Duplex stainless steels are often used today in the oil and gas industry because of their high strength and good corrosion resistance. New developments in arctic conditions and at high pressure require the qualification of these materials at very low temperatures. This paper will present the results of an extensive test program dedicated to assessing the low-temperature behavior of various heavy-wall duplex stainless steel forgings, hot isostatically-pressed (HIP) connectors and hot extruded pipes at temperatures down to –60 °C. Several welding processes were also evaluated. The implications for the design of duplex stainless steel production facilities will be discussed.

The massive use of air gaps in tooling, per the Evisto® concept, can confine the heat contributed by the cast alloy in a small volume. The resulting high die wall temperatures are turned to account to cast parts having ultra-thin walls, of the order of one millimetre thick. Effective thermal insulation limits thermal exchanges to slow the cooling of a cast alloy. The property that best characterizes this effectiveness is the reciprocal of thermal conductivity, thermal resistance. Air was chosen as the insulating material because of its many advantages: very favourable thermal conductivity, limited application cost, and zero purchase cost. Evisto®, an innovative tooling design, has been used to produce plates 1 mm thick measuring 130 by 200 mm and automobile seat backs 1.2 mm thick measuring 390 by 576 mm. The mechanical properties of the castings so produced complied with standard EN 1706 of May 2010 for aluminium alloy castings. A patent application was filed for the Evisto®concept in August 2010.

An investigation was carried out to quantify and characterize the corrosion behavior of AZ61A magnesium alloy joints. Extruded 6-mm-thick Mg alloy plates of AZ61A grade were butt-welded using a solid-state, environmentally cleaner welding process, the friction stir welding process. The weld specimens underwent immersion, salt spray, pitting and galvanic corrosion tests in order to quantify and characterize the corrosion rates of the welds with the influence of different pH values, chloride ion concentrations and the corrosion time. The corrosion rates, microstructure, scanning electron microscopy and X-ray diffraction analysis concluded the optimum parameters for the usage of the magnesium alloy welds for the best service applications.

The hot ductility of Ti-bearing steel was studied by theoretical calculation and a thermal simulation experiment. Meanwhile, microsegregation and precipitates were analyzed. The results showed that the S, P and O elements were enriched at the grain boundaries, while the hot ductility was deteriorated by inclusions of (Fe, Mn, Si, Al)(S,O) in the interdendritic region. At a temperature of 1300 °C, large TiN particles have little effect on the hot ductility. In the temperature range from 1000 °C to 900 °C, the Reduction of Area (R.A) declined rapidly from 81.77% to 31.77%, with the size of particles decreasing from 5 to 20 nm and quantity increasing from 1.2 inds/μm2 to 354 inds/μm2, respectively. In the temperature range from 900 °C to 850 °C, R.A decreased from 31.77% to 30.12% with the ferric films gradually thickening. The critical stress, 63.58 MPa, was equal to tensile strength at 912 °C. Intergranular fracture occurred easily with higher critical stress below 912 °C.

Cet article présente les derniers travaux réalisés par Dassault Aviation dans le domaine des charges et des vibrations aéroacoustiques, liées à la pression engendrée par l’ouverture, en vol, d’une soute à armement. En effet, dans le cadre du programme de drone nEUROn, Dassault Aviation établit les charges aéroacoustiques s’exerçant sur la structure de la soute à armement et analyse ainsi leur effet en termes de fatigue acoustique et de vibrations d’équipements. Etant données la bande de fréquences étudiée et la complexité des charges aéroacoustiques, de nouvelles méthodologies et de nouveaux outils ont été développés pour prédire le comportement dynamique de la structure, dans le domaine des basses et moyennes fréquences. Ces méthodes, leur application novatrice chez Dassault Aviation pour ce qui concerne la prédiction de l’environnement vibratoire dans le cadre du nEUROn, ainsi que les tendances d’améliorations ultérieures issues de cette application, font l’objet de cet article.

