Wyniki wyszukiwania - Biblioteka Nauki

1

Continuous modification of cast iron by the FLOTRET method

100%

Hanus A. , Hanusová P.

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tom Vol. 12, iss. 3

43-48

EN

Increasing demands on the utility properties of materials used for castings have led to the production of cast iron with a modified shape of graphite, where the required properties are achieved by a change in graphite shape, its size and layout, and a change in the basic structure of the metal. This paper is focused on the continuous method of producing spheroidal graphite FLOTRET. In the introductory section is summarized the theoretical foundations of the secondary treatment of cast irons, especially the FLOTRET flow method, describes the advantages and disadvantages of the method. The practical part is divided into laboratory and operational tests. Laboratory experiments were conducted on a laboratory-type modifier FLOTRET chamber, which was designed and hydraulically optimized. Experiments were focused on the effects of pressure altitude and amount of modifier on the residual values of magnesium, as conditions for a successful modification. The method was tested in two foundries under operating conditions and in one of them was observed a long-term modification process.

2

Continuous Modification of Cast Iron By the FLORET Method

100%

Hanus A. , Hanusová P.

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3

Kvalita materialu odlitku

80%

Havlicek F. , Kozelsky P. , Hanus A.

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tom R. 4, nr 11/1

181--187

CS

Prednaska pojednava o kvalite materialu odlitku v celem jeho prurezu a hodnotach materialovych vlastnosti. Vyznamny vliv na kvalitu matrice ma krystalizace a jeji pruvodni jevy predevsim segregace prvku. Byly sledovany hodnoty vsech druhu mechanickych vlastnosti, chemickeho slozeni, makrostruktury a hustoty matrice u ocelovych odlitku s rozdilnou hmotnosti i s rozdilnymi tloust'kami sten [...]

EN

The lecture deals with the quality of materials for castings in their whole sections and the values of material properties. It is crystallisation and its accompanying phenomena, especially element segregation, that have a significant influence on matrix quality. Values of all the kinds or mechanical properties, the chemical composition, macrostructure and density of the matrix with steel castings of various weights and different wall thicknesses were observed. To two castings, the influence of melt pulsation at solidification was applied as well. Furthermore, values of material properties of annealed and unannealed castings were ascertained. The results obtained were used for modifications of some manufacturing processes, thermal modes and for a proposal for contractual takeover conditions concerning quality for steel castings of the weight of more than 20 t. The results contribute to the knowledge from the area of foundry and material engineering.

4

Surface quality of foundry pattern manufactured by FDM method - rapid prototyping

80%

Hanus A. , Špirutová N. , Beňo J.

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tom Vol. 11, iss. 1s

15-20

EN

The goal of this paper was to verify the possibilities of using 3D models produced by means of the FDM technology for actual foundry production. Experimental models were produced using Dimension sst 768 3D printer. Two types of castings (type I - simple plates, type II - jewellery) were cast in plaster moulds. The models were burnt out at 500 oC. The goal of the experiment was to verify the effect of modifications upon surface quality of the resulting casting. The ABS model was tested with unmodified surface, chemically treated surface, blasted surface and blasted and etched surface together. The results of the experiment have confirmed the assumed effect of both mechanical and chemical modifications of the model surface on casting surface quality.

5

Effect of supplemental water source on performance of calves during milk feeding and their cross-sucking after weaning

70%

Broucek J. , Uhrincat M. , Sistkova M. , Soch M. , Hanus A.

