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1
Content available Influence of Component Proportions in Casting Process on Hardness and the Quality of Cast Iron
Saikaew Charnnarong, Harnsopa S.
Archives of Foundry Engineering
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2023
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Vol. 23, iss. 2
35--42
EN
The purposes of this study were to investigate the impact of proportions of cast iron scrap, steel scrap, carbon and ferro silicon on hardness and the quality of cast iron and to obtain an appropriate proportion of the four components in iron casting process using a mixture experimental design, analysis of variance and response surface methodology coupled with desirability function. Monte Carlo simulation was used to demonstrate the impacts of different proportions of the four components by varying the proportions of components within ±5% of the four components. Microstructures of the cast iron sample obtained from a company and the cast iron samples casted with the appropriate proportions of the four components were examined to see the differences of size and spacing of pearlite particle. The results showed that linear mixture components were statistically significant implying a high proportion of total variability for hardness of the cast iron samples explained by the casting mixtures of raw materials. The graphite of the sample casted from the appropriate proportion has shorter length and more uniform distribution than that from the company. When varying percentages of the four components within ±5% of the appropriate proportion, simulated hardness values were in the range of 237 to 256 HB.
2
Content available Effect of Alloying Additives and Casting Parameters on the Microstructure and Mechanical Properties of Silicon Bronzes
Witasiak Dawid, Garbacz-Klempka Aldona, Papaj M., Papaj P., Piękoś Marcin, Kozana Janusz, Maj Maria, Peret-Nowak Małgorzata
Archives of Foundry Engineering
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2023
|
Vol. 23, iss. 3
110--117
EN
The studied silicon bronze (CuSi3Zn3Mn1) is characterised by good strength and corrosion resistance due to the alloying elements that are present in it (Si, Zn, Mn, Fe). This study analysed the casting process in green sand moulding, gravity die casting, and centrifugal casting with a horizontal axis of rotation. The influences of Ni and Zr alloying additives as well as the casting technology that was used were evaluated on the alloy’s microstructure and mechanical properties. The results of the conducted research are presented in the form of the influence of the technology (GS, GZ, GM) and the content of the introduced alloy additives on the mechanical parameters (UTS, A10, and Proof Stress, BHN). The analysis of the tests that were carried out made it possible to determine which of the studied casting technologies had the best mechanical properties. Microstructure of metal poured into metal mould was finer than that which was cast into moulding compound. Mechanical properties of castings made in moulding compound were lower than those that were cast into metal moulds. Increased nickel content affected the BHN parameter.
3
Content available Effect of Post Cast Heat Treatment on Cu20wt.%Sn on Microstructure and Mechanical Properties
Slamet S., Suyitno S., Indraswari Kusumaningtyas I. K.
Archives of Foundry Engineering
|
2021
|
Vol. 21, iss. 4
87--92
EN
Casting is one method of making metal components that are widely used in industry and up to date. The sand casting method is used due to its simplicity, ease of operation, and low cost. In addition, the casting method can produce cast products in various sizes and is well-suited for mass production. However, the disadvantage of casting, especially gravity casting, is that it has poor physical and mechanical properties. Tin bronze Cu20%wt.Sn is melted in a furnace, then poured at a temperature of 1100°C into a sand mold. The cast product is a rod with 400 mm in length, 10 mm in thickness, and 10 mm in width. The heat treatment mechanism is carried out by reheating the cast specimen at a temperature of 650°C, holding it for 4 hours, and then rapid cooling. The specimens were observed microstructure, density, and mechanical properties include tensile strength and bending strength. The results showed that there was a phase change from α + δ to α + β phase, an increase in density as a result of a decrease in porosity and a coarse grain to a fine grain. In addition, the tensile strength and bending strength of the Cu20wt.%Sn alloy were increased and resulted in a more ductile alloy through post-cast heat treatment.
4
Content available Effect of High-tin Bronze Composition on Physical, Mechanical, and Acoustic Properties of Gamelan Materials
Slamet S., Suyitno S., Kusumaningtyas I., Miasa I. M.
