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The purpose of using modern technology is to reduce costs, facilitate the work and simplify as far as the most comprehensive set of operations. One of many modern technological processes involved in the refining of materials are technologies of surface hardening using a laser beam. This method can harden precisely defined areas with minimal thermal influence of surrounding areas it is possible to achieve less residual stress and less distortion of components compared the volumetric hardening, it is also possible to use controlled robotic units and all for the absence of cooling, which proceeds spontaneously to the surrounding material itself and atmosphere. These advantages of laser surface hardening are used by companies for which the prospect of minor damage to the material, increase of the material durability, material stiffness ensuring etc. is initiation for the use of modern technology.

The possibilities for reparation by hard facing of the damaged working parts - the hammers of the secondary stones crusher are investigated in this paper. The analyzed crusher is stationary and it belongs into a group of the process equipment aimed for producing the crushed stone. The produced stone is later used for manufacturing various construction materials like asphalt, concrete, etc. Wear of the crusher's working parts occurs during the exploitation due to operation with very hard materials. That wear is usually abrasive and of high intensity what causes failure of the working parts and consequently the machine's downtimes and appearance of various types of losses, primarily financial ones. To prevent that, and to reduce the downtimes as well, one uses reparation technologies, one of which is hard facing. The analysis of the mass losses of the hard faced parts, after certain number of hours of the crusher's field operation, is performed in this paper.

Cutting tool wear monitoring is one of key problems in automation of machining processes. Apart from the cutting tool wear monitoring for the cutting tool change and cutting tool failure, cutting tool wear monitoring may be one of the components for the adaptive control of a machining process. This paper is focused on the design of turning cutting tool wear sensors of the system flap - jet principal with increased extend. On the geometric principles in cutting with a turning cutting tool, the relations among the output of jet mouth, clearance angle and cutting tool wear were expressed. Two variants of turning cutting tool sensors were designed and experimentally verified. The results of experiments have proved the possibility to apply cutting tool wear sensor of the system flap - jet principal with increased extend in practical use.

Paper deals with comparasion of methods for resolving stress state on the example of forged crane hook of selected load. For suitability of the comparasion is necessary to achieve comparable stress values by different methods. Problem of solving of different assignments by different methods is very extensive, and because of it, there is not clear answer, which of methods is universal and so always optimal. Any factors, that enter to the calculation and influence it, is the best way to choose an optimal method for solving of strength problems in mechanics.

An important aspect of rail vehicle dynamic analysis is a ride comfort analysis and a prediction when passengers and cargo can experience adverse conditions. The computational software utilisation helps to determine forces and accelerations in various positions through the body of the rail vehicle in order to predict ride properties or evaluate ideas for ride comfort in advance. This paper is aimed to the dynamic simulation of the rail vehicle running on a real track. The rail vehicle model creation, computations performance and determination of accelerations badly needed for the ride comfort evaluation is performed by SIMPACK package. Parameters of passenger rail vehicle model correspond to the four-axle two-bogie BR481 rail vehicle. The track model on that the vehicle has been run corresponds to the real track section in Slovakia.

The most widely used technologies of founding Al-Si cast alloys are gravitation and semi-centrifugal casting, casting under pressure and so on. The contribution deals with influence of different casting method on changes of Fe intermetallic phases. Casting into metallic mould and sand mould were used for experimental work for comparison Fe-rich formation. Fe is a common impurity that leads to the formation of complex Fe-rich intermetallic phases. The dominant phase is plate-shaped Al5FeSi. These phases are unwaited, because reduce properties of aluminium casting. The experimental materials have most common addition Mn. The addition of Mn may reduce Al5FeSi phase and promote formation Fe-rich phases Al15(FeMn)3Si2 in "skeleton like" or "Chinese script" form. This knowledge was confirmed. The present study is a part of larger research project.