Ecosystem goods and services (EGSs) are of crucial importance for the economic and social development of human communities. The well-established life cycle assessment (LCA) method is facing a number of challenging improvements to define new Characterization factors (CFs) for life cycle impact assessment (LCIA) of EGSs. Very recently, extensive work conducted under the UNEP/SETAC Life Cycle initiative has been completed with the goal of providing new LCIA methods and spatially differentiated mid-point CFs for land use and land use change impacts on biodiversity and ecosystem services. However, the implemented models do not enable one to assess the actual damage to ecosystem functionality, and thus the relationship among EGSs and related areas of protection (e.g. AoP of “Natural Resources”) remains undefined. This paper aims at investigating the potential characterization ability of the Emergy method for LCIA of EGSs. The goal is to use the extensive libraries of Unit Emergy Values (UEVs) of primary services and resources as CFs for LCIA to evaluate the physical contribution of EGSs in supporting life cycle processes. Having its roots in thermodynamics and systems ecology, Emergy can appraise a larger and more diversified (than LCA) number of EGSs through a common physical denominator, i.e. the solar emjoule or seJ, which measures the solar energy embodied in natural products. Emergy thus has a typical Nature-oriented perspective, accounting for the available energy that is used up by the natural cycles, directly and indirectly, to generate biotic and abiotic resources. A library of selected UEVs (more than 100) for biophysical EGS valuation has been framed including values collected from the Emergy literature and formulated on the latest planetary baseline (i.e. 15.2E + 24 seJ/yr). Advantages and limitations for future application of these values toward an LCIA mid-point impact characterization of Emergy are discussed. UEVs may represent mid-point LCIA factors for ecological contribution analysis, enabling one to account for the memory of energy previously required to produce EGSs, which can be used as a proxy to assess the future environmental work necessary to regenerate the used EGSs. However, the added value of Emergy for LCA is still debated, mainly because of the low accuracy and unclear meaning of the UEVs in relation to the availability of resources. Therefore, Emergy can be conceived as a suitable physical measure complementary to the economic valuations and current “user-side” tools applied in LCA.

Refractory castables containing alumina-magnesia/self-forming spinel (MgAl2O4) are used in impact pads of steel ladles in steelmaking processes. In order to understand the wear mechanisms of refractory materials, several recipes were tested from a corrosion, slag resistance and thermal shock point of view. The results show that the corrosion is extremely limited at the slag/refractory interface for all cases. Nevertheless, for higher cement alumina content castables, the formation of cracks is observed in refractory castables into which slag can penetrate. The slag reacts with the alumina to form a new phase such as hibonite (CA6) and calcium dialuminate (CA2). The volumetric change of these reactions involving CA2 and CA6 lead to the apparition of macro-cracks. Thus, the penetration of slag and steel are increased, causing hot mechanical properties to degrade. For lower cement alumina castables, the formation of micro-cracks is avoided by controlling volume expansion. Thus, the slag deposit reacts with alumina grains and the matrix at the slag/refractory interface to produce a monomineral layer of hibonite. In this way, the monomineral layer acts as a barrier and limits the penetration of slag and steel into the refractory lining. Thus, to increase the lifetime of refractory castables containing alumina-magnesia/self-forming spinel, it is advised to control volume expansion in order to avoid the formation of cracks and limit the penetration of secondary metallurgy steel ladle slag.

Deposition of Ni3P nano-scale layer on B4C nanoparticles in four contents of sodium hypophosphite as reducing agent including 5, 10, 15 and 30 g/l via electroless coating were done to investigate the effect of reducing agent content on the coating thickness of deposited Ni3P. The bath pH and temperature was 5.5 and 85 °C, respectively and the coating time was 25 min. The powders were characterized by transmission electron microscopy (TEM) and the phases present were revealed by X-ray diffraction (XRD). Nickel and phosphorous contents of the coatings were measured by inductively coupled plasma analysis (ICP). The results revealed that by increasing the reducing agent content from 5 g/l to 30 g/l the average coating thickness increased from 19 nm to 28 nm. Although the increasing effect of adding sodium hypophosphite content was preserved, there is a critical amount for sodium hypophosphite content to increase the coating thickness.

A laser-welded blank (LWB) offers several notable benefits including decreased part weight, reduced manufacturing costs, increased environmental friendliness and improved dimensional consistency. However, in order to take advantage of these benefits, designers need to overcome the formability of LWBs and be able to accurately predict the LWB forming characteristics early in the design process. We present a new approach to predict the maximum elongation of the laser seam; for example, for Advanced High-Strength Steel (AHSS)-based LWBs. This approach is based on a coupling model taking into account the thermal, metallurgical and mechanical phenomena. A comparison of numerical and experimental results shows very good agreement. These approaches offer a considerable advantage in obtaining the formability limits for all configurations.

