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1
Content available Structure and Mechanical Properties of the CO2 Laser Welded Joint of AZ91 Cast
Dziadoń A., Musiał E.
Archives of Foundry Engineering
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2020
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Vol. 20, iss. 3
9--14
EN
Plates of AZ91 cast magnesium alloy with a thickness of 3.5 mm were butt-welded using a laser power of 2000 W and helium as the shielding gas. The effect of the welding speed on the weld cross-sectional geometry and porosity was determined by microscopic analysis. It was found that to avoid the formation of macropores, welding should be carried out at a speed of 3.4 m/min or higher. Non-equilibrium solidification of the laser-melted metal causes fragmentation of the weld microstructure. Joints that were welded at optimal laser processing parameters were subjected to structural observations using optical and scanning microscopy and to mechanical tests. The mechanical properties were determined through Vickers hardness measurements in the joint cross-section and through tensile testing. The results indicate that the hardness in the fusion zone was about 20 HV (30%) higher than that of the base material. The weld proved to be a mechanically stable part of the joint; all the tensile-tested specimens fractured outside the fusion zone.
2
Content available Analiza wtrąceń niemetalicznych w odlewach ze stopu AZ91 wykonanych z udziałem złomu obiegowego w procesie wysokociśnieniowego odlewania
Konopka Z., Chojnacki A.
Prace Instytutu Odlewnictwa
|
2016
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Vol. 56, no. 4
321--328
PL
W artykule przedstawiono wyniki badań wpływu udziału złomu obiegowego we wsadzie stopu AZ91 na zmianę struktury odlewów wykonanych metodą wysokociśnieniowego odlewania, ze szczególnym uwzględnieniem tworzenia się wtrąceń niemetalicznych. Na podstawie obserwacji wtrąceń metodą mikroskopii skaningowej określono skład chemiczny tych wtrąceń w wytopach z różnym udziałem złomu obiegowego we wsadzie.
EN
The article presents research results of the process foundry return influence in the AZ91 alloy charge on the change in the structure of castings made by the high-pressure casting method, with special consideration of the formation of non-metallic inclusions. Based on the observations of inclusions by the scanning microscopy method, the chemical composition of the inclusions in melts with different process scrap contents in the charge was determined.
3
Content available Formation of Structure and Properties in Casting Processes on the Example of AZ91 Magnesium Alloy
Augustyn B., Szymanek M., Kapinos D., Boczkal S., Korczak P.
Archives of Foundry Engineering
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2014
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Vol. 14, iss. 2
43--48
EN
Contemporary materials engineering requires the use of materials characterised by high mechanical properties, as these precisely properties determine the choice of material for parts of machinery and equipment. Owing to these properties it is possible to reduce the weight and, consequently, the consumption of both material and energy. Trying to meet these expectations, the designers are increasingly looking for solutions in the application of magnesium alloys as materials offering a very beneficial strength-to-weight ratio. However, besides alloying elements, the properties are to a great extent shaped by the solidification conditions and related structure. The process of structure formation depends on the choice of casting method forced by the specific properties of casting or by the specific intended use of final product. The article presents a comparison of AZ91 magnesium alloys processed by different casting technologies. A short characteristic was offered for materials processed by the traditional semi-continuous casting process, which uses the solidification rates comprised in a range of 5 - 20⁰C/s, and for materials made in the process of Rapid Solidification, where the solidification rate can reach 106⁰C/s. As a result of the casting process, a feedstock in the form of billets and thin strips was obtained and was subjected next to the process of plastic forming. The article presents the results of structural analysis of the final product. The mechanical properties of the ø7 mm extruded rods were also evaluated and compared.
4
Content available Analysis of the Crystallization of AZ91 Alloy by Thermal and Derivative Analysis Method Intensively Cooled in Ceramic Shell
Rapiejko C., Pisarek B., Czekaj E., Pacyniak T.
