The targeted carbide-free bainitic TRIP microstructure have been obtained in the studied steels thanks to a specific alloy-design, following a classical hot-rolling schedule followed with a fast cooling regime and a coiling stage. Excellent balance between tensile strength and ductility are achieved and explained by transformation hardening phenomena. The sharp influence of gamma stabilizing elements (copper/nickel/manganese) on phase transformations and mechanical properties is highlighted.

As the global economy grows and evolves in the 21st century emerging technologies will require mineral commodities on a greater scale and in a larger number of applications than ever before. The explosive growth in the economies of other nations and the concomitant and explosive increase in demand for raw materials are the reasons for potential supply restrictions. The portfolio of minerals and metals needed for manufacturing is dynamic. If the supply of any of the raw materials used in everyday products and in new emerging technologies was curtailed, many high-tech sectors of the European industries could be significantly affected. For example, the so called “tuning metals” or “spice metals”, although used only in small and essentially as “functional alloyings” in conventional metals are indispensable as “power amplifier” of modern materials used in vehicle construction. These materials are in principle recyclable. However, in most cases it is impossible to recycle them because of the minor concentration in application, thus they are being “consumed”. The Faculty of Georesources and Materials Engineering of RWTH Aachen University is initiating thereupon an integrated interdisciplinary research. The three divisions of the faculty, i.e. Raw Materials and Waste Disposal Technology, Metallurgy and Materials Technology as well as Geosciences and Geography, collaborate on the issue of sustaining critical raw materials availability so that the supply of materials needed for futures industries can be guaranteed. Objective of this research cooperation is to develop life-cycle strategies for critical raw materials which are fundamental for emerging technologies. Securing the availability of raw materials may be accomplished by improving the efficiency of the raw materials chain and by enhancing the raw materials base. Increasing also the knowledge base in this field will enable the European society to transfer more resources into economically efficient and technically manageable as well as politically and socially acceptable mineral and metal reserves. Assuring a sustainable availability of critical metals will be of paramount importance for technical innovations. Researchers and scientists from the Faculty of Humanities at RWTH Aachen University are also involved to study the relation between raw materials supply and economic as well as social matters. Mapping out sustainable strategies for securing the supply of raw materials in the long run requires the competence and input of scientists in fields of natural, engineering, political, economical, and social sciences. Demand and supply of raw materials are affected by the economy, whereas global political and social issues have impact on the same economy.

Brass-graphite composites were fabricated by adding graphite/Cu/Zn compact powderusingthe stir-casting technique and their tribological behavior against a brass disk wasstudied under simulated actual conditions, in comparison with the common graphite/brasscomposite The tribological properties of the brass-graphite composite were compared withdifferent percentages of graphite in the structure using the pin-on-disk method. Theexperimental results showed that the 7−9 wt.% graphite creates a better wear resistance in high-pressureapplications. Continuous Zn layers successfully covered the surface of the graphiteparticles, which could contribute to the improvement of interfacial wettability betweengraphite and brass. In this study, brass-graphite composites containing 8.4 ~ 15 wt.% of Ni-coated graphitewere fabricated. The friction coefficient of composites decreased with increasing graphitecontent. The wear resistance was improved by the addition of Ni-coated graphite butdegraded at high graphite content. The results indicated this composite showed much bettermechanical properties and tribological properties in comparison with brass. The compositewith 11.7 wt.% nickel-coated graphite showed the best tribological properties.

During the cold rolling of metal alloy sheets, the control of lubrication constitutes one of the major industrial problems. The aim of the study reported in this article concerns the rheological characterization of two industrial lubricants, under conditions close to those met in rolling. The application of EHD models then allows to calculate the lubricant film thickness, which is compared to the values measured by interferometry in a ball/disk contact.

The paper has compiled the actual status for grades X80 and X100 from a point of view of a plate manufacturer. An outlook for a possible extension of feasibility and further development is also given. It can be summarized: 1) plates for gas transporting pipes with strength level of grade X80 are nowadays available up to 25.4 mm and can be produced with the same reliability and reproducibility as lower grades; 2) extension of grade X80 to higher plate thickness even in combination with very low design temperature is practicable; 3) during development stages of grade X100 different approaches has been applied. The current preferred approach to produce plates for pipes with design temperature of 0 °C makes use of a low carbon content in combination with a medium carbon equivalent. So called HACCII process is applied to produce these plates. Plates in thickness up to 20 mm for pipe diameter up to 3611 (~914 mm) have been produced with adequate properties; 4) further development is required and started to extent grade X100 to higher thickness, higher pipe diameter and lower design temperatures.