Archives of Foundry Engineering
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2021
|
Vol. 21, iss. 1
137--145
EN
High tin bronze alloy (Cu>17wt.%Sn) is commonly as raw material to fabricate musical instruments. Gamelan musical instruments in Indonesia are produced using tin bronze alloy raw materials. The tin bronze alloy used by each gamelan craftsman has a different tin composition, generally in the range of Cu(20-24) wt.% Sn. This study aims to investigate the effect of microstructure, density, and mechanical properties of Cu(20-24)wt.%Sn against the acoustic properties processed by the sand casting method. The material is melted in a crucible furnace until it reaches a pouring temperature of 1100ºC by the sand casting method. The specimens were subjected to microstructure observations, density and porosity as well as mechanical properties testing including tensile strength, bending strength, hardness, and modulus of elasticity. Mechanical properties data then used to calculate several parameters of acoustic properties including speed of sound (c), impedance (z) and radiation coefficient (R). Processes simulation using Finite Element Analysis (FEA) and Experiment Method Analysis (EMA) were carried out to determine acoustic properties including sound intensity, natural frequency and damping capacity. The experimental result shows that the increase in tin composition in Cu(20-24) wt.% Sn changed the microstructure of coarse grains into dendrite-columned fine grains. Physical properties of density decrease, while porosity increases. Mechanical properties including tensile strength, modulus of elasticity, and bending strength decreased, while the hardness of the alloy increases. The calculation of acoustic parameters such as the speed of sound (c), impedance (z) and radiation coefficient (R) has decreased. Moreover, sound intensity (dB), natural frequency (Hz) and damping capacity also decrease with increasing tin composition. Hence, tin bronze alloy Cu20wt.%Sn is the recommended raw material for the manufacture of gamelan instruments through the sand casting method.
5
Content available A Study of Inclusions in Aluminum and Titanium Deoxidized 4130
Tuttle R. B., Kottala S.
Archives of Foundry Engineering
|
2018
|
Vol. 18, iss. 1
129--134
EN
In this paper, the authors investigated the size distribution of titanium oxide (TiO2), titanium nitride (TiN) and titanium carbide (TiC) inclusions in a titanium deoxidized 4130 steel and compared it with the 4130 base alloy composition inclusions. TiN and TiC inclusions are of particular interest due to their role as heterogeneous nuclei for various phase reactions in steels. Two types of samples were prepared, a polished sample and a filtered sample. Electrolytic dissolution was employed to make the filter paper samples. The size range of titanium inclusions was found to be more than that of the non-metallic inclusions from 4130 base alloy heat. Titanium inclusions from the filter and polished samples were round in shape. TiC and TiN inclusions were not found in the electrolytic extraction samples. Inclusions and their chemistries were analyzed using scanning electron microscope and energy dispersive spectrometer. The inclusion size range was larger for the titanium deoxidized samples than the base alloy. However, in both steels the majority of inclusions had a size smaller than 10 μm.
6
Content available Influence of the Chemical Composition on Electrical Conductivity and Mechanical Properties of the Hypoeutectic Al-Si-Mg Alloys
Dybowski B., Szymszal J., Poloczek Ł., Kiełbus A.
Archives of Metallurgy and Materials
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2016
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Vol. 61, iss. 1
353--360
EN
Due to low density and good mechanical properties, aluminium alloys are widely applied in transportation industry. Moreover, they are characterized by the specific physical properties, such as high electrical conductivity. This led to application of the hypoeutectic Al-Si-Mg alloys in the power generation industry. Proper selection of the alloys chemical composition is an important stage in achievement of the demanded properties. The following paper presents results of the research on the influence of alloys chemical composition on their properties. It has been revealed that Si and Ti addition decreases electrical conductivity of the Al-Si-Mg alloys, while Na addition increases it. The mechanical properties of the investigated alloys are decreased by both silicon and iron presence. Sodium addition increases ductility of the Al-Si-Mg alloys.
