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Properties of Cu-Al-Mn shape memory alloy after cold drawing
Get PDFU ovom radu provedena je mikrostrukturna karakterizacija Cu-Al-Mn legure s prisjetljivosti oblika. Legura Cu-11,9Al-2,5Mn (mas. %) s prisjetljivosti oblika dobivena je postupkom vertikalnog kontinuiranog lijevanja u obliku šipke promjera 8 mm. Procesom toplog valjanja i kovanja u profiliranom alatu dobivena je šipka promjera 4,80 mm. Šipka je zatim bila podvrgnuta procesu hladnog vuĉenja ĉime je dobivena ţica promjera 4,47 mm, 3,22 mm i 1,80 mm. IzmeĊu provlaka hladnog vuĉenja uzorci su bili toplinski obraĊeni na 580 °C/60 minuta i 600 °C/60 minuta. Mikrostrukturna karakterizacija uzoraka provedena je optiĉkom svjetlosnom mikroskopijom (OM) i pretraţnom elektronskom mikroskopijom (SEM) s energijsko disperzijskom spektrometrijom (EDS). Detaljnom analizom mikrostrukture zamijećena je dvofazna (α + β) mikrostruktura u lijevanom stanju, dok uzorci nakon hladnog vuĉenja pokazuju dvofaznu (martenzit + α) mikrostrukturu. Odabrani uzorci su zatim bili podvrgnuti postupku toplinske obrade na 900 °C/15 minuta te su naglo ohlaĊeni u vodi sobne temperature. OM i SEM analizom uzoraka vidljiva je martenzitna mikrostruktura koja nastaje kao posljedica hlaĊenja legure iz β-faznog podruĉja. Mikrotvrdoća uzoraka raste sa smanjenjem promjera ţice. Uzorci nakon toplinske obrade pokazuju niţe vrijednosti mikrotvrdoće u odnosu na uzorke nakon hladnog vuĉenja.In this paper, microstructural characterization of Cu-Al-Mn shape memory alloy was performed. The Cu-11.9Al-2.5Mn (wt.%) shape memory alloy was produced by vertical continuous casting technique obtaining bars of 8 mm in diameter. With the process of hot rolling and forging in a profiled tool the 4.80 mm bar was produced. The bar was then subjected to a cold drawing process to obtain a wire of 4.47 mm, 3.22 mm and 1.80 mm in diameter. Between cold drawing runs, the samples were heat treated at 580 °C/60 minutes and 600 °C/60 minutes. Microstructural characterization of the samples was performed by optical microscopy (OM) and scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS). A detailed analysis of the microstructure revealed a two-phase (α + β) microstructure in the as-cast state, while the samples after cold drawing showed a two-phase (martensite + α) microstructure. The selected samples were then subjected to heat treatment procedure at 900 °C/15 minutes which was followed by rapid cooling in room temperature water. OM and SEM analysis of the samples revealed a martensitic microstructure as a result of cooling the alloy from the β-phase region. The microhardness of the samples increases with decreasing wire diameter. Samples after heat treatment show lower values of microhardness compared to samples after cold drawing
Effects of preferred grain orientation on the on lüders bands appearance
No full textIn this paper, the influence of preferential grain orientation was examined. Parallel tests were conducted on the
samples from the same steel strip, taken in the direction and perpendicular to the direction of rolling the strip. Steel
strip has a homogeneous fine-grained ferrite-pearlite microstructure. Using the methods of thermography it has
been found that at the beginning of the plastic flow Lüders bands occur, pointing to the fact that the preferential
grain orientation, in the case of steel with the fine-grained ferrite-pearlite microstructure, has no effect on the appearance of the Lüders bands
The effect of annealing time on properties of austenitic stainless steel
Get PDFU ovom radu provedena je mikrostrukturna analiza, ispitivanje mikrotvrdoće i udarne radnje
loma austenitnog nehrđajućeg čelika AISI 316L. Ispitivanja su provedena prije i nakon
žarenja na 850 °C. Vrijeme žarenja tijekom ispitivanja je bilo od 30 do 90 minuta. Nakon
žarenja, uzorci su ohlađeni na sobnoj temperaturi. Mikrostrukturna analiza ispitivanih uzoraka
provedena je optičkom mikroskopijom (OM) i pretražnom elektronskom mikroskopijom
(SEM) opremljenom uređajem za energetsko disperzijsku spektroskopiju (EDS). Ispitivanja
udarne radnje loma provedena su na uređaju Charpyju na sobnoj temperaturi. Početno valjano
stanje ispitivanog čelika pokazalo je prisutnost tipičnih izduženih poligonalnih zrna austenita i
delta ferita, dok uzorci nakon žarenja pokazuju prisutnost i razvoj sigma faze u mikrostrukturi
tijekom žarenja. Mikrotvrdoća je mjerena Vickersovom metodom te je utvrđeno da porast
vremena žarenja nema značajniji utjecaj na mikrotvrdoću. Porastom vremena žarenja smanjila
se udarna radnja loma što se može povezati s mikrostrukurnim promjenama. Nakon
ispitivanja udarne radnje loma provedena je fraktografska analiza prijelomnih površina
pomoću pretražnog elektronskog mikroskopa.In this paper, microstructural analysis, microhardness testing and fracture impact tests of
austenitic stainless steel AISI 316L were performed. Investigations were performed before
and after annealing at 850 °C. The annealing time during the investigation was 30 to 90
minutes. After annealing, the samples were cooled down to room temperature.
