No abstract

The cooling curve analysis (CCA) has been used extensively in the metal casting industry, usually to predict alloy composition and microstructure constituents. The use of CCA can be expanded to other areas of solidification if the zero curves can be properly calculated. In this paper the Newtonian and Fourier techniques of zero curve determination are described. These techniques were developed to calculate latent heat and to determine the correlations between solid fraction and temperature/time for Al-7 wt%Si alloy. The importance of the changes in heat capacity and density of solid and liquid phases during solidification on the latent heat calculations was examined. The latent heat calculated by Computer-Aided Cooling Curve Analysis (CA-CCA) method is compared with those reported in the literature. The effect of experimental procedure and type of sampling cup on the latent heat calculations were studied for both techniques.Key words: Thermal Analysis, Al-Si alloys, Newtonian and Fourier methods. ABSTRAKTAnaliza krivih hladjenja je siroko primenjivana metoda u livnicama železnih i ne železnih metala/legura. U svakodnevnoj livačkoj praksi ova metoda je često korišćena za određivanje sastava legura i njihovih struktura. Primena ove metode može se znatno proširiti ukoliko bi se osnovna (nulta) linija ocvršćavanja legura matematicki tačno interpretirala. Newtonian i Fourier-ova metoda su opšte poznate metode za izračuna-vanje osnovnih/nultih linija krivih hlađenja. Obe metode su razvijene u cilju izračuna-vanja latentne toplote oslobođene tokom očvršćavanja čvrste faze različitih legura (u ovom radu su primenjene na leguri Al-7 wt.% Si). Uticaji promene gustine i toplotnog kapaciteta čvrste i tečne faze na izračunate vrednosti latentne toplote su analizirani u ovom radu. Izračunate vrednosti latentne toplote očvršćavanja su upoređene sa literaturnim podacima. U radu je takođe analiziran utical vrste tigla na eksperimentalno dobijene rezultate.Ključne reči: Termijska Analiza, Al-Si legure, Newtonian adn Fourier metode.

The potential use of an Al-9Si-1Cu alloy (W328 alloy) as a replacement for W319 alloy in engine blocks was investigated.. The ambient mechanical properties (tensile, hardness and fatigue) of sand and permanent mould cast test bars along with bars machined from a sand cast automotive component were studied. The tensile properties were evaluated in as-cast and T6 heat-treated conditions. The effects of Fe and Mn on properties were also investigated. The castings in W328 alloy exhibit lower porosity than W319 alloy, which is attributed to the smaller solidification range and feeding distance and larger volume fraction of the eutectic phase. Higher iron levels increased the level of intermetallics and reduced properties. The addition of Mn did not offset the effect of higher iron levels. The W328 alloy offers some advantages over the 319 alloy and is a potential candidate for production of automotive components such as engine blocks and cylinder heads.