Repository of Faculty of Metallurgy University of Zagreb
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Adsorption of acetic acid on the waste from metallurgical production
No full textU ovom radu određivana su adsorpcijska svojstva otpada iz metalurške proizvodnje. Kao adsorbensi su korišteni otpadna kalupna mješavina i anodna prašina, a kao adsorbat octena kiselina. Dobiveni rezultati ukazuju na to da otpadna kalupna mješavina ima veći kapacitet adsorpcije u odnosu na anodnu prašinu. Ravnotežni eksperimentalni podaci su obrađeni Freundlichovom i Langmuirovom izotermom. Kinetika procesa opisana je s Lagergrenovim i Ho i McKey modelima. Dobiveni rezultati su pokazali da se adsorpcija octene kiseline na otpadnoj kalupnoj mješavini odvijala prema Freundlichovom i Lagergrenovom modelu, a adsorpcija octene kiseline na anodnoj prašini prema Langmuirovom i Ho i McKey modelu
Optimisations in continuous casting of Cu based alloys by numerical simulation
Get PDFExperimental study and numerical model for the thermo-mechanical properties in continuous casting (CC) of Cu-Al alloys is presented. This is a prerequisite basis for further development of Cu based shape memory alloys (SMA) with various alloying elements (like Ni or Mn). A coupled thermo-mechanical numerical simulation of the CC process is implemented and applied to the full non-equilibrium process conditions. In the experimental part, we used simple yet effective vertical continuous casting system. For the quantitative comparison, we implemented a special temperature measurement system within a graphite crystalliser that enables us to monitor the temperature profile at several spots around the solidification front in real time. The present analysis of the various process parameters’ effect on the solidification process includes: casting speed, thermal contact conductivity, liquid metal temperature, and cooling system set up. For microstructural examination we prepared samples from rods that were subsequently investigated by optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDXS) analysis. Comparisons of the experimental results and numerical simulation were carried out. We developed a comprehensive numerical simulation model that quantitatively describes non-equilibrium time- dependent temperature profile, solid fraction and microstructure features in as cast state. Results from the coupled thermo-mechanical and microstructural simulations compare favourably with experimental data suggesting the casting speed as a key parameter in process optimisation
The effect of heat treatment on mehanical properties of CuAlMn shape memory alloy
Get PDFU ovom radu je prikazan utjecaj toplinske obrade na mikrostrukturu i mehanička svojstva
CuAlMn legure s prisjetljivosti oblika. Legura kemijskog sastava Cu – 8,30 % Al – 9,4 % Mn
(mas.%) je pripremljena iz čistih metala (>99,5 %), a zatim lijevana kontinuiranim
vertikalnim postupkom u zaštitnoj atmosferi argona. Najprije je proizveden ingot (Ø 110 x
180 mm) koji je korišten kao ulazni materijal za lijevanje šipke promjera Ø 8 mm. Provedena
su ispitivanja vlačne čvrstoće, granice razvlačenja, istezanja, kontrakcije i tvrdoće nakon
lijevanja, kaljenja (900 °C/30'/H2O) i popuštanja (100 – 300 °C/60'/H2O). Mikrostrukturna
karakterizacija uzoraka legure provedena je optičkom mikroskopijom (OM) i pretražnom
elektronskom mikroskopijom (SEM) s EDS analizom. S pretražnim elektronskim
mikroskopom je također provedena analiza prijelomnih površina. Nakon lijevanja CuAlMn
legure vlačna čvrstoća je iznosila 627 MPa, istezanje 8,5% i kontrakcij a 17,88 %. U lijevanoj
leguri utvrđena je djelomična prisutnost martenzitne faze dok je nakon kaljenja
mikrostruktura u potpunosti bila martenzitna. Značajan porast vlačne čvrstoće i značajan pad
istezanja uočeni su nakon popuštanja 200 °C/60'/H2O i 300 °C/60'/H2O.This paper shows the effect of heat treatment on microstructure and mehanical properties of
CuAlMn shape memory alloy. Alloy with the chemical composition of Cu – 8.30 Al – 9.4 %
Mn (wt.%) was prepared from pure metals (>99.5 %) and then the alloy was casted by
continuously vertical casting tehnique, under protective argon atmosphere. The prepared ingot
(Ø 110 x 180 mm) was used as an input material for casting into 8 mm diameter bars. The
tensile strength, yield strength, elongation, reduction in area, and hardness were examined
after casting, quenching (900 °C/30'/H2O), and ageing (100 – 300 °C/60'/H2O). The samples
were microstructurally analysed using optical microscopy (OM) and scanning electron
microscopy (SEM) along with EDX analysis. Using scanning electron microscopy fracture
surfaces were also tested. Test resulted in tensile strength of 627 MPa, elongation of 8.5% and
reduction in area of 17.88% after casting of CuAlMn shape memory alloy. The alloys
revealed some martensitic phase after casting, but after quenching microstructure was
completely martensite. The tensile strength drastically increased and elongation drastically
decreased after ageing at 200 °C/60'/H2O and 300 °C/60'/H2O
Possibility of using thermography and digital image correlation for determination of stress and strain distribution in deformation zone
