Artykuły (CN-mafe)

Permanent URI for this collectionhttps://repo.agh.edu.pl/handle/AGH/102851

Artykuły czasopisma Metallurgy and Foundry Engineering

Browse

Now showing 1 - 20 of 216

Access status: Open Access ,
Decorative layers on silicon bronzes
(2011) Muskała, Karolina; Nadolski, Maciej; Derda, Anna
Decorative coatings artificially obtained on the surfaces of copper castings, commonly called artificial patinas in opposition to natural patinas, allow for adjusting the colour, the gloss, and the colour intensity of a casting to the customer demands. A decorative coating is a part of the artistic casting and the key element to the impression exerted by a sculpture. The colour, the type, and quality of a decorative coating depend on the author's intention, so that an artistic foundry should deal successfully with a variety of demands. Beside exerting the strictly artistic impression, patinas have one more goal to achieve - it is the corrosion protection. Natural patinas arising nowadays are characterised by Iow quality, irregular thickness, numerous cracks, and the dull taupe-brown colour. Therefore there exists need of generating decorative coatings in a controlled way. The present work is aimed to determine the influence of mechanical abrasive working applied to the surfaces of BK331 silicon bronze castings on the quality and durability of the obtained decorative coating for given recipes for patinating solutions.
Access status: Open Access ,
High-temperature rheometry of blast furnace synthetic slags doped with TiO₂ and TiN
(2015) Migas, Piotr; Ślęzak, Marta
Development has been conducted regarding the methodology of rotational measurements with a high temperature rheometer using Searle's method. The rheological analysis of liquid systems CaO-SiO2-Al2O3-MgO-TiO2 slags, and solid particles of titanium nitride TiN are presented (within a range of 0.1-0.7 of the volume fraction of TiN). The measurements were conducted at a range between 1310°C and 1500°C, which is typical for high-temperature zones in a blast furnace. The main objective of the study was to analyze the possibilities of viscosity measurements in homogenise and heterogenic systems (not standard systems within the industrial practice). The measurements were conducted for totally liquid blast furnace slags which show similarity to ideally viscous Newtonian bodies and also for heterogenic systems.
Access status: Open Access ,
The influence of iron powder and disintegrated steel scrap additives on the solidification of cast iron
(2010) Kopyciński, Dariusz; Dorula, Józef
The study proves that by introducing the iron powder and disintegrated steel scrap to low-sulphur cast iron still before the inoculation carried out with a conventional graphitising inoculant, the mechanical properties similar to those obtained during the inoculation treatment carried out on cast iron with the recommended high sulphur content are achieved. The said operation increases the number of crystallisation nuclei for dendrites of the primary austenite. In this case, the iron particles act as substrates for the nucleation of primary austenite gp due to a similar crystallographic behaviour of the regular face centered cubic lattice The more numerous are the dendrites of primary austenite, the less free space is available in the interdendritic spaces for the formation of graphite eutectic grains, which makes the structure more refined (more eutectic grains) and the mechanical properties higher.
Access status: Open Access ,
Features of 2017A and AlSi9Mg aluminum alloys friction stir welded with root-side heating
(2016) Mroczka, Krzysztof; Pietras, Adam; Jura, Jerzy
Aluminum alloys 2017A and AlSi9Mg (hypo-eutectic silumin) were friction stir welded with a relatively high linear velocity (over 1 m/min) and use of an additional heat source from the root side of the weld. Macrostructure investigation (with high-resolution images) showed no effect of heating on weld quality. The welding process caused significant fragmentation of the secondary phases in the AlSi9Mg alloy. Furthermore, it was proven that the material above the weld nugget was not mixed and contained micro-defects that were not caused by welding. Also, it contained cavities on the boundaries between Si-particles and the matrix. Based on hardness distribution, a slight strengthening of the cast alloy was observed at the bottom and middle parts of the weld. However, the hardness of the 2017A alloy initially decreased and then increased due to natural aging. This means that the FSW process produced a metastable state in the alloy.