7
Content available Influence of Age Hardening Parameters on the Microstructure and Properties of the AlSi7Mg Sand Cast Alloy
Poloczek Ł., Dybowski B., Rodak K., Jarosz R., Kiełbus A.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 4
3035--3042
EN
Aluminium alloys are characterized by a low density, acceptable mechanical properties and good technological properties. This unique connection of features made aluminium alloys perfect structural material for the transportation industry. Also, due to their good electrical conductivity they also found application in energy production industry. High mechanical properties and electrical conductivity of the Al-Si alloys with Mg addition may be achieved by heat treatment. However, the highest mechanical properties are achieved in the early stages of age hardening - due to precipitation of coherent phases, while high electrical conductivity may be achieved only by prolonged aging, during precipitation of semi-coherent or fully noncoherent, coarse phases. Carefully heat treated AlSi7Mg alloy may exhibit both fairly high electrical conductivity and slightly increased mechanical properties. The following article present results of the research of influence of heat treatment on the properties and microstructure of sand cast AlSi7Mg alloy. Microstructure observations were performed using light microscopy, scanning electron and scanning-transmission electron microscopy. Hardness and electrical conductivity of the AlSi7Mg alloy were investigated both in as-cast condition and after heat treatment. Maximum hardness of the alloy is achieved after solutioning at 540°C for 8h, followed by 72h of aging at 150°C, while maximal electrical conductivity after solutioning at 540°C for 48h, followed by 96h of aging at 180°C. Increase of the electrical conductivity is attributed to increasing distance between Si crystals and precipitation of semi coherent phases.
PL
Stopy aluminium charakteryzują się małą gęstością, dobrymi właściwościami mechanicznymi, a przy tym bardzo dobrymi właściwościami odlewniczymi. Połączenie tych cech powoduje że stopy te znajdują szerokie zastosowanie w przemyśle motoryzacyjnym. Ich dużą zaletą jest również wysoka przewodność elektryczna oraz cieplna, dzięki której znajdują również zastosowanie w przemyśle energetycznym. Uzyskanie tak wysokich właściwości mechanicznych i przewodności elektrycznej w przypadku stopów Al-Si z dodatkiem Mg może być osiągnięte tylko poprzez przeprowadzenie obróbki cieplenj. Najwyższe właściwości mechaniczne są osiągane w początkowej fazie utwardzania wydzieleniowego (wydzielanie się koherentnych faz), podczas gdy uzyskanie wysokich wartości przewodności może być osiągnięte tylko przez długotrwałe starzenie, podczas wydzielania się pół koherentnych lub niekoherentnych, dużych faz. W przypadku stopu AlSi7Mg, starannie dobrana obróbka cieplna może powodować znaczne podwyższenie przewodności oraz polepszenie właściwości mechanicznych. Ninjiejszy artykuł przedstawia wyniki badań wpływu parametrów obróbki cieplnej na strukturę i właściwości stopu AlSi7Mg, odlanego grawitacyjnie do form piaskowych. Obserwacje mikrostruktury prowadzone były prz użyciu metod mikroskopii świetlnej, elektronowej mikroskopii skaningowej oraz elektronowej mikroskopii transmisyjnej. Twardość i przewodności stopu AlSi7Mg badano zarówno w stanie lanym, jak i po obróbce cieplnej. Maksymalną twardość stopu uzyskano po przesycaniu w 540°C przez 8h oraz starzeniu w temperaturze 150°C przez 72h. Maksymalną przewodność elektryczną uzyskano po przesycaniu w 540° C przez 48h, oraz starzeniem w temperaturze 180°C przez 96h. Wzrost przewodności elektrycznej spowodowany jest zwiększeniem się odległości pomiędzy kryształami Si oraz wydzielaniem się półkoherentnych faz.
8
Content available Ultrasound Wave Attenuation of Grain Refined High – Zinc Aluminium Sand-cast Alloys
Krajewski W. K., Buraś J., Krajewski P. K., Piwowarski G.
Archives of Foundry Engineering
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2015
|
Vol. 15, iss. 2
51--54
EN
The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150 dB/m.
9
Content available Influence of the Mould Material Coatings on the Microstructure of AlSi7Mg Alloy
Dybowski B., Poloczek Ł., Jarosz R., Kiełbus A.