Microstructural analysis of the investigated samples was performed by optical microscopy
(OM) and scanning electron microscopy (SEM) equipped with device for energy dispersive
spectroscopy (EDS). Impact energy tests were performed on a Charpy device at room
temperature. The initial rolled state of the test steel showed the presence of typical elongated
polygonal grains of austenite and delta ferrite, while after-annealing samples showed the
presence and development of sigma phase in the microstructure during annealing.
Microhardness was measured by the Vickers method and it was found that an increase in
annealing time had no significant effect on microhardness. With increasing annealing time,
the impact energy, which can be associated with microstructural changes, has decreased. After
impact energy testing, fractographic analysis of fracture surfaces was performed using a
scanning electron microscope
Numerical stress and displacement analysis of the selfstanding round bin
Get PDFU radu je provedena numeriĉka analiza naprezanja i pomaka savijanja samostojećeg okruglog koša pomoću metode konaĉnih elemenata. Sve linearne statiĉke analize prikazane u radu napravljene su metodom konaĉnih elemenata u programskom paketu Autodesk Inventor Professional. U teorijskom dijelu rada dan je pregled teorija ĉvrstoće, izraĉuna dopuštenih naprezanja i konaĉnih elementa korištenih u numeriĉkoj analizi. Detaljno je opisano modeliranje geometrije sklopa samostojećeg okruglog koša i svi koraci pri izradi numeriĉke simulacije. Na jednostavnim primjerima izvršena je verifikacija konaĉnih elemenata. Numeriĉka simulacija samostojećeg okruglog koša provedena je diskretizacijom konstrukcije s tetraedarskim i ljuskastim konaĉnim elementima. Nakon provedene numeriĉke simulacije savijanja, analizirani su rezultati te optimirano prihvatljivo opterećenje koje zadovoljava uvjet ĉvrstoće.Numerical analysis of stress and displacement of bending selfstanding round bin was conducted using the finite element method. All the linear static analysis presented in the work were made by the finite element method in the Autodesk Inventor Professional software package. In the theoretical part of the paper, a review of strength theory, calculation of permitted stress and finite elements used in numerical analysis was given. A detailed description of the modelling of a selfstanding round bin assembly geometry and all the steps in creating a numerical simulation was given. In simple examples, verification of finite elements was performed. The numerical simulation of a selfstanding round bin was performed by the discretization of the structure with the tetrahedral and the shell finite elements. After the performed numerical bending simulation, the results are analysed and an acceptable load witch satisfy the condition of strength is optimized
Statistical Analysis of the Combined ECAP and Heat Treatment for Recycling Aluminum Chips Without Remelting
Get PDFThe main aim of this paper is to present an environmentally friendly method for aluminum recycling. Development of new recycling technologies in order to increase scrap reuse potential and CO2 emission savings are of the main importance for aluminum circular economy. In this paper, aluminum chips waste was recycled without any remelting phase in order to increase energy and material savings. The presented process is usually called solid state recycling or direct recycling. Solid state recycling process consists of chips cleaning, cold pre-compaction and hot direct extrusion followed by a combination of equal channel angular pressing (ECAP) and heat treatment. Influence of holding time during solid solution treatment and both artificial aging time and temperature on mechanical properties of the recycled EN AW 6082 aluminum chips were investigated. A comprehensive number of the experiments were performed utilizing design of experiments approach and response surface methodology. Regression models were developed for describe the influence of heat treatment parameters for presented solid state recycling process on mechanical properties of the recycled samples. Utilizing novel procedure high quality recycled samples were obtained with mechanical properties comparable with commercially produced EN AW 6082 aluminum alloy in T6 temper condition. Metallographic analysis of the recycled samples was also performed
Different corrosion behaviour of CuNi10Fe1Mn alloy condenser tubes in seawater
