<p>U disertaciji je izvršena karakterizacija mikrostrukture i mehaničkih osobina<br />nelegiranog austemperovanogi nodularnog liva (ADI materijala), kao i uticaja<br />mikrostrukture na prelaznu temperaturu u intervalu od -196 do +100&deg;C.<br />Utvrđeno je da mehaničke osobine ADI-ja zavise od morfologije ausferitne<br />mikrostrukture i količine zadržanog austenita, tj. parametara austemperovanja.<br />Na osnovu mehaničkih osobina utvrđen je i opseg procesiranja u skladu sa<br />standardima ASTM, ISO i EN. Zaključeno je da prelazna temperatura ADI<br />materijala zavisi od količine i stabilnosti zadržanog austenita. U višem<br />temperaturnom opsegu (iznad cca. -25&deg;C) dominantna je količina zadržanog<br />austenita, dok na nižim temperaturama, stabilnost. Visoka obogaćenost<br />ugljenikom, stabilnog zadržanog austenita sprečava stvaranje martenzita na<br />niskim temperaturama, a time i pojavu krtosti kod ADI-ja.</p> / <p>The object of this thesis was to characterize microstructure and mechanical properties<br />of the unalloyed ADI material (Austempered Ductile Iron). In addition, the influence of<br />microstructure on the ductile to brittle transition temperature (DBTT) by Charpy impact<br />test in temperature interval from 196 to +100&deg;C has been studied. The all properties<br />obtained depend on the morphology of microstructure and the amount of retained<br />austenite, i.e. on the austempering parameters. According to the mechanical properties<br />and standard requirements (ASTM, ISO and EN) the processing window has been<br />proposed, also. It was found that DBTT is influenced by amount and stability of retained<br />austenite. In upper temperature range (above cca. 25&deg;C) the most influence factor on<br />DBTT is amount of retained austenite, while at the lower temperatures the stability is<br />more prominent. Stability of high carbon retained austenite at lower temperatures<br />prevents transformation to martensite and thus the embrittlement of ADI.</p>

Structural Optimization techniques are widely used in product development process in ‘modern industry’ to generate optimal designs with only sufficient material to serve the purpose of the component. In conventional design problems, the design process usually generates overdesigned components with excess material and weight. This will in turn increase the life time cost of machines, both in terms material wastage and expense of usage. The thesis “Design of a weight optimized casted ADI component using topology and shape optimization” deals with redesigning a component from a welded steel plate structure into a castable design for reduced manufacturing cost and weight reduction. The component “Drill Steel Support” mounted in front of the drilling boom of a Face Drilling Machine is redesigned during this work. The main objective of the thesis is to provide an alternative design with lower weight that can be mounted on the existing machine layout without any changes in the mounting interfaces. This thesis report covers in detail procedure followed for attaining the weight reduction of the “Drill Steel Support” and presents the results and methodology which is based on both topology and shape optimization. / Strukturoptimering används ofta i produktutvecklingsprocessen i modern industri för att ta fram optimala konstruktioner med minsta möjliga materialåtgång för komponenten. Konventionella konstruktionsmetoder genererar vanligtvis överdimensionerade komponenter med överflödigt material och vikt. Detta ökar i sin tur livstidskostnaderna för maskiner både i termer av materialavfall och användning. Avhandlingen "Konstruktion av viktoptimerad gjuten ADI-komponent" behandlar omkonstruktionen av en komponent från en svetsad stålplåtstruktur till en gjutbar konstruktion med minskad tillverkningskostnad och vikt. Komponenten “Borrstöd” monterad i framkant av bommen på en ortdrivningsmaskin är omkonstruerad under detta arbete. Huvudsyftet med avhandlingen är ta fram en alternativ konstruktion med lägre vikt och som kan monteras på befintlig maskinlayout utan någon ändring i monteringsgränssnittet. Denna avhandling innehåller en detaljerad beskrivning av förfarandet för att uppnå viktminskningen av "borrstödet" och presenterar resultaten samt metodiken som baseras på både topologi- och parameter- optimering.