Archives of Foundry Engineering
|
2015
|
Vol. 15, iss. 1 spec.
13--16
EN
Family of the aluminium alloys with silicon addition is an important group of non-ferrous casting alloys. They exhibit very good technological properties, especially castability. Aluminium alloys are known for their low density, which in connection with high mechanical properties and relatively low price create very good structural material. Magnesium addition to the Al-Si alloys enables their age-hardening, resulting in even better mechanical properties. However, formation of the microstructure of the alloy has to be precisely controlled to avoid formation of massive, brittle silicon crystal. Presence of large, platelet-like particles of silicon, dramatically decreases material mechanical properties. Second factor, which must be taken into consideration is casting porosity, which may significantly decrease fatigue life of the element. Many researches consider effect of modification or refining on the microstructure of the castings made from the Al-Si alloys. However there is lack of detailed investigation on the mould components influence on the microstructure. Such components may be protective coatings applied for the mould sand during the gravity casting of Al-Si alloys. Following paper presents results of the research on the influence of applied mould protective coatings on the microstructure of AlSi7Mg sand cast alloy. Five different protective coatings were applied. Macro observations, qualitative and quantitative microstructure evaluation of the AlSi7Mg alloy was conducted during the researches. Results revealed, that application of the coatings does not influence the size and distribution of the α- Al dendrites, however it influences size of Si particles in a significant way. It was revealed that application of water-based coatings affects the heat flow in the mould material-liquid alloy system, thus causing growth of silicon particles.
10
Content available Effect of Mould Components on the Cooling Rate, Microstructure, and Quality of WE43 Magnesium Casting Alloy
Dybowski B., Kiełbus A., Jarosz R.
Archives of Metallurgy and Materials
|
2014
|
Vol. 59, iss. 4
1527--1532
EN
We investigated the impact of the applied cooling and feeding method on the microstructure and metallurgical quality of castings made from WE43 magnesium alloy. Six identical plates with dimensions of 100x50x20 mm were sand cast for use as samples. Each casting was fed and cooled in a different way. The solid solution grain size was evaluated quantitatively using the Met-Ilo software program, and casting defects were observed using a scanning electron microscope Hitachi S3400N. The finest solid solution grain was observed in the castings with only the coolers applied. Non-metallic inclusions were observed in each plate. The smallest shrinkage porosity was observed in the castings with feeders applied.
PL
Celem badań było zbadanie wpływu zastosowanej metody chłodzenia i zasilana na mikrostrukturę i jakość metalurgiczną odlewów wykonanych ze stopu magnezu WE43. Sześć identycznych płyt o wymiarach 100x50x20 mm, chłodzonych i zasilanych na różne sposoby, odlano do formy piaskowej. Wielkość ziarna roztworu stałego zostały wyznaczone ilościowo w programie Met-Ilo. Obserwacje wad odlewniczych prowadzono na skaningowym mikroskopie elektronowym Hitachi S3400N. Najmniejszym ziarnem roztworu stałego charakteryzowały się odlewy z zastosowanymi tylko ochładzalnikami. W strukturze każdego z odlewów stwierdzono wtrącenia niemetaliczne. Najmniejszą porowatością skurczową charakteryzowały się odlewy z zastosowanymi nadlewami.
11
Content available Characterization of the Parameters of Sand Moulds in Compaction Process by Use of the Industrial Computer Tomography (ICT)
Kadauw A.
Archives of Metallurgy and Materials
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2014
|
Vol. 59, iss. 3
1097--1101
EN
One main problem in moulding is the proper characterization of the local density of the mould, the best without its destroying, for assessment the quality of the mould and to compare results of compaction modeling with experimental results. Industrial computer tomography (ICT) is a technique that allows the non-destructive and contact-free visualization and characterization of the internal and external parts of physical objects including also sand moulds. It is possible to apply ICT technique for the specific research presented here. Moulding sand compaction plays an important role for the quality of the mould and as the consequence for the quality of manufactured casting. The required quality of the castings can be achieved by selecting optimum manufacturing process parameters. The determination of these parameters is often carried out by trial-and-error-method, which is expensive and time consuming. To improve the understanding of the influence of various parameters, mathematical modeling of the compaction processes using numerical solutions was performed. Theoretical results of the compaction simulations have then been compared with practical results of mould compaction obtained by ICT. Itwasfound that simulation results agree well with data from computer tomography and provide insight into the spatial distribution of the density of sand moulds under industrial condition.