Archives of Foundry Engineering
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2014
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Vol. 14, iss. 1
97--102
EN
The work presents the test result of the influence of cooling rate on the microstructure of AZ91 alloy, Vickers micro-hardness and Brinell hardness. Studies cooling and crystallization of AZ91 alloy was cast into the ceramic shells pre-heated to 180°C and then air-cooled at ambient temperature or intensively super cooled in the liquid coolant. The TDA method was applied to record and characterize the thermal effect resulting from the phase transformations occurring during the crystallization of AZ91 alloy. The kinetics and dynamics of the thermal processes of crystallization of AZ91 alloy in the ceramic shells were determined. Metallographic tests were performed with the use of an optical microscope. A comparison of these test results with the thermal effect recorded by way of the TDA method was made. Influence of cooling rate of AZ91 on HV0, 01 micro-hardness and Brinell hardness alloy was examined.
5
Content available remote Influence of design factors on weldability of the AZ91E alloy
Adamiec J.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 1 spec.
339--344
EN
Basic design factors which influence weldability include casting shape, its stiffness and type of welded joint. The influence of casting stiffness on weldability, understood as susceptibility to hot cracking, in conditions of constant joint stiffness has been determined on the basis of the Fisco test results, and in conditions of varying stiffness on the basis of the Houldcroft test.
6
Structure and properties of the AZ91 magnesium alloy welds created with the use of Friction Stir Welding (FSW)
Adamiec J., Zadroga L., Chabko T.
Inżynieria Materiałowa
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2008
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Vol. 29, nr 4
320-325
EN
The welding of Mg alloys is technologically difficult. It is connected with fast heat influence and welding tensions as a result of the heat affected zone which cause the Assuring of the joint both hot and the cold one. An aim of the work was the qualification of the parameters of the FSW process off the mg casting sheets joining from the mg alloys, so to obtain the correct joint. In this work one presented the findings of the micro - and of macrographic research, mechanical research of weld and the research of influence of the heat zone. Research were supplemented with fractographic research. As a result of proposed here research one formulated the pool of the FSW welding parameters assuring the obtainment of joints which will fulfill the terms of acceptance.
PL
Spawanie stopów Mg jest trudne technologiczne. Jest to związane z szybkim odprowadzaniem ciepła oraz powstającymi w wyniku tego naprężeniami spawalniczymi powodującymi pękanie złącza zarówno gorące jak i pękanie zimne. Celem pracy było określenie parametrów procesu FSW łączenia odlewanych elementów ze stopów Mg, tak aby uzyskać prawidłowe połączenie. W pracy przedstawiono wyniki badań mikro- i makrograficznych, mechanicznych zgrzeiny i strefy wpływu ciepła. Badania zostały uzupełnione o badanie fraktograficzne. W wyniku przeprowadzonych badań opracowano pulę parametrów zgrzewania FSW zapewniających uzyskanie złączy spełniających warunki odbioru.
7
Charakterystyka połączeń magnezu i stopu AZ91 z komponentami węglowymi
Olszówka-Myalska A., Myalski J., Przeliorz R., Botor-Probierz A.
Inżynieria Materiałowa
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2008
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Vol. 29, nr 3
138-144
PL
Badano połączenia magnez-włókno węglowe oraz stop magnezu AZ91--włókno węglowe i stop magnezu AZ91-cząstka węgla szklistego powstałe w próżni, w temperaturze 650°C. Stwierdzono, na podstawie obrazów SEM zgładów i przełomów, występowanie zwilżania włókien i cząstek zarówno magnezem jak i stopem AZ91 (rys. 8-13). Na granicy magnez-włókno nie stwierdzono strefy produktów oddziaływania ani fragmentacji włókien - otrzymane połączenie miało charakter mechaniczny (rys. 8, 9). W kompozytach z osnową ze stopu AZ91 obserwowano różnice w połączeniu komponentów w zależności od typu zbrojenia węglowego. Dla układu AZ91-włókno stwierdzono bardzo dobre połączenie między komponentami (fragmentacja włókien, brak dekohezji na granicy rozdziału) i równocześnie obecność strefy oddziaływania chemicznego (rys. 10, 11). Strefa ta ulegała degradacji pod wpływem wody. Połączenie AZ91-cząstka węgla szklistego było dobre, ale nie obserwowano intensywnego oddziaływania pomiędzy komponentami (rys. 12, 13). Dodatkowo wykonano analizę termiczną DSC mieszanin komponentów (rys. 14, 15). Nie stwierdzono oddziaływania magnez-węgiel podczas nagrzewania i chłodzenia w zakresie temperatury 20-720°C. Dodatkowe efekty cieplne wystąpiły podczas badań zarówno mieszaniny AZ91-włókna węglowe, jak i mieszaniny AZ91-cząstki węgla szklistego. Uzyskane wyniki wskazują na wpływ dodatku aluminium do osnowy magnezowej, a także rodzaju komponentów węglowych i sposobu ich łączenia (rys. 7) na połączenie powstałe w próżni, w tej samej temperaturze.