Self-hardening aluminium alloy AlZn10Si8Mg represents an innovative class of light aluminium alloys and they present high mechanical properties, which make them suitable for many applications in different industrial fields, especially in transport industry. The most important and relevant feature of the self-hardening alloys is related to their good performance, without the need of any heat treatment: they are subjected to a natural ageing phenomenon at room temperature after a storage period of about 7-10 days. The possibility to avoid the heat treatment represents an important benefit, contributing to considerably reduce both the production cost of some components and the amount of energy. Furthermore, without heat treatment the risk of component's deformation during the production is eliminated.
The Charpy impact energy of experimental cast alloy was measured at -196°C, -20°C, 20°C, 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C and 400°C in terms of the total absorbed energy. Effect of temperature to microstructural changes and fracture surface on the impact toughness was investigated. A combination different analytical techniques (light microscopy upon black-white etching, scanning electron microscopy (SEM) upon deep etching) were therefore been used for the identification of the various phases.

The results of an experimental study on influence of cerium addition on structural characteristics of 42CrMo4 steel are presented. Alloying with cerium was carried out using profile filled with powdered mixture of mischmetal. The samples were taken from two ingots cast in the VHM's steelworks with standard time of casting of about 14 minutes. Three steel bars from one of the produced ingots were prepared by forging. Chemical composition, macro- and microstructure, X-ray EDX chemical microanalysis, hardness of the all steel samples were obtained. Cerium addition resulted in the formation of micrometer size inclusions which can be utilized for controlling the grain size structure of steel castings. The majority of the particles have settled at the bottom part of the casting, indicating that the convection flow during solidification was very weak. The cerium addition slightly diminished hardness of the steel. A segregation phenomenon causing inhomogeneous distribution of cerium over entire volume of as-cast samples after relatively rapid crystallization process of the steel was revealed.

The paper deals with some problems of quantitative metallography which includes evaluation of microstructure by etalons, measurement of structural parameters by coherent test grids and automatical image analysis. Some advantages and disadvantages of these methods are shown in this contribution on the example of evaluation of microstructure of graphitic cast irons. The automatical image analysis enables to eliminate some disadvantages of evaluation of microstructure by etalons and by coherent test grids but it has also some negatives.

This article is interested about drilling the holes to the alloy wheels. Tested were drills to drilling holes for screws and service holes. For screw holes was tested the three-stage drill with inserts from polycrystalline diamond. Drilled are two different diameters and the transition spherical or conical surface. The service holes were drilled with cemented carbide drill availible from Mapal labeled Mega-drill-Alu-180. During test, was modified the geometry of the drill and we watched what will be the effect of applied modification. Tested was seven variants of regrinding the drill. We evaluate the surface roughness, but also if the drill has the right position and not be pushed away from its axis. Finally was tested drill with three edges. This drill bit is from company Mapal labeled Tritan.

Quality of high-pressure castings is influenced by many factors. Structure and mechanical properties of these castings are mostly influenced by properties of casted material, technological parameters and thermal conditions in die casting mould. Thermal conditions in system casting - die casting mould is ensured by tempering system. However there is problem with thin cores and thin protrusions of die casting mould which is not possible to keep on the optimal temperature during casting by commonly available methods. Thus there is overheating in these places. It leads to the porosity of casting and also to the unsufficinet treatment of critical places of moulds which causes the lowering of their service time. With regard to the increasing requires on the castings quality is in practice searching still new possibilities how to cool down these critical places. One of the possibilities is to ally cooling by liquid CO2 into such places. This paper deals with the monitoring liquid CO2 cooling effect that is applied into the die casting mould core.

The aerospace industry is one of the biggest consumers of advanced materials because of its unique combination of mechanical and physical properties and chemical stability. Highly alloyed stainless steel, titanium alloys and nickel based superalloys are mostly used for aerospace applications. High alloyed stainless steel is used for the shafts of aero engine turbines, titanium alloys for compressor blades and finally nickel base superalloys are used for the most stressed parts of the jet engine - the turbine blades. Nickel base superalloys were used in various structural modifications: as cast polycrystalline, a directionally solidified, single crystal and in last year's materials which were produced by powder metallurgy. In this chapter, a problem of polycrystalline (equiaxed) nickel base superalloy turbine blades - such as the most stressed parts of the aero jet engine - will be discussed. Also the application of quantitative metallography and colour contrast on the ŽS6K Ni-base superalloy are the main objectives discussed in this chapter.

