Solid State Phenomena Vol. 212

Abstract: In manufacturing of air compressors, piston engines and guides, lubricants are used to result in formation of a continuous oil film that separates the friction surfaces. The continuity of this film within the entire operating range of the friction pair, from starting to steady state, is the guarantee of proper operation. The surface geometry of friction elements plays significant role in maintaining continuity of the oil film. The widely used method for obtaining proper surface condition of the structural components of piston systems is the honing process. This method consists of shaping the microgeometry of the surface of friction pair elements by material removal processing methods (turning, grinding, laser processing) to prevent rapid spreading of lubricant, and thus to prevent breaking of the oil film. In case of Al-MMCs using for manufacturing the parts of machines working under friction with lubrication conditions the shaping of their working surface by honing is limited by the machining efficiency. The investigations on surface geometry of elements made of composites including ceramic reinforcement revealed that presence of reinforcement particles on the working surface bring the changes which can be used for shaping the correct oil film. The investigations presented in this article can be used for evaluation of lubricant propagation process on the composite material surface.

Abstract: Presented article describes results of studies concerning on influence of forming processes on alloy characteristics based on the FeAl intermetallic phase matrix. Microstructure of the alloy was evaluated with optical microscope after crystallization and forming process. Measures of hardness were taken using Vickers method. Static tensile test was used to set limitation of malleability and ultimate tensile strength. Crack surface after static tensile test was observed using scanning electron microscope.

Abstract: This paper is a synthetic presentation of the current state of knowledge on the fundamentals of cold production of thin and narrow steel strips. Such strips are semi-finished products used to manufacture final products which are widely used in a number of industries. The production devices are characterised and methods as well as technologies of their manufacture are discussed. For cases where wire is flattened to obtain strips with naturally rounded edges, the deformation phases with a uniform and non-uniform draft across the width of the strip have been identified. Changes in the widening coefficient and the rounding radius of the strip edge are described for these phases as a function of draft.

Abstract: The change of matrix and usage of the aluminum alloys designed for the metal forming in making the composite suspension allows to extend the processing possibility of this type of materials. The possibility of the metal forming of the composites obtained by mechanical mixing will extend the range of composite materials usage. Applying of the metal forming e.g. matrix forging, embossing, pressing or rolling, will allow to remove the incoherence of the structure created while casting and removing casting failures. In order to avoid the appearance of the casting failures the homogenization conditions need to be changed. Inserting the particles into the matrix influences on the shortening of the composite solidification. The type of the applied particles influenced the sedimentation process and reinforcement agglomeration in the structure of the composite. Opposite to the composites reinforced with one-phase particles applying the fasess mixture (glassy carbon and silicon carbide) triggered significant limitation in the segregation process while casting solidification. Inserting the particles into the AW-AlCu2SiMn matrix lowers the mechanical properties tension and impact value strength. The most beneficial mechanical properties were gained in case of heterofasess composites reinforced with the particle mixture of SiC and glass carbon. The chemical composition of the matrix material (AW-AlCu2SiMn) allows to increase additionally mechanical characteristics by the precipitation hardening reached through heat casting forming.

Abstract: Department of Materials Science at Silesian University of Technology since 10 years conducts researches to learn about the structural phenomena which occur during hot plastic treatment which are aimed at elaboration of a technology of heat and plastic treatment of selected alloys from Al-Fe diagram. The iron aluminides have been among the most widely studied intermetallics because their low cost, low density, good wear oxidation and corrosion resistance, to create wide prospects for their industrial applications, for components of machines working at a high temperature and in corrosive environment. The problem limiting their application is low plasticity and brittle cracking susceptibility. Consequently, the research of intermetallic-phase based alloys focuses on their plasticity. For the development of thermo-plastic treatment technology, it is necessary to determine internal variables describing the structure of an alloys being deformed is the inhomogeneity, grain size, as well as the grains misorientation angles and texture. The paper presents the course of structural changes of Fe-38Al with Zr, B Mo and C additions under the influence of hot plastic deformation with application of a few different temperatures of the process with given speed of deformation. For the structure and substructure investigations were used a light microscopy and transmission electron microscopy.

Abstract: Due to some specific features (high corrosion resistance and long-life durability in particular) as well as interesting aesthetic appeal, zinc-titanium strips are widely used as roof coverings, facade panels and rain gutters. The Zn-Ti strips are manufactured either in the hot rolling lines or in the reverse rolling mills at elevated temperatures. A problem of determination the average flow stress of zinc-titanium strip in the latter mentioned technology and in the actual rolling conditions is discussed in the paper. The analysis is based on the results of plastometric compression tests, FEM simulations and industrial practice.

Abstract: Sanicro 25 stainless steel (X7NiCrWCuCoNbNB25-23-3-3-2) is a preferred material for structural elements of boilers with supercritical and ultracritical parameters. Welded joints are critical sites that are vulnerable to failure. Hand-welded and automatically uniform welds of Sanicro 25 are evaluated in material studies, and the structure and basic mechanical properties of welded joints are examined. The proposed welding technology for Sanicro 25 ensures proper microstructure, and has obtained quality class B certification.

Abstract: The effect of heat treatment on the structure and hardness of the ZnAl240Cu3 alloy is presented in the paper. ZnAl40 and ZnAl40Cu3 alloys were tested. The scope of the examination included: dilatometry, structural and hardness tests. There are two transformations taking place during the heating and the reverse transformation during cooling. Most important for the alloy is the first transormation which occurs at lower temperatures (from 104°C to 131°C). There are found, that long-term soaking at 185°C results in a significant decrease in the hardness of the ZnAl40Cu3.alloy. The reason for the observed decrease in the hardness of the ZnAl40Cu3 alloy by soaking at a temperature of 185°C is primarily disappearance of dendrites.

Abstract: Alloys from group Mg-Ag-RE-Zr are characterized by creep resistance up to 200°C, good casting and mechanical properties. Defects of magnesium alloys are propensity to cracks and deformations during heat treatment, low corrosion resistance. Welding technologies are most often use to repair of casts, mainly nonconsumable electrode welding in inert gas cover. About possibility repair or regeneration of magnesium alloy castings by welding depends on their weldability. Weldability of most magnesium alloys is good however, welding and surfacing cast elements create many problems. The purpose of this research work was develop a repair welding technology of casts magnesium alloy. Research project consisted of weldings and padding trials, microstructure and mechanical properties tests. Presented research results in this paper support conclusion that casts alloy QE22 reveal susceptibility to stable connection.

Abstract: Over the last few years national as well as international research centres conducting research on the development of high-manganese steels. Some of these materials belong to the group of AHS steels, are characterized by the twinning induced plasticity (TWIP) effect which is a new type of steel possessing together with high strength a great plastic elongation, and an ideal uniform work hardening behavior. It is therefore a good candidate for deep drawing applications in the automobile and railway industry. The article presents the results of researches of TWIP-type austenitic steel in case of determination some of the more important parameters for continuous casting simulation process and the results of tests regarding the influence of strain parameters on sensitivity to plastic forming and deformation strengthening. It has been shown that the researched steel reaches a zero plasticity temperature at 1250°C. The deformation tests indicate its good workability of hot processing within the temperature range of 1100 ÷ 800°C. The relation between yield stress and strain during the hot deformation is typical for the presence of dynamic recrystallization processes. The tested steel has good formability and high mechanical properties, especially when being deformed at a high strain rate. Analysis of the substructure of researched steel was indicate presence of mechanical twinning.