EN
The bonding of the magnesium-carbon fibre, AZ91 alloy-carbon fibre and AZ91 alloy-glassy carbon particle formed in vacuum at the temperature of 650°C was investigated. On the background of SEM images of polished cross sections and fractured cross sections the wettablity of the fibres both by magnesium and AZ91 alloy was confirmed (Fig. 8-13). Since the products interaction zone at the magnesium-fibre interface or fibre fragmentation were not observed in AZ91-carbon fibre system - only mechanical bonding formation was an outcome (Fig. 8, 9). In the composites with AZ91 matrix some differences between fibre and particle bonding mechanism were noticed. The bonding in the AZ91-carbon fibre system was very good (carbon fragmentation without decohesion at interface). Additionally, the presence of the chemical interaction zone and the zone decomposition in contact with water were evident (Fig. 10, 11). The bonding in the AZ91 -glassy carbon particles system was good as well, however the intensive reaction between components was not observed (Fig. 12, 13). The complementary thermal analysis of components mixtures by the DSC method has been performed (Fig. 14, 15). The effects of magnesium-carbon interaction during heating and cooling at the temperature range of 20-720°C were not detected. The additional thermal effects appeared during investigations of both the AZ91-carbon fibres and of the AZ91-glassy carbon particles. The results of presented experiment show that aluminium addition in the magnesium matrix, the type of carbon component and the method of components consolidation (Fig. 7) affect the interface structure formed in vacuum at the same temperature.
8
Content available remote Non-standard heat treatment of cast AZ91 magnesium alloy
Braszczyńska-Malik K. N., Kamieniak J.
Archives of Foundry Engineering
|
2008
|
Vol. 8, iss. 1 spec.
31--34
EN
Results of microstructure and mechanical properties investigations of AZ91 magnesium alloy as-cast and after heat treatment are presented. Cylinder samples for uniaxially compression tests were annealed at a temperature of 423 and 623 K for 16 hours (without solution annealing). Alter annealing at 423 K precipitates of γ-Mg17Al12 phase in areas enriched in aluminum solid solution were observed whereas annealing at 623 K caused only homogenizing of solid solution. Investigated materials showed insignificant changes in ultimate compression strength and clearly increase value of yield strength of samples annealed at 623 K.
9
Content available remote echanical properties of high-pressure die-casting AZ91 magnesium alloy
Braszczyńska-Malik K. N., Zawadzki I., Walczak W., Braszczyński J.
Archives of Foundry Engineering
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2008
|
Vol. 8, iss. 4
15-18
EN
Results of mechanical properties of high-pressure die-casting AZ91 magnesium alloy are presented. Performed examinations allowed to determine influence of plunger velocity in the first and second stage and intensification pressure on the ultimate tensile strength (UTS), yield strength (YS), elongation (A5 and Agt), Brinell hardness (HB) and impact strength (IS) of samples cast on 320 tone cold chamber machine. Obtained results revealed the highest properties at median used parameters and also the most powerful effect of plunger velocity in the first stage. The maximum values of mechanical properties obtained from the performed experiments were: UTS 250 MPa, YS 160 MPa, A5 7%, 70 HB, IS 7 J.
10
Content available remote Thermal analytical investigations of the magnesium alloy AZ91
Braszczyńska-Malik K. N.
Archives of Foundry Engineering
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2007
|
Vol. 7, iss. 2
177-180
EN
The results of thermal derivative analysis (TDA), differential scanning calorimetric (DSC) measurements and microstructure investigations of commercial AZ91 magnesium alloy are presented. The performed examinations allowed to determine the microstructure after solidification process and also precipitation process during continuous heating of supersaturated solid solution. The [alpha]-phase and [alpha]+[gamma] semi-divorced eutectic were observed in as-cast material, whereas both discontinuous and continuous precipitates of [gamma] phase were revealed after heating supersaturated AZ91 alloy.
