Search

The welding procedure and technology for welding the cover of the tube girder is presented in this paper. The tube cover is made of the C-Mn steel. The welding has to be performed over the whole perimeter in the V groove. Since the structure in question is a very responsible one (a part of the assembly of the large hadron collider - LHC), the check of the base metal chemical composition and the mechanical properties had to be conducted before actual prescribing of the welding process type and the complete welding technology. Then the weldability of the base metal was estimated, which showed that this particular steel was conditionally weldable with application of preheating. The welding technology was prescribed, based on the previously determined parameters including the welding procedure and the filler metals selection. The prescribed technology was afterwards executed on the selected experimental samples. To verify that the selected technology was adequate, the hardness and the microstructure of all the zones of the welded joints were determined. Analysis of executed experimental welds on chosen samples has confirmed that the welding technology was appropriate and that it could be applied to the real part - the LHC assembly. [ABSTRACT FROM AUTHOR]

The objective of this work was to determine the wear resistance of layers hard faced by the high-alloyed filler metal, with or without the austenite inter-layer, on parts that operate at different sliding speeds in conditions without lubrication. The samples were hard faced with the filler metal E 10-UM-60-C with high content of C, Cr and W. Used filler metal belongs into a group of alloys aimed for reparatory hard facing of parts damaged by abrasive and erosive wear and it is characterized by high hardness and wear resistance. In experiments, the sliding speed and the normal loading were varied and the wear scar was monitored, based on which the volume of the worn material was calculated analytically. The contact duration time was monitored over the sliding path of 300 mm. The most intensive wear was established for the loading force of 100 N and the sliding speed of 1 m.s-1, though the significant wear was also noticed in conditions of the small loading and speed of 0.25 m.s-1, which was even greater than at larger speeds. [ABSTRACT FROM AUTHOR]

Possibilities to influence the deep drawing process during its duration are limited and generally consist of influences at the flange of the thin sheet, mainly by the contact pressure (the blank holding force). The common characteristics of previous investigations were setting of the fixed values of the blank holding force or the holder's pressure within the ironing tool. The objective of this investigation was the continuous setting of the variable pressure during the sliding process, via the preset functions, in order to analyze the variable pressure influence on the ironing process. This is why an experimental computerized device was designed and constructed for analyzing the influence of the variable contact pressure on the sliding process of the model strip during the flat-die test. The multi-parameter experiment was conducted; various materials of the tested pieces were applied (primarily thin sheet made of Al alloys and low-carbon steels sheet, with and without coating); different versions of the tool's contact elements were used, with various friction regimes and influential parameters (variable contact pressure during the sliding process, etc.). This experimental device practically represents a simulator for realization and studying of the physical model of an important segment of the ironing process in the completely realistic conditions (materials, tools, etc.). The aim was to find the optimal combination of the variable contact pressure and the tribological parameters, so that the punch force, as one of the process output parameters, would have the minimal value, as well as to avoid the undesired effects during the forming (difficult sliding of the flange, appearance of thin sheet's wrinkling, structural destruction, etc.). Understanding the mutual dependence of the holder's variable pressure and other influences should enable improvement of the ironing process control and should contribute to better understanding of the phenomena occurring at the thin sheet's flange. [ABSTRACT FROM AUTHOR]

The theoretical and experimental analyses of the friction welding pressure influence on the plastic deformation level and the quality of the friction welded joint are presented in this paper. The joint of the tempering and the High-Speed steel was realized by the friction welding. The objective was to relate the two basic process parameters - the friction and compacting pressures - to plastic deformation parameters during the friction welding of two the steels. The fact that materials are dissimilar additionally complicates the welding procedure and its analysis. The friction welding is a specific and complex process, since in the joint zone material is heated and plasticized with necessary action of the multi-step pressure to realize the joint. The total deformations in the axial and radial directions are directly dependent on the applied welding pressure. Considering that geometry and shape of the friction welded joint directly depend on the friction pressure, some welded joints' basic shapes obtained with various pressures are presented. The experimental investigation was conducted on cylindrical samples made of the two steels and the analysis of results served for establishing the influences of the friction and compacting pressures on changes of the steel samples dimensions and shapes. [ABSTRACT FROM AUTHOR]

An analysis of the anisotropy properties of austenitic steel AISI 304 (X5CrNi 18-10) at elevated temperatures is presented in this paper. Considerations of the anisotropy problems are presented in the theoretical part of the paper, as well as the procedure for determination of the normal anisotropy coefficient. The experimental part of the paper describes the plan, methodology and equipment for testing of material's normal anisotropy and mechanical characteristics. The objective of conducting the experiments was to investigate influence of temperature on normal anisotropy, as well as on the mechanical properties of the considered material. The normal anisotropy was monitored by the coefficient - the so-called "r-value". Besides that, the tensile strength, yield stress and elongation at break were monitored, also. The tests were done on the 0.7 mm thick sheet metal within the temperature range 20 to 700 °C. [ABSTRACT FROM AUTHOR]

In this paper, the detailed procedure for defining the optimal technology for welding the structures made of the high strength steel S690QL is presented. That steel belongs into a group of steels with exceptional mechanical properties. The most prominent properties are the high tensile strength and impact toughness, at room and at elevated temperatures, as well. However, this steel has a negative characteristic - proneness to appearance of cold cracks. That impedes welding and makes as an imperative to study different aspects of this steel's properties as well as those of eventual filler metal. Selection and defining of the optimal welding technology of this high strength steel is done for the purpose of preserving the favorable mechanical properties once the welded joint is realized; properties of the welded metal and the melting zone, as well as in the heat affected zone, which is the most critical zone of the welded joint. [ABSTRACT FROM AUTHOR]

In this paper are considered the most important properties of a special class of high strength steels S690QL, which can be classified into the group of special low alloyed steels. The high strength steels belong into a group of high quality steels. They possess exceptional mechanical properties, especially tensile strength and toughness. Those favorable properties are being achieved by application of special procedures of thermo-mechanical processing and simultaneous alloying with adequate elements. The advantages that the S690QL steels have with respect to other steels are being presented here. However, possibilities for application of those steels in responsible welded structures are limited due to their only relatively good weldability. The special procedures for improving it are discussed here, primarily preheating, controlled heat input during welding and additional heat treatment of the welded joint. The aim of this paper is to point to the possibility of application of these steels for manufacturing of the responsible welded structures, and simultaneously to point to the fact that the properties of steels as declared by manufacturer (chemical composition, mechanical properties etc.) are not always reliable and that they can vary depending on the batch. [ABSTRACT FROM AUTHOR]

This paper is aimed at presenting results of an experimental analysis of the different types of lubricants influence on the multi-phase ironing process. Based on sliding of the metal strip between the two contact elements a special tribological model was adopted. The subject of experimental investigations was variations of the drawing force, contact pressure and the friction coefficient for each type of the applied lubricants. The ironing process was conducted in three-phases at the constant sliding velocity. The objective of this analysis was to compare all the applied lubricants in order to estimate their quality from the point of view of their applicability in the multi-phase ironing process. [ABSTRACT FROM AUTHOR]