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[en] Steel making processes are continuously improved in order to attend the increasing requirements of the cleanness of the liquid metal. At the refining stages, as deoxidation and desulphuration, the formation of inclusions of oxides and sulphides is promoted, which on the other hand, are the most frequent inclusions. In this work a mathematical simulator of the precipitation and chemical composition of non-metallic inclusions at different steps of the steel making process is presented. To this purpose, it is assumed that inclusions formed by reoxidation can be simulated by increasing arbitrarily the oxygen levels consumed by the residual elements (aluminium, calcium, etc) and starting the chemical reaction with less powerful deoxidants (silicium and manganese). Accordingly, different operative conditions can be simulated. Numerical predictions are compared with experimental results of industrial trials, as well as results included in the bibliography. (Author) 7 refs
[en] In many European countries infrastructure, -road as well as railway infrastructure-, needs intensive investments to follow the growing demands of mobility and goods traffic. Steel or steel composite bridges offer in this context viable and very sustainable solutions. Due to its unlimited recyclability steel can in general be seen as the ideal material for such sustainable constructions, but especially when designers or fabricators exploit the nowadays available possibilities of steel industry very cost-efficient and remarkable constructions are realizable. This paper will highlight some of these newest developments in heavy plates for bridge building. For example, for small span railway bridges the so-called thick plate trough bridges have proven to be a favourable concept. Very heavy plates with single plate weights up to 42 t allow building these bridges very efficiently out of one or very few single plates. Another interesting development is the so-called longitudinally profiled plates which allow a varying plate thickness along the actual loading profile. As last point the rising entry of higher strength steels in bridge building will be discussed and it will be shown why thermomechanically rolled plates are the ideal solution for these demands. (paper)
[en] Fully automatic radiographic testing of cast light metal components is a state of the art technology. The contribution describes its application in weld testing. A new method for evaluating X-rays of welds is presented which were tested using an innovative X-ray camera with maximum spatial resolution and a wide range of grey values. Further, a novel concept for handling test objects significantly shortens testing times. The pipes are not moved longitudinally; instead, the longitudinal motion is made by the X-ray emitter and sensor, which reduces the testing time by up to 30 percent. The specially developed X-ray detector has a sensitive surface of 200 mm x 50 mm with a total of 4.2 million pixels. Neither the evaluation electronics nor the light-sensitive camera chip are exposed to the direct X-radiation so that no damage will occur at photoenergies up to at least 250 keV. Many tests, e.g. according to EN 13068 and EN 462-5, have shown that the image quality in general and especially the local resolution exceeds the specifications of the EN 584 standard on weld testing with X-ray films. The pictures taken by the camera serve as input data for fully automatic evaluation. All stages of image processing implement 16-bit digitalisation depth in order to make use of the high dynamic range of gray value images. This means that in the whole processing chain, there will be no loss of information from downscaling of the gray values. In the first stage of image processing, the gray values are transformed into penetrated material thicknesses in preparation of the measurement of fault length in the direction of incidence at a later stage. In the next stage, external boundaries and the middle of the weld are detected, followed by an adaptive filtering stage. Additionally, information on the accurate location of the weld is transmitted to the control system of the mechanical parts, so that optimum positioning of the weld with respect to the camera is ensured. The adaptive filter can detect defects like cavities, cracks or inclusions. Finally, the characteristics of the detected defects are compared with the specifications of the quality standards. The results, together with the original image data of the pipe, are archived electronically and stored falisfication-proof on DVD. (orig.)
[en] The cycling and static strengths of a wide range of high-strength steels have been experimentally tested. Correlation between the three parameters-microplastic deformation, strain hardening coefficient, and the slope of the curve to the axis of load cycles-has been established
[ru]В статье приводятся экспериментальные данные по испытанию на циклическую и статическую прочность широкого спектра высокопрочных сталей. Установлена корреляция между тремя параметрами: микропластической деформацией, коэффициентом деформационного упрочнения и тангенсом угла наклона кривой усталости к оси циклов нагружения
[en] The goal of this three-year project was to improve the production systems in use by steel foundries in the United States. Improvements in the production systems result in less rework, less scrap, and less material handling, all of which would significantly reduce the energy demands of the process. Furthermore, these improvements would allow the companies to be more competitive, more responsive to customers' needs, deliver products with less lead time and require less capital. The ultimate result is a stronger domestic steel casting industry, which uses less energy. A major portion of this research involved the deployment of student researchers at steel foundries, to study their production systems and collect data
[en] The Spanish steel sector considers that after 20 years of application of the Protocol, Spain is clearly at the head of the world on the knowledge about unintended radioactivity in the ferrous scrap. We have the data, the knowledge, and the experience of all the agents that participate or do have any responsibility on the management of the multiple facets existing in this problematic. The sector has been preparing deeper and deeper and is pushing for years in order to enhance our own surveillance systems but also the surveillance carried out by other national and international actors that could avoid a possible incident in our factory, and thus null the chances of the exposition of the public. However, on the latter the results are not as good as we expect, as the progression is is very slow. The article comment upon the main lines of work, few of the studies in which the steel sector has participated on this regard. Thanks to the voluntary scheme of the Protocol allows them to be solved in a collaborative way by all the involved agents but without the rigidity of a legal text. A priori, I have identified at least 15 no initially considered situations that have originated a multitude of tailored solutions to address aspects that at the end of the 90s were unimaginable. In this article, I address few of them that serve as a practical example of how a voluntary Protocol allows solving in an efficient way – but not always simple - new arising situations. These unexpected situations emerge in this problematic of unintended radiological material within the metal recycling loop. It is worthy highly that these solutions have been assessed by expert from all the involved areas; and all of them sitting in the same table.