What environmental constraints will materials have to face in the future? Can current measurement tools like LCA (Life Cycle Analysis) support the choices of material and adapt to these constraints to pave the way to a sustainable world? Are there some alternative or complementary approaches to enhance the quality of information for decision makers? The aim of this article is to provide answers to these three questions. The society of tomorrow, in the second half of the 21st century, will be a society where the circular economy will play a more important role and thus will help reduce materials waste. This is a critical aspect of sustainability. To get there, the decisions have to be enlightened and fair, because the decisions (or non-decisions) made today shape the world that future generations will have to manage. Furthermore, Lord Kelvin used to say: “what you can’t measure, you can’t improve”. Therefore, these decisions have to be supported by measurement tools that will properly capture the stakes of reuse and recycling at the end of life of products. Today, LCA is the common tool used to address this matter. However, the present article has shown that LCA cannot incorporate the whole complexity of sustainability. LCA is good at considering micro-scale issues, comparing one solution with another, in a static approach. How can it give right directions to decision makers in order to support the vision of a circular economy? The application of different standards showed that it is not easy at all and that recycling product at their end of life are not rewarded equally and sometimes not promoted at all. Therefore rebound effects leading to contradictory decisions may occur. LCA alone is not enough to make enlightened decisions. It should be complemented by other methods. This was proposed in the last part. Based on the IPAT equation, this approach tries to capture different aspects that are not addressed properly by LCA, due to the fact that the functional unit is too restrictive, that the time dimension and prospective approach should be more integrated, and that it should enlarge the scale of the analysis to the macro-economy and the socio-economy. It should also recognize that the efforts have to be shared by different players including material industry and manufacturers, policy makers and society in general. As a general conclusion, we are convinced that tomorrow’s society will recognize the value of materials that are recyclable and reusable, like steel has been for many decades. But there is still a clear need to addressing, in research and development, the improvement of the metrics, combining social, environmental and economic assessment, so that the sustainability value of materials is properly measured. These are the objectives of the Sovamat Initiative and the SAM conferences.

To optimize the process and improve the degree of reduction, a two-stage experiment was designed. It was carried out in a micro-fluidized bed. It is operated as a differential reactor to ensure every particle in the micro-fluidized bed is at equal temperature, concentration and residence time. The experiment used iron ore powder from Yangdi. The reducing gas and temperature in the pre-reduction stage were, respectively, pure CO and 625 °C. In the final reduction stage, the temperature and reducing gas were, respectively, 800 °C and pure CO. The residence time was between 10 min and 60 min. In addition to the experiment, a microscopic technique was also carried out. The test shows a significant influence of the temperature and residence time of the two-step experiment on the final reduction degree.

The finite difference method of the low-alloy wear-resistant steel quenching process was studied. The temperature field and cooling rate variation of thickness of 45-mm wear-resistant steel (NM450) were calculated for different quenching practices. The microstructure and hardness of quenched plates were examined. The results indicate that when quenching started, the cooling rate was highest on the subsurface and decreased gradually until the center of the plate. However, as the quenching progressed, the cooling rate distribution along the plate thickness was reversed. The cooling rate increased linearly when the heat transfer coefficient (HTC) increased from 0–10 000 W/m2 K, and then the speed gradually slowed down until achieving the maximum cooling rate. Close to the plate mid-thickness, the maximum cooling rate was easily reached. Compared with high-pressure (HP) quenching and low-pressure (LP) quenching, under the HP + LP continuous quenching mode, it is possible to obtain a high critical cooling rate in the temperature range of 900 °C–400 °C and small temperature difference between the surface and center below 400 °C. The microstructure and hardness distribution on the plate surface for the HP + LP quenching mode indicated 100% martensite on the surface and martensite with a little granular bainite in the plate center, while the hardness difference in the entire steel plate was less than 7%. This study provided guidance for the formulation and optimization of wear-resistant steel.

Le but de ce travail est une contribution à l’étude de l’efficacité d’utilisation du traitement de phosphatation au zinc pour la lutte contre la corrosion des armatures dans le béton. Pour réaliser cette conversion chimique superficielle, des échantillons en acier rond à béton ont subi une phosphatation cristalline dans un bain de phosphate de zinc modifié par des ions Ni2+. Par suite, nous avons évalué leur comportement à la corrosion dans une solution simulée du béton au moyen de différentes techniques électrochimiques. Les résultats obtenus montrent que le traitement de phosphatation permet d’améliorer d’une manière significative la résistance à la corrosion de l’acier. En effet, les échantillons phosphatés, par rapport à ceux non phosphatés, présentent des valeurs de potentiel de corrosion et de piqûration plus nobles ainsi que des densités de courant de corrosion plus faibles. Les mesures d’impédances confirment cette tendance, les spectres obtenus montrent une nette augmentation de la résistance de transfert de charges conjointement à une diminution de la capacité de la double couche électrochimique des échantillons traités. Cette action protectrice est due au fait que la couche de phosphate obtenue joue le rôle de barrière physique face à la diffusion des ions chlorures d’une part, sa dissolution en surface dans la solution simulée fortement alcaline libère les ions PO43- rentrant dans la réaction de formation d’un film de passivation jouant le rôle de barrière chimique face à l’amorçage de la corrosion par piqûres, d’autre part.

