Wyniki wyszukiwania - BazTech

1

Microstructural features evaluation of age-hardened A 226 cast alloy by image analysis

Kucharikova L., Tillova E.

Production Engineering Archives

|

2017

|

Vol. 17

3--8

EN

Age-hardening provides one of the most widely used mechanisms for the strengthening of aluminum alloys. The age-hardening involves three steps: solution treatment, quenching and aging. The temperature of solution treatment and aging is very important in order to reach desired properties of castings. The optimum temperature of solution treatment and aging led to formation microstructural features in form which does not lead to decreasing properties, but increasing ones. The major micro-structural features in A 226 cast alloys which are responsible for increasing properties are: eutectic Si particles, Cu-rich phases, Fe-rich phases and porosity. The increase of properties depends on morphology, size and volume of microstructural features. In order to assess age-hardening influence on microstructural features in A226 cast alloys were used as possibilities of evaluation by means of image analysis. Quantitative analysis decelerate changes in microstructure includes the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu) further increase in the hardness and tensile strength in the alloy. Changes of mechanical properties were measured in line with STN EN ISO.

2

Impact of rotary swaging and age hardening on mechanical properties of EN AW 2024

Kövér M., Sláma P., Palán J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2015

|

Vol. 72, nr 2

61--66

EN

Purpose: Invention of severe plastic deformation methods led to increased interest in ultra-fine grained materials. The hardenable aluminium alloys were extensively studied in the last decade. It was revealed that combination of severe plastic deformation and age hardening can significantly improve the material properties of these alloys. In this article we performed such progressive thermo-mechanical treatment and following mechanical testing and metallographic analysis. The aim was to evaluate the influence of this treatment on mechanical properties, mostly the effect of various age hardening temperatures and time. Aluminium alloy EN AW 2024 was chosen for the experimental procedures. Impact of processing parameters on mechanical properties was determined by tensile testing. Metallographic analysis was used for evaluation of the straining influence on grain morphology. In the conclusion we denoted significant strain hardening effect, present shear bands and change in aging kinetics. Design/methodology/approach: The experimental material was processed by progressive thermo-mechanical treatment. The evaluation was performed by simple tensile testing and light microscopy. The first conclusions were derived from determined mechanical properties and based on similarities in available publications with related topic. Findings: The research results roughly confirm the recovery-precipitation complementary effect, observed in other hardenable aluminium alloys or the same hardenable alloy deformed by other SPD technique. The impact of both parts of processing – deformation and age hardening on mechanical properties was evaluated. Research limitations/implications: Future detailed investigation of secondary phase particles and dislocation-precipitate interaction should be performed. This investigation was not performed as it requires transmission electron microscopy. Originality/value: The paper contains first impression on promising SPD technique. As the technique appeared only recently, very few articles were published, considering few light alloys. The paper can help to set parameters for other researchers in this field and promote commercialization of this progressive thermo-mechanical processing

3

Effect of age hardening on corrosion resistance and hardness of CoCrMo alloys used in dental engineering

Dobrzański L., Reimann Ł., Krawczyk C.

Archives of Materials Science and Engineering

|

2012

|

Vol. 57, nr 1

5-12

EN

Purpose: The goal of the study is to research the effect of various time of ageing on corrosion resistance, hardness and structures of Remanium 2000+ Co-Cr-Mo alloys used in prosthodontia. Design/methodology/approach: To investigation was prepared mould, cast in 1430°C and realized the heat treatment: solutioning in 1250°C by 3 hours and then ageing in 850°C by 4, 8, 16 and 24 hours. Electrochemical corrosion examination were made in water center which simulated artificial saliva environment. The evaluation of breakdown potential was realized by recording of anodic polarization curves with use the potentiodynamic methods. Corrosion resistance test were carried out at room temperature and use of the VoltaLabŽ PGP201 system for electrochemical tests. Hardness test were obtained by use the microhardness FM ARS 9000 FUTURE TECH with load 1 kg. Structure observation was made after surface preparation: grinding, polishing and etching by light microscope LEICA MEF4A with the magnification 500x. Findings: The age hardening for Co-Cr-Mo alloys is one of the possible method which effect in forming the hardness. The highest value of hardness were obtain for specimen which was ageing with the longer time. Research alloy characterized dendritic crystals in structure for all realized heat treated process. At specimen after the longer ageing was observed the most of discontinuous precipitation and stacking faults in compare with specimen ageing by 4 hours. The age hardening doesn’t influenced much on electrochemical results and only the open circuit potential changed by decreased while increased ageing time. The values of breakdown potential and repassivation potential kept at a constant level. Practical implications: Research material is used on dentures so it’s demand that their characterized corrosion resistance and result of this work make up an information on what heat treatment parameters may be pay attention for CoCrMo alloys. Originality/value: The paper present effect of age hardening especially the ageing time, on the most important criteria of CoCrMo alloys use in dental engineering.

4

Identification and Analysis of Intermetallic Phases in Age-Hardened Recycled AlSi9Cu3 Cast Alloy

Hurtalová L., Tillová E., Chalupová M.