Access status: Open Access ,
Modified single-zone model of radiation recuperator with microfinned surface
(2007) Karczewski, Krzysztof
Modified single-zone model of radiation recuperator with microfinned surface were elaborated. In this model the researches of heat transfer and hydraulic resistance microfinned elements were applied. To calculate the recuperator wall temperature weight mean temperature was used. By elaborated model radiation recuperator with microfinned surface to glass furnace were calculated. Single-zone model makes possible the project of small overall dimensions recuperators to industrial furnaces.
Access status: Open Access ,
Diminishment of internal polygonization of tubes in hot stretch-reducing mill
(Wydawnictwa AGH, 2010) Stefański, Krzysztof; Kubiński, Wiktor
One of the most important issues in hot stretch-reducing process is the maintaining precision of wall thickness. Exactly the same wall thickness at all cross-sections of tubes after stretch-reducing mill increases suitability of tubes in the next treatment processes. Internal polygonization of tubes and its removal during hot reducing is constantly the most important problem. The study is a presentation of test results for decrease of internal polygonization. Internal polygonization, as a result of deformation of tube wall thickness in all stands during hot reducing, can be minimized first of all by optimization of inter-stand tension. The tubes and pipes with minimal internal polygonization could be obtained during experiments of rolling after applying maximal average tension using a developed system for equations of axial forces equilibrium in the rolling mill.
Access status: Open Access ,
Optimization of casting technology of the pressure die cast AZ91D Mg-based alloy
(2010) Piwowarski, Grzegorz; Krajewski, Witold; Lelito, Janusz
Pressure die casting has become the next area of experimentation on virtual models in computer memory. The article presents an attempt to optimize the manufacturing process of an item made of magnesium AZ91D alloy, which was cast using the pressure technology on a machine with a hot pressing chamber. Special attention was paid to the flow velocity in individual parts of the gating system and in the mould cavity, as well as to the air evacuation from the mould cavity. The aim was to achieve a flawless casting, especially in terms of porosity.
Access status: Open Access ,
Non-invasive analysis and visualization of objects from FSW AlSi9Mg/2017A aluminum alloy joints
(Wydawnictwa AGH, 2018) Wójcicka, Anna; Mroczka, Krzysztof; Kowalski, Marcin
Friction stir welding (FSW) technology allows for the welding of materials that differ in their chemical compositions, microstructures, and properties. When selecting the parameters, it is necessary to analyze the structure of a weld and eliminate the defects. The use of X-ray microtomography creates the possibility of precise imaging of a joint structure - especially when it contains defects (voids). The tests were carried out on an FSW joint made with both 2017A and AlSi9Mg aluminum alloys. The macrostructure was cross-sectional, and a defect was found in the middle part of the joint and on the advancing side. We used a conventional method of observation light microscopy. Then, an analysis was performed using X-ray microtomography, which revealed the shape of the defect in 3D. Individual cross-sections were extracted, which enabled us to measure the geometric quantities. A dependence was found for the shape of the defect on the welding parameters and the variability of its construction. The usefulness of this advanced material imaging technology for the analysis of FSW welds has been confirmed.
Access status: Open Access ,
Influence of orientation relationship between ferrite and cementite in pearlite on stability of cementite plates
(2007) Czarski, Andrzej; Skowronek, Tadeusz; Osuch, Władysław
The aim of the studies performed was to assess an influence of crystallographic orientation relationship (OR) between pearlitic ferrite and cementite on a stability of cementite plates. Diffraction analysis made with an electron microscope showed the existence of the Bagaryatski OR and the Pitsch OR both in the pearlite structure after eutectoid transformation and after each tested time of the sphe-roidization annealing. The obtained results indicate that the crystallographic orientation relationship does not influence the stability of cementite showing lamellar morphology.