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nr 1

6

Structure and mechanical properties of Mg-Si alloys at elevated temperatures

61%

Cizek L. , Hanus A. , Blahoz O. , Tański T. , Dobrzański L. A. , Prażmowski M. , Pawlica L.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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tom Vol. 35, nr 1

37-46

EN

Purpose: of this paper is to extend a complex evaluation of magnesium alloys which requires very often knowledge of structure and mechanical properties at elevated temperatures. These properties are connected with microstructure that is influenced by metallurgical and technological factors and exploitation conditions. Presented knowledge expresses very important information for design and exploitation of these alloys. Design/methodology/approach: The optical and scanning electron microscopy methods were used for metallographic and fracture analyses of studied magnesium alloys after tensile test at elevated temperatures. Findings: Objective of this work consisted in determination of structure and mechanical properties progressive magnesium alloys at elevated temperatures. Research limitations/implications: Knowledge of alloys structure characteristics will be determined new research direction of scope. Practical implications: The results may be utilized for a relation between structure and properties of the investigated material in process of manufacturing. Originality/value: These results contribute to complex evaluation of magnesium alloys properties namely for explanation of structure developed new magnesium alloys. The results of this paper are determined for research workers deal by development new exploitations of magnesium alloys.

7

Mechanical properties and structure of magnesium alloys with graduate content of aluminium at elevated temperatures

51%

Čížek L. , Hanus A. , Greger M. , Juřička I. , Rusz S. , Prażmowski M. , Tański T. , Hernas A.

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2007

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tom Vol. 321, z. 89

91-92

EN

At the contemporary stage of the development of the engineering thought, and the product technology itself, material engineering has entered the period of new possibilities of designing and manufacturing of elements, introducing new methods of melting, casting, forming, and heat treatment of the casting materials, finding wider and wider applications in many industry branches. Therefore the development of engineering aims at designs optimizing, reducing dimensions, weight, and extending the life of devices as well as improving their reliability [1-3]. Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including the magnesium alloys. Magnesium alloys and their derivatives, characterize of low density (1.5-1.8 g/cm3) and high strength in relation to their weight [1,3]. Knowledge of the relaxation properties of metal materials at elevated temperatures is necessary for the verification of susceptibility of castings to the creation of defects during the production and forming processes [1,4]. Temperature limits of materials where highest tension values are generated may be detected with tensile tests under high temperatures. Experimental investigation was made on magnesium alloy AZ91 - samples A and AZ61 - samples B (after ASTM Standard) in initial state as cast. The purpose of the measurement was the study of deformation and tension changing with temperature at the tensile test and in time with simultaneous acoustic emission (AE) measurement (in the case of alloy AZ61). These dependencies were also monitored at various temperatures of sample heating from 15°C to 400°C with crosspiece shift of 6mm/min. The measurement included material sample stress at the given temperature by tension at the INOVA electro hydraulic loading machine with a loading force of 20 kN with possibility of the acoustic emission (AE) monitoring. The test bar with 0 4 mm was warmed up in a graphite furnace in inert atmosphere (argon). The AE scanner records released elastic waves (overshoots) in a frequency band between 30 kHz and 400 kHz. The output from the scanner is carried to the AE preamplifier where it is amplified and impedance-adjusted so it is possible to be transferred to more far-reaching places. The signal is further carried to the EMIS 01 system and to the PC's hard disk and they are processed in the EXCEL. Microstructure of the alloys in initial state is formed by solid solution and by minority phases Mgn(Al,Zn)i2 in massive and dispersion form and showed dendritic segregation. During heating magnesium alloy AZ91 at chosen temperatures there occurs partial dissolution of minority phases. Homogenisation of microstructure is, however, accompanied by simultaneous forming of inter-granular non-integrities, which is unfavourable from the viewpoint of strength and plastic properties, especially at higher temperatures. Failure occurs practically at all temperatures basically by inter-crystalline splitting along the boundaries of original dendrites. Trans-crystalline plastic character of fracture in small areas at 300°C was occurred. Similar temperature dependence was occurred in the case of alloy AZ61. In this case the plasticity properties were at high level. An acoustic emission method was used for a better analysis of the course of the deformation action at the tensile test. The AE method especially enables a study of dynamics of these processes at various temperatures. The opportunity to study deformation processes preceding initiation of cracks and monitoring of initiation and crack growth as up to the macroscopic scale is a big advantage of the AE. The method is therefore used in the technical diagnostics and at a check of technological operations in the production process.