 contents on the titanium loss, aluminum loss and total oxygen content in the steel was studied. It was observed that the oxidation rate of Ti first decreases and then increases with the increase in the content of TiO2 in slag and reaches the minimum when 8%TiO2 is added to the slag. However, the change in the oxidation rate of Al shows the opposite tendency. The total oxygen in the molten steel remains unchanged with time when 8%TiO2 is added to the slag, and the total oxygen of the others increases monotonically with time. The activities of TiO2 and Al2O3 from the calculation of the ion and molecule coexistence theory (IMCT) in the initial slag present the same change tendency, and both first increase and then decrease with the gradual increase in TiO2 in the slag and reach the maximum when 8%TiO2 is added to the slag. The results of a kinetic analysis showed that the rate-determining step of the oxidation of Ti in the steel is the mass transfer on the slag side, and the rate-determining step of the oxidation of Al in the steel is the mass transfer on the metal side.

Brass-graphite composites were fabricated by adding graphite/Cu/Zn compact powder usingthe stir-casting technique and their tribological behavior against a brass disk was studied under simulated actual conditions, in comparison with the common graphite/brass composite The tribological properties of the brass-graphite composite were compared with different percentages of graphite in the structure using the pin-on-disk method. The experimental results showed that the 7−9 wt.% graphite creates a better wear resistance in high-pressure applications. Continuous Zn layers successfully covered the surface of the graphite particles, which could contribute to the improvement of interfacial wettability between graphite and brass. In this study, brass-graphite composites containing 8.4 ~ 15 wt.% of Ni-coated graphite were fabricated. The friction coefficient of composites decreased with increasing graphite content. The wear resistance was improved by the addition of Ni-coated graphite but degraded at high graphite content. The results indicated this composite showed much better mechanical properties and tribological properties in comparison with brass. The composite with 11.7 wt.% nickel-coated graphite showed the best tribological properties.

Since sustainability and environmental issues rose lately, lightweighting has been the point of interest for automotive and aerospace sectors. Lightweighting reduces the fuel consumption of the vehicles and as a result of this reduces emissions. Aluminum, especially wrought aluminum alloys, have large potentials for dramatic weight reduction of structural parts while maintaining the safety and performance. Wrought aluminum alloys are used in automotive skin, bumpers and suspension parts etc. Lightweight suspension parts improve the ride quality and handling, additional to fuel consumption and emission reduction. Holistic life cycle approach takes into account the material flows and related information flows in order to achieve these material flows through the life cycle of the components as well as performance characteristics not only in technical and economic terms but also environmental and social terms. It is necessary to have seamless information flow through the life cycle of the components that could be enabled by the closed-loop product life cycle management (PLM). Closed-loop PLM may also help collection of life cycle information which is necessary to generate performance characteristics and distribution of performance characteristics among life cycle actors.

There are many examples world-wide how mining contributes to sustainable regional development. The LKAB mining and processing of iron ore in the north of Sweden, in the Arctic Region, is such an example. The definition of sustainable mining is however not clear-cut and further studies are necessary to fully understand the impacts on economy, society and environment.

In regard to the sustainability of future cities, an increase in sustainable energy sources needs to be managed. Therefore, the German government decided on increasing the ratio of green energy up to 20% by 2020. In accordance with this, offshore wind energy parks will be constructed, as they provide the advantage of lasting air cleanliness and preserving natural resources. To ensure construction safety, wind energy mills are constructed using ductile steels of large thickness. Here, an application of high-strength steels provides the possibility of reducing the amount of material while construction safety is still ensured. Considering the long life cycle of wind energy mills’ foundation structures and the recyclability of the steel grades used, their construction becomes a relevant factor in reducing CO2 emissions. Furthermore, the use of less material reduces CO2 emissions. Due to existing safety concepts, however, the application of high-strength steels is only conditionally allowed. Thus, the current study concerns the development of a safety concept based on the existing concepts to allow the application of high-strength steels. Furthermore, as the structural steel parts need to be joined, an energy-efficient welding process is utilised: electron beam welding. The structural steel parts and weld joints are investigated with respect to their mechanical properties by analysing their loadability in combination with safety concepts. The load on the material is evaluated to ensure construction safety. In addition to the investigation of safety requirements, the supplied mechanical properties are investigated. As the weld joints show different properties from the base material, the joints are considered the critical part. The joints are investigated concerning strength and toughness. Afterwards the mechanical properties are correlated with the wind energy structures. The prevention of failure is fulfilled when the mechanical properties of the weld joints exceed the required mechanical properties.

The influence of LF refining slag composition on desulfurization and inclusion modification was investigated through industrial experiments and thermodynamic analysis. The results show that the sulfide capacity decreases with the decrease in (%CaO)/(%SiO2) and (%CaO)/(%Al2O3) of the slag. The theoretical sulfur distributions agree well with the analysis results when the sulfide capacity is calculated by Zhang’s model, but the theoretical sulfur distributions are higher than the analysis results when the sulfide capacity is calculated by the KTH model. During the LF refining process, inclusions are transformed from Al2O3 inclusions into CaO-MgO-Al2O3 system inclusions. Higher slag basicity results in higher CaO and MgO and lower Al2O3 content inclusions in molten steel at the end of the LF process.