No full textMicroalloyed steels today represent a significant part of total world production and processing of steel. Although widely used, there are scarce data on the stress distribution in the deformation zone of these steels. The research was carried out on two steel grades, both low-carbon structural steels with the same basic chemical composition, with one of them, additionally microalloyed with niobium. Differences in the stress distribution in the deformation zone between two tested steels were continuously observed and measured using the methods of digital image correlation and thermography. It has been found out that niobium microalloyed steel has significantly more complex material flow and stress distribution in the deformation zone when compared to the plain low carbon steel
Zborniik sažetaka 16. Međunarodno savjetovanje ljevača: Globalna ljevačka industrija- Perspektive za budućnost
No full textFoundry industry as a base branch represents an important factor contributing to the economic potential of each country. Current market development as well as technical and economic objective, the production of high-quality, low-cost and environmentally friendly casting, requires application of recent and advanced materials, as well as production technologies, followed and supported by understanding of production process.
Within the industrial production of castings special significance is dedicated to the development of products based on innovative research activities. The Conference topics were designed as presentations of the current "state of the art" research in collaboration with industry, and production innovation with the aim to improve the competitiveness.
The scope of 16th International Foundrymen Conference (IFC) covers scientific, technological and practical aspects concerning research, development and application of casting technology with the common perspective – increase of competitiveness. Special attention will be focused towards the competitiveness ability of foundries, improvement of materials features and casting technologies, environmental protection as well as subjects connected to the application of castings
Zbornik radova 16. Međunarodno savjetovanje ljevača: Globalna ljevačka industrija - Perspektive za budućnost
No full textFoundry industry as a base branch represents an important factor contributing to the economic potential of each country. Current market development as well as technical and economic objective, the production of high-quality, low-cost and environmentally friendly casting, requires application of recent and advanced materials, as well as production technologies, followed and supported by understanding of production process.
Within the industrial production of castings special significance is dedicated to the development of products based on innovative research activities. The Conference topics were designed as presentations of the current "state of the art" research in collaboration with industry, and production innovation with the aim to improve the competitiveness.
The scope of 16th International Foundrymen Conference (IFC) covers scientific, technological and practical aspects concerning research, development and application of casting technology with the common perspective – increase of competitiveness. Special attention will be focused towards the competitiveness ability of foundries, improvement of materials features and casting technologies, environmental protection as well as subjects connected to the application of castings
Magnesium treatment methods for the ductile iron production
Get PDFDodatak sferoidizacijskih (nodularizacijskih) elemenata u rastaljeno željezo vjerojatno je najvažniji korak u proizvodnji nodularnog lijeva. Postoji mnogo elemenata koji mogu proizvesti sferični oblik grafita. U komercijalnoj praksi najčešće se upotrebljava magnezij. Dodaje se u rastaljeno željezo kao čisti magnezij ili kao magnezijeva legura. Magnezij i njegove legure imaju niske temperature isparavanja, zbog čega se njihov dodatak u rastaljeno željezo mora provesti s velikom pažnjom.
Ovaj rad daje pregled najvažnijih nodularizacijskih elemenata (magnezij, cerij i elementi rijetkih zemalja te kalcij), najčešće korištenih nodularizatora (čisti magnezij, legure nikal-magnezij te ferosilicij-magnezij legure) i postupaka obrade magnezijem koji su se dokazali kao komercijalno najuspješniji (postupak obrade prelijevanjem nodularizatora u otvorenom loncu, „Sandwich“ postupak obrade u otvorenom loncu, postupak obrade u loncu s poklopcem, postupak obrade u loncu uz propuhivanje inertnim plinom kroz porozni čep, postupak obrade uranjanjem nodularizatora, postupak obrade punjenom žicom, postupak obrade u konvertoru, postupak obrade u kalupu i postupak obrade protjecanjem).The addition of spheroidizing (nodularizing) elements to molten iron is probably the most important step in the production of ductile iron. There are a lot of elements that are capable to produce spheroidal form of graphite. In commercial practice, magnesium is most
commonly used. It is added to molten iron as pure magnesium or magnesium alloy. Magnesium and its alloys have low vaporization temperatures and, consequently, their addition to molten iron must be done with extreme care.