Intersittial free (IF) steels used to produce cold rolled sheets are known to be hyper-drawable after recrystallization by continuous annealing. This is reflected by a low proof stress, a high work-hardening coefficient and a high r-value. From an industrial point of view, it is also important now to know how these properties change if annealing does not lead to complete recrystallization.

Dislocations produced during plastic deformation tend to gather in well defined patterns. Both the shape and the structuring degree of these clusters depend on material parameters and on loading conditions. The present work analyzes these relations and classifies the observations in a schematic structural map. While a strong correlation exists between dislocation patterns and mechanical behaviours, it is shown that there is no direct effect of the substructure on either the stress level or the work-hardening rate of the material.

A new advanced and breakthrough technology has been developed for hot slab on-line surface inspection and installed in Aceralia (Spain). This innovative inspection system, integrating novel Conoscopic Holography, CCD cameras, a complex mechanical system and intelligent tools, operates in the real environment of a continuous casting facility, allows on-line hot slab surface inspection of 100% of the production, detecting cracks - without removing the surface scale - and inclusions (peeling a narrow strip on the surface).

Continuous (CDRX) and discontinuous (DDRX) dynamic recrystallizations in the hot working range are compared on the basis of large strain flow curves and EBSD measurements. The same basic mechanisms occur in the two cases, but with different kinetics leading to distinct textures and microstructures. Furthermore, a transition from CDRX to DDRX may occur in high stacking fault energy metals at very high levels of purity.

This paper presents a part of work developed inside theULCOS project, which aims at the radical reduction of CO2emissions from iron and steel production, through new routes thatmust be sustainable, i.e. environmentally-friendly, economicallyviable and socially acceptable. In order to demonstrate theirsustainability, Key Performance Indicators are the main toolsdeveloped inside the work package 9.4, “Sustainability Model& Process Selection Tool”, which aims at making complex issuesmore manageable. Key Performance Indicators (KPIs) are themost useful tools for evaluating and managing not only theenvironmental and economic impacts, but also the social impacts.The assessment of social aspect of sustainability must betaken into consideration, nevertheless the prediction ofsocial impacts is often hard to be done, not only becauseof the lack of a clear cause-effect relationship but alsobecause of the difficulty to analyse and to predict socialphenomena, especially through a quantitative approach.The purpose of this work is to present a methodology, basedon both quantitative and qualitative approaches, carried outin order to develop the social indicator (Local CommunityImpact Indicator), which has primarily taken into accountpossible impacts of a current integrated steelworks on thecommunities within the close vicinity of the plant operations.

Les fontes au chrome sont bien connues pour leurs propriétés à l’usure. Elles sontutilisées dans les domaines miniers, cimentiers ainsi que tant d’autres. Leurs facultés derésister à l’usure sont principalement dues à leur microstructure qui est constituée d’unréseau de carbure eutectique du type M7C3 contenu dans une matriceausténitique ou martensitique. Plusieurs chercheurs ont exploré la possibilité d’améliorerles propriétés à l’usure de ces fontes en agissant sur la microstructure, la morphologiedes composants microstructuraux ainsi que sur leur distribution. Le présent travailconsiste à étudier l’effet du niobium sur le comportement à l’usure d’une fonte au chrome.Des caractérisations par microscopie optique, usure par abrasion et par frottement sontréalisées dans le but de déterminer la résistance à l’usure de cette fonte et le type demicrostructure ayant été à l’origine de cette amélioration. Les résultats obtenus montrentque la fonte étudiée est une fonte à 15 % de chrome. L’addition du niobium a eu un effetsur la microstructure ainsi que sur les résistances par abrasion et par frottement deséchantillons de fontes traitées. La résistance à l’usure augmente avec l’accroissement dela teneur en niobium.