11
Content available remote Influence of delivery state quality on microstructure and mechanical properties of as cast AZ91 Mg alloy
Roskosz S., Adamiec J., Błotnicki M.
Archives of Foundry Engineering
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2007
|
Vol. 7, iss. 1
143-146
EN
In the work evaluation of influence of porosity and microstructure on mechanical properties of AZ91 alloy coming from three suppliers was done. It was found that the structural factors influence the AZ91 alloy's strength properties are: the pores' area fraction, the area fraction of the Mg17Al12 phase of massive and lamellar morphologies, and the Mg2Si phase's area fraction.
12
Content available remote Geometria nadtopień i współczynniki termiczne procesu nadtapiania odlewów ze stopu AZ91
Braszczyńska-Malik K. N., Mróz M.
Archiwum Odlewnictwa
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2006
|
R. 6, nr 18/1
221--226
PL
W pracy przedstawiono wyniki badań wpływu parametrów technologicznych procesu nadtapiania metodą GTAW na geometrię nadtopień oraz sprawność cieplną i sprawność topienia odlewów ze stopu AZ91. Stosowano prędkość skanowania łukiem elektrycznym 200, 400 i 800 mm/min oraz natężenie prądu 100 200 i 300A. Określono szerokość i głębokość nadtopień. Sprawność cieplną i sprawność topienia określono z wykorzystaniem badań kalorymetrycznych. Wyznaczono związki pomiędzy geometrią nadtopień, ilością ciepła wprowadzonego do nagrzewanej próbki, sprawnością cieplną, ilością ciepła niezbędnego do utworzenia nadtopień i sprawnością topienia, a parametrami technologicznymi procesu nadtapiania.
EN
In this work the effect of GTAW process parameters on the fusion geometry, arc efficiency and melting efficient was presented. The surface fusion process was performed under varied electric arc travel speed 200, 400 and 800 mm/min and current intensity 100, 200, and 300A. Relationships between GTAW process parameters and fusion geometry, the total heat content of the weld sample, arc efficiency as well as the heat input that leads to melting of the weld volume, melting efficiency and were analyzed.
13
Effect of ECAP process on grain size of commercial AZ91 alloy
Braszczyńska-Malik K.
Inżynieria Materiałowa
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2004
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R. XXV, nr 3
332-334
EN
Examinations of the microstructure development during equal-channel angular pressing (ECAP) of commercial AZ91 alloy are presented. The initial grain size of the investigated alloy was about ž200 m. Samples were deformed at different temperatures via route Bc through the die characterized by an inner contact angle phi equal 90°. Following the ECAP process the microstructures were homogeneous and exhibited drastic decrease of grain size to 10 žm.
PL
Przedstawiono badania zmian mikrostruktury komercyjnego stopu AZ91 podczas procesu ECAP (equal-channel angular pressing). Początkowa wielkość ziarna badanego stopu wynosiła około 200 žm (rys. 4a). Próbki były odkształcane w różnych temperaturach z rotacją Bc poprzez formę charakteryzującą się kątem phi równym 90° (rys.1). Zastosowanie procesu ECAP pozwoliło na uzyskanie jednorodnej mikrostruktury oraz spowodowało zmniejszenie wielkości ziarna do 10 žm (rys. 4b, c i rys. 5).
14
Content available remote Mikrostruktura odlewów ze stopu AZ91 otrzymanych z zastosowaniem gorącokomorowych maszyn ciśnieniowych
Braszczyńska-Malik K. N., Cibis R., Braszczyński J.
Archiwum Odlewnictwa
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2004
|
R. 4, nr 11/1
72--77
PL
Przedstawiono charakterystykę mikrostrukturalną odlewów ze stopu magnezu AZ91 wykonanych z zastosowaniem gorącokomorowej maszyny ciśnieniowej. Struktura odlewów była efektywnie rozdrobniona (około 10-krotnie) w porównaniu z odlewami piaskowymi. Obserwowano roztwór stały &alpha oraz międzymetaliczną fazę &gamma (Al12Mg17).
EN
Microstructural characterization of high pressure die cast magnesium alloy AZ91 was presented. The alloy have been poured in a 250 t hot chamber high pressure die cast machine. The microstructure of casting was effective refinement (about 10 times) compared with sand casting. The &alpha-Mg and intermetallic &gamma-phase were observed.
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