Archive of Mechanical Engineering

|

2012

|

Vol. LIX, nr 4

385--396

EN

Purpose: The influence of age-hardening solution treatment at temperature 515 degrees centigrade with holding time 4 hours, water quenching at 40 degrees centigrade and artificial aging by different temperature 130, 150, 170 and 210 degrees centigrade with different holding time 2, 4, 8, 16 and 32 hours on changes in morphology of Fe-rich Al15(FeMn)3Si2 and Cu-rich (Al2Cu, Al-Al2Cu-Si) intermetallic phases in recycled AlSi9Cu3 cast alloy. Material/Methods: Recycled (secondary) AlSi9Cu3 cast alloy is used especially in automotive industry (dynamic exposed cast, engine parts, cylinder heads, pistons and so on). Microstructure was observed using a combination of different analytical techniques (scanning electron microscopy upon standard and deep etching and energy dispersive X-ray analysis – EDX) which have been used for the identification of the various phases. Quantitative study of changes in morphology of phases was carried out using Image Analyzer software NIS-Elements. The mechanical properties (Brinell hardness and tensile strength) were measured in line with STN EN ISO. Results/Conclusion: Age-hardening led to changes in microstructure include the spheroidization of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases and Al-Al2Cu-Si phases were fragmented, dissolved and redistributed within alpha-matrix. These changes led to increase in the hardness and tensile strength in the alloy.

PL

Cel: Badanie wpływu utwardzania przez starzenie przesycanie w temperaturze 515 stopni Celsjusza z czasem przetrzymywania 4 godz., hartowanie wodne w 40 stopniach Celsjusza, starzenie przyspieszone w różnych temperaturach: 130, 150, 170 i 210 stopni Celsjusza, przy czasach przetrzymywania: 2, 4, 8, 16 i 32 godziny na zmiany w morfologii stopów odlewniczych AlSi9Cu3 z recyklingu wzbogaconych żelazem (Al15(FeMn)3Si2) lub miedzią (Al2Cu, Al-Al2Cu-Si). Materiał i metody: Pochodzący z recyklingu (wtórny) stop odlewniczy aluminium AlSi9Cu3 jest powszechnie używany, zwłaszcza w przemyśle motoryzacyjnym (dynamiczne, odkryte odlewy, części silnika, głowice cylindrów, tłoki itp.). Mikrostrukturę odlewów badano stosując kombinację różnych technik analitycznych (elektronowa mikroskopia skaningowa w połączeniu z analizą rentgenowską z dyspersją energii (EDX), standardową i z głebokim wytrawianiem), co pozwoliło identyfikować różne fazy międzymetaliczne. Ocena ilościowa zmian w morfologii tych faz została przeprowadzona przy wykorzystaniu oprogramowania analizatora obrazów (Image Analyzer NIS-Elements). Właściwości mechaniczne (twardość w skali Brinella i wytrzymałość na rozciaganie) były mierzone zgodnie z normą STN EN ISO. Wyniki i wnioski: Utwardzanie przez starzenie prowadzi do zmian w mikrostrukturze, które polegają na sferoidyzacji krzemu eutektycznego, stopniowej dezintegracji, skracaniu i ścienianiu faz międzymetalicznych wzbogaconych żelazem. Fazy Al-Al2Cu-Si podlegały fragmentacji, zostały rozpuszczone i redystrybuowane w osnowie stopu. Zmiany te prowadzą do wzrostu twardości stopu i jego wytrzymałości na rozciąganie.

5

Influence of the ageing on mechanical properties of the aluminium alloy AlSi9Mg

Dobrzański L., Reimann Ł., Krawczyk G.

Archives of Materials Science and Engineering

|

2008

|

Vol. 31, nr 1

37-40

EN

Purpose: The goal of this paper was study the influence of temperature and time in the age-hardening on the selected mechanical properties and hardness of the AlSi9Mg alloy. Design/methodology/approach: The efficiency of the age-hardening were tested on laboratory specimens through the statically tension test on ZWICK/Z100. Damages were critically assessed through SEM investigations. Evaluation the mechanical properties of prepared samples were realized by solutioning and then ageing in different periods of time. Findings: Adequately selected time of the ageing improved the hardening and plasticity and reduce the tendency of aluminium to formation of coagulations. Research limitations/implications: The described investigations were limited to changes the mechanical properties of the specimens in different periods of time of aging, in solid temprature. In future research works should show the influence of change of temperature process on studied AlSi9Mg alloy, as well as different lightweight alloy. Originality/value: The paper contributes to better understanding and recognition the mechanisms of agehardening.

6

Teoretické aspekty tepelného spracovania zlievarenských hliníkových zliatin

Schützová D., Lenárthová J., Bobok L'., Lukáč I.

Archiwum Odlewnictwa

|

2006

|

R. 6, nr 18/1

143--148

CS

Mechanické vlastnosti odliatkov významne ovplyvňuje veľkosť dendritických buniek, prítomnosť metalurgických chýb, (napr. dendritická pórovitosť), podiel, veľkosť a kryštalografická orientácia intermetalických zlúčenín, ako aj procesy tepelného spracovania. V príspevku je naznačená teoretická podstata tepelného spracovania hliníkových zliatin.

EN

The paper aims is to point out on the theoretical principles of the heat treating of the Aluminium Alloys. The following major parameters have significant effects on the mechanical properties of the casting products: 1. Size of the dendrite cells. 2. Presence of the metallurgical faults, i.e. dendrite porosity. 3. Fraction, size and crystallographic orientation of intermetallic compounds. 4. Heat treating processes.