Actual number: 4/2020

ISSN 1339-5017 (Online)

Archive:


No. 3-4

HARD MILLING AND HARD DRILLING EXPERIMENT OF ABRASION RESISTANT STEEL HARDOX 500 AT DEPENDENCE OF T = f (vc,fz)

Author: Jozef MAJERÍK, Jaroslav JAMBOR

Abstract: Presented paper deal about the face milling and drilling process of the HARDOX 500 steel. Material abrasion resistance HARDOX 500 have to discharge very hard inquires against mechanical wearing. Manufacturing process of this material is result of various factors effect as are combination of high strength, stiffness and toughness. Materials that are heat-treated thermomechanical include but are not armoured plates and abrasion HARDOX. Are the product of Oxellösund SSAB (Sweden), and used for parts that are subjected to exploitation in the process of growing demand for abrasion resistance. Therefore used for the cup tablespoons loaders, excavators, parts of the stone crushers, the hull truck dumpers for conveyors, sprockets and other. HARDOX 500 are produced by hot rolling at 900 ÷ 920 º C with a reduction of 50 to 85% in the area of a stable austenite, and then to one minute sharply hardened in the water spray. They are rolled in thicknesses from 4 to 80 mm. Their chemical composition is indicative as follows: max 0.29% C, 0.70% Si, 1.60% Mn, 0.025% P, 0.010% S, 1.0% Cr, 0.50% Ni, 0.30% Mo, approximately 0.04% B. After quenching they followed by low temperature tempering at 200 to 300 º C. The structure of the material is low-temperature tempered martensite, with partial residual austenite. Achieved hardness ranges from 470 to 530 HBW, i.e. about 46 to 50 HRC. Can be classified into groups intricately hard machinable hardened steel. In the process of machining these materials operate in highly abrasive cutting tool.

Keywords: hard milling, hard drilling, abrasion resistance steel, HARDOX 500, tool wear.

Vol. 8, 2014, No. 3-4, p. 2-8

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EFFECT OF DUPLEX SYSTEM NITRIDED LAYER – COATING ON THE CHANGE OF SURFACE TEXTURE PARAMETERS OF ALLOY CoCrMo

Author: Ondrej KLANICA, David DOBROCKÝ, Filip ONDERKA, David KUSMIČ

Abstract: The properties of surface of biomedical implants made from CoCrMo alloy which are used as joint replacements have a fundamental influence on durability and functional properties of these implants. Surface texture parameters Ra and Rt are one of the important parameters which directly influences the durability of the coating and thus whole implant. The values of these parameters are given by standards ISO 7206-2:2011 and ISO 7207-2:2011. Three duplex surface systems were individually deposited to improve mechanical properties on the CoCrMo alloy. As a duplex treatment were used the combination of plasma nitriding process with subsequent depositing thin films of the coatings nACo3®, DLC and ZrN. The process of plasma nitriding of CoCrMo alloy was implemented under these conditions: duration time was 10 hours, the ratio of gases H2:N2 = 3:1 and process temperature 450 °C, 500 °C and 550 °C. The surface texture parameters Ra, Rt were measured on the polished surface of the CoCrMo alloy before plasma nitriding then on the polished surface after plasma nitriding and finally on the polished surface after depositing of coating. It was found that the deposition of selected coatings on the surface after application of plasma nitriding influences the surface texture parameters Ra and Rt.

Keywords: CoCrMo alloy, Surface texture, Plasma nitriding.

Vol. 8, 2014, No. 3-4, p. 9-12

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MODELING OF NON-STATIONARY DIFFUSION of ALLOYING ELEMENTS ON EXPOSURE OF STEEL SAMPLES TO MAGNETIC PULSES

Author: Alexander ALIFANOV, Anna MILIUKOVA, Zhanne POPOVA, Dmitry TSIONENKO

Abstract: The model suggested describes a nonstationary diffusion of impurities in alloyed steels under magnetic pulse action. It is established that a non-stationary diffusion of impurities is determined by structural defects that are initiated during pulse processing. On non-stationary diffusion the impurity atoms of a larger radius migrate from the grain boundary into its depth. The interaction of atoms with dislocations hinders their further movement and leads to hardening of a ferrite grain.

Keywords: Diffusion of impurities, steel, magnetic pulse action, structure, defects

Vol. 8, 2014, No. 3-4, p. 13-17

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SIMULATION OF ARMOX STEELS MECHANICAL PROPERTIES DEGRATATION IN HAZ AFTER SELECTED THERMAL CUTTING PROCESSES

Author: Igor BARÉNYI

Abstract: The paper is focused on simulation of conditions which occurs in steels Armox 440, 500 and 600 after their cutting by plasma and laser cutting process. The simulations were carried out with using of TTSteel software which is designed to simulate quenching and tempering processes of steels. The results from simulations were used as a first step in research of changes in HAZ (heat affected zone) after laser and plasma cutting to reduce needed sources in real experiments.