Get PDFTwo CuNi10Fe1Mn condenser tube samples from boat heat exchangers were investigated due to their different corrosion behaviour in exploitation. One tube was in exploitation nearly 20 years before significant corrosion damage occurred (sample 1), while second tube of different manufacturer showed corrosion damages in 2 months of exploitation (sample 2). In its working conditions seawater was passing through the pipes and R407C gas around the pipes. Chemical analysis, microstructural and hardness investigations and laboratory electrochemical investigations of corrosion behaviour of samples in sea water were performed in order to determine the main reason for different durability of condenser tubes. After electrochemical investigations the polarization surface damage was verified by SEM analysis. Both samples belong to the CuNi10Fe1Mn alloy system with the significant difference in the mass fraction of iron content (around 30% higher for sample 1). Samples coincide in the structural sense (type and size of grain) and in mechanical properties (hardness of 133 HV1). Fe content in the CuNi10Fe1Mn alloy has the key role in the corrosion behaviour of the tested samples. It has been found that (regardless of the temperature of the heat exchanger) the corrosion resistance of the tested samples increases with increasing Fe content in the alloy. Namely, the corrosion current decreases in same order, while the polarization resistance and properties of surface oxide layer increase. SEM analysis confirmed less damage on the surface of samples with higher Fe content
Statistical Analysis of the Combined ECAP and Heat Treatment for Recycling Aluminum Chips Without Remelting
No full textThe main aim of this paper is to present an environmentally friendly method for aluminum recycling. Development of new recycling technologies in order to increase scrap reuse potential and CO2 emission savings are of the main importance for aluminum circular economy. In this paper, aluminum chips waste was recycled without any remelting phase in order to increase energy and material savings. The presented process is usually called solid state recycling or direct recycling. Solid state recycling process consists of chips cleaning, cold pre-compaction and hot direct extrusion followed by a combination of equal channel angular pressing (ECAP) and heat treatment. Influence of holding time during solid solution treatment and both artificial aging time and temperature on mechanical properties of the recycled EN AW 6082 aluminum chips were investigated. A comprehensive number of the experiments were performed utilizing design of experiments approach and response surface methodology. Regression models were developed for describe the influence of heat treatment parameters for presented solid state recycling process on mechanical properties of the recycled samples. Utilizing novel procedure high quality recycled samples were obtained with mechanical properties comparable with commercially produced EN AW 6082 aluminum alloy in T6 temper condition. Metallographic analysis of the recycled samples was also performed
Microstructural analysis of cold drawn CuAlMn shape memory alloy wire
Get PDFThe Cu-11.9Al-2.5Mn (wt. %) shape memory alloy was produced by vertically continuous casting technique obtaining bars of 8 mm in diameter which is applicable for plastic deformation. With the process of hot rolling and forging the 4.80 mm bar was produced. Afterwards, the obtained 4.80 mm bar was subjected to cold drawing process. After first run and after fourth run of cold drawing process the wire with diameter of 4.47 mm and 3.22 mm was produced, respectively. Optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) shown the insight in the samples microstructure. The as-cast state sample has two phase (α+β) microstructure. After cold working process the two-phase (martensite+α) microstructure appears. As the result of the cold working process it can be noticed a texture inside the sample depending on cold drawing direction. The microhardness of samples increases as the wires diameter decreases
Properties of CuAlMnNi shape memory alloy after continuous casting and quenching
Get PDFU ovom radu prikazan je utjecaj toplinske obrade na mikrostrukturu, tvrdoću i mehanizam prijeloma CuAlMnNi legure s prisjetljivosti oblika. Legura kemijskog sastava Cu –13 % Al – 2,5 %, Mn – 2,5 Ni (mas.%) je pripremljena iz čistih metala (>99,5 %), a potom je lijevana postupkom vertikalnog kontinuiranog lijevanja u zaštitnoj atmosferi argona. Dobiveni ingot dimenzija (Ø 110 x 180 mm) korišten je kao ulazni materijal za lijevanje šipke promjera Ø 8 mm. Nakon kontinuiranog lijevanja provedeno je kaljenje šipke na temperaturi 900 ºC u trajanju od 15 minuta. Šipka je potom ohlađena u vodi sobne temperature.