PL
Podstawowym problemem w procesie formowania jest prawidłowe określenie rozkładu gęstości w formie, najlepiej metodami nieniszczącymi, w celu oceny jakości formy oraz w celu porównania wyników modelowania procesu zagęszczania z wynikami eksperymentu. Przemysłowa tomografia komputerowa- ICT jest techniką, która umożliwia nieniszczącą oraz bezkontaktową wizualizację oraz charakterystykę wewnętrznych oraz zewnętrznych części obiektów fizycznych, w tym również form odlewniczych. ICT jest możliwe do zastosowania w specyficznych badaniach opisanych poniżej. Zagęszczanie masy formierskiej istotnie wpływa na jakość formy i w konsekwencji na jakość wytwarzanych odlewów. Wymagana jakość odlewów może być osiągnięta przez wybór optymalnych parametrów procesu wytwarzania. Określenie tych parametrów często jest dokonywane metodą prób i błędów, co jest kosztowne i czasochłonne. W celu lepszego zrozumienia wpływu różnorodnych parametrów zastosowano matematyczne modelowanie procesu zagęszczania. Wyniki symulacji porównano z wynikami badań zagęszczenia form z zastosowaniem metody ICT. Wykazano zgodność wyników modelowania oraz wyników pomiarów (ICT), co umożliwia określenie przestrzennego rozkładu gęstości w formie piaskowej w warunkach przemysłowych.
12
Content available Influence of sand-casting parameters on microstructure and properties of magnesium alloys
Kiełbus A., Stopyra M., Jarosz R.
Archives of Metallurgy and Materials
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2013
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Vol. 58, iss. 2
635--640
EN
The paper present the influence of modifying process on chemical composition, microstructure, and selected properties of Mg alloys. Two sand-casting creep-resistant alloys, Elektron 21 and WE43, were analyzed in various forms: without modifiers, with the amount of modifier suggested by the producer, and with this amount increased by 50% and 100%. The volume fraction of eutectic areas, tensile strength, and yield strength were measured and the fluidity and linear contraction were analyzed. The research shows that, in contrast to what is widely assumed to be a positive influence of rare-earth elements on Mg alloys properties, a large increase in the amount of modifiers does not always lead to an improvement in the alloy properties. However, the results are tentative because they may have been influenced by the melting technology used, which can be improved. Rare-earth elements tend to react with fluxes, which could lead to a decrease in mechanical properties and fluidity. More research is planned wherein the alloys are melted under a protective atmosphere.
PL
W artykule zaprezentowano wpływ modyfikacji odlewniczych stopów magnezu na skład chemiczny, mikrostrukturę i wybrane właściwości. Badano 2 stopy odlewane do form piaskowych, przeznaczone do pracy w podwyższonej temperaturze: Elektron 21 i WE43 w czterech wariantach: bez modyfikacji, z ilością modyfikatorów dodaną zgodnie z procedura zalecana przez producenta, powiększona o 50 i 100%. Wykonano ilościową analizę udziału objętościowego eutektyk, zmierzono wytrzymałość na rozciąganie, granice plastyczności, wykonano próbę lejności oraz skurczu liniowego. Wykazano, że mimo powszechnie uznanego za pozytywny wpływu metali ziem rzadkich na właściwosci stopów Mg dodawanie zwiększonych ilości modyfikatorów w stosunku do zaleceń producentów nie zawsze ma dobry wpływ na wyniki. Prawdopodobnie duży wpływ na wyniki badań miała technologia odlewania, wymagająca poprawy - zastosowane topniki mogą reagowac z pierwiastkami stopowymi i powodować obniżenie właściwości mechanicznych i lejności. W przyszłości planowane są podobne badania dla stopów topionych w atmosferze gazowej.