Keywords: Armox 440, 500 and 600, plasma and laser cutting processes, simulation, degradation of mechanical properties, HAZ (heat affected zone), transformation diagrams, CCT, TTT

Vol. 8, 2014, No. 3-4, p. 18-22

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TRENDS IN MECHANICAL PROPERTIES ENHANCING OF STEELS USED FOR GUN BARRELS PRODUCTION

Author: Igor BARÉNYI, Jozef ŠANDORA

Abstract: The paper is focused on recent trends in mechanical properties enhancing of the steels used for sport or army guns barrels. Special conditions are required for these steels including high tensile strength Rm, surface hardness HV (HRC) as well as yield point Rp0.2 or impact value KV (KU). The strength could be improved by choosing some of new progressive materials as are Maraging, TRIP, TWIP or TMT steels. Some of these materials, their chemical composition, properties and strengthening methods are mentioned in the paper. Next part is focused on short description of howitzer or cannon barrel production and its heat treatment. Besides that, effect of electro slug remelting process (ESR) used as a method for barrels quality improving including experimental comparison of ESR treated and non-treated semiproducts is described in the paper.

Keywords: high strength steels, tensile strength, yield point, hardness, Maraging steels, Trip and Twip steels, Electro slug remelting, gun barrels production

Vol. 8, 2014, No. 3-4, p. 23-28

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EFFECT OF STORAGE CONDITIONS ON THE VIABILITY OF AMMUNITION

Author: Štefan PIVKO, Štefan TIMÁR

Abstract: The ammunition during its lifecycle is affected by climatic conditions in parallel with induced environs resulted from its operational use. Its safety and serviceability may be limited by an unacceptable level of degradation of components and materials, which subsequently results in a critical failure. This failure becomes a limiting factor of its operational life Identification of these processes enables appropriate predictions and assessment of the lifecycle period.

Keywords: failure, degradation, lifecycle, mathematical simulation, ammunition.

Vol. 8, 2014, No. 3-4, p. 29-33

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DIGITIZING LARGE-SCALED OBJECTS AND REVERSE ENGINEERING

Author: Štefan TIMÁR, Štefan PIVKO

Abstract: The aim of this paper is describe the application procedure of a non contact laser scanning and preparation of an operating procedure to digitize a selected large-scaled object. Cooperation and communication of 3D data in real-time allows simultaneous activities and the participation of other departments of the organization in the design and technical preparation of production of the product, resulting in a significant reduction in the number of structural discrepancies (inaccuracies). Applying this procedure in practice allows for quick development of an offer matching with demands and needs of customers.

Keywords: reverse engineering, 3D scanning, large-scaled objects, non contact laser scaning, 3D data.

Vol. 8, 2014, No. 3-4, p. 34-37

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EXPERT SYSTEM FOR DESIGN OFF-GRID RENEWABLE ENERGY SOURCES

Author: Vladimír ÁČ, Jaromír SUCHÁNEK

Abstract: The paper is treated with issues of design kits renewable electricity using computer-aided-based expert computer system. The expert system was designed and implemented as a special problem-oriented computer program that enables designers to optimize the functional and performance parameters island (Off-Grid) power sources with maximum use of existing local potential of renewable energy resources. Philosophy expert system is based on a comprehensive approach to solving the problems of specification power demand, through the choice of particular energy facilities with optimum performance dimension, the optimal design of battery power and the optimal design of the entire system. Expert system contains a database of available solar and wind sources of electric power, standby generators, batteries and inverters for automatic optimization proposal system. Timetable commissioning of electrical loads is optimized by genetic algorithm.

Keywords: expert system, computer support, renewable energy, island systems, genetic algorithm

Vol. 8, 2014, No. 3-4, p. 38-44

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DEFECTOSCOPIC DEFECTS RAILS FOR RAILWAYS AND PURPOSE CRACK DETECTION

Author: Eva BREZOVÁ

Abstract: Rail is the one of the most important materials to support and guide railway vehicles safely and smoothly. Since rail sufferes from various interacting forces and environmental atmosphere, wear and fatigue pose large problems with wheel and rail. Hence, wear and fatigue of wheel and rail have been studied so far to keep running safety and some level of riding comfort of vehicle taking into account track maintenance cost. In this review, rolling contact fatigue (RCF) of rail which is one of typical fatigue phenomenon for steel wheel - on-rail system is focused on and the history of RCF defects and the maintenance experience of their mitigation measures in railways are described. The concept of mitigation strategy is balance between wear and RCF. Controlling wear amount is a key word to mitigate RCF defects based on selecting rail material suitable for vehicle/track interaction together with grinding and lubrication. Furthermore, the purpose of Japanese bainitic steel rail is to obtain the suitable amount of wear to prevent the initiation of RCF crack.