Access status: Open Access ,
Solidification conditions of gray and white cast iron. Part I, Theoretical background
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
The present work is based on a heat balance during the solidification of cast iron. Accordingly. an analytical expression was derived to relate the chilling tendency (CT) of cast iron with nucleation and growth processes associated with eutectic graphite and cementite constituents. A relationship is found between the CT and factors such as the physical-chemical state of liąuid, the distribution of nucleation sites, and the density of nucleation sites for eutectic grains. In particular, it is found that the casting modulus (M), enabling determinations of minimum wali thickness for chilled castings or chill widths in wedge shaped castings can be related to the CT. Finally, the present work provides a rationa-lization for the effect of technological factors such as the chemistry of the melt, inoculation practice. holding temperaturę and time on the resultant CT and chill of the cast iron.
Access status: Open Access ,
FT-IR studies of the polymeric binder BioCo1 with modified biopolymer. Part 1
(2014) Grabowska, Beata; Kaczmarska, Karolina
The paper presents structural studies of polymeric water soluble compositions consisting of acrylic derivatives/modified biopolymer. The research FT-IR was focused on novel polymer composition poly(acrylic acid)/modified starch (PAA/CMS) designed for application in the foundry industry - a novel group of polymeric BioCo binders. It was found, that the structure changes occur within groups: carboxyl present in poly(acrylic acid) and carboxyl and hydroxyl groups contained in carboxymethyl starch (vibrations: $ν_{s}$-C=O, $ν_{s}$-$COO^{-}$ and δ-C-O-H).
Access status: Open Access ,
Determination of diffusible hydrogen content in the deposited metal of rutile electrodes by the glycerin method
(2013) Fydrych, Dariusz Marek; Tomków, Jacek; Świerczyńska, Aleksandra
The presence of diffusible hydrogen in welded joints is one of the causes of formation the welding imperfections. Improvement of weldability can be achieved by reducing the hydrogen amount in welded joints. This requires, among others, the finding of sources of hydrogen. For high hydrogen processes the commonly used method of determining the diffusible hydrogen amount is the glycerin method. This paper concerns issues related to the test procedure and the possibility to control the diffusible hydrogen amount in deposited metal.
Access status: Open Access ,
Microstructure and phase composition of the Ni-Si-B-Ag-based plasma spray deposit
(2016) Ziewiec, Krzysztof; Wojciechowska, Mirosława; Jasiński, Marcin; Mucha, Dariusz; Lis, Marcin
The aim of this work is to study the possibility of obtaining an amorphous-crystalline composite starting from Ni-Si-B-based powder grade 1559-40 and silver powder. The process of plasma spray deposition was performed on a water-cooled copper substrate. The cooling rate was assessed using a mid-wave infrared MWIR camera. The microstructure of the deposit was studied using scanning electron microscope SEM with an energy dispersive spectrometer EDS. Phase identification was performed using X-ray diffraction XRD. The studies confirmed an amorphous-crystalline microstructure of the deposits. The predominant constituent of the microstructure was amorphous regions enriched in Ni, Si, and B, while the other constituent was Ag-rich crystalline inclusions identified as a face-centered cubic fcc.
Access status: Open Access ,
Structural construction of hardeners with different hardening rates intended for geopolimer binder systems used for the preparation of moulding sands
(2015) Bobrowski, Artur; Grabowska, Beata; Kaczmarska, Karolina
The paper presents the results of structural investigations of hardeners with different hardening rate for geopolymer binder system Geopol, manufactured by the Sand-Team Company. Studies have shown that these hardeners have similar chemical structures and that the hardening rate of the binder depends on the proper selection of the proportions of the respective components.
Access status: Open Access ,
Banded microstructure in forged 18CrNiMo7-6 steel
(2009) Krawczyk, Janusz Ryszard; Pawłowski, Bogdan; Bała, Piotr
18CrNiMo7-6 steel, after hot forging, exhibits a distinct banding of ferritic-pearlitic microstructure, probably related to the segregation of alloying elements during the ingot crystallization. The heat treatment allowing to obtain bainitic microstructure in this steel is described in the paper. The obtained bainitic microstructure exhibits only very small traces of banding.
