Livarski vestnik 59/2012 Nr. 2

Marco Aloe, Ole Koeser
SIMULATION AND PERFORMANCE OF CASTED PART

F. Unkić, Z. Glavaš, E.Veljačić
THE INFLUENCE OF SILICON AND BORON ON TENSILE PROPERTIES OF DUCTILE IRON

Franc Zupanič, Niko Rozman
TEMPERATURE MEASUREMENT IN THIN-WALL SECTIONS OF CASTINGS

Rebeka Rudolf, Lidija Zorko, Ivan Anžel, Srečko Stopić, Berndt Friedrich
GOLD SCRAP PROCESSING TECHNOLOGY FOR NANOPARTICLES


Marco Aloe, Ole Koeser1

SIMULATION AND PERFORMANCE OF CASTED PART
Abstract

 

Casting simulation has become a stat of the art tool for the industry. It is a veri powerful tool which helps the foundry solve many problems in the production and design department. However for the future, there is a clear trend towards end to end virtual manufacturing and prototyping. This means that the current systems and way of working in the casting industry will meet new challenges. The lecture shows this trend, and illustrates this by showing a few samples: Integrating heat treatment and welding stages after casting and linking the resulting simulation  directly to the virtual prototyping will change the way of working. Moving towards end to end virtual prototyping is not done over night, this is a process which will take several years, but it's important to understand the challenges which we will meet the next few years.

1Modified extract from V. Chaillou, H. Porzner, M. Skrikerud:«The challenge of the Virtual Manufacturing chain to achieve End to End Virtual Prototyping«, Metal Forming Stuttgart 2010

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F. Unkić, Z. Glavaš, E.Veljačić

THE INFLUENCE OF SILICON AND BORON ON TENSILE PROPERTIES OF DUCTILE IRON


Abstract

The influence of silicon and boron content on the tensile strength, 0,2 % proof strength and elongation of ductile iron in the as-cast condition at room temperature was analyzed in this paper. The base melts for the production of ductile iron were produced in medium frequency coreless induction furnace from a charges consisting of pig iron, steel scrap, ferrosilicon and recarburizer. To obtain desired boron content in the melts, granulated NiB containing 16,0 % boron (% always as mass fraction) was added. The Y-blocks were cast in the vertically-parted moulds produced by the CO2 process. The nodularizing treatment of the base melts was performed by in-mould method via FeSiMg5 alloy containing 0,50 % lanthanum. Silicon content in ductile irons varied from 2,65 % to 3,10 % and boron content varied between 0,0004 % and 0,0075 %. Standard tensile test pieces were machined from Y-blocks. Tensile properties of ductile irons alloyed with silicon and boron were compared with the tensile properties of ductile iron grade EN-GJS-400-18-LT.

The obtained results show that the microstructure of ductile irons alloyed with silicon and boron consists of a ferritic metal matrix and increased nodule count. Apart from promoting graphitization and ferrite formation, the increase of silicon content results in increasing ductile iron tensile strength and 0,2 % proof strength compared with the grade EN-GJS-400-18-LT, because the ferrite is strengthened by silicon. The high nodule count facilitates the formation of the high content of ferrite in the metal matrix.

The results of tensile test show that the ductile iron alloyed with silicon and boron had a high value of the ratio of 0,2 % proof strength and tensile strength (approx. 0,75) as compared to the ductile iron grade EN-GJS-400-18-LT (approx. 0,65). Despite this higher ratio, elongation of ductile irons alloyed with silicon and boron is high (as the elongation of ductile iron grade EN-GJS-400-18-LT). SEM analysis shows that the boron is concentrated mainly in graphite nodules.

Key words: ductile iron, microstructure, tensile properties

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Franc Zupanič, Niko Rozman


TEMPERATURE MEASUREMENT IN THIN-WALL SECTIONS OF CASTINGS

Abstract

 

In Al-Mn-Be-Cu alloys a metastable quasicrystalline phase can be formed at sufficiently high cooling rates. The main goal of this research was to determine critical cooling rate for formation of the quasicrystalline phase. Experiments were carried out using gravity casting into various copper dies. Small thermocouples were mounted on the walls of dies to monitor temperature during cooling. Initial measurements were carried out using laser-welded K- and S-type thermocouples with diameters of 0.1 mm and 0.2 mm. The response of thermocouples was considerably improved by applying open joint thermocouples being in direct contact with the melt. Microstructures near positions of sensor were then analysed using SEM (scanning electron microscopy) and EDS (energy-dispersive spectroscopy).

Key words: thermocouple, cooling curves, thin-wall casting

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Rebeka Rudolf, Lidija Zorko, Ivan Anžel, Srečko Stopić, Berndt Friedrich


GOLD SCRAP PROCESSING TECHNOLOGY FOR NANOPARTICLES

Abstract

 

The aim of this work was to prepare gold nanoparticles from gold scrap by using Ultrasonic Spray Pyrolysis (USP).USP is an innovative and powerful tool for the synthesis of particles with controlled and uniform particle size. The mechanism of gold nanoparticles` synthesis by USP was realized by an investigation of the reaction parameters and morphological characteristics of obtained Au nanoparticles. The experimental investigations were performed by an ultrasonic source of 0.8 and 2.5 MHz, acting in a mixture of chloric/nitric acid and by forming aerosols with constant droplet sizes. The droplet’s size depends on the characteristics of the formatted solution and the frequencies of the ultrasound. Subsequent thermal decomposition of the aerosol droplet was performed in a hydrogen and nitrogen atmosphere between 300 and 800 °C.

With the experimental production five different fractions of gold nanoparticles were obtained. For the microstructure characterisation of Au nanoparticles the following techniques were used: SEM andTEM microscopies, and EDX analysis.

Key words: gold scrap, Ultrasonic Spray Pyrolysis, Au nanoparticles, characterisation

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