Keywords: Defects, Rail, Wear, Rolling Contact Fatigue, Preventive Grinding

Vol. 8, 2014, No. 3-4, p. 45-50

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WELDING OF HIGH STRENGTH MATERIALS USED IN THE MANUFACTURE OF SPECIAL EQUIPMENT

Author: Eva BREZOVÁ, Harold MÄSIAR, Pavol RADIČ

Abstract: The paper brings closer knowledge in area of welding of high strength materials such as HARDOX, WELDOX, ARMOX, QSTE often used in the production of special equipment. It describes features of some selected sheet metals, their weld ability, preheat temperature and interpass temperature, a choice of additional material. WELDOX Design steel plates and HARDOX wear resistant plates combine extreme durability with exceptionally good weld ability. All conventional welding methods can be used for welding of these steels with any other wieldable steels.

Keywords: welding, steels, high-strength materials, HARDOX, WELDOX, ARMOX, QSTE

Vol. 8, 2014, No. 3-4, p. 51-61

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THE OPTICAL SPECTRAL BAND OF THE OPTOELECTRONIC IMAGING SYSTEM SELECTION

Author: Ľubomír UHERÍK

Abstract: The paper discusses a specific statistical method, which can be selected optical spectral band activities optoelectronic imaging system. It is used to describe the stochastic sensing optical information and discriminant analysis. How to test the suitability of the optical spectral band is used to minimize the probability of misclassification object to its surrounding use of the determination of the Mahanalobis distance. The suggestions for future research are using adaptive algorithms for estimations of the optical spectral bands with using datasets of the objects and background. The practical implications are identified in machine vision.

Keywords: optical spectral band, Mahalanobis distance, classification of classes of objects, imaging systems

Vol. 8, 2014, No. 3-4, p. 62-65

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SIMULATION MODELLING FOR AN ANALYSIS AND PREDICTION OF STOCHASTIC PHENOMENA IN THE OPERATION, MAINTENANCE AND RISK ASSESSMENT.

Author: Alena BREZNICKÁ, Alexej CHOVANEC, Jiří STODOLA

Abstract: The paper deals with possibilities of stochastic approaches in risk modelling from a point of costs and data relating reliability aiming to define needed parameters of distribution of stochastic variables. Dependability issue can not been dealt in an insulated way as how it has unfortunately happened till now, but, only in a thorough full system approach in respecting technical, technological, economic and other interactions to assess a risk. The paper shows advantages of simulation techniques of modelling.

Keywords: Analysis, reliability, maintainability, availability.

Vol. 8, 2014, No. 3-4, p. 66-69

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BASIS OF RELIABILITY DESIGN

Author: Zuzana JAMRICHOVÁ, Monika PILKOVÁ, Jiří STODOLA

Abstract: The knowledge and experience learnt from product designing have resulted in development of their reliability theory. The classical concept of safe – life is based on product over dimensioned design that considers safety factor or safety margin for measure. However, practical engineering has found this concept in a manner inconvenient as design fault-resistance to determine the ultimate condition and operating stress are random values. A way out is in the concept of stochastic approach to reliability design resulting from the defect-production probability distribution law. That concept allows product designing with predetermined reliability, such as in the example contained in the paper.

Keywords: design classical approach, safety factor, design stochastic approach, safe designing

Vol. 8, 2014, No. 3-4, p. 70-75

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UP-TO-DATE OF AUTOMOTIVE LUBRICANTS

Author: Peter LIPTÁK, Jiří STODOLA

Abstract: During the short time, automobile factories will strive achieve, two-fold increase in energy efficiency and ten-fold reduction in emission levels. On the way to achieving these task, automobile companies will be improving efficiency and emission of engines, while minimizing servicing requirements, as well as introducing new technologies and changing energy sourcing from oil, to gas, and possibly to hydrogen. Numerous supporting technologies, such as electronics, sensors, computers, fuels, lubricants, oil and others, is involved in contribution. The paper deal with expected improvements and changes in lubricant technology. There are up to date technologies, which will with novel surface technologies and engine design changes ,for example lead to fill-for-life engine lubrication, etc.