[es]El sector siderúrgico español, considera que tras 20 años de aplicación del Protocolo, España está claramente a la cabeza mundial sobre el conocimiento de la de radiactividad inadvertida en la chatarra férrica. Se dispone de los datos, el conocimiento, la experiencia de todos los agentes que participan o tienen responsabilidad de algún tipo en la gestión las múltiples facetas existentes en la problemática. El sector se ha ido preparando cada vez más profundamente y lleva años haciendo presión para extender las barreras de vigilancia propias y de otros agentes nacionales e internacionales que pueden evitar un posible incidente en nuestras factorías, y que eviten cualquier exposición del público si se diera el caso. Sin embargo, los resultados no son todo lo bueno que esperamos, dado que la progresión, especialmente a nivel internacional, es muy lenta. El artículo comenta algunas de las principales líneas de trabajo, alguno de los estudios en los que ha participado el sector siderúrgico a lo largo de los últimos años y que, gracias a la colaboración de todos los agentes implicados y al esquema de voluntariedad, permite que cada problemática pueda ser solucionada de un modo ad hoc, sin necesidad de ajustarse a la rigidez de un articulado legal. A priori, y sin realizar una exhaustiva revisión histórica, se identifican al menos 15 situaciones, inicialmente no contempladas, que han dado origen a multitud de soluciones a medida para afrontar aspectos que a finales de los años 90 era absolutamente inimaginables. En el presente artículo se explican algunas de ellas que sirven como ejemplo práctico de cómo un protocolo de carácter voluntario permite solucionar de un modo eficiente, que no necesariamente sencillo, las nuevas problemáticas que se van planteando relacionadas con la presencia de material radiológico inadvertido en el reciclado metálico en sentido amplio. Cabe remarcar de nuevo que las soluciones han sido supervisadas por expertos de todas las áreas involucradas, todos ellos sentados en la misma mesa.
[en] Continuous casting technology of hollow billets has been developed for near-net-shape casting of pipe. A cylindrical water cooled copper mould was used as a core to make a hole at the center of the round billet, while the hot-top casting technique was applied in order to provide space for the submerged entry nozzle and to cast tube blanks of thin wall thickness. A pilot scale casting of a 160mm-diameter billet, which has a 100mm-diameter hole, was conducted and the metallurgical investigation of the billet quality and the numerical analysis were performed to determine the optimum casting conditions. The hot-top casting technique, in which the induction heating (IH) of the oscillating ceramic mould stabilizes the solidification start level, enables both the smooth surface and the thin wall thickness of the hollow billet. The combination of the IH type hot-top casting technique and a water cooled copper mould, create a favourable condition at the shell exterior for generating equiaxed crystal as both fluid flow and thermal conditions, promote high equiaxed structure ratio and elimination of macrosegregation in hollow billets. (author)
[en] The present paper is focused on the advanced deposition technologies, such as electron-beam surfacing in vacuum. Modern electron beam surfacing equipment «LUNa-10» has been developed for iron and steel industry. The present paper contains investigation of properties of composite coatings for different part of metallurgy equipment. Key words: electron-beam surfacing in vacuum, composite coatings, metallurgical
[en] Modeling of the basic oxygen furnace (BOF) process, both for online monitoring and fundamental research, has gained importance in steelmaking industry over the past few decades. Especially models integrating fundamental physicochemical relations are appealing. Even though a vast amount of these kind of models and submodels can be found in the literature, no recent review paper is available which thoroughly discusses the most up-to-date BOF modeling methods. This study aims to do so. In the introductory chapters, an overview is given on the assumptions and models for underlying BOF phenomena, which are frequently used in the BOF models and submodels. Focus was put on six models with emphasis on the chemical aspect of the BOF process. For each model, its assumptions are given and subsequently evaluated, highlighting both their strengths and limitations. The six different models are also compared with each other. Finally, opportunities for future research are discussed.