Mikrostruktura karakterizacija uzoraka CuAlMnNi legure provedena je optičkom mikroskopijom (OM) i pretražnom elektronskom mikroskopijom (SEM) opremljenom s energetsko disperzijskim spektrometrom (EDS). S pretražnim elektronskim mikroskopom je također provedena analiza prijelomnih površina. U uzorcima lijevanog stanja uočena je dvofazna mikrostruktura (α + β), dok je kod uzoraka nakon kaljenja u vodi s 900 °C uz dvofaznu mikrosturukturu zamijećena sporadična precipitacija martenzitne faze. Provedena su ispitivanja tvrdoće nakon lijevanja i kaljenja (900 °C/15 min/H2O). Tvrdoća kaljenog uzorka je bila veća od uzorka u lijevanom stanju. Fraktografskom analizom površine je ustanovljen transkristalni lom.In this paper the influence of heat treatment on the microstructure, hardness and fracture mechanism of the CuAlMnNi shape memory alloy is shown. Alloy with the chemical composition of Cu -13% Al - 2.5%, Mn - 2.5 Ni (wt. %) was prepared from pure metal components (purity >99.5%) and then casted by vertical continuous casting process in the protective atmosphere of argon. The obtained ingot with dimension (Ø 110 x 180 mm) was used as the input material for the Ø 8 mm rod. After continous casting procedure, the rod was quenched at 900 ºC for 15 minutes. The rod was cooled at room temperature water.
The microstructural characterization of CuAlMnNi alloy was performed by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersion spectrometer (EDS). By scanning electron microscop an analysis of the fracture surfaces was carried out. The two-phase microstructure (α + β) was observed in the as-cast state, while in the case of quenched sample, a sporadic precipitation of the martensite phase was observed. Hardness tests measurement in as-cast state and after quenching (900 ° C/15 min/H2O) were performed. The hardness of the quenched sample was higher than the sample in the as-cast state. Fractographic surface analysis revealed transcrystalline type of fracture
Determination of physical-chemical parameters of drinking water
No full textU ovom radu ispitivani su fizikalno – kemijski parametri različitih voda za piće; vodovodne, bunarske i izvorske. Provedena je određivanje nekoliko osnovnih parametara: temperatura, boja, mutnoća, okus, miris, pH vrijednost, vodljivost, tvrdoća kao i udio klorovih i dušikovih spojeva.
Bunarska voda ima nešto veću tvrdoću, dok izvorska voda ima nešto veću koncentraciju dušikovih spojeva, kao i veću vodljivost. Međutim, neznatno bolju kvalitetu ima izvorska voda. Unatoč tome dobiveni rezultati ukazali su na to da su vrijednosti svih ispitivanih parametara ispod zakonom propisanih maksimalno dozvoljenih koncentracija. Na temelju dobivenih rezultata te uzevši u obzir razliku između dubine bunara i broja slojeva između zemljine površine i izvora, vidljivo kako obje vode imaju kvalitetna svojstva za svakodnevnu konzumaciju u obliku vode za piće.In the present study the physical-chemical parameters of different drinking water were examined; from waterworks, well and spring. Several basic parameters were determined: temperature, colour, turbidity, taste, odour, pH value, conductivity, hardness as well as the proportion of chlorine and nitrogen compounds.
Well water has a slightly higher hardness, while the spring water has a slightly higher concentration of nitrogen compounds, as well as higher conductivity. However, spring water has a slightly better quality. Nevertheless, the obtained results indicated that the values of all examined parameters were below the maximum permissible concentrations prescribed by law. Based on the obtained results and taking into account the difference between the well depth and the number of layers between the earth's surface and the spring, it is apparent that both waters have quality properties for daily drinking in the form of drinking water