Online detection and monitoring of phase transformation using non-destructive electromagnetic system in industrial hot strip mill processing of steels are reported. The system renders wide range of possibilities for advanced control and fine tuning of the hot rolling and run-out table cooling parameters. These in turn allow for process modifications to better control the microstructure of hot rolled bands. In particular, such modifications can attenuate the adverse effects of uncontrollable cooling of hot band coils that leads to severely non-homogeneous hot band microstructure. An example of application is given demonstrating how reducing the non-homogeneity of hot band microstructure with the aid of online hot strip mill electromagnetic system can help eliminating the off-thickness defects in advanced high strength steel full hard strips thus contributing to lowering the production costs and increasing the yield.

The aim of this work is to produce metallic coatings onto a steel substrate type E335 in order to hardening and improving the tribological properties of contact surfaces. In this study, two different coatings of stainless steel 18/8 and molybdenum realized with and without bond coat in Ni-Al were sprayed using a thermal flame spray technique. The microstructures of the two deposits are obtained using an optical microscope (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Measures microhardness under a load of 200 g, are performed on the polished surfaces of these two types of deposits. The wear and the determination of the coefficients of friction of the two deposits tests were performed in dry conditions. A pin on disc configuration on a tribometer type TE 91 was used with different normal loads and a sliding speed of 0.5 m/s. The results showed that the microstructures obtained by OM and SEM of stainless steel present a dense and compact microstructure. It contains a low porosity and unmelted particles in comparison with the coatings of Mo. In addition, it was found that the spray-coated stainless steel 18/8 exhibited higher microhardness, higher wear resistance and significantly low friction coefficient in comparison with those of Mo coatings.

The European Waste Framework Directive (2008/98/EC) explicitly specifies the hierarchy for waste management: prevention, preparation for re-use, recycling, other recovery actions, disposal. When selecting waste management options, this waste hierarchy should be followed. A deviation can only be justified by Life Cycle Thinking (LCT) on the overall impacts. The application of this principle in the Flemish waste management practice triggered the need for evaluation of treatment options for several waste streams. Alternative treatments were evaluated for waste batteries, used frying oils and waste oil. The evaluation methodology combined life cycle assessment with technical and economical viability criteria. These cases show that LCT does not allow to establish a “general priority order”. In each case reasons for deviation from the standard waste hierarchy could be given, but also none of the evaluated options can be considered as the best. The evaluation showed that the priority is largely dependent on location-specific characteristics of inputs, outputs, processes and installations and that the establishment of local and global environmental priorities always implies a value choice. In this presentation, we will present the results of the three cases and provide a methodological framework for life cycle thinking in waste management policy.

les différentes méthodes qui utilisent l’essai d’indentation pour estimer la ténacité sont revues et commentées. Pour les matériaux fragiles, les formules sont principalement basées sur la mesure des fissures formées par l’indenteur ou, si l’essai est instrumenté, sur les décrochements (pop-in) observés sur la courbe charge-déplacement. D’autres méthodes moins connues peuvent utiliser la mesure de l’ouverture en fond de fissure, une équivalence entre la longueur de fissure formée et l’accroissement de pénétration de l’indenteur ou le clivage provoqué par une indentation proche du bord du matériau étudié. Pour les matériaux ductiles aucune fissure n’est visible à la surface, même pour les fortes charges appliquées. Dans ce cas la ténacité est reliée par la mécanique continue du dommage à un dommage critique mis en évidence par la diminution du module d’élasticité avec l’augmentation de la profondeur d’indentation. Toutes ces méthodes permettent de calculer la ténacité avec une incertitude pouvant aller au maximum à 50 %.

At the end of 2008 and in response to the economic crisis, the EU launched a Recovery Plan supported by technology initiatives, one of them being the European Green Car Initiative (EGCI) to help the car industry design next-generation passenger vehicles, which address fuel efficiency and carbon footprint issues at the level of the challenges of the 21st century. The European steel sector, which supplies material to the European car industry, which builds 1/3 of all passenger cars in the world, has launched an extensive, bold and imaginative series of projects to address lightweight design, cost, safety, sustainability, availability, recycling, electric applications and Life Cycle Assessment (LCA), which are the main technical topics, as steel retains an essential role in the design of these future green vehicles. Highlights of these are presented here, such as the development of new steel grades, either new advanced high-strength steels or low-loss steels for electric cores, the co-design of steel solutions with OEMs and the importance of LCA in vehicle conception.