Access status: Open Access ,
Drying and hardening of ceramic moulds applied in the investment casting technology - investigations of the process kinetics
(2011) Zych, Jerzy; Snopkiewicz, Tomasz
Ceramic moulds applied in the investment casting technology are multilayer structures, built in an alternating process of depositing and drying of successive layers. Each individual layer is formed from a fluid (liquid) ceramic moulding sand and a grain matrix. In the current, environmentally technology fluid ceramic sands based on ethyl silicate are being substituted by ceramic sands containing colloidal silica as a binder. The ability and rates of drying and hardening of these new colloidal (water) ceramic moulding sands are quite different than of the ones which have a binder dissolved in alcohol. The kinetics of the process based on new binders is not well known. The technological principle requires that the successive layer deposition is done only when the one deposited previously is already sufficiently dry. Investigations of the possibility of application of some methods including: ultrasound, resistance and weigh method are presented in the paper. Advantages and disadvantages of each method are indicated as well as the assessment of their practical suitability is perfomed.
Access status: Open Access ,
The influence of welding method on microstructure and mechanical properties of aluminum alloys joints
(Wydawnictwa AGH, 2019) Noga, Piotr; Richert, Maria Wiesława; Węglowski, Marek Stanisław
Rapid technological progress in recent years has led to an intensified interest in alternative methods of joining metals. Today's industry is constantly demanding new joining processes, which enable high-quality welded joints in a wide range of thicknesses of combined materials at low production cost. There are at least several dozen welding methods currently available. The selection of the process depends on the type of welded materials, acceptable heat input, as well as future working conditions. The paper presents the results of the microstructural examination and mechanical properties of joints of the aluminum alloy for plastic working such as EN AW-6082. The paper presents the results of microstructural observations and mechanical properties of EN AW-6082 aluminum alloy. Methods used for joining were successively TIG (welding with a non- -consumable electrode in a shield of inert gases), MIG (welding with a consumable electrode in a shield of inert gases), EBW (electron beam welding) along with FSW (friction stir welding method). TIG (welding with a non-consumable electrode in a shield of inert gases), MIG (welding with a consumable electrode in a shield of inert gases), EBW (electron beam welding) along with FSW (friction stir welding method) were used as joining techniques.
Access status: Open Access ,
The ancient slag-pit furnace and the reduction process in the light of a new archaeological concept and metallurgical research
(2008) Bielenin, Kazimierz; Suliga, Ireneusz
In this work the state of archeological and experimental research into slag-pit fournace in the Świętokrzyskie Mountains region was valued. The new archeological concept of 'the surface of free solidification' and results of its metallurgical verification were presented. Obtained results constituted piece of evidence supporting the theses connected with the concept of the surface of free solidification of the slag blocks.
Access status: Open Access ,
Modelling of microstructure development in forging of a windmill shaft
(2006) Sińczak, Jan; Skubisz, Piotr; Łukaszek-Sołek, Aneta; Pietrzyk, Maciej
The paper presents the results of investigation of microstructure evolution in hot-deformed steel in the process of forging of large forgings. Using a forging of a windmill main shaft as an example, description of the technological process is presented, focused on phenomena occurring in the microstructure during hot-forging. Investigation of the microstructure during and after forging of a shaft was made. The results of theoretical calculation of microstructure evolution during subsequent stages of production cycle are based on temperature changes plots derived from industrial practice. Simulation of microstructure evolution allowed plotting changes of grain size and recrystallized volume fractions versus time during forging and reheating operations.
Access status: Open Access ,
Hot cracking of nickel-based superalloy turbine blade
(2015) Rakoczy, Łukasz; Tuz, Lechosław; Pańcikiewicz, Krzysztof
The aim of this study was to present the hot cracking behavior of a blade originating from a turbine blade segment. The crack was induced by a gas tungsten arc welding process, and the research material was a MAR-M247 nickel based superalloy. This alloy is considered to be difficult to weld because of its high tendency to crack. Light microscopy and scanning electron microscopy show the occurrence of cracking in the melted zone, heat-affected zone, and base alloy. A scanning electron microscopy investigation revealed that cracks are propagated by stresses and liquation of the low temperature constituent.