13
Content available Effect of vortex runner gating system on the mechanical strength of Al-12SI alloy castings
Ahmad R., Hashim M. Y.
Archives of Metallurgy and Materials
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2011
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Vol. 56, iss. 4
991-991
EN
Gating system design is an essential element in casting process which affects significantly the molten metal flow behavior, heat transfer and solidification of the melt. Optimum gating design will lead to a good quality of casting product. One of the major components in gating system is runner. This study was conducted to determine the effect of vortex runner diameter gating system on the mechanical strength of Al-12Si alloy casting. Simulation was conducted to study the behavior of the fluid flow and the results obtained showed close agreement with the results obtained from the experiment. Experimental results showed that the casting product with bigger vortex runner diameter gating system led to the improvement of average bending strength.
PL
Układ wlewowy to podstawowy element w procesie odlewania, który znacząco wpływa na płynięcie ciekłego metalu, transport ciepła oraz krzepnięcie metalu. Optymalny układ wlewowy gwarantuje dobra jakość odlanego produktu. Jednym z głównych elementów układu wlewowego jest kanał wlewowy. Celem pracy było zbadanie wpływu średnicy kanału układu wlewowego na wytrzymałosc mechaniczna odlewów ze stopu Al-12Si. Celem zbadania zachowania przecieczy przeprowadzono symulacje i otrzymane wyniki wykazują dobrą zgodność z wynikami otrzymanymi doświadczalnie. Wyniki doswiadczeń pokazały, że zastosowanie większej srednicy kanału układu wlewowego prowadzi do poprawy średniej wytrzymałości odlewów na zginanie.
14
Content available remote Structure and properties of grain-refined Al-20wt% Zn sand cast alloy
Krajewski W. K., Buraś J., Żurakowski M., Greer A. I.
Archives of Metallurgy and Materials
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2009
|
Vol. 54, iss. 2
329-334
EN
Recent foundry industry requires a development of cast alloys whose melting is both energy saving and environmentally friendly; these are two important priorities of the EC programme. The Al – based cast alloys with increased Zn content could response to these demands because of their good mechanical properties, especially the strength and damping ones, and also relatively low melting temperatures. However, the AlZn – based alloys require grain refining to improve their plastic properties. The presented work is devoted to structural characteristics of the grain - refined high - zinc aluminium alloy Al - 20 wt% Zn. The system studied was Al - 20 wt% Zn alloy (AlZn20), Zn - 4.6 wt% Ti master alloy (ZnTi4 MA), ZnAl - 4 wt% Ti (ZnAl -Ti4 MA) as well as the traditional refiners Al - 5 wt% Ti - 1 wt% B (AlTi5B1 MA) and Al - 3 wt% Ti - 0.15 wt% C (AlTi3C0.15 MA). SEM (scanning electron microscopy), LM (light microscopy) and TA (thermal analysis) investigations showed high effectiveness of the used master alloys as grain refiners of the inoculated with them AlZn20 alloy. The initial examinations of the damping properties were performed using an ultrasonic pulse - echo method. The obtained results showed, that attenuation coefficient of the grain refined AlZn20 alloy, naturally aged before casting during 1 year, decreases by about 10 - 30 % together with increased structural fineness. It was stated that the higher grain refinement of the examined AlZn20 sand cast alloy, the higher decrease of its attenuation coefficient.
