Livarski vestnik 60/2013 nr. 2
J. Rosc, D. Habe, G. Schindelbacher, P. Schumacher
Austrian Foundry Research Institute, Parkstr.21, 8700 Leoben, Austria
Chair of Casting Research, Montanuniversität Leoben, Franz-Josef-Str. 18, 8700 Leoben, Austria
Danijel Mitrović , Aleš Strmole, Jožef Medved and Primož Mrvar
Livar d.d., Ljubljanska c. 43, 1295 Ivančna Gorica
University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Materials and Metallurgy, Aškerčeva 12
prof.dr.sc. Faruk Unkić, Gordana Gojsević-Marić, dipl.ing., Damjan Žveglić, dipl.ing., Branko Dikić, dipl.ing.
University of Zagreb, Faculty of Metallurgy, Croatia
Elkem AS, Branch Office Zagreb, Croatia
KOVIS Livarna d.o.o. Štore, Slovenia
J. Rosc, D. Habe, G. Schindelbacher, P. Schumacher
Austrian Foundry Research Institute, Parkstr.21, 8700 Leoben, Austria
Chair of Casting Research, Montanuniversität Leoben, Franz-Josef-Str. 18, 8700 Leoben, Austria
NOVEL DEVELOPMENTS IN COMPUTED X-RAY TOMOGRAPHY FOR AL ALLOYS
ABSTRACT
The performance of an Al casting depends on the delicate balance between unavoidable processing defects such as pores and optimised material properties of the remaining matrix. With the introduction of computed X-ray tomography a detailed investigation technique has become available showing defects from a critical size for the casting to function right down to minor processing defects. However, this 3 dimensional technique is still not standardized as it is the case for 2 dimensional metallographic methods to determine pore sizes and distribution. On the other side the performance of the load caring matrix can be improved by obtaining a uniform fine microstructure. This paper will give an overview on the current state of the art to quantify pores and their effects on mechanical properties.
Danijel Mitrović , Aleš Strmole, Jožef Medved and Primož Mrvar
Livar d.d., Ljubljanska c. 43, 1295 Ivančna Gorica
University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Materials and Metallurgy, Aškerčeva 12
EFFECT OF VIBRATION AND COOLING RATE EFFECT ON EVTECTOID TRANSFORMATION IN SPHEROIDAL GRAPHITE CAST IRON
ABSTRACT
The following paper addresses the influence of vibration and cooling rate effect on eutectiod transformation in EN-GJS-500-7 spheroidal graphite cast iron, with hardness ranging in thick section size from 240 HB and 170 HB in thin cast walls. Mentioned castings were poured in Livar d.d. foundry by automatic horizontal green sand moulding line in standard casting mode.
The eutectoid transformation has been investigated using several different techniques. Metallographic analysis with optical microscope, differential scanning calorimetry (DSC) and hardness measurements over various dimensions of tested specimens were performed and tensile strength was measured at room temperatures.
Image analysis was used to evaluate nodule count, morphology of the graphite particles and percentage of microstructural constituents. Chemical compositions have been determined by flame spectroscopy.
With a casting simulation and thermal analysis software, the calculations and predictions of solidification, cooling curves and mechanical properties have been performed.
Keywords: eutectoid transformation, spheroidal graphite cast iron, cooling rate, vibration
prof. dr. Faruk Unkić, Gordana Gojsević-Marić, dipl. ing, Damjan Žveglić, dipl. inž, Branko Dikić, dipl.inž.
University of Zagreb, Faculty of Metallurgy, Croatia
Elkem AS, Branch Office Zagreb, Croatia
KOVIS Livarna d.o.o. Štore, Slovenia
TRANSFORMATIONS CHARACTERISTICS OF DUAL MATRIX STRUCTURES ADI
ABSTRACT
In presented study Ni, Cu, Mo low alloyed spheroidal graphite cast iron intended for austempering and production of castings GJS grade 800-10 in according to HRN-EN 1564: 2011 was investigated. Spheroidal graphite cast iron was produced by so called duplex melting procedure and melt treatment by Sandwich method. The investigation samples where taken from the casting with relevant thickness of 50 mm, which was poured in the green sand mould. On the base of chemical composition by Thermo-Calc (TCW 4) programme, the equilibrium phase diagram was constructed and upper and lower critical temperatures were calculated, which define the intercritical austenitising interval or interval of partial austenitisation. Simultaneous thermal analysis of low alloyed spheroidal graphite cast iron by differential scanning calorimetry (DSC) method was also performed and the relevant temperatures of eutectoide phase region determined. On the basis of metallographic analyses by Analysis ®´Materials Research Lab software, in the intercritical interval annealed and in water quenched samples of spheroidal graphite cast iron, the share of individual phase was determined depending on the partially austenitised cast iron temperature.
Keywords: Ausferritic spheroidal cast iron, Characteristics of transformations, Dual matrix structure, Intercritical austenitising temperature
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