Based on a model of microstructure evolution, an appropriate rolling schedule has been worked out to produce ultrafine grained steel (2 to 5 μm) on the hot strip mill. This rolling schedule is characterized by a large reduction in the finishers followed by strong cooling. Implementing such a rolling schedule on a conventional HSM raises major problems: increased rolling torque and force, lowered crown and shape control, disturbed looper control, accelerated roll damage, increased slip between strip and roll, insufficient cooling efficiency. These problems have been solved on the new Nakayama HSM by introducing innovative processes such as: single roll drive with different diameter and a new CVC, curtain wall cooling in the finisher, low inertia hydraulic looper, new high-speed steel rolls with solid lubrication.

The efficiency of dephosphorisation is governed by thethermodynamic behaviour of phosphorus and oxygen in moltenmetal, and P2O5 and FeO in slag. The equilibrium distributionof phosphorus and oxygen, for a wide range of chemicalcompositions simulating the evolution of slag composition duringa typical BOF blow, has been experimentally determined. Amathematical model for estimation of the activity coefficients, asa function of the chemical composition, was also attempted.

Les aciers austénitiques sont largement employés dans le cœur des réacteurs nucléaires et sont donc soumis à des flux importants de neutrons, conduisant à de fortes évolutions de leurs propriétés dont une des plus importantes est le gonflement (expansion volumique isotrope). Cette déformation induite par l’irradiation est due à la formation de cavités. Le gonflement est un phénomène à seuil qui dépend des conditions d’irradiation, température et flux mais aussi de l’état métallurgique du matériau et de sa composition chimique. Le changement de matériaux, de l’acier 316 au 15–15 Ti, a permis d’augmenter d’un facteur 3 la durée de vie des assemblages des réacteurs à neutrons rapides refroidis au sodium.

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.

The hydroforming technology is well-known since several years and undergoes an extremely dynamic development in automotive applications, especially in Germany and the United States. The hydrofoming of sheet metal pairs is still at a pre-industrial stage. This publication presents the process and draws attention to some particular results of research work. Principal working directions for investigations, regarding the transfer of the hydroforming process for sheet metal pairs to industry are mentioned.

This article presents and discusses some modern techniques for high resolution orientation measurements in electron microscopy, including electron backscatter diffraction (EBSD) in the scanning electron microscope and spot and Kikuchi diffraction as well as dark field conical scanning in the transmission electron microscope. The techniques are compared with respect to their applicability to studies of nucleation processes during recrystallization of highly deformed metals. These investigations make high demands on orientation measurements, as high spatial and angular resolution and insensitivity to lattice defects are required.

A physically based model to predict the strengthening kinetics induced by copper precipitation in the system Fe-Cu has been developed. The effects of aging time, temperature and composition are integrated in the model. The results of the calculations are in good agreement with the experimental observations.

The demand for precious metals by manufacturers of electricaland electronic equipment has increased significantly over thepast few years. Although precious metal concentrations inappliances are very low, these metals have a high economicand environmental relevance compared to other substancespresent in much higher quantity (e.g. iron, copper, plastics). Thisresearch project aims at describing and quantifying the flowsof small waste electrical and electronic equipment (sWEEE)in Germany and in the USA for the year 2007, based on acombination of expansive experimental investigations carriedout at TU Berlin and a review of the relevant literature. Theresults revealed that, in 2007, only around a third of the goldcontained in desktop personal computers was recovered inGermany, and over 60% was lost for the cycling economy.Despite the lack of data, insufficient collection and losses ofprecious metals due to inadequate treatment were identifiedas the main weaknesses of the system. The results reveal newfindings on precious metal cycles and support the developmentof strategies for reducing the losses of precious metals relatedto electronic waste management. The method is not only usefulfor assessing the recovery of valuable substances, but also forquantifying systematically the amount of hazardous substancesthat is disposed of in an environmental-sound way versus directreleases to the environment.

The original viscoplastic framework at low homologoustemperature is based on the coupling of the E. Rauch'soriginal approach for mixing athermal and viscous termin the flow stress of ferritic steels, a general viscoplasticpotential and a microstructure based quasi-static behaviorlaw. The formalism gives accurate results in excellentagreement with available experimental results with only twoadjusted parameters, over a wide range of strain rates andtemperatures.