PL
Współczesny przemysł wymaga rozwoju stopów odlewniczych, których przetapianie jest energooszczedne oraz przyjazne środowiskowo – są to dwa ważne priorytety programów Unii Europejskiej. Odlewnicze stopy na osnowie Al o podwyższonej zawartości Zn powinny odpowiadać powyższym wymaganiom, ponieważ cechują się one dobrymi właściwościami mechanicznymi, szczególnie wytrzymałościowymi i tłumiacymi, i równocześnie stosunkowo niska wartością temperatury przetapiania. Jednak stopy na osnowie AlZn wymagają zabiegu rozdrobnienia struktury w celu polepszenia ich właściwości plastycznych. Niniejsza praca jest poświęcona charakterystyce zmodyfikowanych, wysoko-cynkowych stopów Al. Badaniom poddano stop Al - 20 wag% Zn (AlZn20), zmodyfikowany przed odlaniem do formy piaskowej dodatkiem nowych zapraw modyfikujacych typu Zn - 4.6 wag. % Ti (ZnTi4 MA), ZnAl - 4 wag. % Ti (ZnAl -Ti4 MA) oraz zapraw tradycyjnych Al - 5 wag. % Ti - 1 wag. % B (AlTi5B1 MA) i Al - 3 wag. % Ti - 0.15 wag. % C (AlTi3C0.15 MA). Badania SEM (scanning electron microscopy), LM (light microscopy) i TA (thermal analysis) wykazały wysoka efektywność rozdrabniania ziaren stopu AlZn20 przez zastosowane zaprawy modyfikujące. Wstępne badania własciwości tłumiacych, wykonane przy pomocy ultradźwiękowej metody wykazały, iż współczynnik tłumienia zmodyfikowanego stopu AlZn20, naturalnie starzonego po odlaniu przez okres 1. roku, zmniejsza się o około 10 - 30 % wraz ze wzrostem stopnia rozdrobnienia struktury. Zmniejszenie to jest tym większe, im większy jest stopień rozdrobnienia ziaren badanego stopu AlZn20.
15
Content available remote Metal head-dependent HTC in sand casting simulation of aluminium alloys
Cellini G. S., Tomesani L.
Journal of Achievements in Materials and Manufacturing Engineering
|
2008
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Vol. 29, nr 1
47-52
EN
Purpose: In order to obtain reliable sand casting products, it is essential that the temperature distribution within the alloy during cooling is accurately known at each point by FEM simulation. This requires a great precision in setting the Heat Transfer Coefficients (HTC) at the boundaries. In particular for castings of big size, chills are frequently at different heights, so that remarkable differences arise from the metal head effect. Design/methodology/approach: An A356 alloy was cast and cooled. The castings were mono-directionally solidified in a experimental equipment modified to accept a controlled variable metal-head. HTC were evaluated in a side arm, where a chill end ensured a dominant unidirectional heat flow during cooling. At the end of a square horizontal channel, an aluminium chill of the same section and 60 mm in depth determined nearly one-dimensional cooling conditions. Findings: The evolution of heat transfer coefficient (HTC) in the sand casting of A357 aluminum alloy against aluminum chills is evaluated with different metal heads in order to study the effect of pressure on the HTC. Inverse modeling techniques based on Beck's analysis were used to determine the experimental evolution of HTC as a function of time, casting temperature and chill temperature. The HTC evolution at the casting-chill boundary is then described as a function of local parameters such as casting-chill interface pressure (as long as they are in contact) and interface gap (when solidification shrinkage occurs and the casting detaches from the chill). Practical implications: Finally, the experiments are reconstructed by means of coupled thermal-stress numerical analyses and the predicted cooling curves are fitted to the experimental ones by adjusting model parameters. As a result, the best parameters for describing the HTC evolution are found, thus allowing to extrapolate any possible HTC behavior on chills at different heights for the same casting. Originality/value: Some transient interface pressure can develop between casting and chill, the effect being negligible in HTC evaluation with the aim to precisely predict the cooling evolution inside the casting.
16
Rapid tooling in sand casting applications
Dolinsek S., Kopac J., Brtoncelj G., Kosic P.
Archives of Materials Science
|
2007
|
Vol. 28, nr 1-4
30-34
EN
Rapid tooling refers to process and technologies that help shorten time from planning to producing tools and with which the production costs are reduced. Classic technological procedures, such as turning, milling or casting are still the most common way of producing products from a wide range of available materials; rapid tooling is an option how to make those procedures faster, cheaper and better. On the example of the casting model we present the analysis of time and costs savings between separate procedures of rapid tooling according to classic production of casting application with high-speed cutting.
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