Keywords: fuel economy, emission, extend drain, power train trends, coatings, lubrication research, additives

Vol. 8, 2014, No. 3-4, p. 76-80

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HYBRID PHOTOVOLTAIC EQUIPMENT IN URBAN AREAS

Author: Ivan KOPECKÝ, Danka RAKÚSOVÁ, Monika PILKOVÁ

Abstract: Decreasing reserves of fossil fuels, an increase of a world-wide population and demands of individuals for energy in the whole world, a deepening dependence of a present civilization on a reliable provision of energy, a threat to biosphere, where a power economy has been created, including transportation as well as unstableness of sources and fuel consumption form an environment, that will significantly differ from a trouble free situation that the citizens of industrial developed countries of the 20th century had got accustomed to when fueling and using the energy.

Keywords: Photovoltaic cell, renewable source, energy, solar sensor, power plant.

Vol. 8, 2014, No. 3-4, p. 81-86

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PLASMA SPRAYING COATING OF AlSi + 70% SiC

Author: Mária LIČKOVÁ, Pavol TÖKÖLY, Jozef ELIÁŠ

Abstract: The paper presents the concept of technological creation of coating carbides TiC. Spraying parameters deposition rate (APS) and porosity (CDS) were determined. Microstructure and wear resistans of the obtained coatings were showed and hardness of APS coating , the hardness of CDS coating.

Keywords: Plasma, Coating, Aluminum, Hardness Microstructure, Strength.

Vol. 8, 2014, No. 3-4, p. 87-89

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METHODOLOGY OF RISK ANALYSIS

Author: Peter LIPTÁK, Jiří STODOLA, Danka RAKÚSOVÁ

Abstract: Modern society, yet a human being existence on the Earth are connected with the nature and environment which we are trying to adapt to our needs. Such activity is associated with many risks threatening not only the environment but the existence of human being on the Earth itself. Starting from the beginning of the 21st century mankind is being affected by many crises resulting in casualties, material losses and natural damage. The society responds to crises origin by predicting consequences, planning, creating human and material resources and also by creating system theory development and crisis management experience. The paper presents general resources, principles and comments on risk problems and its system analysis.

Keywords: Definition, analysis, probability and risk management possibilities, risk system approach

Vol. 8, 2014, No. 3-4, p. 90-93

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CHANGES IN MECHANICAL PROPERTIES OF SELECTED UHSS STEELS AFTER THEIR CUTTING BY LASER AND PLASMA

Author: Igor BARÉNYI

Abstract: The paper deals with armoured martensitic ultra high strength steels of Armox type and changes of their mechanical properties after the application thermal cutting processes as are plasma or laser cutting. The paper consists of theoretical part with explanation of the principle of plasma and laser cutting as well as experimental part describing experiment and results of the influence of cutting heat on tensile strength and yield strength of studied steels

Keywords: armour steels, martensitic steel, ultra high strength steel, ARMOX, plasma cutting, laser cutting, mechanical properties, tensile strength

Vol. 8, 2014, No. 3-4, p. 94-98

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DEGRADATION OF MECHANICAL PROPERTIES OF SELECTED UHSS STEELS IN HAZ AFTER THEIR WELDING

Author: Igor BARÉNYI

Abstract: The paper deals with welding process of ARMOX armoured martensitic steels. The steels are sensitive on temperature above 200°C due to specific processing in their production. The paper describes the level of degradation of mechanical properties at heat affected zone (HAZ) which is created as the consequence of the heat influence by welding process. The paper also includes the experimental parts to determine the level of the degradation of microstructure, tensile strength and microstructure changes in HAZ which cause that.

Keywords: armour steels, martensitic steel, ultra high strength steel, ARMOX, welding,Heat affected zone, mechanical properties, tensile strength, hardness, microstructure

Vol. 8, 2014, No. 3-4, p. 99-103

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DETERMINATION OF AVERAGE MAXIMUM OF ORIONIDS METEOR SHOWER FROM VISUAL OBSERVATION

Author: Jozef Drga, Martin Bulko

Abstract: This article deals with a method of investigation of Orionid meteor shower ZHR profile. The collected data were fitted with Gauss-like functions in order to determine the maximum of this meteor shower activity. This peak was found at solar longitude λ = 208.554° ± 0.156°. The activity date range of Orionids stream, determined from our data, starts approximately on September 26 and ends on November 9.

Keywords: Orionids, visual meteor observations, Zenithal Hourly Rate, meteor shower, population index

Vol. 8, 2014, No. 3-4, p. 104-107

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