Recycled aluminium alloys are made out of aluminium scrap (new or old) and workable aluminium garbage by recycling. Due to the increasing production of recycled aluminium cast alloys is necessary to ensure their strict metallurgical control. The mechanical properties and the microstructure character depends on the chemical composition; melt treatment conditions, solidification rate, casting process and the applied thermal treatment. The mechanical properties depend on the morphologies, type and distribution of Si, Cu, Mg and Fe-phases, on the grain size, DAS and porosity distribution. Improvement of mechanical properties and structure of Al-alloys can often significantly increase the using lifetime of a casting. Different elements are added to achieve the optimum casting and mechanical properties. Modification can be achieved by several methods as faster solidification, mould vibration, melt agitation in mushy state and melt inoculation by using chosen elements like Sr, Na, Sb etc. Present work is focused on study of the effect of Sr-modification on the structure and mechanical properties of recycled AlSi10Mg cast alloy. For study and identification of intermetallic phases' was utilized standard (HF), colour (MA) and deep etching (HCl) in order to reveal the three-dimensional morphology of the silicon particles and intermetallic phases. For element composition of the specimen was used X-ray (EDX) analysis. Finally, the effect of modification on silicon morphology and fracture surface was examined.

The main object of this research was the influence of plastic deformation on magnesium alloy AZ61 with 0.5 wt. % of Ca. Tested specimens were loaded by three - point bending test and by pressure deformation. Hardeing and softening were measured also. Specimens were studied in two structural states: as - cast state and in state after heat treatment. During three - point bending test specimens were plastically deformed by dislocation slip and twinning. The compression loading of experimental specimens after heat treatment led to slip and twinning plastic deformation. Cracks were created in the surrounding area of the indentation and there was also cracking of intermetallic phases present in the microstructure. Changes in the intensity and distribution of plastic deformation were caused by deformation strengthening and shifting of grain boundaries. Grain reorientation and strengthening of neighbouring grains occurred during the growth of plastic deformation and the hardness was increased. After reaching annealing temperature of 300 °C, decrease of the material hardness was observed.

When selecting the optional parameters in machining inner cylindrical surfaces the diameter of a borehole cannot be ignored. Also in finish precision machining, when fulfilling strict accuracy and surface quality parameters economically, it was presumed that the size of the borehole diameter has got an effect on the machining times of different procedures. Five different hard machining methods are compared here on the basis of time consumption. The common characteristic feature of the comparative investigations of different hard machining procedures is that their benchmark is always the traditional grinding. This time, too, that has been chosen. It is presented how the borehole diameter influences the machining times and the most economical procedure is proposed to be selected for given borehole diameter.

This article deals with dry turning of nickel superalloy - Inconel 718. The different ceramic inserts were applied for cutting process. These inserts were produced by Greenleaf Corporation company. This paper discusses durability of cutting inserts, the different intensity of tool wear at various cutting parameters. The most suitable cutting conditions are chosen in the scope of applied tools.

During turning, in the course of the deformation of the material, a metallic deposit, a so-called built-up edge (BUE), may occasionally form, which may damage the surface and shorten the tool life. We have observed the effect thereof on chip formation using microscopic techniques and have developed a mathematical model for this process. Laboratory experience confirms the numeric solution of the time-delayed autonomous differential equations. This model can be applied to other technologies as well where the thickness of the undeformed chip varies.

The effect of microstructural banding (or so called segregation bands) on energy absorption capacity of dual-phase steels (DP steels) was examined by product of tensile strength and uniform elongation (TS×UE), as well as by Charpy V-notch impact test. A series of DP steels with different volume fractions of martensite (VFM) was prepared by intercritical annealing at temperatures ranging 740 to 840 °C. It was found that increasing of VFM has an inverse effect on values TS×UE and notch toughness. The results on samples with a notch and pre-cycled crack showed that presence of segregation bands influences capacity of steels to absorb the energy in initial stage as well as in stage of crack propagation.