This paper gives a review of the most important nodularizing elements (magnesium, cerium and other rare earth elements and calcium), the most commonly used nodularizers (pure magnesium, nickel-magnesium alloys and magnesium-ferrosilicon alloys) and magnesium treatment methods that have proven to be the most commercially successful (open ladle pour-over process, sandwich open ladle treatment, tundish cover treatment, porous plug process, plunging method, cored wire treatment, converter method, in-mould treatment and flow-through process)
Solidification sequence of Al-2, 5wt.%Mg-0, 7wt.%Li alloy
No full textDetermination of solidification sequence of Al- 2, 5wt.%Mg-0, 7wt.%Li alloy represents a challenge due to the strong influence of chemical composition, grain structure and thermodynamic parameters on the phase precipitation and transformation. Modelling of equilibrium phase diagrams in correlation with simultaneous thermal analysis, X-ray diffraction and metallographic investigations enables determination of solidification sequence. Besides commonly precipitated intermetallic phases, expected in the alloy containing >2, 0wt%Mg, stabile δ (AlLi) phase was also found. These phases nucleated at the αAl grain boundaries and grow at the expense of previously precipitated metastable δ’ (Al3Li) causing the formation of precipitation free zones
Metallic Materials for Use in Dentistry
No full textDentistry as a branch of medicine has an important role in the health of the human, while applying new technologies the maintaining of oral health is much more effective. For that purpose many dental products are used, such as crowns, bridges, implants, which are made of various metallic materials the mostly by casting or forging. They have to possess an adequate properties among which a biocompatibility, hardness and strength are the most important. Metal as an individual element with its properties does not meet certain conditions, therefore, the process of alloying results in different alloys that may be applied in oral environment. The most common classification of metallic materials for use in dentistry divides them in: noble and non-noble alloys and dental amalgames. Further, development of new technologies provides a new metallic materials with more adequate properties. Among them, titanium and titanium- based alloys stand out as materials of future in dentistry. Also, progress in computer technology results in faster production of economic dental products of much more quality
Influence of vertical reinforcements on strength of circular manhole cover
Get PDFU radu je provedeno nekoliko numeričkih linearnih statičkih simulacija savijanja lijevanog kružnog kanalskog poklopca (šahte) promjera 600 mm u svrhu dimenzioniranja položaja i broja vertikalnih ojačanja. Analize pomaka i naprezanja provedene su metodom konačnih elemenata u programskom paketu Autodesk Simulation Mechanical. Verifikacija numeričkih rezultata provedena je na primjeru tanke kružne ploče, za koju su izračunata analitička rješenja savijanja.
Nakon verifikacije numeričkog postupka tankoj kružnoj ploči dodana su s donje strane dva cirkularna vertikalna ojačanja: unutarnje i vanjsko. Numeričkim simulacijama istražen je utjecaj položaja unutarnjeg cirkularnog ojačanja na čvrstoću kružnog kanalskog poklopca, gdje su ekvivalentna naprezanja praćena energijskom teorijom čvrstoće (HMH - von Mises). Pošto variranjem položaja unutarnjeg cirkularnog ojačanja najveća ekvivalentna naprezanja ostaju na samoj ploči provode se simulacije s dodanim radijalnim ojačanjima. Variranjem broja radijalnih ojačanja izabire se optimalna izvedba ploče.In this paper several numerical linear static simulations of bending circular manhole cover with 600 mm diameter are performed in order to dimension the position and the number of vertical reinforcement. The analysis of displacement and stress using the finite element method in the software package Autodesk Simulation Mechanical were conducted. Verification of numerical results on the solution of thin circular plate was performed for which analytical bending solutions were calculated.
After checking the numerical procedure on the thin circular plate, two circular vertical reinforcements were added on the underside: internal and external. Numerical simulations investigated the influence of the inner circular reinforcement position on the strength of the circular canal lid, where equivalent stresses are followed by energy theory of strength (HMH - von Mises) were monitored. Since by varying the position of the inner circular reinforcement the greatest equivalent stresses remain on the board, simulations with added radial reinforcements are performed. By optimizing the number of radial reinforcements, the optimum plate design is chosen